With ever-rising fuel prices, designing efficient hydraulic systems can pay big dividends for users of mobile hydraulic vehicles. Join Design World as we take an in-depth look at three critical areas of mobile hydraulic system design: filtration, sensors and sealing. Our expert panel presents critical design tips and answering your questions. Attendees will learn: * How to use in-cylinder position sensing to optimize hydraulic functions on mobile equipment * How to select the appropriate filtration grade for a specific application * How do shaft requirements impact mobile hydraulic sealing products The panel includes: Dr. Christian Bauer, Staff Scientist, Pall Corp.; Haubold “Hub” vom Berg, Technical Marketing Manager, MTS Sensors, Mobile Hydraulic; and Joel Johnson, VP of Technology, Simrit. The panel is moderated by Design World Editorial Director, Paul J. Heney.

1. Best Practices for
Mobile Hydraulic
Design

2. Before We Start
This webinar will be available afterwards at
designworldonline.com & email
Q&A at the end of the presentation
Hashtag for this webinar: #DWwebinar
Other resources:
 www.mobilehydraulictips.com
 www.pneumatictips.com

3. Presenters
Moderator
Paul Heney
Haubold vom Berg
Joel Johnson
Dr. Christian Bauer
Design World
MTS Systems,
Sensor Division
Simrit Division,
Freudenberg-NOK
Pall Corporation

4. WTWH Webinar for Mobile Hydraulic Design, October 13th 2011
Filtration Solutions for Off-highway Vehicle
On-board Hydraulic Systems
Filtration Solutions for Off-highway Vehicle On-board Hydraulic Systems
Presented by:
Christian M. Bauer, Ph.D.
Pall Corporation
Scientific and Laboratory Services Department (SLS)
Port Washington, New York

5. Contents
•
•
•
•
Application description
Contamination control
Filtration technology for hydraulic fluid power applications
Summary

6. Application Description
• Multiple hydraulic subsystems
o
e.g. boom, arm, bucket, dump, level, swing
• High duty cycles
• High actuating pressure
• Critical components
o
o
o
Hydraulic cylinders
Directional valves
Gear/piston pumps
• High contamination environment
• Recirculatory system
• Return line filtration
o
o
Built-in bypass
Change-out per maintenance schedule

7. Contamination Control
• Contamination type:
o
o
Environmentally ingressed contamination:
• Dust and dirt from the environment
Internally generated contamination:
• Wear debris from normal or abnormal wear of system
components
(pumps, bearings, valves, seals, etc.)
• Fluid degradation products (e.g. precipitated additives
due to water ingression)
• Contamination effect:
o
Accelerated wear of system components, e.g.
• Control valves (stiction) – hydraulic systems
• Bearings (fatigue wear) – lubrication systems
• Gears (fatigue wear) – lubrication systems
• Pumps (abrasive wear) – hydraulic and lubrication
systems
Photomicrograph of typical
contamination, 100X magnification

8. Dynamic Clearances and Abrasive Wear
LOAD
Dynamic Fluid Film
Thickness (µm)
Abrasive Wear Effects
• Dimensional changes
• Leakage
• Lower pump efficiency
• Generated wear = more wear
Typical components subjected to Abrasive wear
• All hydraulic components (pumps, motors, spool
valves and cylinders)
• Gears

9. Impact of Wear Control on Component Life
To minimize wear and maximize component service life, clearance size
particles must be removed from the system.
Component
Pump motor
Hydrostatic transmission
Valve
Valve spool
Roller bearing
Journal bearing
Fluid
Improvement
4 to 10x increase in pump and motor life
4 to 10x increase in hydrostatic transmission (HST) life
5 to 300x increase in valve life
Elimination of valve stiction
50x extension of roller bearing fatigue life
10x extension of journal bearing life
Extension of fluid service life and reduction of disposal costs
through reduced contamination caused fluid degradation

