How Do Gears and Pulleys Work Together?

February 9, 2017

Gears and pulleys are two of the founding members of the rotary power transmission family. Built from disc-like components, they manipulate forces by altering their dimensional outlines. The resizing of a gear's diameter, for example, manipulates transmitted power by altering velocity. Similarly, pulleys multiply force by adding wheels to their workings. Interestingly, gears and pulleys can work together. Just how do we pull off this concurrent mechanism?

Coupling Simple Machines

The wheels and looping lines of a pulley transfer linear momentum via rotational action. Similarly, gears use direct-contact teeth to carry power. Pulleys link their rimless wheels by means of ropes, cables, and chains. In order to couple these related processes together, well, an amalgamation of parts is necessary. The gears still function as before, but there's some mechanical discontinuation between the two gears, a space between the two wheels. This gap is spanned by a pulley linkage that loops around the now toothed rim of both gears.

Amalgamated Applications

The gear chain on a bicycle adopts this operational principle. Likewise, gears and pulleys function as composite assemblies in the transmissions of motorcycles and cranes. They're the drive chains that convey power through "sprocket" wheels and turning chains so that elementary vertical movement is transformed into right-angled radial power. Conversely, the same method is used as a means to synchronize discretely operating mechanical innards. Separate rotational subsystems fit this description, assemblies that work independently but require some level of coordinated movement. Vehicle timing belts are a prime example of a meshing rotational system, but this principle also applies to conveyor belts and other forms of processing machinery.

Shaft-Mounted Mechanical Conversion

True pulley systems employ a featureless wheel with a simple rim. The composite gear and pulley add sprockets and specially shaped teeth to the pulley to move chain links instead of rubber belts or ropes. Alternatively, a pure pulley wheel can occupy the same drive shaft as a gearing assembly so that the shaft acts as a simple power converter. In this case, the direct contact spur gears are also turning a pulley wheel, which, in turn, pulls a cable, perhaps to lift an elevator or move a crane cable drum and its rigging.

Everyday examples of amalgamated gears and pulleys function in thousands of separated spur wheels, with sprockets and chains taking on the role of the bridging link. Meanwhile, purebred examples of these meshing components lock together companionably on shared drive shafts to manipulate direct contact radial energy while driving long loops of cable through rimless pulley wheels.

Kelmar Engineering

95 Wayo St, Goulburn, NSW 2580

Phone: (02) 4823 9931


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