$$-$$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

$$ \le - 1$$

$$0$$

$$1$$

$$ \ge 2$$

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.