10. Industry Fluid Cleanliness Recommendations
• Cleanliness recommendations* are based on:
o
o
o
o
o
System operating pressure and duty cycle
Operating environment
Component sensitivity and life expectancy
Economic liability and cost of downtime
Safety environment
* Based on bottle sampling; cleanliness recommendations based on online particle monitoring would be significantly lower. On-line monitoring
is strongly recommended for today’s operating system conditions.
System
Components
<140 bar
(<2000 psi)
140-210 bar
(2000-3000 psi)
>210 bar
(>3000 psi)
Servo valves
Proportional valves
Variable volume pumps
Fixed piston pumps
Pressure/flow control valves
Gear pumps
16/14/11
17/15/12
17/16/13
18/16/14
19/17/14
19/17/14
15/13/11
16/14/12
17/15/12
17/16/13
18/16/14
18/16/14
14/12/10
15/13/11
16/14/11
17/15/12
17/16/13
18/16/14

11. Impact of Filtration on Abrasive Wear in Hydraulic Pumps
This test on 3,000 psi (207 bar) piston pumps clearly shows the wear-reducing benefit of
filtration. The report concludes that the dominant wear mechanism causing pump performance
degradation was hard particle abrasive wear between sliding surfaces.
• Pump parameters
measured:
o
o
o
o
o
o
Presented at SAE A6 Meeting – J. Ohlson, NADC
Piston to cylinder bore
Universal link-pin clearance
Pressure control pilot valve
clearance
Pressure control
piston diameter
Pump flow

12. Valve Shifting Force vs. Contamination in Fluid
• Conditions of Directional Valve
o
o
o
Flow: ~ 15 gpm (56.8 L/min)
Pressure: 3,000 psi (207 bar)
Valve Radial Clearance: 8 µm
• Valve held stationary and under
pressure before shifting force
was measured
This study illustrates how valve silting/stiction from
particle build-up between moving surfaces increases
valve shifting force. Note how the highest force is
required when the valve is challenged by particles in the
dynamic clearance size range (~ 10 µm).
Reference: Oklahoma State University

13. Benefits of High-Performance Filtration
• Inadequate filtration
o
o
System stabilizes at high contamination
level
High metallic content in contaminant
• Replacement with high
performance filtration
o
o
Rapid reduction of contamination in
system
Significant reduction of metallic content
• Re-installation of inadequate
filtration
o
o
Re-starts “chain reaction of wear”
Rapid rise of contamination level and
metallic content

14. High Performance Filter Element Construction
In-to-out flow path
Upstream cushion layer
Benefit: Reduces the chance of
cross contamination during filter
element change
Benefit: Reliable, consistent
performance
Outer helical
wrap
High performance
filtration medium
Benefit: Improved
performance over the service
life of the filter element, more
consistent fluid cleanliness
Up and downstream mesh
layers
Benefit: Reliable consistent
performance and resistance
to severe operating conditions
Benefit: Extended filter element
service life for lower operating
costs
Anti-static design
Benefit: No damage to filter element
or housing or other system
components from electrostatic
discharge; minimizes fluid
degradation
Laid-over pleat shape
Coreless/Cageless design
Benefit: Lighter, environmentally friendly
element; reduced disposal costs; easy filter
element change-out
Benefit: Smaller filter element
for an application; improved
resistance to cyclic and surge
flows and cold starts

15. Filtration Medium - Importance of Fiber Diameter
Fiber size and fiber density govern the filter medium’s pore size and porosity
Cellulose
15 to 25 μm
Polymeric
Glass fiber
10 to 15 μm
Benefits of smaller fiber diameter:
• Higher dirt capacity
• Lower pressure drop
• Longer service life
1 to 5 μm
Benefits of inert inorganic fibers:
• Wide chemical compatibility
• No swelling
• No shelf life limitations

16. Tapered Pore vs. Uniform Pore Structure
Tapered Pore Design
• Coarser upstream surface acts as a
pre-filter, capturing larger particles,
allowing finer downstream pores to
capture critical clearance-sized particles
• Reduces operating costs by combining
maximum particle retention with extended
service life
Uniform Pore Design
• Limits the effective use of the available
void volume to capture particles
• Increases operating costs by reducing the
total number of particles captured and
hence filter service life

