Kiln measuring

A.
PRESHUTDOWN PROCEDURES
Refer to Figure 1 for typical orientation and common terminology for reporting kiln
details. In long distance telephone discussions and also in written descriptions of
kiln problem zones, the "reporter" should clarify pier numbering sequence (starting
count at discharge end or at feed end) and should avoid local landmarks and/or
compass directions when describing work areas for the kiln.
1. ANALYZE AND RECORD SHELL CONDITION
Before a hot, on-stream kiln is shut down for maintenance and realignment,
observe the shell closely for indications of distortion and runout conditions.
If runout is excessive, especially at feed or discharge ends, make
arrangements for cutting the shell for realignment of the affected sections.
Sometimes certain zones of the shell-including riding ring sections-are so
badly distorted that new shell sections must be installed to eliminate the
maintenance problems. In addition to observing kiln shell conditions,
measure runout at predetermined test locations along the entire kiln length.
Use these measurements to plot graphic views of the cross-sectional shape
of the shell at the various test locations; also plot the plan views of the shell
at test points 180° apart on the circumference. Use the following procedure
to measure and plot shell runout:
a. Prepare a sturdy support stand for installation on the drive pier. This stand
will be used to hold a piece of chalk in a steady position for marking a
straight line around the circumference of the slowly rotating shell. Usually
catwalks are too far from the kiln for service as test work platforms. Many
kilns do not have walkways for close-up inspection between support piers. A
rigid work surface, within easy reaching distance of the kiln shell, is
necessary for preparing reference lines and for obtaining actual test
measurements. Scaffolds can be prepared for this work, but assembly and
moving time must be considered A self-propelled, hydraulically operated,
telescoping, two-man work basket is a convenient way to move between test
points. As a third alternative, a small crane may be used to lift and hold a
"basket" for use as a two-man work station. The basket must be secured
against swinging or turning by attaching and anchoring at least two tag lines.
b. Although it can be extremely hot and uncomfortable, it is possible to
measure and record the shell runout of an operating kiln. Since some kilns
now rotate at speeds as high as 4 rpm, make arrangements for rotation at no

more than 1 rpm during the test work period at any single premarket test
line. This lower speed reduces the possibility of misreading the fractional
reference marks on a foot rule or scale. If the production department agrees
to reduce kiln speed to 1 rpm while runout is measured at individual test
lines, but returns to faster rotation speeds between tests, the control room
must be advised when the test team is ready and also when it is finished at
each test position. Two-way F.M. radios are useful for such contact.
c. Predetermine the extent of the analysis to be performed, then mark the
shell for testing at positions along spans between tire sections and at both
ends as follows:
(1) Measure the circumference of the shell at the reference line, then mark
off 12 equal spaces around the shell. If the shell contains permanent fixtures
(manholes, thermocouples, etc.) that can be used as reference points for
follow-up work, select one of these items for marking the 0°/360° (or 12:00
position) test line, as shown in Figure 2. This line is to be the index line for
marking the entire length of the kiln shell. After marking position No. 12,
mark remaining space marks (1 through 11) as they come into position with
rotation of the kiln. Prepare a combination support and slide surface for
service as a fixed reference point for measuring and recording the shell
dimensions at the twelve test stations on each test line. Arrange the slide
surface perpendicular to the shell at whatever position is dictated by the
final position of the work platform. Position the end of the slide surface as
close to the shell as possible after determining the approximate shell runout
at that test point.
(3) Record the number and location of the line being tested and. also indicate
the twelve test points in vertical columns, 1 through 6 and 7 through 12 for
quick comparison of readings @ 180° apart (1/7, 2/8, etc.).
(4) Move to each test line in turn and repeat the above measuring and
recording procedure at each location. After all test lines have been
processed, release the test team to other activities.
CAUTION
When measuring runout of a hot kiln shell it is important to know that the
runout is not influenced by a temporary warp condition such as will be found
when the refractory lining and/or material coating is not equally thick,
especially along longitudinal lines 180° apart in random zones of the kiln.
Uneven shell temperatures, resulting from varying insulation values of
different thickness of the lining, will cause the kiln shell to form a temporary
bow shaped warp condition. Shell temperature at the thin zone of lining will

be relatively higher than at the heavily coated zones. The hot side of the kiln
shell will expand more than the relatively cool side. The hot side will form a
convex line-for maximum plus runout-while the cool side @ 180 ° away on the
shell circumference will form a concave line, or maximum minus runout
position. When recording shell runout, shell temperature(s) at positions 180°
apart must- be considered for final analysis of the actual condition of the
shell for rotation relative to a true axis. Use infrared heat recording
equipment, or use magnet-back dial type contact thermometers for
verification of shell temperature at each test station around the shell at
predeterminedtest lines. Measurement of a "cold" kiln will not be influenced
by unequal shell temperatures caused by condition of the lining, but it is
important to consider the possibility of a temporary warp caused by sunlight
or from adjacent operational kilns. The side of the "cold" kiln exposed to
heat sources will be considerably warmer than the "shady" side and this
imbalance will cause the shell to become bow-shaped enough for
measurement of significant runout. Shell temperature should be equalized
prior to start of runout tests at idle kilns.
d. Prepare master work report sheets for the following entries:
(1) One sheet for test figures and runout comparisons, and for converting "as
read" dimensions to relate to an average figure as though plus and minus
values had been recorded by a dial indicator. See Figures 3 and 3A for a
blank sheet and a filled-in example.
(2) One sheet (to relate to the figure entry sheet) for plotting a cross-
sectional view of the kiln shell in relation to a true circle, as shown in
Figures 4 and 4A.
(3) One sheet for plotting plan views of the shell profile as would be seen at
points 180 ° apart with each rotational move of 30° of the kiln. See Figures .5
and 5A.
(4) Prepare sufficient copies to cover all test points and the cross-sectional
plot and to allow for probable layout errors when preparing the sheet for
plotting the plan views.
(5) Enter dimensional data and plot approximate shell contours on
appropriate work report sheets. With dimensions now being transformed into
graphic patterns, the actual condition of the shell can be analyzed to
determine a plan of action for repair and/or realignment work. Now it will be
possible to decide whether or not to (1) replace any part of the shell, (2) cut
and realign the existing shell, or (3) to plan on realigning tire sections and
support rollers for improved operation of the kiln.
2. CHECK TIRE AND SUPPORT ROLLER CONTACT SURFACE CONTOURS

If these faces are not flat, smooth and parallel to the axis of the shaft,
arrange for an in-place true-up on the affected surfaces. Typically, tires and
rollers in need of surface true-up will also be peened outward past the side
faces as shown in Figure 6. These protrusions must be removed, and corners
must be rounded at approximately %a" radius.
NOTE
True-up work on tire and roller surfaces should be done in advance of a
planned kiln shutdown for realignment tests and adjustments. Unless the kiln
service crew is familiar with the procedure for recalculating support set
points, and has access to original reference drawings, tire section
misalignment may occur and cause serious maintenance problems after the
true up work is finished. It is not enough to merely move individual rollers a
distance equal to the amount removed from combined radii of tire and
roller. The actual amount will vary according to original design, but will be
somewhere in the range of 1 .7 to 2 units inward for each unit of 1 removed
from combined radii of tire and roller. Perform true-up work with a belt
grinder arrangement to produce a smooth surface truly parallel to either the
roller shaft axis or the kiln axis in the case of the tires. Standard machining
procedures, if handled carefully, will produce surfaces that are parallel to the
axis of the roller or tire, but unless the final cut is made with a broad-nose
tool, the finish will be slightly coarse and extra sensitive to roller skewing
adjustments until the surface becomes smooth after a period of operation.
3. OBSERVE SHELL AND TIRE TEMPERATURES
Monitor shell and tire temperatures, at all pier positions, during various
phases of operation. Maintain a log book and charts that will clearly indicate
changing and potentially dangerous conditions. The shell plate is heated
from within by heat that bleeds through the refractory. The massive tires are
cooled by ambient air and act as heat sinks on the relatively thin kiln shell.
Temperature differences are taken into consideration for each tire position
on the kiln. Allowance is made for the difference in expansion by machining
the shell pads smaller than the bore of the tire. The smaller diameter shell
will advance within the tire during every revolution of the kiln. Since the
ambient-air cooled tire acts as a heat sink, heat from the shell is absorbed
very slowly. If the shell is heated too rapidly in relation to the tire, it will (1)
over expand beyond the built-in allowance for expansion, (2) become choked
within the partially expanded tire and (3) if the shell continues to over

expand after becoming choked inside the tire, it will bulge outward at both
sides of the tire as shown in Figure 7. The shell will be permanently deformed
into what is referred to as a coke bottle shape, i.e. squeezed in at the middle.
After the tire is fully expanded and an insulating coating builds up on the
refractory lining, the shell will cool down to its normal operating
temperature. Along with contraction of the shell, excessive clearance will
occur between shell pads and the bore of the tire as shown in Figure 7. As a
result, the shell assumes an oval shape because there is now room for the
sides of the shell to bulge out toward the tire to accommodate the top of the
shell as it sags from its own unsupported weight. See Figure 8.
The shell will now move into three distinct radius conditions during rotation;
it is (1) approximately normal below the horizontal centerline of the tire, (2)
somewhat flattened at the upper area of the tire, (3) pinched above the
horizontal centerline at the points where shell contour changes from round to
flattened. Compressive forces are exerted on refractory linings at the pinch
point on the upward moving side of the kiln and at the downward moving side
of the kiln, as the shell moves into and through this configuration during
rotation. Tire and shell contours will also be slightly distorted at contact
points on support rollers. Along with crushing the refractory lining, there is
the inevitable extreme overheating of the shell plate under the tire. In
addition to an overexpansion problem, the shell plate can become super-
heated to the point where it becomes plastic enough to be hot-formed as its
own weight forces it to mold itself inward on the tire during rotation. In
cases where sections of refractory lining drop off in the area under the tire,
additional hot spots can cause inward blisters (flat spots) to form on the
shell. The above conditions can originate when the shell temperature is
raised too rapidly when the kiln is started for the first time after original
installation, or after being down for installation of new refractory.The
conditions can also develop gradually as the refractory lining becomes
increasingly thin. By controlling shell temperature to avoid choking inside
the tires and by establishing a routine schedule for recording shell and tire
temperatures, increased temperature differentials provide advance warning
of diminishing clearance between spacer pads and the tire and indicate the
need to schedule a shutdown for refractory replacement work to avoid shell
damage.
CAUTION
When differential motion between tire and shell pads cannot be detected,
there are two possible reasons for lock-up:

