$$-$$1

0

1

2

should always be along PQ

Can be oriented along any direction

should always be perpendicular to PQ

should be along QP when the body undergoes pure translation

Grashof’s rule states that for a planar crank-rocker four bar mechanism, the sum of the shortest and longest link lengths cannot be less than the sum of the remaining two link lengths.

Inversions of a mechanism are created by fixing different links one at a time.

Geneva mechanism is an intermittent motion device

Gruebler’s criterion assumes mobility of a planar mechanism to be one.

$$ \le - 1$$

$$0$$

$$1$$

$$ \ge 2$$