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Consider the following statements regarding cams : 1. A cam in which the follower moves radially from the centre of rotation of the cam is known as a disc cam. 2. A globoidal cam is a double-disc cam, the two discs being keyed together and are in constant touch with the two rollers of a follower. 3. A conjugate cam can have two types of surfaces, convex or concave. 4. In a spherical cam the follower oscillates about an axis perpendicular to the cam, the axis of rotation of the cam. Which of the above statements are correct?  

Consider the following statements regarding cams : 1. A cam in which the follower moves radially from the centre of rotation of the cam is known as a disc cam. 2. A globoidal cam is a double-disc cam, the two discs being keyed together and are in constant touch with the two rollers of a follower. 3. A conjugate cam can have two types of surfaces, convex or concave. 4. In a spherical cam the follower oscillates about an axis perpendicular to the cam, the axis of rotation of the cam. Which of the above statements are correct?   Correct Answer 1 and 4 only

Explanation:

Cams are classified according to:

  • shape
  • follower movement and
  • manner of constraint of the follower.

According to shape

  • wedge and flat cam,
  • radial or disc cam 
  • spiral cam
  • cylindrical cam
  • conjugate cam
  • globoidal cam
  • spherical cam.

Globoidal cams:

  • A globoidal cam can have two types of surfaces, convex or concave.
  • A circumferential contour is cut on the surface of rotation of the cam to impart motion to the follower which has an oscillatory motion.
  • The application of such cams is limited to moderate speeds and where the angle of oscillation of the follower is large.

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Radial or Disc cams:

A cam in which the follower moves radially from the centre of rotation i.e. perpendicular to the axis of the cam is known as a radial or disc cam.

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Conjugate cams:

It is a double-disc cam and is preferred when the requirements are low wear, low noise, better control of the follower, high speed, high dynamic loads, etc.

Spherical cams:

In a spherical cam, the follower oscillates about an axis perpendicular to the axis of rotation of the cam.

Note that in a disc cam, the follower oscillates about an axis parallel to the axis of rotation of the cam.

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