• Interference from a slug formation between a spacer pad and the bore of
the tire, where metals from one or both surfaces are being gouged deeper
and deeper to increase the size of the slug as it is drawn across the pad. The
slug will eventually fall free when it clears the trailing edge of the pad, but
while it is enlarging itself, it will appear as if the tire is locked in position on
the shell.
• The kiln shell has already expanded enough for spacer pads to be choked
inside the tire. A typical reaction to this lock-up condition is to lubricate the
bore of the tire to make contact surfaces slippery enough for differential
rotation movement. Whether or not the bore of the tire should be lubricated
at all (except for application of dry graphite) is debatable. When differential
movement cannot be detected, the underlying reason must be laminated;
lubrication will not help. Knowledge of shell and tire temperature
differentials during normal operation of the kiln is valuable should it become
necessary to prepare for shimming work, spacer pad replacement or
replacement of the entire tire section shell and pads.
4. CHECK FOR EXCESSIVE CLEARANCE BETWEEN SHELL SPACER
PADS FIND BORES OF THE TIRES
Excess clearance is the space remaining between pads and the tire when
the kiln is operating and in normally hot and expanded conditions. As
mentioned previously, allowance was made for the greater expansion of the
kiln shell within relatively cooler tires. With the outside diameter of the shell
pads being somewhat less than the inside diameter of the tire, the shell rolls
inside the tire as the kiln rotates. The distance the shell advances inside the
tire is directly related to the difference in diameters (AD). Differential
movement of kiln and tire indicated by the dimension between match marks-
will be referred to as "creep”. Total clearance and (AD) can be determined in
two ways when the shell is hot, without actually working on top of the shell
for testing with feeler leaf gauges.
"Creep" is occasionally (and erroneously) referred to as "slippage”. Since the
rotating kiln shell is the driving force for rotation of the loose tires, by virtue of
weight and friction, "slippage" can occur when spacer pads and bores of tires are
made slippery by introduction of high lubricity grease. This condition is undesirable
since wind-borne contaminants can cling to the grease and cause excessive wear at
tire and pad surfaces. Measurement of "creep" is not acceptable for calculation of (
0D) when there is any differential movement enhanced by special lubrication of tire
bores and pad surfaces.
Excess clearance must be considered when planning for potential corrective
work by shimming or by installation of over-size shell spacer pads.

a. Use the following procedure to obtain the difference in diameters (AD)
between the shell and the tires:
(1) Place match marks at a pad surface or tire retainer block, and on the side
face of the tire; then measure the distance between these marks after one or
more revolutions of the kiln as shown in Figure 9 .
(2) If the distance was measured after more than 1 revolution, divide the
dimension by the number of revolutions to determine the average for 1.
(3) Difference in diameters (AD) can be determined by dividing travel per
revolution by pi (3 .1416).
Example:
Y4" (measured) = 0.750" -. 3.1416 = 0.239" difference in diameters (AD)
b. Use the following procedure to obtain clearance and creep of the kiln shell
and tire:
(1) Record clearance and creep in chart form by placing a magnet-backed
tracing surface on the side face of a tire. Then position a spring-loaded
pencil holder (mounted on a magnetic base) in an appropriate location for
tracing shell movement patterns in relation to the tire through several
revolutions of the kiln. The kiln must be stopped briefly for mounting this test
equipment.
(2) Place the material on the shell and tire at the approximate bottom dead
center position where the shell is normally fully seated inside the tire.
Position the pencil at the side of the tracing surface that trails the direction
of rotation; the advancing shell carries the marker across the surface toward
the upward moving side of the kiln. The initial point of contact of the marker
becomes the bottom of the wave pattern that forms on the tracing surface.
(3) As the tracer moves upward during rotation, the shell advances and
moves away from the bore of the tire; the pencil draws a curving line on the
chart surface. On the downward moving side, after passing top dead center,
the pattern reverses as the shell moves back into the bore of the tire. See
Figures 10 and 10A.
(4) Distance between start and stop points of individual waves is the
distance the shell advanced inside the tire during one revolution of the shell.
Distance between high and low peaks is the total clearance between shell
pads and the tire at that test point. If the shell is distorted under the tire, the
procedure should be repeated at points 90° apart around the shell.
Clearance, as recorded in this test, is not the actual difference in diameters
(A D), since the shell orality is included in the tracing. To determine actual
(AD), divide the recorded clearance by V2 of pi (1.571).
Example:

Measured, or recorded, clearance of 3/a" 0.750" 1 .571 = 0.447" A D. A D @
0.477" X pi (or 3.1416) = 1 .498" travel per revolution. For comparison: If
travel, as measured in 4.a., would have been 1 %a", then 1 .5" : 3.1416 =
0.447" A D. If this work is performed when the kiln is hot, AD, is the total
excess clearance to be considered for alignment work or maintenance
planning. If done when the kiln is cold, calculate the initial clearance
required to satisfy shell and tire expansion factors.
5. REPLACING PADS AT TIRE SECTIONS
If excess clearance, as determined in Step 4, is the result of wear on pad
surfaces, and not from shell distortion, after the kiln is shut down install new
pads but do not use pads at the original design thickness unless off-center
rotation of the shell can be tolerated at the tire position being considered. If
eccentric rotation cannot be tolerated, as at a thrust tire which will affect
girth gear runout and mesh condition at the drive pinion(s), pads must not be
as thick as the original nominal thickness. The original pad outside diameter
was the result of machining oversize pads on a heavy shell section that was
rolled, and braced internally, to certain tolerances for out of- roundness.
Pads are not necessarily at uniform thickness around the circumference of
the shell. This original condition may be further complicated by slight ovality
of the shell. Use shim plates with thinner pads, if necessary as shown in
Figure 11. Place the shim plates between the pads and the shell to maintain
the axis of the shell at the axis of the tire. Shims may not be required in
areas where original pads were less than the original theoretical design
thickness.
6. USING SHIMS TO TEMPORARILY FILL-IN EXCESSIVELY LARGE
SPACES BETWEEN SHELL PADS AND TIRES
CAUTION
This application is a temporary, expensive, emergency, "band aid" procedure
to be performed at shutdown. It is to be used as a stopgap measure to
provide time in which to prepare and receive a replacement shell section. If
the shell plate is distorted into a "V or "U" shape, shim work will not be
worth the effort, time or expense. If spacer pad surfaces are in reasonably
good condition, and if shim thickness will be at least Y16", it may be feasible
to plan for the work. After determining the actual A D for the hot and
expanded shell and tire, subtract 0.125" from that figure to allow clearance
for final fit-up, then divide the remainder by 2 to determine average shim
thickness. If excess clearance is further complicated by bulges or flat spots

on the shell plate, vary shim thickness upward or downward in these areas,
as required.
7. REPLACING SHELL SECTIONS IN AREAS WHERE DISTORTION
CAUSES PROBLEMS
Observe and replace the shell at shutdown when the following conditions are
encountered:
a. A shell which is wrinkled, blistered, or otherwise distorted from previous
overheating caused by loss of refractory. This damage is often caused by kiln
misalignment that had set up cyclic stress forces on the shell which, in turn,
placed compressive forces on the lining. This condition is often associated
with dog leg runout of the shell, with crossover being noted at one or more
tire positions during rotation. See Figure 12. Actual shell runout profiles
would be verified as previously described in Step 1, a through d.
b. Extreme distortion of the shell under a tire with hot running excess
clearance more than '/a", and with the shell and spacer pads being too
crooked for shims or pad replacement work.
c. Along with b. above, spacer pad welds will probably break frequently and
there will be scraps of temporary hold down clamps and retainers. Original
retainers for the tire will have broken off and been reset in any number of
ways.
d. Frequent need to replace refractory at any tire section because of shell
ovality related to excessive clearance between shell spacer pads and the
bore of the tire (as described previously in Step 4).
e. When narrow, band-type wrinkles (bulges) appear on the kiln shell-usually
near a tire section-and is further complicated by weld failure in the joint
between the intermediate thickness plate section and the thinner plate
forming the main span between the piers. This condition is usually the result
of kiln shell misalignment, either as a result of misplacement of support
rollers or excessive clearance conditions at one or more tires. Cyclic bending
stress in the shell places compressive forces on the refractory, which
eventually fails in the bending zone. The shell is then overheated in this
exposed area and misalignment is self-corrected to some extent because the
hot shell becomes deformed in the compression zone during rotation.
Thermal stress at the step-down joint between intermediateand nominal
thickness plates, with the heavier plate resisting the expansion of the
lighter plate, sometimes leads to failure of the weld. The combination of shell
distortion (wrinkles) plus weld failure is usually less than one-half of the
circumference of the shell. See Figure 13.

