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CRANKS AND CRANKSHAFTS
V. Ryan © 2004 - 2024
 

Cranks have many uses and they can be found in some toys as part of a mechanism or in serious machinery such as car engines. Some cranks are attached to mechanisms that are difficult to turn or rotate.

 

The wind-up mechanism found inside an old gramophone is called a Spring-Driven Motor.

The crank handle is wound up by hand. The energy is stored within the mechanism, in a coiled spring. To release the energy, the handle / spring is allowed to un-wind. This drives the internal mechanism of the gramophone, playing the music on the record.

   
 
The internal energy storage mechanism is seen below.
 
 

The crank acts like a lever, increasing mechanical advantage (the distance between the handle and the central shaft is increased - this makes it easier to turn).

 
 
 

Below is a good example of a crank shaft. When a shaft has two or more cranks it can be called a crank shaft. A typical example of a crank shaft can be found on small mechanical vehicles made for young children. As the child peddles the crank shaft rotates the wheels and the vehicle moves forward.

 

 

 
 
 

QUESTION:

1. Design a toy for a young child the operates with a crank or crank shaft.

2. Explain how a crank shaft on a pedal car makes it easier to move the car forwards.

   
EXAMPLE OF A MECHANICAL TOY BASED ON A CRANK

   
   

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