Important Short Questions and Answers: Kinematics of Cam Mechanisms Cams

1.  What is a cam? Give some examples?

A Cam is a rotating machine element, which gives reciprocating or oscillating motion to another element known as follower. Examples are:

Radial or Disc, Cylindrical or Barrel, End or Face cams and Wedge cams.

2.     What is the Classification of cams?

·        According to cam shape

·        According to follower movement

·        According to manner of constraint of the follower

3.     Classify cams based on their shape.

•   Wedge cam   •        Radial cams          • Spiral cams

•   Drum cams   •        Spherical cams    

4.     What is the classification of followers?

(i)              According to follower shape

(ii)             According to motion of follower

5.     What is a roller follower?

In place of a knife edge roller is provided at the contacting end of the follower

6.  What is a Spherical follower?

In the contacting end of the follower is of spherical shape.

7.  What is meant by angle of ascend?

The angle of rotation of the cam from the position when the follower begins to rise till it

reaches its highest points. It is denoted by θ

8.  What is meant by angle of descend?

The angle through which the cam rotates during the time the follower returns to the initial

position. It is denoted by θr.

9.  What is angle of dwell?

It is the angle through which the cam rotates while the follower remains stationary at the

highest or the lowest.

10. What is meant by angle of action?

The total angle moved by the cam during its rotation between the beginning of rise and the end of return of the follower.

11. What is radial or disc cams?

In radial cams the follower reciprocates or oscillates in a direction perpendicular to the

cam axis. The cams are all radial rams. In actual practice, radial cams are widely used due to their simplicity and compactness.

12. What is dwell?

The zero displacement or the absence of motion of the follower during the motion of the

cam is called dwell.

13.            What are the classifications of follower according to follower shape?

·     Knife edge follower

·     Roller follower

·     Mushroom or flat faced follower and

·     Spherical faced or curved shoe follower

14.            What are the classifications of follower according to the motion of the follower?

·     Reciprocating or translating follower

·     Oscillating or rotating follower

15.            What are the classifications of followers according to the path of motion?

·  Radial follower                            

· Offset follower

16. What is the motion of the follower?

The follower can have any of the following four types of motions

Uniform velocity

Simple harmonic motion

·   Uniform acceleration and retardation · Cycloidal motion.

17. What is the application of cam?

Closing and opening of inlet and exit valve operating in IC engine .

18. What are the necessary elements of a cam mechanism?

Cam-The driving member is known as the cam Follower-The driven member is known as the follower. Frame-It supports the cam and guider the follower.

19. Where are the roller follower extensively used? (Ap/May-2008)

Roller followers are extensively used where more space is available such as in stationary gas oil engines and aircraft engines.

20. Write the formula for maximum velocity.

Vo (max) = 2ωs

θo

Vr (max) = 2ωs