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mechanisms (1.mechanisms are devices that transmit and convert forces and…
mechanisms
1.mechanisms are devices that transmit and convert forces and motion from a driving force or input element to an output element .
they allow us to carry out certain tasks more easily and more efficiently.
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Mechanisms that transmit motion and force in a straight line from one point to another.
Examples include levers and fixed, mobile and compound pulleys.
2.1 Levers: A lever is a rigid bar that is supported by a fulcrum. F is the force or effort applied at one end of the bar. R is the resistance or load which acts at the other end of the bar. d is the distance from F to the fulcrum. r is the distance from R to the fulcrum. The following equation indicates a balanced lever: Fxd=Rxr it is called the law of the lever
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2.2Fixed pulley: A fixed pulley is balanced when the effort F is equal to the resistance of the load, R : F=R 
2.3 Movable pulley: a moveable pulley is balanced when it satisfies this equation: F= R/2
2.4 Compound pulley: this is a system of fixed and moveable pulleys, often called block and tackle. If we use more pulleys, the system becomes more complex, but less effort is needed to move the load. uses : lifts, goods lifts and cranes
- ROTARY MOTION MECHANISMS: these mechanisms transmit motion and effort in a circular way, from the input to the output. They include friction drives,pulley systems,gears and worm gears.
3.1 friction drives: the ratio between the rotation velocity of the wheels or pulleys depends on the relative size of thge wheels. It is expresed by the following equation: N1X D1= N2XD2---- D1/D2=N2/N1
3.2. Pulleys with belt. They consist of two pulleys or wheels that are a certain distance apart. Their axles are parallel and they rotate simultaneously due to the effect of the belt. The rotation of one axle is transmitted to the other through the connected pulleys.
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