When narrow wrinkles develop in the shell downhill from, but close to the hot
end tire, it is usually because the refractory lining became too thin and the
shell became more flexible in the heavy stress zone. The weight of the
unsupported end of the kiln causes cyclic bending at the stress point, where
compression destroys two or more circles of refractory bricks. The shell then
becomes superheated where lining failed and the shell becomes wrinkled in
reaction to the sagging end of the section. These wrinkles usually form
around the full circumference of the shell and are sometimes accompanied
by failure of the weld in the step-down joint at the intermediate and nominal
thickness plates. Although it is possible to realign the end of the kiln shell
and reweld the joint, the repair should be considered as being temporary.
The heat affected shell should be replaced with a suitable length of new
shell plate.
8. CHECK GIRTH GEAR ALIGNMENT AND DRIVE PINION(S) MESHING
CONDITION
This is not an all-out precision test conducted with precision test equipment.
It is merely necessary to open inspection panels to permit visual observation
of changing mesh conditions during rotation of the kiln and to check on the
position of the gear rims in relation to the ends of the pinion teeth. Off-center
position of the gear centerline in relation to the axial centerline of the pinion
usually is related to a problem at the thrust arrangement for the kiln. If the
gear has moved far enough off center at the pinion, it is highly probable that
the rim of the gear has rubbed the panel of the gear guard and that the
scuffing action has eliminated the pitch line reference points on the ends of
the gear teeth. See Figure 14. It is important to know the position of the girth
gear in relation to the pinion(s), especially if the kiln has been in the same
operating position for a prolonged period of time. Wearing of tooth flanks will
form step patterns so that if the kiln should change position and bring the
high points of the gear teeth into mesh, the concentrated loading could lead
to sudden failure of the gearing. Gear damage would prevent rotation of the
kiln which, if hot, would become badly warped and with sufficient runout
would destroy air seals and other components. See Figure 1 .5. In some
cases, a disk grinder can be used-to smooth off ridges on tooth flanks.
Reverse the gear and/or pinion if wear patterns are not acceptable for
changing the operating position of the kiln.
9. CHECK CONDITION OF TIRE SIDE FACES AND RETAINERS
"Full floating" kilns are moved into proper operating position by adjustment
of support rollers. These kilns have thrust tires which are intended to be in a
position where there is no contact against either of the thrust rollers except

when kiln operation and load conditions vary. Roller skewing, when correct,
causes the tire to move against retainers at the uphill side of the tire so that
the retainers bear the thrust load for moving the kiln. In addition to thrust,
retainers and side faces of tires are subjected to scuffing caused by the kiln
shell advancing within the tire during rotation. When rollers are over-adjusted
at any time, there will be extremely high pressure on the retainers;
eventually the retainers will wear down-, but they will also cut into the side
face of the tire. When this happens, the shell will lock into the tire at the
underside of the kiln so that countermoves of the rollers will not move the
tire away from the retainers, but the shell will continue to advance within the
tire during rotation. See Figure 16 When the support rollers are over-adjusted
to the point where the kiln moves uphill to have the thrust tire hard against
the upper thrust roller, that tire will touch the lower retainer arrangement;
the downhill side face of the tire can become undercut when this condition
becomes extreme. Since the kiln would continue to move uphill inside the
thrust tire as the retainers and tire side face continue to wear away, the
position of the girth gear in the pinion would change and lead to problems
referred to previously in 8. Refer to Figure 15.
NOTE
Conditions described above will be reversed when the thrust tire moves hard
against the lower thrust roller for continuous operation.
At plain tires, it may be possible to install oversize retainer blocks to
eliminate the undercut tire condition, but at the thrust tire there may not be
sufficient clearance for an oversize retainer to pass the top of the thrust
roller. Alternate action would be required when there is a clearance problem
at the thrust rollers.
10. CHECK POSITIONS OF TIRES ON SUPPORT ROLLERS AT ALL
PIERS
Record shell temperatures at various zones on a routine basis to establish
profiles through various phases of operation. Since refractory thickness and
material coating will directly influence the amount of heat reaching the kiln
shell, a temperature profile is valuable for determining the best operation
position of the tires on each tire shell section. See Figure 17. When recording
positions of tires on support rollers, check the following details for possible
corrective work at individual tires:
a. Is the tire against the uphill or downhill retainer arrangement and how
much clearance exists at the other retainer?
b. Where is the thrust tire in relation to upper or lower thrust rollers?

c. Is there an excessive amount of clearance between the thrust tire and
either of the retainer arrangements? If so, did the kiln move uphill or downhill
inside the tire? See Figure 16.
This information is of special importance when shell section replacement is
being considered; complete details are required for accurate allowances for
expansion of the shell from the thrust arrangement to all other tire sections.
11. CHECK FOR SHELL DISTORTION AT REINFORCING RINGS ON
OLDER KILNS
Older kilns may still have high, narrow reinforcing rings welded around the
shell. If so, check both sides at each ring for distortion of the shell
(especially in the hot zone of the kiln) These rings restrict the diametrical
expansion of the shell and distortion is often accompanied by cracking of the
shell along sides of the rings and sometimes directly under them. See Figure
18.
12. VISUALLY CHECK THRUST ROLLER ASSEMBLIES
If the thrust tire is touching and turning a thrust roller, rotation should be
free and smooth with no overheating of the bushing or thrust disk. If rotation
seems to be "jerky", or if scuff and scrape marks are seen on tapered
contact faces of the tire and roller, it is a strong indication that the bushing
and shaft are damaged and at least partially seized. If the thrust roller
appears to be tilted in relation to the equipment slope line, i.e. high toward
the tire, extremely heavy kiln thrusting pressure probably has forced the
roller shaft to wear into the longitudinal axis of the bushing thereby causing
the tilted operating position. If a thrust roller rises up out of its housing
during rotation, it is usually because the assembly is on the wrong side of the
frame centerline; it should be off-center at least %6' toward the downward
moving side of the kiln. If the thrust assembly is actually on the correct side
of the frame centerline, but still rises during rotation, it is probably because
either uneven wear or field machining of support rollers shifted the kiln off-
center toward its own down turning side, thus having the same effect as
moving the roller in the wrong direction See Figure 19 & 19-A.
13. CHECK HYDRAULIC THRUST ASSEMBLIES
Kilns with hydraulically operated thrust assemblies may have thrust
arrangements on 1, 2, or 3 piers depending upon the size of the kiln and the
number of support piers. By utilizing a series of limit switches to control the
start and stop sequence of the pump, the kiln should be moving uphill and

downhill a distance of about 1-%2 " to 2" in continuous cycles. Normally,
support rollers are adjusted in neutral positions with centerlines either
parallel to the kiln centerline or slightly skewed to relieve some of the
gravitational thrust of the kiln at the thrust roller(s). Since hydraulic thrust
arrangements generally do not have backup thrust rollers at the uphill side of
the tires, roller skewing must not, in itself, cause the kiln to travel uphill. See
Figures 20 and 21. If drive amperage rises above normal, check support roller
assemblies for direction of shaft thrust. If one or more roller is thrusting
against the high bearing end plate and thrust washer, the condition is forcing
the kiln downhill and increasing the load on the thrust assembly.
14. CHECK FOR OIL LEAKS AT SUPPORT ROLLER SHAFT
SEALS
With the equipment set at a certain slope angle, oil leaks are found at the
high side bearing assembly. Oil escaping from the bearing travels down the
shaft to the roller side wall and then to the rolling contact surface, where its
lubricity cancels out the effectiveness of skewing adjustments and so
increases the downhill gravitational thrust of the kiln. The only time an oil
leak is found at a low side bearing assembly is when the seal is bad and the
oil reservoir is over filled. Under certain conditions, when a shaft seal is bad
at a downhill bearing, dirt and/or rain water can work its way into the bearing
housing. See Figures 22 and 23.
15. CHECK TEMPERATURES OF THE ROLLER SHAFT AND
THE BEARING HOUSING END PLATES
Typical support roller bearing lubricants start to break down at about 180°F.
Sometimes the shaft and bearing overheat because of over-skewing of the
roller and occasionally because of sludge build-up on the oil collector
pockets for the bearing bushing. If corrective adjustment of the roller does
not relieve the overheating, or if application of a solvent (for breaking up
sludge) does not cool the bearings, set up an oil cooler with a circulating
pump arrangement to continue operation until it is possible to shut down the
kiln. Phenolic resin composition thrust washers, now being used in support
roller assemblies, will disintegrate when they are overheated. This condition
would result in damage at the end of the shaft and possibly result in damage
to the oil distribution tray and oil elevator arrangement caused by
interference at the opposite end of the shaft.

NOTE
In addition to items listed in the preceding pre shutdown considerations, the
following procedures are for total survey and analysis of most mechanical
aspects of rotary kilns. Not all of the items would be checked out as
standard and routine procedures. Actual check-out will be determined by the
field engineer to suit maintenance problems reported by representatives of
the client.
Pre shutdown Procedures Illustrations
FIGURE TITLE
1. Orientation and Common Terminology for Reporting Kiln Details.
2. Layout of Shell Runout Test Lines and Stations.
3. Kiln Shell Runout Test Record (Report Form).
3-A. Kiln Shell Runout Test Record (Sample Filled in with Typical
Test Figures).
4. Kiln Shell Runout Profile (Report Form).
4-A. Kiln Shell Runout Profile (Sample Filled in with Typical Test
Figures and Contour Related to Figure 3-A Report Sheet).
5. Kiln Shell Distortion (Report Form).
5-A. Kiln Shell Distortion (Sample Filled in to Show Actual Report of
Runout Test Figures and Profiles as Seen 180° Apart with Every
30° of Rotation of the Kiln Shell).
6. Kiln Riding Ring and Roller Wear Profiles.
7. Choked Kiln Shell Under a Tire-Distortion.
8. Tire Section Distortion.
9. Quick Check for Tire Section Excess Clearance.
10. Tracing Clearance Between Kiln Tires and Spacer Pads (Includes
Shell Ovality)
10-A Tire and Shell Clearance and Creep.
11. Installation of Kiln Tire Section Shims.
12. Typical Kiln Shell Warp Problems.
13. Kiln Shell Distortion Caused by Excess Clearance Between Tires
and Spacer Pads.
14. Kiln Gear and Drive Pinion Relationship.
15. Kiln Gear and Pinion Wear Problems.
16. Kiln Maintenance Problem -Undercut Thrust Tire.
17. Reference/Data Sheet for Kiln Analysis.
17-A. Reference/DataSheet for Kiln Analysis (Sample

FIGURE TITLE
Test Figures from Actual Field Tests).
18. Kiln Shell Distortion at Reinforcing Rings.
19. Thrust Roller Misalignment Problems. (Kiln Clockwise Rotation).
19-A. Thrust Roller Misalignment Problems. (Kiln Counterclockwise
Rotation).
20. Support and Thrust Roller Alignment (Kilns with Counter-
clockwise Rotation).
21. Support and Thrust Roller Alignment (Kilns with Clockwise
Rotation).
22. Kiln Roller Assemblies with Independent Bearings.
23. Kiln Roller Assemblies with Connected Bearings.
24. Field Work Procedures Gear Guard Dis-Assembly.

Scope of Layout and Test Work Illustrations
FIGURE TITLE
25. Kiln Frame Offset Line and Main Centerline Correction.
26. Reference Sheet for Recording Roller Set-Point Dimensions.
27. Position of Leveling Rod for Elevation Test work on Kiln Support-Frame
Beams.
28. Test Arrangement for Measuring Tire Thickness. (Kilns with Continuous
Retainer Bands.)
29. Test Position for Measuring Tire Thickness. (Kilns with Continuous
Retainer Bands.)
30. Slope Test at Kiln Roller Assembly Support Frames.
• Manual ED-30. Kiln Riding Ring Assembly Clearance.
• Drawing 728-85-1-2537. Riding Ring Pad Gap (Inches) .
31. Arrangement for Removing Bearing Housing End Plate for Maintenance
Work.
32. Kiln Roller Assembly Lubrication System. Interference and Potential
Damage.

