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LINEAL TRANSMISSION

Levers:

A lever is a rigid bar that can pivot on a point of support called a fulcrum .It is used to lift load by applying forces to a point on the bar. We call the applied force effort , whereas the load to be lifted or the resitance that must be overcome is known as the resistance.

               

Class 1 Levers  first_class_lever                                                                              

The fulcrum is located between the weight or resistance to overcome and the point where the force is applied.

Class 2 Levers          

With a Class 2 lever, the fulcrum is moved to one end of the lever, with the load in the middle and the force at the other end. Every time you pick up a wheelbarrow you use a class 2 lever, with the wheel’s axle is the fulcrum.

Class 3 Levers 

The effort is located between the fulcrum and the resistance.

Pulleys:

Pulleys are used to lift heavy loads. They are wheels with a grooved rim.

Resultado de imagen de fixed and movable pulley

Moveable pulleys:

 

A movable pulley is a pulley that is free to move up and down, and is 

attached to a ceiling or other object by two lengths of the same rope.

 

Fixed pulleys:

A fixed pulley changes the direction of the force on a rope or belt

that moves along its circumference. 

 

 

 

MOTION CONVERSION MECHANISM

imageSome mechanisms convert motion as well as transmitting it.

  • Screw and nut:

This mechanism consists of a screw and a nut. The rotatory motion of the nut is converted to forward linear motion in the screw.

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  • Rack and pinion

This mechanism consists of a toothed wheel that meshes with a toothed bar. The rotatory motion of the pinion is converted to linear motion in the rack.

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  • Crank and slider

This mechanism consits of a rigid bar that is connected at one end to a crank.

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  • Cams

They are usually elliptical in shape. They are  attached to a shaft and, as they rotate, they drive an element called the follower. A spring keeps the follower in permanent contact with the cam.

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  • Eccentric cam

It is a mechanism similar to a regular cam. Its consist of a wheel where the axis of rotation isn’t the geometrical centre. Its converts rotatory motion into linear reciprocating motion and is used older sewing machines.

eccentric3

ROTATORY TRANSMISSION MECHANISM

 

  • Friction Wheels:

Friction wheels 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.

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Transmission Ratio:

It’s the ratio between the size of the friction wheels and the speed of rotation:

 

  • Belt and pulley system:

The system is madeup of two pulley wheels joined by a belt that slots into the grooved rim of the wheels.

  • Gears

It is a mechanism consisting of two wheels with teeth.

  • Chain and sprocket systems

These systems consist of two toothed wheels separated by a distance and connected by a chain that meshes with the teeth of the two wheels.hola.gif

  • Worm gear:

This rotary transmission mechanism consists of a worm that is fitted to the driver shaft and a toothed wheel that is fitted to the driven shaft.

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