1. MECHANISMS
UNIT 5

2. Output force and motion
1. WHAT IS A MECHANISM?
Mechanisms transmit and transform motion from an input source (motor) to an output receptor. This transmission and transformation lets us perform different types of work with more comfort and less effort.
Input force and motion
Mechanism
Output force and motion

3. Output force and motion
1.1. Parts of a mechanism:
Input force and motion
Mechanism
Output force and motion

4. 1.2. Classification of mechanisms:

5. 2. LINEAR MOTION MECHANISMS
2.1. LEVERS
A lever is a rigid bar that it is used with a point of support or a fulcrum

6. LAW OF THE LEVER: F X f= R x r F:effort, R:load
TYPES OF LEVERS:

7. EXAMPLES TYPE 1 LEVERS
SCISSORS
SEESAW
PLIERS

8. EXAMPLES TYPE 2 LEVERS
HANDCART
BOTTLE OPENER
NUTCRACKER

9. EXAMPLES TYPE 3 LEVERS
EYEBROW TWEEZERS
FISHING POLE
STAPLER REMOVER

10. 2.2. PULLEYS A. FIXED PULLEYS
A fixed pulley is a wheel that rotates around an axle that is fixed to an immobile surface.
A fixed pulley is balanced when the effort, F, is equal to the load, R
F=R

11. B. Moveable pulleys
A moveable pulley has two pulleys, one is fixed while the other can move in a linear direction.
F = R / 2

12. 3. ROTARY MOTION MECHANISMS 3.1. Friction drive
Made up of two or more wheels that are in contact. The motion of the first wheel makes the other wheel turn, transmitting the motion. The relation between the rotation velocities of the wheels depends on the sizes of the wheels

13. N1: velocity of the primary drive wheel
N2: velocity of the output wheel
D1: diametre of the primary drive wheel
D2: diametre of the output wheel

14. 3.2.Pulleys with belts
These are two pulleys or wheels that are a certain distance apart.
They rotate simultaneously because of the belt.

15. 3.3. GEAR MECHANISMS AND COGWHEELS
Cogwheels are sets of wheels that have teeth called cogs. These teeth mesh together so that one wheel moves the other.

16. N1 x Z1 = N2 x Z2 Z1 /Z2 = N2 /N1
N1 : velocity of the wheel 1 N2 : velocity of the wheel 2 Z1 : number of teeth of the first wheel Z2 : number of teeth of the second wheel

17. 3.4. GEAR MECHANISMS WITH A CHAIN
N1 x Z1 = N2 x Z2 Z1 /Z2 = N2 /N1

18. 3.5. PULLEY TRAINS WITH BELTS
N4/N1 =(D1XD3)/(D2XD4) N1: velocity of the drive pulley N4: velocity of the driven pulley D1, D2, D3, D4: diametres of the pulleys

19. 3.6. GEAR TRAIN N1: velocity of the drive wheel
N4/N1 =(Z1XZ3)/(Z2XZ4)
N1: velocity of the drive wheel
N4: velocity of the driven wheel
Z1, Z2, Z3, Z4: number of teeth in the wheels

20. 4. MECHANISMS THAT TRANSFORM MOTION
4.1. FROM ROTARY INTO LINEAR MOTION
RACK AND PINION L= P X Z X N L: velocity of the movement of the rack
P: distance between two of the teeth, in milimetres.
Z: number of teeth in the pinion.
N: number of rotations per minute of the pinion

21. b) WINCH (AND CRANK HANDLE)
It consists of a crank handle attached to the axle of a cylindrical drum (or winch)

22. 4.2. FROM ROTARY INTO RECIPROCATING MOTION
a) CRANK-LINK-SLIDER
As the wheel rotates, the crank transmits the rotary motion to the link, which moves the slide with a reciprocating motion