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Which of the following mechanisms are examples of force closed kinematic Pairs? A. Cam and roller mechanism B. Door-closing mechanism C. Slider-crank mechanism

Which of the following mechanisms are examples of force closed kinematic Pairs? A. Cam and roller mechanism B. Door-closing mechanism C. Slider-crank mechanism Correct Answer A and B only

Self-closed pair:

When the two elements of a pair are connected together mechanically. The contact between the two can be broken only by destruction of at least one of the members.

All lower pairs and some higher pairs are closed pairs. Sliding pairs, turning pairs, spherical pairs and screw pairs are also closed pairs.

Forced-closed pair:

When two links of a pair are in contact either due to force of gravity or some spring action. In this, the links are not held together mechanically e.g. cam and follower pair (because spring is used to keep the motion constrained).

Door closing mechanism, has a torsion spring loaded follower in contact with door.

Slider-crank mechanism does not require such force.

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