17. Laid-over Pleat Shape vs. Fan Pleat Shape
Unused
volume
Mesh
Layer
Traditional
Fan pleated
filter element
Mesh
Layer
Core
Filter
Medium
Mesh
Layer
Laid-over pleat
filter element
Filter
Medium
Mesh
Layer

18. Field Cleanliness Levels Achieved with High-Performance Filtration
ISO 4406 Cleanliness Target
Hydraulic systems truck 1
• Brake
• Hoist
• Torque converter
• Steering
Achieved ISO 4406
Cleanliness Level
-/18/15
-/16/13
-/16/13
-/16/13
-/12/9
n/d
n/d
-/13/10
Hydraulic systems truck 2
• Brake
-/18/15
-/13/9
• Hoist, Torque converter
-/16/13
n/d
• Steering
-/16/13
-/14/12
• The high level of cleanliness achieved protects critical system components against
excessive wear and, potentially, premature failure
o Low cost of ownership to end user due to increased uptime
o Fewer OEM warranty claims

19. Summary
• On-board hydraulic systems on off-highway mobile equipment are
characterized by
o
o
o
High duty cycles and high loads
Tight clearances and tolerances of critical system components
• Hydraulic cylinders
• Directional and proportional valves
• Load sensing pumps and motors,
High contamination environment
• Maintaining high levels of fluid cleanliness critical to reliable operation
o
o
Requires high efficiency, stress-resistant filtration technology
• Consistent performance over the entire maintenance period
Critical system components are protected against excessive wear
• Low cost of ownership to end user due to increased uptime
• Fewer OEM warranty claims

20. Intelligent Hydraulic Cylinders to improve Safety, Efficiency and Control
Best practice to automate a mobile hydraulic
machine to increase safety, efficiency and control
using in-cylinder position sensors.

21. Intelligent Hydraulic Cylinders to improve Safety, Efficiency and Control
Feedback
Command

22. Intelligent Hydraulic Cylinders to improve Safety, Efficiency and Control
Barrel
Rod / Shaft
Magnet
Magnetostrictive
Sensor
Electronic

23. Intelligent Hydraulic Cylinders to improve Safety, Efficiency and Control
- Automation of
work motion
- Programmable
work limits
- Electro-hydraulic
end of stroke
damping
- Track tension

24. Intelligent Hydraulic Cylinders to improve Safety, Efficiency and Control
- Front loader,
parallel guidance
- Cabin
suspension, auto
leveling
- Hitch control
- Suspension
- Steering, steerby-wire,
autoguidance

25. Intelligent Hydraulic Cylinders to improve Safety, Efficiency and Control
Important design features
-
in-cylinder design
Non-contact technology
Sensor/Magnet system
IP 67 sensor
IP 69K connector system
EMI protection 200 V/m
Withstand more then 100oC

26. Best Practices For Mobile Hydraulic Sealing
How OEM Design Engineers Incorporate Sealing Into Hydraulic
Systems On Mobile (Off-road) Equipment
Joel Johnson, Global Vice President of Technology
Simrit, Division of Freudenberg-NOK Sealing Technologies

27. Hydraulic Systems and Sealing – A Very Broad Topic
• There are many items
in a hydraulic system
that require sealing
Hydraulic Remote Controls
Drive Motors
Hydrostatic Drive Pumps
Filters
• We will focus on:
Control Valves
o Pumps
o Motors
o Cylinders
Hydraulic Pumps
Hose & Fittings
Cylinders

28. Hydraulic Systems and Sealing – Relative Motion
• First question - does it reciprocate or rotate?
• Different sealing solutions for each
o An engine turns a pump which converts mechanical energy
into fluid energy
o The pump
• Turns a hydraulic motor which turns a shaft (i.e. an axle)
• Energizes a cylinder that lifts – reciprocating motion

29. Typical Pressure Variation
• What is the pressure range?
Low
o Low pressure – usually less than 50 psi
Medium
o Medium pressure – 50 to 500 psi
o High pressure– 500 to 6000+ psi
High

30. Rotating Application – Elastomer Lip Design
R
adial load distribution and
shearing stress characteristic
in the area of contact
Housing
O ilside
outside
S
tructure
distorted in
circumference
Oil
S
egment
streams
O verall stream
Contact width
Contact
angles
Shaft
a
S
liding motion
b
Radial seals must create a pumping action!