B.
PRELIMINARY TEST PREPARATION PROCEDURES
The following work must be finished before scheduled test work can begin:
1. Clean and degrease pier and support frame surfaces before laying out
reference marks. Clean and lubricate adjustment screws to facilitate
adjustment work.
2. Clean out debris and/or oil spills under the carrying rollers in the areas
between support frame beams so that test work can be performed at each
unit.
3. Clean the drive pier to allow ready access to all drive train components,
especially the drive pinion assembly.
4. Clean the gear guard, at the area enclosing the drive pinion(s), for removal
of at' least one segment (of guard) to permit close inspection of the girth
gear and drive pinion teeth. See Figure 24.
5. Certain original installation drawings are required in order to return the
kiln to its designated operating position. Essential drawings are:
• Foundation/anchor bolt layout (for elevations and spacing dimensions).
• Drawings and/or tables showing design dimensions and set points for tires
and carrying rollers.
• Drive arrangement drawings, with girth gear and drive pinion reference
data.
6. The kiln should be shut down and cool before test work begins. It is very
difficult to obtain accurate readings when optical test equipment must sight
through heat radiation waves. Laser beams will be deflected by heat waves.
The preferred time for optical test work is when the kiln is shut down for any
other reason, planned or unplanned. Alternate procedures for "hot alignment"
test work are available but each step must be repeated several times to
obtain mathematical averages for an accuracy factor of plus or minus 1
millimeter (0.04") for lines, elevations, measurements and calculations. Kiln
owners must consider the value of continuous production in order to justify
the higher cost of "hot alignment" test procedures
C.
INITIAL SURVEY AND LAYOUT WORK

EQUIPMENT REQUIRED
The following equipment must be available to perform the initial survey and
layout work:
1. Transit or theodolite (with adjustable leg tripod) plus accessories
(Preferred magnification range = 40 X).
2. Optical level with sufficient magnification power for reading within %2" at
distances of up to 300 ft.
CAUTION
In many cases where "PLANT ENGINEERING" optical survey equipment is set
up for precision test work, it is found to be unsuitable for the job (including
when almost new). Prior to the start of kiln alignment test work, optical
equipment should be tested, adjusted, and certified as being accurate.
3. Surveyors leveling rod, with bull's-eye level and spotting targets.
4. High quality steel tape line-100 ft. long-for measuring circumferences of
tires and rollers.
5. Steel tape rules-12 ft. to 25 ft. range.
6. Folding rules (wood)-6 ft. long.
7. Starrett combination square with 12" and 24" blades and a center head
attachment.
8. Machinists spirit levels-6" and 12" (Starrett No. 98), or equal.
9. Precision heavy duty straight edge- .8 ft. long.
10. 4ccurate V-bar, 12" long, with flat top surface machined to match the
designed slope angle for the kiln.
11. Assortment of typical hand tools for maintenance work, including
precision test equipment.
12. Two-way radios for relaying signals and instruction.
PERSONNEL REQUIRED
The following personnel must be available to perform the initial
survey and layout work:

1. One Consultant or Field Service Engineer. Manufacturers field
representatives do not carry or use tools and test equipment except to verify
readings and/or optical equipment sight points. Two Service engineers will
be needed if necessary to cover shift work.
2. An Engineer-Surveyor who is accustomed to working with an accuracy
factor of %2" for optical test work on machinery.
3. Rod man or assistant to work with the Engineer- Surveyor.
4. Two maintenance mechanics (millwrights) for mechanical odd jobs,
moving ladders, plus going for material and equipment.
5. Additional help may be needed if heavy assemblies must be dismantled. It
is possible to arrange for a fully equipped three-member team for optical test
work and measurements.
D.
SCOPE OF LAYOUT AND TEST WORK
The following section describes the work to be performed to test
the kiln's general condition:
1. Check support frames for centerline reference marks on top surfaces of
individual beams.
2. Check, near ends of beams, for possible offset centerline reference marks.
3. Verify (or establish) an offset line (tape rule measurement plus, transit
work) then measure back toward the center of each beam (all frames) to
verify accuracy of old marks (or to establish new marks). After setting new
centerline marks on all frames, measure outward to the opposite ends of the
beams for placement of offset reference line marks. If possible, project the
offset lines onto the firing floor and set a reference pin for quick setup of the
instrument. See Figure 25.
NOTE
The thrust assembly support frame is considered to be the control point for
kiln alignment work. The only exceptions to this standard are: (1) the
monolithic drive and kiln-support pier has settled or shifted, or (2) the
support frame has shifted. In these cases, the frame would have to be reset
to satisfy elevation, slope and centerline requirements, and would again
be the control point for alignment work. Since kiln shells are not always the
same inside diameter throughout and support mechanisms and tires often
differ in size, it is not always possible to project offset lines at the same

dimension away from the main centerline on all frames. In such cases, shoot
the offset marks onto the pier surface (preferably on brass plugs) and then
transfer them to convenient working points on the beams. Actual distance
from the true longitudinal centerline should be indicated on the frames and
recorded on maintenance data sheets. See Figure 26.
4. Check comparative elevations (Deltas) of frames at the following check
points:
• Beam to beam and frame to frame. Hold the leveling rod (or scale) as
closely as possible to the transverse centerlines of top surfaces of the
beams.
• Check at both ends of the beams at the transverse centerline of both
beams for all frames. See Figure 27.
NOTE
Transverse centerlines of support frame beams are not always accessible for
placement of a leveling rod or scale. Since the equipment is set on a specific
slope or angle; significant elevation errors will be recorded if test points vary
only a few inches on the sloped surface. Test points must be at the same
relative positions, away from the centerline marks, for optical level test
work; e.g. hold the rod against the downhill side of the bearing adjustment
screws at all test positions at outside ends of the frames.
• If major maintenance work is scheduled for kiln drive arrangement, check
Delta elevations between the thrust frame beams and pinion assembly
pedestal beams. Measure the circumference of each tire and support roller at
three positions, i .e. near both sides and at the center Since it is not possible
to wrap a tape around the tire or roller at the contact areas, scribe lines
across their faces approximately 180° apart. The scribed lines enable the
circumferences to be measured in two steps: first measure the open areas
between the scribe lines, then rotate the kiln and measure the remaining
distance. Slide the line back and forth to insure that it is seated properly
before actually recording the dimension. Convert circumferencedimensions
to diameter and radius figures for follow-up calculations. See Figure 34.
Measure the thickness of each tire to determine" the inside diameter and
radius. Do not be misled by the radius cut at the edges of the bores and
outside rolling surfaces. Some older kilns have full circle retainer bands at
the tires; to measure their tire thickness, it may be necessary to cut out
small sections of the bands. As an alternative, use a straddle frame
arrangement with the legs set at a predetermined distance from a cross
member. The legs must be long enough to span the tire and retainers and

rest upon the tire spacer pads under the tire. This arrangement is shown in
Figures 28 and 29. Use the following method to record location
identifications: Tires-identify by pier numbers starting to count from the low
end of the kiln.
. Piers are numbered in reverse order at some kilns. Verify actual direction of
the count and indicate on report sheets. Refer to Orientation Sketch
(Figure 1).
• Support Rollers-show position on piers from left to right side of the pier
when viewed from the discharge end of the kiln. Refer to Orientation Sketch
(Figure 1). Check slope of individual support frames. Use the 8' long precision
straightedge, with slope gauge block and 12" long precision level placed
parallel to longitudinal centerlines of the frames. Beam surfaces must be
clean, and the straightedge must rest firmly on both beams. See Figure 30.
A procedure for checking excessive clearance between kiln shell space pads
and bores of the tires was described in A .4 preceding; if that procedure was
not performed when the kiln was hot, clearance conditions must be verified
now. See Figures 9 and 10. With the kiln shut down and cold, use leaf
gauges and, where necessary, gauge bars to measure the clearance between
pads and tires at the top of the kiln shell. For accurate results, this cold test
will require prior knowledge of differences in temperature (AT) at each tire
and this shell section during various phases of operation. Also consider that
clearance measured by a gauge will include some shell ovality. See Figure 8.
If temperatures were not monitored prior to shut down, estimate the A T at
individual tire positions based upon (1) the location of the tire, (2) the
anticipated operating temperature of the shell at that position, and (3) the
cooling effect of ambient temperatures on each tire. Refer to Manual ED30
and drawing number 728-8.5-.1-2,537 for procedure for determining cold
clearance between tires and kiln shell. The predetermined,or estimated, A T
must be used with the known inside diameter of the tire for calculation of the
difference in expansion between the pads and the bores of the tires. The
known, or estimated, difference in expansion must be subtracted from the
cold clearance figure before corrective work dimensions are determined for
shim work, pad replacement, or for machining pads for replacement of shell
sections. Example: Assume the tire bore to be 15'9" diameter.
Assume 275°F A T attire and pads. Clearance measured at %" (0.875")
15'9 = 189" X 275°F = 51975 X 0 .0000066 coefficients = 0.343035"
Expansion at shell and tire. 0.875" Cold clearance (measured)
(-) 0.343” Expansion (calculated) 0.532"
Excess clearance 0.532" clearance = 2 = 0 .266" to be considered for
shimming, extra pad thickness, or when planning pad surface radius for a
replacement shell section. Remove the end plates from the support roller

bearing housings for internal inspection of bearing bushings, shaft surfaces,
and the thrust washers on the end plates. See Figure 31.
If bushings are deemed to be in poor condition, replace them prior to
performing major alignment test work. If one bushing is found to be
defective, replace both bushings at that roller assembly, because the other
used bushing is at least partially worn and is mismatched for working with a
new bushing. Point contact of the shaft on mismatched bearing bushings
causes extreme pressure, overheating and possible extensive damage.
Bronze thrust washers are considered bad when: the oil collector pockets
and distribution grooves no longer exist.
• excessive wear allows the roller shaft to travel far enough to cause
interference between oil elevators and oil distribution trays. The former are
on the ends of the shaft, and latter are attached to the top inside surfaces of
the housing. the end of the shaft is in danger of touching the heads of the
mounting bolts for the washer. Thrust washers prepared from phenolic resin
material, do not require oil collector pocket or groove preparation. These
washers wear down rapidly if the end face of the roller shaft is not perfectly
smooth. Excessive wearing of this type of thrust washer can lead to
interference problems and contact between bolt heads and roller shaft as
with bronze washers. Also, phenolic resin washers disintegrate if shaft
temperaturerises toward 300°F. The following steps complete this internal
inspection:
• Check oil elevators and distribution trays for damage or distortion from
possible earlier interference. See Figure 32.
• Check condition of shaft seals. Older assemblies, with connected bearings
require removal of the roller for access to the lower half of the seal which is
mounted inside the housing. Apply Permatex Form-A-Gasket for sealing when
resetting end plates at the housings.
E.
EXTERNAL ALIGNMENT TEST WORK
Use either a transit or a theodolite to sight along the side of the kiln and
align it with the centerline of the tires to check alignment of the vertical
centerlines. Then move the instrument to a position on top of the kiln, adjust
it to match the slope angle of the kiln, and align it on vertical centerlines of
the tires for checking horizontal (slope) centerline alignment. See Figure 33.

