Dept. of Mechanical Engg.
Presented By: Ajay Savita
Roll no: 0928ME121007
Cams are used to convert rotary motion to
oscillatory motion (almost always) or
oscillatory motion to rotary motion (rarely)
For high speed applications – example,
internal combustion engines
Objectives of this chapter:
◦ Learn fundamental concepts and terminology
◦ Learn how to design a cam and follower set to
achieve a desired output motion.
In IC engines to operate the inlet and exhaust valves
Based on modes of Input / Output motion
1 Rotating cam – Translating follower
2 Rotating cam – Oscillating follower
3 Translating cam – Translating follower
a) Radial or disc cam
b) Cylindrical cam
c) End cam
In radial cams, the follower reciprocates
or oscillates in a direction perpendicular to
the cam axis.
In cylindrical cams, the follower
reciprocates or oscillates in a direction
parallel to the cams axis.
It is also
the cam as
shown in fig
Follower is the element to which the motion
of cam is provided
i.e. Reciprocating or oscillating motion
The cam follower rises and falls at a constant speed. The start and stop of the follower is
very abrupt and rough.
Modified Uniform Velocity
The modified uniform velocity motion smoothes out the roughness of the uniform
velocity motion by adding a radius at the high and low points of the cam motion.
The follower motion has a smooth start and stop but the speed is not uniform. This type of
motion is used where the cam rotates at a very fast speed.
The uniform acceleration is the smoothest motion of all of the cams and causes the
follower to maintain a constant speed throughout the cam travel.
1.According to the shape of follower
Knife edge follower
Flat faced follower
Spherical faced follower
When the motion of the follower is along an
axis passing through the centre of the cam, it
is known as radial followers. Above figures
are examples of this type.
When the motion of the follower is along an axis away
from the axis of the cam centre, it is called off-set
follower. Above figures are examples of this type.
1. Reciprocating or Translating
2.Oscillating or Rotating
Cam profile: The outer
surface of the disc cam.
Base circle : The circle
with the shortest radius
from the cam center to
any part of the cam
Trace point: It is a point
on the follower, and its
motion describes the
movement of the
follower. It is used to
generate the pitch curve.
Pitch curve : The path
generated by the
trace point as the
follower is rotated
about a stationery
Prime circle: The
smallest circle from
the cam center
through the pitch
Pressure angle: The
angle between the
direction of the
and the normal to
the pitch curve.
Pitch point: Pitch
point corresponds to
the point of
Pitch circle: A circle
drawn from the cam
center and passes
through the pitch
point is called Pitch
Stroke: The greatest
distance or angle
through which the
follower moves or