ROTARY MOTION

Definition of Rotary Motion

Rotary motion can be defined as change in position around a fixed axis, like the motion of the blade of a ceiling fan or the tyre of a moving car. There are two types of rotary motion, namely:

(i) One way rotary motion: This allows continuous rotation and can only be brought to rest by the application of a brake. When rotary motion is constrained to only one direction (i.e. either clockwise or anti clockwise only), it is described as a ‘one-way’ rotary motion.

It may be intermittent as in the seconds’ arm of a mechanical clock or continuous as it is with the rotary motion of a crankshaft or armature of a generator. Electric fans, grinding machines, milling and many other industrial machines, operates on one-way rotary motion.

A change in the direction of a one-way rotary motion of the moving part usually leads to a big problem or even disaster. For example, changing the direction of motion of a radiator fan leads to over-heating of the engine; reversing the rotation of the circular saw blade will not only produce a cut but will also damage the blade.