Tires must be measured as described in D .5 to obtain the actual radius or
each unit for consideration when setting up for tests and when trial
dimensions have been recorded. See Figure 34.
Essentially, this merely re-establishes a straight line through the axis of the
kiln; it does not account for elevation errors or shell runout. As mentioned in
D .3., Note, the thrust frame is always the control point when considering
realignment moves. Refer to Figure 37 for test work details.
KILN HORIZONTAL ALIGNMENT MEASUREMENTS AT THE SIDE OF
THE KILN.
(See Figures 33 and 37)
a. If possible, set up the instrument on the firing floor for alignment with the
offset reference marks on the support frame beams, refer to D.3. Verify that
there is an unobstructed line of sight to all tire test points. See Figure 33.
If the burner building is totally enclosed, and it is not possible to cut an
opening in a wall panel, set the instrument on a support pier in line with the
offset reference marks. A continuous line of sight between high and low
support frames is preferred for this work. Turning 180°, or "tumbling" the
telescope, is not recommended unless the instrument was recently tested
and certified for accuracy.
b. Use the center head and scale, plus a 6" long spirit level, to establish the
true center position reference points for tests. See Figure 34.
c. Prepare a light weight, but not flimsy, straight test rod at a length suitable
for reaching from the tire centerline reference marks outward past the line of
sight (offset) for the instrument. Attacha foot rule (or tape rule scale) to the
test rod for reading and recording the dimension seen on the sight line. Place
the test rod on the premarket reference point on the tire and guide it to the
horizontal level condition by a spirit level. It is often convenient to rest the
rod on a powerful magnet placed on the tire at the reference mark and to
brace the other end on a lightweight tripod with an elevating center bar. See
Figure 35.
d. With the offset reference line being at a known dimension outward from
the main longitudinal centerline, and knowing the actual working radius of
each tire, compare wanted dimension from tire axis to the line of sight
against "as found" dimensions for determination of the existing alignment
condition.
Example:

= Dimension from kiln centerline to offset line. Actual working radius of the
tire. Target dimension for the instrument line of sight. T D - R. Short
dimensions on the line of sight indicate that the tires vertical centerline is
misaligned toward the sight line. Long dimensions on the line of sight
indicate that the tire is misaligned away from the line of sight.
NOTE
As indicated earlier, the thrust assembly support frame is always the control
point for kiln alignment work. The only time the thrust tire is shifted is for
correction of its own centerline misalignment. Other tires must be shifted
for alignment with the thrust tire when it is in the correct position.
KILN VERTICAL ALIGNMENT MEASUREMENTS ON TOP OF
THE KILN.
(See Figures - 33 and 37)
NOTE
Place test equipment at a convenient working position at either end of the
kiln shell, or on a specially prepared platform on the fire hood or feed
housing. Appropriate safety precautions must be considered for all work to
be done on the top surface of the kiln shell.
a. Use a center head, a 12" long scale, and a combination square attachment
with built-in spirit level to establish true-center referencemarks on tops of
tires and at the position selected for setting up the test instrument on the
kiln shell. See Figure 36.
op-dead-center of the kiln shell, at the instrument set-up position, is merely
for quick reference for the plumb bob (or optical plumb) for the equipment.
Since the shell may be warped to some degree, it may be necessary to make
transverse adjustments to align the telescope on a line of sight across
centerline of at least two tires one of which must be the thrust tire.
b. Set up the instrument and establish a true line of sight, then adjust (tilt)
the telescope to match the slope angle planned for the kiln. See Figures 33
and 37. Instrument height above the shell is determined by the design of the
gear guard. If the guard totally encloses the girth gear, the instrument must
be set high enough for sighting above the topmost segment. If the guard
encloses only the gear teeth and rims, the instrument may be set low for
sighting through open spaces between spring plates

c. Sight on a "rod" or scale placed on the premarket centerline reference
points on the tires. Record dimensions seen on the line of sight at each test
position. If tire surfaces are in good condition, the rod or scale should be
tilted perpendicular to the kiln axis for accurate reading on the sight line.
Use a framing square to guide and control the rod.
d. Using the thrust tire as the basic reference point, add the test dimension
read at this tire to the known radius of the tire to obtain a bench mark
dimension for comparison of readings at the other tires. As in step E.l.d.
consider the working radius of each tire for determination of tire-to-sight line
dimension required for slope alignment relative to the thrust tire.
NOTE
This test will indicate the alignment condition of the tires in relation to the
planned slope angle for the kiln but it will not verify elevation in relation to
the support frames. Verification of elevations requires physical measurement
from tire centerlines to top surfaces of roller assembly support frames. See
Figure 38.
Again, the position of the thrust tire determines the realignment moves to be
made at the other tires. Thrust tire elevation must satisfy girth gear/drive
pinion meshing conditions, and must also be suitable for match-up of taper
faces of the tire and thrust rollers, assuming that thrust disks are in good
condition under the thrust roller journals in assemblies which utilize 360°
bronze bushings.
• Measure the thread pitch on bearing adjustment screws on all roller
support frames. Horizontal misalignment dimensions, when divided by the
thread pitch, will indicate the number of turns of the screws needed for
moving the tire into position. One roller assembly would move inward; the
other assembly would move outward, as needed, for horizontal realignment
of the tire section. See Figure 39.
e. If elevation adjustments are necessary for correction of vertical
measurements for alignment of the tires in relation to the slope line, the
dimension between the horizontal centerline of the tire and the horizontal
centerline of the rollers must be adjusted for calculation of a dimension,
for moving the rollers.
f. In order to reset rollers in one preplanned move, give inward moves plus
values and give outward moves minus values. When corrective dimensions
for vertical and horizontal alignment adjustments are compared at individual

positions on a single support frame, minus values may reduce or cancel out
plus values. This would avoid unnecessary extra work when roller
assemblies are actually being moved.
g. Check for excessive clearance between shell spacer pads and bores of
tires as described in Sections A.4. and D .7. Step D.2.d. describes
adjustments required to move the tires into alignment along the slope line,
but these adjustments do not correct the kiln shell misalignment caused by
excessive clearance between shell spacer pads and bores of tires. In order
to place the kiln axis at a neutral position where it will be properly aligned
when in operation (and hot), support rollers must be moved inward to raise
the kiln of the total excess clearance dimension. With this final setting, tire
axes would be misaligned, but the shell sections at the tires would be
aligned for operation. This shell alignment would reduce the bending stress
that would otherwise be concentratedat shell joints at both sides of the tire.
As in E.2.e., the dimension between horizontal centerlines of the kiln and
support rollers (as shown on reference drawings) must be adjusted for
recalculation of support roller set points. See Figure 39.
A procedure for resetting and adjusting support rollers is described in
Section I. Alternate kiln alignment procedures are presented on following
pages. Resetting and adjustment of rollers will be similar, regardless of the
procedure for testing kiln alignment.
FIGURE

External Alignment Test Work Illustrations
FIGURE TITLE
33. Kiln External Alignment Test Work.
34. Arrangement for Locating Horizontal Centerlineof Kiln Tires.
35. Arrangement for Positioning Test-Rod for Optical Testing of Kiln
Tire Section Alignment.
36. Arrangement for Locating Vertical Centerline (top dead-center)
of Kiln Tires and Shell.
37. Reference Sheet for Kiln Alignment (External).
38. An Arrangement for Cross-Checking Elevation for Kiln Alignment.
39. Kiln Shell Realignment Calculation Considerations.

F.
KILN TIRE SECTION REALIGNMENT BASED UPON
SURVEY WORK AND CALCULATIONS
This procedure is used as a cross check of the support roller set points
which were established by optical test work and measurements. It is,
accurate enough to stand alone when external testing is not possible
because sight lines are blocked, or when through center internal testing is
not possible or feasible. Calculations compensate for frame elevation
discrepancies and for unequal wearing (or field dressing) of support rollers
and tires. All calculations are intended to place each roller in the required
position for placing the axis of the kiln, at individual tire positions, at the
original design set points. This procedure, together with "Hot-Kiln" Alignment
Survey procedures developed by the author, is the only method the author
now uses for testing kiln tire section alignment.
1. PRELIMINARY WORK
(See Figure 40)
a. Verify, or establish, the longitudinal centerline and offset reference lines
on all support frame beams as described in D.1 .2. and 3. See Figure 22.
b. Verify the difference in elevations (A E) between individual support frame
beams on each pier and from pier to pier as described in D .4.
c. Measure circumferencesof tires and support rollers as described in D .5.
d. Check the slope of individual support frames as described in D.6. If the
frame is not on the correct slope, check for grout breakdown or for possible
tilting of the support pier. See Figure 30.
e. Check slope conditions on tops of individual rollers. If the roller is not on
the correct slope, but the frame is all right and the roller is not taper shaped,
check for uneven wearing of bearing bushings. See Figure 30.

