Mechanisms

EFFORT- force applied
LOAD - the weight the force is acting on
FULCRUM - the pivot

First Class Levers
The fulcrum is between the load and the effort like a pair of scissors.

• The effort is applied by your hand at one end
• The load is the resistance against the cutting edge
• The fulcrum is the screw which holds the two halves together and allows for movement

Second Class Levers
The Load is applied between the effort and the fulcrum. The effort needed is less than the load because it is a lot nearer to the fulcrum.

other examples include nutcrackers

Third Class Levers
The effort is applies between the load and the fulcrum. The effort needed is greater than the load, but the amount of movement is multiplied. 

This is a simplified version, others include pumping a weight

Cranks 
Convert rotary movement into linear, like a bicycle.

Cams
Converts one type of movement into another.
eg/ a rotary cam converts rotary motion to reciprocating motion (up and down).

stage one and two in a simple mechanism

stage 3 and 4

Springs
Their are four main types of springs.

• resist extension
• resist compression
• resist radial movement
• resist twisting

resists radial movement

resists twisting

Linkages
transfers one mechanical motion to another. Most often used to convert cams to cranks or vice versa. An example is when a metal tool box opens and out pop a load of different levels inside.

one example of the many shapes of linkages.A Push-Pull mechanism

others include;

• Tongs

• Moving Wings

• Push-Pull

Gears
Similar to linkages they transfer one motion to another. The teeth of the gear wheels mesh with each other. They can make things go faster or slower and are used on bikes, hand whisks, bottle openers and toys.They can be used in 3D working models.

Chain and Sprocket
Mainly used in bicycles. As the pedals push the chain links with the sprocket and the wheel turns. This what makes it possible to cycle up hill comfortably.

example of graphically created chain and sprocket.

Pulley
A grooved wheel with a belt running through the groove. The belt stretches making it shock absorbent. They control how fast things run like cassettes and also make lifting heavy weights easier on things such as cranes.

If one wheel is bigger than the other the bigger one rotates more slowly but with more force. A twist in the belt makes the wheels turn in opposite direction.
These can also be digitally created for 3D graphical models.