31. How Pressure Effects Seal Designs
Pressure deformation causes increased seal
contact with the shaft, thus increases friction,
heat generation, and wear.
Special Issues with Pressure Seal Applications
Seal must resist lip deformation from internal fluid pressure to minimize friction, wear, and heat.
Seal material should have high mechanical strength.
Special retention and support mechanisms are usually required to resist seal back-out and extrusion.
System eccentricities need to be more carefully considered than with non-pressure seals.
Surface finish parameters may need to change depending upon pressure

32. Typical Low Pressure Seal (BABSL) With 50 PSI Limit
14.5 psi (1 bar)
Deformation
 60

33. Typical Low Pressure Seal (BABSL) With 50 PSI Limit
43.5 psi (3 bar)
Deformation

34. Typical Low Pressure Seal (BABSL) With 50 PSI Limit
101 psi (7 bar)
Deformation

35. Typical Low Pressure Seal (BABSL) With 50 PSI Limit
145 psi (10 bar)
Deformation

36. Unique Designs for Specific PV Ranges
Choose a seal design to match the pressure / velocity curve (PV)
PRESSURE (PSI)
SEAL LIFE
1600
1400
1200
1000
800
600
400
200
High Pressure
Designs
Standard Oil
Seal
Medium Pressure
Designs
0
0
1
2
3
SPEED (RPM X 1000)
4
5
6

37. Application of Seals in Hydraulic Cylinders
Prevention of outside dust invasion
Prevention of external oil leakage
Reduction of high pressure and high temperature
Prevention of internal oil leakage
Piston seal
Restraint of
eccentricity
Wear ring
Contamination seal
Removal of foreign object in oil
Piston
End
Wiper seal
Rod seal
Buffer seal
Rod
End

38. Hydraulic Cylinder Market Requests
•
High Temp - handle continuous 120 degree Celsius upper temp limit
•
High Pressure - capable of 6000 psi (42 MPa) @ 0.5mm diametrical extrusion gap
•
Cold Temp - TR10 of -30º C; - 40º C actual application capability
•
Fluid Compatibility - compatible with standard hydraulic and biodegradable fluids
•
Water and chemical resistance - hydrolisis and glycolosis resistant
•
Retrofit – in North American, DIN, and JIS standard grooves

39. Hydraulic Cylinder Reported Field Problems
Excessive Temperature
•
Hydrolysis / Glycolysis
.
Problem: excessive temperature levels; oil sump temperatures
can be much lower than those by the seal; increased
temperatures due to high friction between seal and running
surface.
Problem: influence of water or glycol at temperatures
over 40 °C break the chemical bonds of the material.
Water can separate from some bio-oils at elevated
temperatures.
characteristics: hardening of material; loss of interference;
often very shiny brown color
characteristics: crumbling material; often matte brown
color can be found either in the oil or filter.

40. Temperature Effect on Long-Term Life
•
Bench test
Field samples
100
100
90
90
80
Rem ai Interference（
ng
％）
•
If conditions are good (no problems with contamination, oil, rod surface, etc.), the packing
usually fails due to loss of remaining interference (wear and material related).
Bench testing can be correlated to actual field test results. Bench test hours are usually less
than actual field hours due to accelerated test conditions.
Our bench testing has shown that increasing or decreasing the system temperature can
increase or decrease the system life by 5 to 20 times.
Rem ai Interence（
ng
％）
•
Low temp
70
Low temp
80
70
5~20 times effect60 life
on
50
with temp change
60
50
40
30
20
High temp
10
40
30
High temp
20
10
0
0
1
10
100
1000
10000
100000
1
10
100
1000
Ti e（ ）
m
ｈ
Ti e（ ）
m
ｈ
Remaining Interference（Rod Seal）
10000
100000

