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:explode: Mechanism :explode: (Rotary motion mechanism (Variation in…
:explode: Mechanism :explode:
Linear motion mechanism
Levers
A lever is a rigid bar that is supported by a fulcrum.
R is the resistance or load which acts at the other end of the bar
d is the distance from F to the fulcrum
F is the force or effort appbed at one end of the bar
r is the distance from R to the fulcrum
Types
Class 2
Class 3
Class 1
Law of the lever: F · d = R · r
Pulleys
Types
Movable pulley: F = R/2
Compound pulley
This ts a system of fixed and moveable pulleys, often called block and tackle.
F = R/2n
F = R/n^2
Fixed pulley: F = R
Rotary motion mechanism
Worm gear
Nwheel = Nscrew · Zgrooves/Zwheel
Gear mechanism with a chain
N1 · Z1 = N2 · Z2 -> Z1/Z2 = N2/N1
Gear mechanisms and cogwheels
N1 · Z1 = N2 · Z2 -> Z1/Z2 = N2/N1
Gear train
N4/N1 = Z1 · Z3/Z2 · Z4
Pulleys with belt
They consist of two pulleys or wheels that are a certain distance apart
Pulley trains with belts
N4/N1 = D1 · D3/D2 · D4
Friction drives
N1 · D1 = N2 · D2 -> D1/D2 = N2/N1
N1 and N2 are the velocitiess of the primary drive wheel and the output whee
D1 and D2 are the corresponding diametres
Variation in velocity
Constant
velocity remains constant
Reducing system
velocity is reduced
Multiplying system
velocity is increased
Mechanism that transform motion
From rotary into linear
Nut and bolt system
Winch and crank hand
r is the radius of the winch and d, the length of the crank handle
F · d = R · r ---> F = R · R · r/d
F is the force applied and R, the resistance.
Rack and pinion system
Z is the number of teeth in the pinion.
N is the number of rotations per minute of the pinion
P is the distance between two consecutive teeth in millimetres
L = P · Z · N
L is the velocity of the rack's movement in millimetres per
minute
From rotary into reciprocating motion
Crankshaft
Cam
Crank-link-slide
Eccentric cam
Other mechanism
Mechanisms that store energy
By traction
By torsion
By compression
Connecting mechanisms
Fixed connections
Movable connections
Clutches
Mechanisms for controlling and directing motion
Band brakes
Drum brakes
Disc brakes
Supports: bushings and bearings
Bushings
Bearings
