Mechanisms: Bell Crank
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If you want to change the direction of movement or force through 90 you can use a linkage device called a bell crank (so called because it was used in victorian times in linkages used to operate doorbells and servants bells). A common device which uses this mechanism is the brakes of a bicycle. Here the force from the handlebar lever is turned through 90 to squeeze the brake block against the wheel rim.

If the fulcrum is at an equal distance from the input and output then the movement of the output will be equal to the movement of the input. Otherwise the movement will be different and the system will have some degree of mechanical advantage.

Copyright D&T Online 1997

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