C
CALCULATION OF SUPPORT ROLLER SET POINTS
Original installation drawings are needed for comparison of "planned" and
"as found" dimensions and calculations.
a. Check installation drawings for reference elevations at pier work points.
These elevations are shown either as a dimension from a zero elevation
datum line or as an actual elevation above sea level. Also check for frame
height for each pier. The approximate frame height is shown and is merely
for calculation of the elevation at centerlines on top surfaces of support
frame beams. Add frame height to the work point elevation to obtain a
reference-only figure for a theoretical work point for the bearing support
surfaces at the transverse centerline for the frames. See Figure 43.
Consider the dimension from frame centerline to the transverse centerline of
each beam: Multiply this dimension by the percentage of slope, (or the given
slope per foot) for the equipment, for a figure that indicates rise or
drop between frame and individual beam centerlines. See Figure 40.
b. From figures obtained in F.l .b., and F.2.a., calculate the A E between all
beams at all support frames. Use the low beam for the frame on pier 1 as the
000 index point. Indicate AE at both ends of the beams. If the index beam
is not level, show the low end as the 000 reference point. Average-out
figures for high and low beams to show a figure for the centerline of the
frame.
c. Compare "as found" d E's with "planned" A's for possible adjustment of
the dimension from the bearing support surfaces to the horizontal centerline
of the kiln. If this dimension must be adjusted to compensate for frame
elevation errors, the dimension between the horizontal centerlines of the
roller and the kiln must be adjusted a like amount, since this dimension is
the base leg for right triangle calculation of the support roller set point.
If it is necessary to compensate for excess clearance between spacer pads
and a tire, as described in E.2.h., the dimension from roller centerline up to
the kiln centerline must be further adjusted for recalculation of roller set
points. See Figures 8, 9, 10, 13, 39, and 40.
d. Recalculate roller set points (distance from the vertical centerline of the
kiln and support frame) to compensate for support frame elevation errors,

excess spacer pad to tire clearance, and for reduced radii of tires and rollers.
See Figure 41 (Sample Original Calculations), 42 (Field "fillin" sheet)
and 42-A (Example). For reference purposes: A2 = B2 - C2 "A" is the
dimension between vertical centerlines of the kiln and frame and a roller.
"B" is the hypotenuse obtained by adding the radius of the tire to the radius
of the roller at each roller position. "C" is the adjusted dimension, as
described in F.2.c., between horizontal centerlines of the kiln and individual
support rollers.
e. Calculate working dimensions to utilize offset reference lines at ends of
support frames for resetting rollers. Subtract dimension "A" (from F.2.d.) from
the dimension from the frame centerline to the offset reference line to
obtain a dimension from the vertical centerline of the roller to the offset line
at each roller position. From this dimension, subtract the known radius of the
roller to obtain a working dimension from the outside face of the roller, at its
horizontal centerline to the offset line. This procedure is necessary for
resetting support rollers on the thrust pier, where the area directly under the
kiln is blocked by the thrust arrangement. It also allows work to be
performed in less cramped and somewhat cooler areas, away from the center
of the kiln, at other piers. See Figure 26.
See Figure 43 for a data sheet for kiln support assemblies.

Based Upon Survey Work and Calculations Illustrations
FIGURE TITLE
40. Kiln Realignment Preliminary Work.
41. Examples of Calculations for Support Roller Set Points.
41-A. Filled in" examples of calculations.
42. Calculation Sheet for Roller Assembly Set Points.
42-A. Calculation Sheet for Roller Assembly Set Points (Sample filled
in with typical data and calculations)
43. Field Work Procedure. Inspection and Resetting Data for
Maintenance Work (Kilns) .

G.
INTERNAL (THROUGH CENTER) ALIGNMENT TEST
PROCEDURE
The procedure described in this section is the standard, required
alignment of a new kiln. It can also be used for alignment of repaired or
replacement tire sections for older kilns having undamaged tire sections
which can be used for reference target layout work. See Figure 46.
The procedure is not recommended for routine maintenance test work for the
following reasons:
• Target layout work will not be accurate if there is any form of shell
distortion at tire sections where the targets would be placed.
• Refractory lining would have to be removed for access to the bare shell for
target layout work.
• At best, tire sections may be aligned, but with no regard for elevation or
position relative to the horizontal centerline for the frames, housings, thrust
arrangement, and drive assembly.
. It is usually very dusty inside the kiln, even with feed end draft, and the use
of optical test equipment or a laser beam is difficult, or impossible, since the
line of sight would be deflected.
• There often is danger of physical injury if an overhead portion of a ring or
slab of product coating should break loose.
. Vibration from adjacent operating equipment sometimes makes it
impossible to focus on a precise point on the target.
• Interference in chain section with castable refractory.
1. TEST EQUIPMENT AND MATERIAL
If conditions are favorable for this alignment procedure, prepare the
following test work equipment and material:
a. Transit or theodolite, or laser beam equipment with adjustable tripod or
support stand.
b. Target-support batter boards or adjustable spiders for installation in the
shell at target positions. Whatever is used to support a target must be

marked for drilling a through center sight hole after it is locked in position in
the kiln shell. See Figure 44.
c. String of lamps for adequate illumination of the full length of the kiln.
d. A sturdy platform for entry into the kiln through either fire hood or
feed housing doors.
e. At least two "sticks" @ 3/4' + 1 ", in lengths to suit the radius of the kiln
plus 6". Taper one end of each stick to form a point for trammel layout work.
See Figure 46.
f. A target kit consisting of:
• Plain white 4" X 6" index cards
• Staple gun or heavy duty thumb tacks
. Push pins
. Pocket scales and sharp pencils
. At least one pair of wood beam trammels (Starrett No. 59A or similar)
• Bright-beam pocket flashlights
g. Two-way radios or sound powered telephones for contact between the test
instrument and target positions.
h. Portable steps for access to centers of large diameter kilns at instrument
and target positions. It may also be necessary to prepare a sturdy support
frame to elevate the test equipment in large diameter kilns.
2. PREPARATION OF THE KILN.
(See Figure 45)
a. Inside the kiln, measure from ends of the shell to approximate
axial centerline positions of tire sections. Clearly identify and mark each
position.
b. Chip out at least one full circle of bricks at each premarket work point.
c. On the bare shell, mark a reference line parallel to the exposed side faces
of one of the remaining circles of brick at each test position.
d. Install target boards, or spiders, at-but not necessarily in-the spaces
where bricks were removed. These target supports must be placed at the
uphill edges of the cut-outs so that marked target cards will face downhill, in
view of the test instrument.

e. Test the kiln draft system for a damper position suitable for dust-free
ventilation of the kiln.
PREPARATION OF TARGETS AND TEST EQUIPMENT.
(See Figure 46)
a. Verify inside diameter of the kiln shell at target positions where bricks
were removed. Prepare wood beam trammels for the chord length for eight
spaces for the inside diameter of the shell. (Chord length for eight spaces on
the circumference of a circle with a diameter of 1 is 0.382683). Multiply this
length., by the actual inside diameter of the kiln to obtain the dimension for
spacing the trammel points on the wood beams. Use this setting to divide the
reference line (refer to H.2.c.) into eight equal spaces at each target
position.
b. Prepare test targets.
(1) Using the pointed end of the trammel stick for contact on the shell plate,
set the steel pointed trammel clamp to suit the radius of the kiln plus 1”.
(2) Place the pointed end of the stick on one of the eight marks on the
reference line, then scribe an arc on the surface of the target board. Repeat
this move at marks 90° apart, on the reference line, to form a four-sided
"box on the surface of the target board.
(3) Use a pocket scale and sharp pencil to form an X with lines between
diagonally opposite corners of the box.
(4) Shorten or lengthen the setting of the trammel clamp, then shift the
layout work 45° for marking a second box from the four remaining marks on
the reference line. Form a second X from diagonally opposite corners of this
box.
(5) If the shell would be perfectly round, the intersecting lines would cross at
the center points for both boxes; this would be the true axis of the shell at
that position. If X centers are separated, place a mark midway between the
two centers and use this point as the neutral center for alignment test work.
(6) After marking centers on target boards, use an expansion bit to drill a 2"
diameter peep hole through each board.
(7) After drilling peep holes, use a staple gun or thumb tacks to secure index
cards in balanced positions over the holes. Card tops must not be loose,
since they must eventually work like hinges for lifting the cards for through-
sighting to other target positions and then returning to' original positions.
Use one or two push pins to hold bottom edges of the cards in position for
layout and test work.

(8) Remove steel points from the trammel clamps and replace with sharp
pencils. Repeat G.3.b., 1) through
5), this time marking on the index cards at all test positions.
c. Instrument Set-Upand Alignment Test See Figure 47 The following is for
setting up on the rough surface of the shell lining, near the discharge end of
the kiln, with no access to reliable reference points for centering the
equipment. The support for the instrument may be an adjustable tripod, or a
heavy pedestal with elevation and transverse adjustment features.
Use the following procedure to set-up the equipment and perform the
alignment test:
(1) Chip away material coating and/or rough surfaces of the refractory lining
to provide a solid footing for the tripod or pedestal at approximately the
vertical centerline of the kiln. Set up the support and check for steadiness.
Install the test instrument and adjust the support to raise the line of sight to
the approximate horizontal centerline of the kiln.
(2) Sight on the target at tire section No. 1, nearest to the instrument, or at a
suitable alternate tire section, then lock the instrument in that position.
Refer to this target as the front sight for the test.
(3) Raise the first target card and attempt to focus on the target within the
thrust tire shell section. Determine exactly where the line of sight (or laser
beam) falls in relation to the center mark on that target. Refer to this
location as the back-sight for the test. It may be necessary to use a larger
card for this first test, or the instrument operator may be able to "read" a
scale to determine the distance between target center and the crosshairs on
the line of sight. The off-center position and dimension, along with the
distance between targets and the distance from the front sight to the test
instrument, will be factors for calculation of tentative correctiveadjustments
for alignment of the equipment for overall test work. Repeat tests and
adjustments until the transit crosshairs (or laser beam) falls on centers
of targets used as front and back sights for alignment of the instrument.
NOTE
If the instrument line of sight is reasonably close to the center of the back
sight target in this preliminary test, work may be simplified if the barrel of
the test instrument is adjusted to place the sight center on the marked
target center. This minimizes the effects of possible errors in instrument set-
up or target layout work. Projection of an error at a near target would give a
magnified false impression of a misalignment condition. In this procedure,
the sight line "error", in relation to the center of the front sight target card,
will be a more accurate indication of corrective adjustments requiredat the

test instrument.
(4) When the instrument is aligned on front and back sight targets, and is
locked in position, raise intermediate target cards for clear sighting to the
most distant target. Focus on that target and determine the position of the
instrument center in relation to the target center. Misalignment will be
indicated by the direction and distance of the instrument sight center in
relation to marked target centers.
(5) Repeat test procedures (in turn) on intermediate targets and mark
positions of the sight center in relation to the target center at each test
position.
NOTE
This test, as described above, would seem to presuppose that front and back
sight tire section targets are control positions for follow-up adjustment work
for realignment of the kiln. This is not necessarily true. Actual adjustment
work is largely a matter of judgment after considering the conditions at the
thrust arrangement and drive system. If the thrust tire is correctly positioned
relative to the thrust roller assemblies, and if the girth gear and drive pinion
(s) are in a satisfactory meshing condition, support rollers at the thrust pier
are not to be disturbed. If, however, conditions must be improved at these
check points other tire position must be realigned to suit the adjusted
position of the thrust tire. As indicated earlier, this test when used without
supportive tests, will merely indicate the straightness (or lack of) of the
kiln shell tire sections. Slope, elevation, centerline cross-over, or relationship
with other equipment will not be verified or corrected with this procedure.
(6) After tire section misalignment is verified, and agreement reached
regarding corrective measures, support rollers must be adjusted to shift the
axis of each tire section to the position required for realignment.
Mi.-nor misalignment may (possibly) be corrected by adjusting support rollers
when the kiln is standing idle, but major moves will require that the kiln be
rotating to facilitate the adjustment work. Since rotation would rule out any
possibility of monitoring the work with the test equipment, misalignment at
individual targets should be recorded and treated as described in E.2.f for
control of the realignment work without unnecessary counter movement of
the rollers.

