1. REPORT ON DESIGN AND
ANALYSIS OF UNIVERSAL
Ankit Sahu (14BMA0042)
Utkarsh Anand (14BME0688)
Vivek Patodkar (14BME0326)
2. PROBLEM STATEMENT
8. MACHINING PROCESS
10. DISCUSSION & CONCLUSION
A coupling is a device used to connect two shafts together at their ends for the purpose of
transmitting power. The primary purpose of couplings is to join two pieces of rotating
equipment while permitting some degree of misalignment or end movement or both.
A Universal coupling is a special type of coupling in which misalignment of shafts is
allowed. Shafts are free to move any direction in order to transmit torque or power from
one shaft to another.
In this project work a Universal coupling was designed, in which safe torque on shafts
and pin size of cross determined.
Finally, the Universal coupling made by Mild Steel, which is low cost and available in
Yoke assemblies are one of the most important components in steering system of an
automobile.it generally subjected to torsional stresses and bending stresses due to weigh
of the components. The stresses in either direction, while moving the vehicle to the right
or to the left, happen to be a source of failure of the mechanical joint. The two halves of
the yoke, the web connecting the two halves or the shaft in the linkages are prone to
failure. In such event, the driver could lose control leading to an accident. The steering
yoke being a component posing threat to the ‘safety’ of the vehicle and its occupants, the
design of the same needs to be reviewed for encoring structural integrity. The design
review could look into aspects dealing with the material properties and/or the geometry
of the part/s. For this work no radical change is sought in design and the existing design
shall be reviewed for feasible alternatives calling for minimal changes in the development
or production further.
Ns2 …………………………………………………. Angular velocity of the driven shaft
Ns1 ………………………………………………… Angular velocity of the driver shaft
Θ……………………………………………………. Angle between axes of the shafts
α………………………………………………….... Angle of the driving shaft from the position
where the pins of the drive shaft yoke are
M……………………………………………………Torque applied to shaft
Sb………………………...…………………………. Bearing stress
Ss…………………………………………………. Transverse shear stress
Sc……………………………………………….…. Compressive stress
A…………………………………………………...Cross-sectional area of pin
d………………………………………………...…Diameter of pin
I……………………………………….……….…. Mass moment of inertia
Couplings are mechanical elements that ‘couples’ two drive elements which enables motion
to be transferred from one element to another. The drive elements are normally shafts. We
tend to see lot of applications of the couplings mainly in the automobiles, for example the
drive shaft which connects the engine and the rear axle in a bus or any automobile is
connected by means of a universal joint.
The primary purpose of couplings is to join two pieces of rotating equipment while permitting
some degree of misalignment or end movement or both. By careful selection, installation and
maintenance of couplings, substantial savings can be made in reduced maintenance costs and
There are various types of coupling based on area of application and misalignment or degree
of freedom to move in any direction. Such as the universal coupling allows the shafts to
move in any directions. The different types of alignments are:
Fig.1.1: Different types of alignment
Details about different types of coupling will be discussed latter.
The main objectives of this project work are-
I. To solve a problem related to Universal coupling
II. To design that problem
III. To calculate the safe torque on shaft.
IV. To know about its application.
The main concept of the universal joint is based on the design of gimbals, which have been in use
since antiquity. The first person known to have suggested its use for transmitting motive power
was Gerolamo Cardano, an Italian mathematician, in 1545, although it is unclear whether he
produced a working model. In Europe, the device is often called the Cardan joint or Cardan shaft.
Christopher Polhem of Sweden later reinvented it, giving rise to the name Polhemsknut in
Gaspar Schott ((1664), who called it the paradoxum, but mistakenly claimed that it was a
constant-velocity joint. Shortly afterwards, between 1667 and 1675, Robert Hooke analysed the
joint and found that its speed of rotation was nonuniform, but that this property could be used to
track the motion of the shadow on the face of a sundial. The first recorded use of the term
universal joint for this device was by Hooke in 1676, in his book Helioscopes. He published a
description in 1678, resulting in the use of the term Hooke's joint in the English-speaking world.
In 1683, Hooke proposed a solution to the non-uniform rotary speed of the universal joint: a pair
of Hooke's joints 90° out of phase at either end of an intermediate shaft, an arrangement that is
now known as a type of constant-velocity joint.
The term universal joint was used in the 18th century and was in common use in the 19th century.
19th century uses of universal joints spanned a wide range of applications. Numerous universal
joints were used to link the control shafts of the Northumberland telescope at Cambridge University
in 1843. The term Cardan joint appears to be a latecomer to the English language.
