1.WHAT IS A MECHANISM?

 

               
  1. WHAT IS A MECHANISM?

The moving parts of a bicycle are examples of everyday mechanisms:

• The chain of a bicycle transfers motion to the back wheel.
• The bar of a seesaw forms a lever that we can use for fun.
• The gears inside old-fashioned clocks let us measure time.
• The pulley system above a well helps us to bring up water.

They make work easier because they transmit and transform force and motion.
All of these mechanism 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. 

1.1. The parts of a mehanism.
Mechanisms transmit and transform force and motion from an input source (motor) to an output receptor. This transmission and transformation lets us perform different types of work with more comfrt and less effort.


Input of force and motion➨Mechanism➨Output force and motion

1.2. CLASSIFICATION OF MECHANISMS 
We can classify mechanisms by the work that they do and how they function.                        

Transmission of motion:

• Linear transmission  ➙ Lever, pulley and block and tackle.

• Rotary transmission➙ Friction wheels, belt drive, gears and chain drive.

Transformation of motion:

•  Rotary-linear➙Wheel, rack and pinion, nut and bolt and crank.
• Reciprocating rotary-linear➙Crank and rod, crankshaft, cam and eccentric cam.

Motion control:

• Direction control➙Ratchet and freewheel.
• Speed reduction➙Brake. 

Energy accumulation:

•  Absorption/Dissipation➙Spring.

Connection:

• Linkage➙Clutch.
• Support➙Plain bearing.

1.3. 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.