Internal (Through Center) Alignment Test Procedure Illustrations
FIGURE TITLE
44. Kiln Shell Alignment Test Batter Boards.
45. Shell Preparation Plus Target Installation and Layout.
46. Kiln Alignment Target and Layout Trammel.
47. Internal Alignment Test (Operational Kilns).

H.
KILN ALIGNMENT QUICK CHECK
(See Figure 48)
This procedure is not intended to stand alone for realignment of kiln tire
sections. Its main purpose being merely to spot check tire alignment
conditions after startup of a new kiln, or to monitor alignment of tires after a
kiln has been reset on the basis of more thorough procedures. Support pier
and frame surfaces must be maintained in clean condition and centerline
reference marks must be preserved and easy to find. Information and
dimensions from report sheets for prior tests will be useful for determination
of target dimensions for comparison of planned and as found dimensions.
Although the kiln should be shut down for this work, it should not be shut
down specifically for the job except for a maximum of five minutes at
individual tire positions. This procedure would be useful as a back-up test for
the internal alignment test described in Section G.
1. PERFORM THE STANDARD QUICK CHECK PROCEDURE
a. Uncover longitudinal centerlinemarks on the support frame and span both
beams with tight wire or straight edge.
b. Use a center head with 12" scale, and a try square attachment (with spirit
level) to find the bottom centerline of the tire. Transfer this mark to both side
faces of the tire; use a sharp pencil or a metal scriber.
c. Hold a folding or tape rule against the side face of the tire and parallel to
the scribe line, to establish a measurement line perpendicular to the axis of
the kiln. Record the dimension between the tight wire, or bottom edge of the
straight edge, to the bottom of the tire at the scribed centerline mark.
d. Add the known, previously determined, radius of the tire (refer to D.5.)
to the dimension recorded in H.l.c.
e. Refer to maintenance records or reports, and also to original installation
drawings, to obtain the planned and/or adjusted dimension from the surface
of each support frame to the horizontal centerline of the kiln.
f. Compare planned and as found dimensions to determine alignment
conditions of the horizontal centerline of each tire. This will not account for
pier elevation or slope setting deviations. If comparative elevations were
checked (as in D .4.), records should indicate discrepancies to be
considered when using this quick check procedure.

g. Place a plumb line directly on the centerline scribe mark on the side face
of the tire, then check the position of the plumb bob in relation to the tight
wire or straight edge extension of longitudinal centerline marks on support
frame beams. This will be a quick check of alignment of the vertical
centerline of the tire. Accuracy of this test depends upon accuracy of the
centerline marks as reestablished in Step D.3.
G
PERFORM THE SPECIAL PROCEDURE AT THRUST
ASSEMBLY SUPPORT FRAMES.
(See Figure 49)
NOTE
In this test, the center zones of the frames are blocked by thrust rollers and
bearing bases.
a. Establish offset centerline reference marks (as in D.3.) at outer ends of
support frame beams. See Figures 25 and 26.
b. Use a center head and scale combination, plus a spirit level to find the
horizontal centerline position at both sides of the tire (on the rolling contact
face). See Figure 34.
c. Refer to E.1.c. for the procedure for measuring the distance from the tire
centerline reference marks down t (the top surface of the frame. This
dimension is used (a: described in H .11) to determine the alignment
condition of the horizontal centerline of the thrust tire.
d. Using the same set-up as above (as described in E.l)
c, consider the dimension from the longitudinal centerline of the thrust frame
to the offset reference lines as being the control dimension for checking
alignment of the vertical centerline of the thrust tire.
e. Subtract the known radius of the thrust tire from the dimension between
main frame centerline and the offset lines to obtain a reference dimension
outward from the tire face to the offset line. Mark this dimension on the test
rod.
f. Hold the test rod against the face of the tire with a magnet, if possible, at
the premarket horizontal centerline position. Use a spirit level on the test rod
to ensure accurate test rod, drop a plumb bob down to the offset line.

This line is usually a tight wire or straight edge between marks on the
beams. Position of the plumb bob point, in relation to the offset line,
indicates indicates the alignment condition of vertical centerline of the kiln.
NOTE
Quick check procedures for checking alignment of horizontal centerlines of
tires do not account for excess clearance conditions between shell pads and
tires. Allowance must be made, as in other test work, for such excess
clearance. Sketch sheets (Figures 48 and 49) show basic tools and
equipment for quick check procedures. Permanent quick check
arrangements (in simplified forms) would facilitate routine inspection
procedures.

Kiln Alignment Quick Check Illustrations
FIGURE TITLE
48. Kiln Alignment Quick Check (Spot Checks Only).
49. Quick Check for Alignment at Kiln Thrust Tires (Also Useful at
Plain Tire Locations.).

I.
RESET AND ADJUST SUPPORT ROLLERS
This procedure describes the relocation of support rollers to set points
calculated for individual units as determined by alignment test procedures
described earlier.
The procedure assumes that roller contact faces are parallel to the
centerlines of the shafts, and that tire contact faces are parallel to their own
axes, as would be the case with new equipment or with material that has
been accurately field dressed (as described in A.2.). It is also assumed
that offset reference lines have been placed at ends of support frame beams
(as described in D.). Minor misalignment may be corrected when the kiln is
cold, or during the dry-out/warm-up period when the kiln returns on stream.
The kiln should be rotating to facilitate adjustment of bearing bases at each
support roller position.
NOTE
Continuous rotation of a cold kiln is often restricted by the condition of newly
installed refractory brick linings. If individual brick circles were not laid up
properly, continuous rotation of the kiln may eventually cause loose bricks to
shift and fall away from the shell, sometimes in large areas. Some owner-
operators welcome the opportunity to test the integrity of the lining, before it
is subjected to high operating temperatures, by rotating the cold equipment.
Correct extreme misalignment of tire sections after the kiln is operating and
the shell is hot enough to be more flexible, to accept possible new stress
forces at old warp zones. With the kiln operating, frequently check the gear
mesh conditions to prevent damage when support rollers are being reset.
See Figures 14 and 15.
Use the following procedure to reset and adjust the support rollers:
1. Before starting major realignment adjustments, plot misalignment
patterns in plan and side views. These plotted patterns establish a logical
sequence for resetting individual tire sections. With this information, and
data concerning conditions at the thrust pier and drive arrangement, roller
set point figures can be revised, to relate to the thrust tire section if the
elevation (horizontal centerline) is acceptable at that position. See Figure 50.
2. Start roller resetting work at the tire section having the worst

misalignment problem. Adjust this section until the shell alignment is better
than the next worst tire section. Then alternate work between these two
sections until they are as good as, or better than, the third worst section.
Perform this work alternately at individual piers until all sections are in
alignment and the thrust tire is in the correct position relative to the thrust
roller assemblies. Depending upon age and application of the kiln, there may
be from three to seven tries to be aligned. Two support kilns do not require
this type of alignment and adjustment procedure, but they are to be set to
suit centerline and elevation requirements.
NOTE
In all cases, true alignment of the vertical centerline of the thrust tire to
match the longitudinal centerline of the thrust support frame is critical for
correct mechanical reaction of the tapered thrust rollers which must, in turn,
be offset toward the down turning side of the kiln (See Figures 19, 20, and
21). Elevation of the horizontal centerline of the thrust tire may vary from the
design dimension if there is satisfactory mating of tire and roller taper faces
and if gear and drive pinion mesh is satisfactory.
3. Add the recalculated dimension, from frame centerline (longitudinal) to the
support roller centerline, to the known radius of the roller to obtain a
reference dimension for between the longitudinal centerline of the frame to
the outside face. of the roller at the horizontal centerline position. Subtract
this dimension from the dimension from the frame longitudinal centerline to
the offset reference line to obtain a dimension for physically measuring the
distance from the offset line to the face of the roller. See Figure 26.
4. Measure the roller positions by placing plumb lines on the contact faces
above the horizontal centerlines of the rollers. Suspend the plumb bobs in
cans of oil placed on the pier surface and then measure between the offset
line and the plumb lines. Hold the plumb line near the edges of the roller
and position the tape rule, or folding rule, truly perpendicular to the offset
line to avoid any incorrect (long) readings. This procedure is not to be used
when a roller is cone shaped. If a support roller is cone-shaped, it will be
necessary to work at the axial centerline of the roller, using the average
radius obtained from measurements recorded near edges on the contact face
of the roller. Working with a single plumb line at this position will require
testing of roller thrust to verify when the roller axis is parallel to the kiln
axis. See Figures 58 and 59.