Couplings are mechanical elements that ‘couples’ two drive elements which enables motion to be
transferred from one element to another. The drive elements are normally shafts. Couplings are
used to connect two shafts for torque transmission in varied applications. It may be to connect
two units such as a motor and a generator or it may be to form a long line shaft by connecting
shafts of standard lengths say 6-8m by couplings.
Types of Coupling:
Based on the area of applications there are various types of coupling available. But they are generally
categorized in the following varieties-
i. Rigid Couplings
ii. Flexible or Compensating Couplings
iii. Miscellaneous Couplings
Rigid Couplings are mainly used in areas where the two shafts are coaxial to each other. There are
many types of couplings that fall under the rigid couplings category. They are
i. Flanged Coupling
ii. Muff coupling
Fig : Flanged Coupling Fig : Muff coupling
Flexible or Compensating Couplings :
Flexible couplings are normally used in areas where the coaxiallity between the connecting shafts
is not always assured and in areas where there is a possibility of occurrence of shocks in the
transmission is applicable. They are also called as Elastic Couplings. By construction these
couplings tend to have an elastic member in between the two connecting entities. The different
types of flexible couplings are
Flanged Pin Bush Couplings
Gear Tooth Coupling
Universal Coupling or Hooke’s Coupling (OUR CONCERN)
This group of couplings incorporate design features which are frequently unique,
approximations or combinations of universal, Oldham and flexible shaft couplings. Such as- Jaw
type coupling and Sleeve type coupling.
Universal Coupling or Hooke’s coupling:
A universal joint, (universal coupling, U-joint, Cardan joint, Hardy-Spicer joint, or Hooke's joint)
is a joint or coupling that allows the shafts to 'bend' in any direction, and is commonly used in
shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented
at 90° to each other, connected by a cross shaft. The universal joint is not a constant velocity
Fig : Universal Coupling
A simple brief about Universal Coupling:
A universal joint is like a ball and socket joint that constrains an extra degree of rotational
freedom. Given axis 1 on body 1, and axis 2 on body 2 that is perpendicular to axis 1, it keeps
them perpendicular. In other words, rotation of the two bodies about the direction perpendicular
to the two axes will be equal.
In the picture, the two bodies are joined together by a cross. Axis 1 is attached to body 1, and axis
2 is attached to body 2. The cross keeps these axes at 90 degrees, so if you grab body 1 and twist
it, body 2 will twist as well.
A Universal joint is equivalent to a hinge-2 joint where the hinge-2's axes are perpendicular to each
other, and with a perfectly rigid connection in place of the suspension.
Universal joints show up in cars, where the engine causes a shaft, the drive shaft, to rotate along its
own axis. At some point you'd like to change the direction of the shaft. The problem is, if you just
bend the shaft, then the part after the bend won't rotate about its own axis. So if you cut it at the
bend location and insert a universal joint, you can use the constraint to force the second shaft to
rotate about the same angle as the first shaft.
Fig 2.10: A simple brief about U joint
Types of Universal coupling:
The universal couplings are categorized as-
i. Single joints
ii. Double joints
iii.Telescopic or assembled joints
Single joints Universal coupling:
Precision single joints suit angles up to 45° and speeds to 4000 r/min. Shaft sizes 6 to 50 mm,
dimensions to DIN 808.
Fig : Single Joint Fig : Double joint
Double joints Universal coupling:
Precision double joints suit angles up to 90° and give constant velocity output. Shaft sizes 6 to 50 mm,
dimensions to DIN 808.
Assembled joints Universal coupling:
Telescopic universal joint with plain bearings either to standard lengths or customised to your
requirements. Angles up to 45° per joint and speeds to 1000 r/min, Type HA offers higher
Fig 2.13: Telescopic Joint
Field of Applications of Universal Coupling:
Typical applications of universal joints include-
Medical & optical devices
Textile machineries etc.
Considering cost, strength, ease of access taken into account the selected material for this design is
Machine & Apparatus Required:
Drafting: It’s a pre-manufacturing process in which a replica of the designed prototype is
Fig.4.1: A typical draft Fig 4.2: Gas Cutting
Gas Cutting: Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding,
or gas welding in the U.S.) and oxy-fuel cutting are processes that use fuel gases and oxygen
to weld and cut metals, respectively.
The common methods used in cutting metal are oxygas flame cutting, air carbon-arc cutting, and
plasma-arc cutting. The method used depends on the type of metal to be cut and the availability
of equipment. As a Steelworker, oxygas or air carbon-arc equipment is the most common type of
equipment available for your use.
