Home Chapter 15 Chains, sprokets, belt drives, worm gear, pulleys

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Chains, sprokets, belt drives, worm gear, pulleys


Artists like Tim Hawkinson and Authur Ganson have done works that use gearing and the idea of the gear as an aesthetic.

Chain and Sprocket

This is a positive drive because the drive sprocket will not slip as it drives the secondary sprocket.This is in important consideration if your mechanism cannot slip at all costs.

Small chains and sprockets that can be screwed to a motor shaft are are available from Small Parts Inc


3D model of a chain and sprocket


Belt Drive

With this configuration a connection is made between two shafts, causing one shaft to turn the other shaft in the opposite direction. This is a friction drive, and if the tension of the belt is not accurate, one wheel can slip while the other wheel turns. You can place another wheel on the belt to adjust the tension of the wheel.


Belt Drive


Worm Gear

Worm gears are important mechanisms for large gear reductions. They have a property that no other gear has: the worm can turn the gear, but the gear cannot turn the worm. This makes for a great breaking mechanism when the motor is not turning.


Worm Gear

Arthur Ganson works with complex and often hand made mechanism and is a cross between an engineer and a choreographer. His works vary from highly complex machines that allow a chair to dance through the air, as with Machine with Chair and another work, where the chair seems to spontaneously fly apart etitles Corys Yellow Chair. Other works revel in the beauty of the mechanisms, such as the work Small Tower of 6 Gears, which uses a worm gear to turn all the other gears in a tower of gears.

In the work Thinking Chair, Ganson is using a worm gear to allow a yellow chair to walk around a stone, as if to try and find a place to settle down.


Thinking Chair by Arthur Ganson. 2009. 


Thinking Chair by Arthur Ganson. 2009. 


You can also drive a plate back and forth using a threaded rod (below). This device, connected to a fast-spinning motor, can be an effective way of creating pull string mechanics by attaching a wire or flexible cable to the moving elements.


The plate moves up and down the threaded rod attached to a DC gearhead motor.


A cable or wire can be attached to the moving plate to create pull-string mechanics.


A pulley is a wheel with a groove for a rope or cable to run through. It can be used to reduce the force needed to move an object and also reverses the direction of the force needed to lift the object. The amount of work needed to lift the object remains the same when using a pulley, but the magnitude of the force is decreased because it is spread over a longer distance. Using more than one pulley will make the distance (the rope) longer and less force will be needed to lift the object, yet the workload will remain the same because more pulling of the longer rope will be necessary to lift the object to the same height. There are a number of different pulleys available.




You can find pulleys at Small Parts Incorporated or Grainger and they are available in nylon, delrin plastic, or with a bearing surface that have very little friction. Pulleys can also be used to spin and rotate objects when combined with belts.