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MECHANISMS - Coggle Diagram
MECHANISMS
1 . Machines and mechanisms
We use the word machime to describe a set of elements or parts that work together and use energy to perform a task and obtain a result
Driven element
Converting and transmitting element
Driver element
Devices that transmit and convert motion are called mechanims
Motion transmission mechanisms
Rotary transmission mechanisms
Linear transmission mechanisms
Motion conversion mechanisms
Simple machines :linear transmission mechanisms
The law of lever describes the forces of a lever in equilibrium
Class 2 : E x Ae = R x Ar =R = E x Ae : Ar
Class 3 : E x Ae =R x Ar = E = R x Ar : Ae
Class 1 : E x Ae = R x Ar = E = R x Ar : Ae
Pulleys are used to lift heavy loads . They are wheels with a grooved rim
Fixed pulleys
Moveable pulleys
Example : Weitght of 100 N = F = R = 100 = F = R : 2 = 100 : 2 = 50 N = F = R : 4 = 100 : 4 = 25 N
A lever is a rigid bar that can pivot on a point of support called a fulcrum
3 . Rotary transmission mechanisms
Friction whells are a set of two wheels located one next to the other . Motion is transmitted between the wheels ( driver and driven ) by the friction between them .
The transmission ratio ( i ) is the radio between the size of the friction wheels and the speed of rotation :
i = w1 : w2 = d2 : d1
Where w1 and w2 are the speeds of rotation of wheels 1 and 2 and d1 and d2 are their diametres , respectively .
In toothed wheels , the transmision ratio ( also called the gear ratio ) is calculated according to the number of the teeth on each wheel using this formula :
i = w1 : w2 = z2 : z1
Where w1 and w2 are the speeds of wheels 1 and 2 , and z1 and z2 are the number of teeth on each wheel
Example : Wheel 1rotates at 100 rpm = w4 : w1 = z1 x z3 : z2 x z4 = w4 : 100 = 10 x 10 : 20 x 40 = w4 = 12 , 5 rpm
Chain and sprocket systems
These systems consist of two toothed wheels ( sprockets ) separated by a distance and connected by a chain that meshes with the teeth of the two wheels .
Worm gear
This rotary transmission mechanism consists of a worm that is fitted to the driver shaft and a toothed wheel ( called a worm wheel ) that is fitted to the driven shaft .
i = z1 : z2 = 1 : z2
Where z2 is the number of the worm wheel
Example : Mechanism with 40 teeth that rotates at 100 rpm = w2 : w1 = z1 : z2 = z1 = 1 = w1 = z2 : z1 x w2 = w1 = 100 x 40 = 4,000 rpm
Belt and Pulley
A gear is a mechanism consisting of two wheels with teeth
This system is made up of two pulley wheels joined by a belt that slots into the grooved rim of the wheels
i = w1 : w2 = d1 : d2
Motion conversion mechanisms
Some mechanisms convert motion as well as transmitting it .
Rack and pinion
L = p x z x w
Crank and slider
Screw and nut
Eccentric cam
Cams
5 . Other mechanisms
Ramp
Ratchet
Wedge