Facing:Facing is the process of removing metal from the end of a work-piece to produce a flat
surface. Most often, the workpiece is cylindrical, but using a 4-jaw chuck you can face rectangular or
odd-shaped work to form cubes and other non-cylindrical shapes.
facing operation on Lathe machine Turning operation on Lathe machine
Turning:Turning is the removal of metal from the outer diameter of a rotating cylindrical
work-piece. Turning is used to reduce the diameter of the workpiece, usually to a specified
dimension, and to produce a smooth finish on the metal. Often the workpiece will be turned so
that adjacent sections have different diameters.
Grinding:Grinding is a finishing process used to improve surface finish, abrade hard
materials, and tighten the tolerance on flat and cylindrical surfaces by removing a small amount
of material. Information in this section is organized according to the subcategory links in the
menu bar to the left.
Fig.:Grinding operation Fig :Drilling operation
Drilling:Drilling is a cutting process that uses a drill bit to cut or enlarge a hole of circular
cross-section in solid materials. The drill bit is a rotary cutting tool, often multipoint. The bit is
pressed against the work piece and rotated at rates from hundreds to thousands of revolutions
per minute. This forces the cutting edge against the work-piece, cutting off chips from the hole
as it is drilled.
Various Machines were used for several machining processes: -
I. Lathe machine was used for facing, turning.
II. Drilling machine was used for drilling & boring.
III. Grinding machine was used for surface finishing.
IV. Welding apparatus was used to connect different parts at the time of setting up.
To design is either to formulate a plan for the satisfaction of a specified need or to solve a
problem. If the plan results in the creation of something having a physical reality, then the
product must be functional, safe, reliable, competitive, usable, manufacturable, and marketable.
Design is an innovative and highly iterative process. It is also a decision-making process.
Decisions sometimes have to be made with too little information, occasion-ally with just the right
amount of information, or with an excess of partially contradictory information. Decisions are
sometimes made tentatively, with the right reserved to adjust as more becomes known. The point
is that the engineering designer has to be personally comfortable with a decision-making,
A universal coupling (universal joint, or Hooke’s joint) is used to connect two shafts which
intersect but which are not necessarily in the same straight line, as shown in Fig below. The
angular velocity of the output shaft is not equal to the angular velocity of the input shaft, unless the
input and output shafts are in line. The ratio of speeds is given by
Ns2 = angular velocity of the driven shaft
Ns1 = angular velocity of the driver shaft θ=angle
between axes of the shafts
α= angle of the driving shaft from the position where the pins of the drive shaft yoke are in the plane
of the two shafts.
A torque of 40N m is applied to shaft S1 of a universal joint in which S1 and the output shaft S2 are
in the same horizontal plane.
a. Determine the torque on shaft S2 for the position shown in Fig.
b. Determine the size of the pins of the connecting cross for an allowable bearing stress of 14
MPa (per projected area), an allowable bending stress of 140 MPa, and an allowable shear
stress of 70 MPa.
c. Calculate the maximum shear stress on section E-E, which is 50 m from axis Y-Y.
The components of F, acting on the shaft S1, are
and F sin200
The torque acting on the shaft S1 due to the action of the cross is
Mt= ( F cos200
or, 40 = ( F cos200
or, F = 851N
The torque on the shaft S2 is
0.05 =(851)(0.05) = 42.6 Nm. (Ans.)
(1) The size of the pins will depend on the maximum load, which occurs for the position shown.
The maximum pin load is 851N.
Diameter of pin based on bearing:
Sb = F/A
or, 140 * 106
or, d = 10 mm
(2) Diameter of pin bending on based:
s = M c /I
or, d = 7.2 mm
(3) Diameter of pin based on transverse shear:
or, d = 4.6 mm
Therefore, bearing dictates the minimum size of pin; a 10mm diameter pin should be
Mechanical couplings have a principal use in the connection of rotating shafts for the transfer of
rotary motion and torque. As with all mechanical devices, a coupling must match its’ intended
purpose and application parameters, including many different performance, environmental, use
and service factors. There are various reasons for which a coupling fails, such as-improper
installation, excessive vibration, abnormal noise and chattering etc. The failure of coupling can
be minimized by proper maintenance, such as-checking and changing lubricant regularly,
performing visual inspection, checking signs of wear and fatigue and cleaning coupling
Mechanical design is a complex undertaking, requiring many skills. Design and fabrication of a
Universal coupling was done in this project work. In designing problem safe torque on shaft was
determined. The cross pin size (diameter) was determined considering bearing stress, shearing
stress and bending stress taken into account. The application of a universal coupling also studied
in this project work.