41. Simrit’s Innovative Rod Sealing Solutions
General Description
Detailed Testing Data
Available
110 degree C
Solution
U641
U641

U801
All Urethane sealing system
Potential 5X Life
Increase
120 degree C
Solution
UH05
G928

U641 “all urethane” solution
o Best cost / benefit commercially available
solution on the market
o Seal design handles pressure needs
o Years of lab and field proven results
o Retrofits in existing grooves
o Retrofits in existing tools
o Extremely hydrolysis and glycolysis resistant
o Good low temperature capability (-21 C)
U801
IUY sealing system
UH05 / G928 high temp systems
o Unique 120 deg C capable urethane buffer plus
proprietary HNBR rod seal
o Sealing system handles pressure needs
o Lab tested with exceptional results
o Current production for select cylinders
o Retrofits in existing grooves
o G928 is extremely water and glycol resistant; UH05
has good resistance
o Best low temperature solution (-40 C)

42. Piston Seal Standardization
Different piston designs
 Numerous designs prevent standardization
 Many different piston seal designs are necessary
 No clear optimization based on operating conditions
currently Polyurethane
Target
Polyurethane
Piston design to ISO 7425-1
 Standardization of housing and seal possible
 Substitution - PTFE to Polyurethane or Polyamide
 Substitution - multiple component seal to 2-piece
 Up to 30% cost saving for cylinder / seal
PTFE
Multiple component seals
PTFE
2-piece using PA
Goal: only use 2 piece piston seals and minimize the need for more expensive PTFE seals

43. Standard Sealing Solutions in ISO Standard Sizes
Polyurethane
Housing for piston seals
Simrit offers polyurethane,
polyamide, and PTFE
solutions that can fit into
the ISO 7425-1 piston
housing groove standards
while matching the cost /
performance objectives of
the cylinder.
Fiber re-enforced
Bronze filled
PTFE















PA 6.6 GF
Highest sealing capability
Higher friction than PTFE
Most optimal pricing level
Simple assembly
Up to 40 MPa with correct extrusion gap
Mid sealing capability
Lower to mid friction
For extreme low or high stroke speeds
(<0,05 m/s ... > 0,8 m/s)
For high temperatures (up to 200°C)
Up to 40 Mpa with the correct extrusion gap
Lowest sealing capability
Lowest friction
Rougher surf finishes possible
Capable of running over ports etc.
Used for extreme operating conditions (up to
80 MPa)

44. Standard Designs Matched With Performance Expectations
• Leakage is internal
to the system
• Choose seal design
based on friction
verses sealing
capacity
High
50MPa
Precision
Molded
PA
High
Strength
Bronze
Filled
PTFE
HDP330
Pressure resistance
• The piston seal has
slight leakage
segment
Construction
equipment
Excavator
30MPa
High
Strength
Bronze
Filled PTFE
OMK-MR
98 Shore A
Extrusion
Resistant
Urethane
Simko 300
Wheel loader
Crane
Industrial
equipment
Forklif t
Steel mill
Injection machine
10MPa
Low
Increasing Sealing Capability
Increasing Friction
Electric
product

45. Questions?
Design World
Simrit Division, Freudenberg-NOK
Pall Corporation
MTS Systems, Sensor Division
Paul Heney
Email: pheney@wtwhmedia.com
Phone: 440.234.4531 ext. 104
Twitter: @DW_Editor
Dr. Christian Bauer
Email: Christian_Bauer@pall.com
Phone: 516.801.9139
Joel Johnson
Email: Joel.Johnson@simrit.us
Phone: 847.421.1621 ext. 81222
Haubold “Hub” vom Berg
Email: hub.vomBerg@mts.com
Phone: 919.677.2370

46. Thank You
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