WHAT IS A MECHANISM?

Altought these mechanisms are quitte different, they all have something in common. They make work easier because they transmit and transform force and motion.
All of these mechanisms require an input force and motion from some type of source. In the case of a bicycle, our leg muscles are the input source.
Mechanisms transmit motion and force to receptors that finally perform the work.
This is the output force and motion. In the case of an analogue clock, the output receptors are the hands of the clock that move in circles to show the time.


THE PARTS OF A MECHANISM

Mechanisms transmit and transform force and motion from an input source to an output receptor.This transmission and transformation lets us perform different types of work with more comfort and less effort.
CLASSIFICATION OF MECHANISMS

Ø  Transmition of motion:

Linear tranmission: Lever, pulley and block and tackle

Rotary tranmission: Friction wheels, belt drive, gears and chain drive

Rotary-linear: Wheel, rack and pinion, nut and bolt and crank

Reciprocating rotary-linear:  Crank and rod, crankshaft,cam and eccentric cam.

Ø  Motion control:

Direction control: Ratchet and freewheel

Speed reduction: Brake

Ø  Energy accumulation:

Absorption/Dissipation: Spring

Ø  Connection:

Linkage: Clutch

Support: Plain bearing

CONSERVATION OF ENERGY AND WORK IN MECHANISMS

Mechanisms seem to increase force, but they can't create energy on their own. All mechanisms produce the same amount of work that is done to them, including energy that is lost to friction and heat.

If a mechanism increases force, it must decrease motion. Similarly, if a mechanism increases motion, it must decrease force. In this way,energy and work are conserved.