Cam and Follower | Interview Question and Answers

Cam and Follower | Interview , viva , oral Question and Answers

1. What is cam?

A cam is a rotating machine element which gives reciprocating (or) oscillating motion to another element known as follower

2. Define tangent cam?

When the flanks of the cam are straight and tangential to the base circle and nose circle, the cam is known as tangent cam.

3. What is the classification of followers?

(i) According to follower shape
(ii) According to motion of follower

4. What are the different motions of the follower?

(i) Uniform motion,
(ii) Simple harmonic motion,
(iii) Uniform acceleration and retardation, and
(iv) Cycloidal motion.

5. What is a roller follower? What is a Spherical follower?

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

6. Explain offset follower.

When the motion of the follower is along an axis away from the axis of the cam centre, it is called offset follower.

7. Define trace point in the study of cams.

It is a reference point on the follower and is used to generate the pitch curve. In case of knife edge follower the knife edge represents the trace point and the pitch curve corresponds to the cam profile. In a roller follower the centre of the roller represents the trace point.

8. Define pressure angle with respect to cams.

It is the angle between the direction of the follower motion and a normal to the pitch curve. This angle is very important in designing a cam profile. If the pressure angle is too large, a reciprocating follower will jam in its bearings.

9. Define Lift (or) Stroke in cam.

It is the maximum travel of the follower from its lowest position to the topmost position.

10. Define undercutting in cam. How is occurs?

The cam profile must be continuous curve without any loop. If the curvature of the pitch curve is too sharp, then the part of the cam shape would be lost and thereafter the intended cam motion would not be achieved. Such a cam is said to be undercut. Undercutting occurs in the cam because of attempting to achieve too great a follower lift with very small cam rotation with a smaller cam.

11. What do you know about Nomogram?

In Nomogram, by knowing the values of total lift of the follower (L) and the cam rotation angle (β) for each segment of the displacement diagram, we can read directly the maximum pressure angle occurring n the segment for a particular choice of prime circle radius (R0).

12.What are the classifications of cam based on the follower movement?

1) Rise-Return-Rise (R-R-R) cams,
2) Dwell-Rise-Return-Dwell (D-R-R-D) cams,
3) Dwell-Rise-Dwell-Return-Dwell (D-R-D-R-D) cams,
4) Dwell-Rise-Dwell (D-R-D) cams.

13. What are the different types of cams?

1. Wedge (or) flat cams
2. Radial (or) Disc cams
3. Spiral cams
4. Cylindrical (or) Barrel (or) Drum Cams
5. Conjugate cams
6. Globoidal cams
7. Spherical cams

14.What do you know about gravity cam?

In this type, the rise of the cam is achieved by the rising surface of the cam and the return by the force of gravity of die to the weight of the cam.

15. Define Trace point.

It is a reference point on the follower to trace the cam profile. In case of a knife edge follower, the knife edge itself is a tracing point and in roller follower, the centre of the roller is the tracing point.

16. Define pressure angle.

It is the angle between the direction of the follower motion and a normal to the pitch curve. This is very important in cam design as it represents steepness of the cam profile. If the pressure angle is too large, a reciprocating follower will jam in its bearings.

17. Define Prime circle.

The smallest circle drawn tangent to the pitch curve is known as the prime circle.

18. Define Angle of Ascent.

The angle of rotation of cam from the position when the follower begins to rise till it reaches its highest position is known as angle of ascent. It is also known as out stroke and is denoted by θ0.

19. What is meant by Simple Hormonic Motion?

When a body rotates on a circular path with uniform angular velocity, its projection on the diameter will have simple harmonic motion. The velocity of the projection will be maximum at the centre of and zero at the ends of the diameter. In case of acceleration and retardation, the values will be zero at the centre and maximum at the ends of diameter.

20. What are the different shapes of high speed cams?

1. Circular Arc cam with flat faced follower
2. Tangent cam with reciprocating roller follower

21. Define cam angle.

It is the angle of rotation of the cam for a definite displacement of the follower.

22. What are the classifications of follower based on the follower movement?

i) Reciprocating (or) translating follower.
ii) Oscillating (or) rotating follower.

23. Define Pitch curve.

The locus of the tracing point is known as the pitch curve. For the purpose of laying out the cam profiles, it is assumed that the cam is fixed and the follower rotates around it.

24. What are the classifications of the follower based on the path of motion of the follower?

a) Radial follower.
b) Offset follower.

25. What are the classifications of cam base on the constraint of the follower?

a) Pre-loaded spring cams.
b) Positive drive cams.
c) Gravity cams.