Model: C07 Simple Spur Gear Mechanism
Before the 19th century, spur gears were usually made of wood, except in the case of clocks. These millwork gears had radial hardwood teeth or cogs, usually in the larger gear, called the spur wheel, and spindles or rounds between parallel discs in the smaller pinion gear. Willis credits Smeaton in 1769, as the first to use cast iron in large gear wheel pairs. However spur gears of brass have been found in a first century BCE, Greek calender device called the Antikythera Mechanism.

Behind the two gears is a grounded link connecting the revolute joints on each of the gear centers. This model illustrates that a kinematic chain of three links can have one degree of freedom when one link is grounded, if one constraint between two links has a higher pair as in the gear tooth contact. The circular brass cylinders extending from the two gears on this model were designed to permit the user to ground either one of the gears using the pedestal model H-1. Fixing one of the gears would lead to a planetary motion of one gear rolling on another. Reuleaux designed this model to allow the instructor to illustrate three inversions of one kinematic chain.

Francis Moon 2004-00-00

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