Preliminary tests may indicate excessive skewing of individual roller
assemblies. Correct this condition before proceeding with roller resetting
work. See Figure 51.
NOTE
At kilns where support rollers are installed in connected bearing
arrangements, the outside edge of the connecting pan may extend beyond
the outside faces of the rollers to cause interference for plumb lines. Under
these circumstances, place a center head and scale on the roller face, at the
horizontal centerline, to move the plumb line outward to a dimension that
would clear the connecting pan. If necessary, adjust the dimension between
offset line and roller face for this new line position.
5. After adjusting a roller to a position parallel to the offset line, use a metal
scriber to mark the support beam surfaces to indicate starting positions of
the bearing bases. Compare calculated dimension from offset line to roller
face (from 3 above) with the actual dimension when the roller is parallel to
the offset line. Determine the direction the roller must be moved, inward or
outward, and record the distance the assembly must be shifted. Then place a
dial indicator at the inner vertical face of both bearing bases to monitor total
movement of the bases and to avoid moving into skew positions.
If possible, arrange for simultaneous adjustment of both bearings at a roller
assembly to avoid the repeated reversing of roller thrust pressure.
Otherwise, the pressure would be unavoidable if the work crew has to move
from bearing to bearing during the resetting adjustments.
6. Move from roller to roller, and pier to pier (as in 1.2.) to avoid forcing the
shell into new alignment positions at support piers. Total movement of the
bearing bases must be monitored and controlled so that they remain within 0
.005" of each other (if moved simultaneously), and within 0.010" if moved
alternately. Record total movement of both bearing bases until the
preplanned movement dimension is attained. This can be verified either by
measuring from scribed reference marks to the bases, or by cross-checking
from the offset line to the face of the roller (as described in 1.4.). Since
support rollers should have been adjusted to be parallel to the longitudinal
centerline of the kiln at the start of the adjustment procedure, dial indicator
totals should be equal when the roller is at the new set point position. To be
certain that the roller is parallel to the kiln centerline, test bearing housing
end plates for indication of shaft thrust. Make skew adjustment, of not more
that 0 .005" at a time, to move the roller into a neutral position. If adjustment
work must be delayed, for any reason, rollers should not be skewed (in
relation to the longitudinal centerline) more that 0 .010”. Check gear and
pinion mesh conditions frequently when tire sections are being repositioned,

especially if the thrust section must be shifted, to avoid going too far into (or
out of) mesh, and to avoid dangerous changes in tooth contact patterns that
would indicate concentrated zone loading. See Figures 14 and 15.
NOTE
Do not worry about step-down wear patterns on girth gear and drive pinion
tooth flanks if these teeth were examined earlier (as in A.9.) and if
correction action was taken (reversing the gears) to eliminate the problem.
After the kiln has been realigned, gear and pinion alignment must be
rechecked during a preplanned shutdown period if drastic changes were
made at the thrust tire section. If moves at the thrust section were small,
verify gear mesh conditions by slowing the kiln for observation of these
gears; it may be possible to resume operation without resetting the drive
equipment. If drastic changes were made at the thrust tire section, it will
probably be necessary to shut down for realignment of drive components.
Total realignment of drive components is rarely needed since, typically, it is
the thrust tire that moves out of position far enough to cause trouble at
the drive pinion; when the thrust section is reset to its proper position, the
problem at the pinion is usually eliminated. This step describes an alternate
procedure to use for resetting support rollers when it is known that roller
and/or tire contact faces are tapered, i.e. cone shaped units.
NOTE
Although it is not recommended that a kiln be realigned when rollers or tires
are cone shaped, or irregular in any manner, it is sometimes important to
correct serious misalignment problems before a kiln service company can
true up the surfaces. This procedure should be considered to be a temporary,
short term, arrangement to improve tire section alignment. Since point
loading of the uneven surfaces would increase Hertz pressure to the danger
point, the best that can be said in favor of this procedure is that when roller
centerlines are parallel to the kiln centerline, contact surfaces irregularities
will be clearly seen and an accurate estimate can be made for the amount of
true up work to be performed. a. Refer to roller dimensions (as recorded in
D.5.), then use the neutral radius (average of short and long dimensions)
for measuring from the offset line to the outside face of the roller at the
horizontal and axial centerline positions.
b. Add the recalculated dimension between the longitudinal centerline of the
frame and the vertical centerline of the roller, to the radius of the roller at
the neutral center position, to obtain the dimension from the frame
centerline

to the outside face of the roller. Subtract this figure from the dimension from
the frame centerline to the offset line to obtain the dimension for measuring
from the offset line to a plumb line placed at the neutral centerline of the
roller face.
c. Check thrust direction of the roller, then skew as needed, to move the
roller into a neutral position with its own centerline parallel to the kiln
centerline.
d. The resetting procedure is the same as in steps described in 1.5.,1.6.,
and 1.7. Parallelism of the roller, during the resetting period, must be
monitored by observing the dial indicators and by checking bearing end
plates for indications of shaft thrust which must be carefully controlled

Reset and Adjustment of Support Rollers Illustrations
FIGURE TITLE
50. Kiln Alignment Test Comparison Sheet.
50-A. Kiln Alignment Test Comparison Sheet (Sample with Entries
from Actual Field Test).
51. Support Roller Assembly Realignment Control.

J
ADJUSTMENT OF SUPPORT ROLLER ASSEMBLIES FOR
THRUST REQUIREMENTS
This step describes the support roller skewing adjustments which are used
to satisfy kiln thrust design arrangements upon completion of roller
realignment. See Figure 51.
1. FLOATING KILNS
Some kilns require skew adjustments of support rollers to overcome
gravitational thrust to move the kiln into a floating position. In this position,
the thrust tire does not touch either of the thrust rollers when the kiln load
and temperature conditions are considered to be normal for the material
being processed. From this floating position, the thrust tire drifts uphill or
downhill to contact either of the thrust rollers as load and temperature
conditions vary in the kiln. Thrust assemblies for floating kilns use full 360°
bushings which have clearance for a film of oil between the bushing and
the shaft for the taper-face roller. The bearing bases are not water cooled
except for special process conditions. Neither of the thrust assemblies
should be forced to carry continuous thrust loading of the kiln. Movement of
individual bearing bases must be monitored by dial indicators to avoid over
adjustment of any assembly and to have all roller assemblies carrying
approximately equal thrust? loads. See Figure 52.
Starting from a proven neutral position, with roller longitudinal axis parallel
to the kiln longitudinal axis, all support rollers are to be skewed, as required
for direction of kiln rotation, to move tires uphill against their high side
retainers, at which time the kiln shell starts to react to the roller skew
positions. See Figures 53, 54, and 55 Variations in kiln production loads will
affect roller and kiln thrust. With rollers skewed for long term typical
conditions, heavier production loads will increase thrust reaction in direction
(s) determined by skew angles. Heavier loads cause heavier thrust reaction;
lighter loads cause lighter trust reactions.
2. FULL THRUST (GRAVITATIONAL) KILNS
Full thrust kilns usually use large, heavy duty, antifriction bearings at the
thrust roller assemblies. With thrust assemblies being capable of carrying
gravitational thrust loads, set the support rollers in neutral positions, with
longitudinal axes parallel to the axis of the kiln. If a roller (s) assumes a
reversed thrust attitude, where the shaft thrusts against the uphill bearing
housing end plate, the contrary skewing causes the kiln to move downhill

which increases the load on the downhill thrust assembly. In extreme cases,
overloaded thrust assemblies require increased torque for rotation of the
kiln; in some situations, the drive motor (s) will drop out of circuit
because of overload conditions. For the sake of the operation, it is best to
move slightly away from neutral roller positions by deliberately skewing
rollers for thrusting toward their downhill bearing thrust washers and
end plates. In most cases, this can be achieved with skewing of 0.005" to
0.010" in the correct direction from the parallel position.
KILNS WITH HYDRAULICALLY OPERATED, MOVING
THRUST ASSEMBLIES
Hydraulic thrust arrangements may be found on anywhere from one to three
support piers, depending upon age and size of the kiln . Essentially, the
arrangement consists of an anchored hydraulic jack set in position to push
the thrust roller housing uphill when the pump is activated, and then to allow
the kiln to return downhill when the pump is deactivated
. Total travel distance for the kiln, ... from downhill to uphill positions, is
between 1V2" and 2”. The hydraulic pump cycle of operation is controlled by
limit switches activated by the position of the tire. The constant
travelling of the kiln is intended to eliminate uneven wearing (step-down
patterns) at tires and at the girth gear and drive pinion (s). Set the support
rollers in neutral positions, as in I.2. above. They may be skewed slightly to
relieve part of the load on the hydraulic pump and jack arrangement for
moving the kiln to its uphill position. This arrangement does not have the
safety factor of a hurts roller assembly on the uphill side of the thrust tire (s).
Instead, it depends on cam activated limit switches to energize alarms or
kiln drive shutdown controls. It is extremely important that support roller
skew adjustments do not totally cancel out the gravitational thrust of the kiln
so that the kiln moves uphill without the help of the jacks.
NOTE
Adjustment of support rollers for "floating" kilns reduces maintenance
problems at thrust tire and roller arrangements, but at the expense of the
support roller assemblies when normal wear and tear is considered.
Energy requirement is lowest when support rollers have been carefully
adjusted, and when the thrust tire is in the neutral (floating) position
between the thrust rollers. With full thrust and hydraulic thrust kilns, there is
somewhat of a trade-off: reduced wearing and maintenance at support

roller positions, but increased wear, maintenance, and sometimes energy
requirement resulting from full-time loading of the downhill thrust
assemblies. Owner/operators may prefer a compromise, where controlled
skewing (within strict limits) would offset some of the gravitational thrust of
the kiln for reduced wearing of thrust components and reduced energy
requirement for rotation of the kiln, but with slightly increased wearing at
tire and support roller assemblies. For rule of thumb guidance for roller
assembly skewing, see Figures 56 and 57.
CAUTION
Skewing adjustments at individual roller assemblies requires patience; work
must not be rushed. Each roller is brought to a neutral position (no thrust in
either direction) and then adjusted in moves of 0 .005" to 0.010" at a time,
followed by a waiting period for a reaction, until thrust conditions are
correct for the support rollers and kiln thrust arrangement.

Adjustment of Support Roller Assemblies for Thrust Requirements
Illustrations
FIGURE TITLE
52. Kiln Thrust Tire and Roller Arrangements.
53. Kiln Support Roller Adjustment and Testing.
54. Support Roller Adjustment and Typical Errors (Clockwise
Rotation of Kiln).
55. Support Roller Adjustment and Typical Errors
(Counterclockwise Rotationof Kiln).
56. Roller Adjustment Using Rule of Thumb (Facing Down-Turning
Side of Kiln).
57. Roller Adjustment Using Rule of Thumb (Facing
Up-Turning Side of Kiln).

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