FRC Mechanical


Gears modify and transmit motor power into torque, speed and direction. Two or more gears working together are called a transmission, gearbox, or gearhead. When two gears have unequal number of teeth, then speed and torque will be different. A large gear driving a smaller gear will give more speed, but less torque. A small gear driving a larger gear will give more torque, but less speed. In essence, torque can be traded for speed or vice versa by adjusting the ratio of the gear teeth between the two interacting gears.

Types of Gears

The basic types of gears include:

  • Spur gears – one of the simple and most common type of gear, they are flat with parallel teeth along the edge. They are found in the in the FIRST robot transmissions.
  • Worm gear – capable of very high torque thus harder to back drive, but less efficient than spur gears. These are found in window motors.
  • Rack & Pinion gears – a rack is a long flat bar with teeth, the pinion is a spur gear that forces the rack one way or another. These are found as part of car-type steering systems.
  • Face gears – changes the direction of force only in a right angle. This is how the spinning drive shaft along the length of a car translates at right angles to drive the rear wheels.
  • Bevel/Miter Gears – another way to change the direction of force, but at almost any possible angle
  • Helical Gears – a refinement of the simple spur gear, these are flat gears but with angled teeth. These run quieter and smoother than spur gears.


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    • gerardo sanchez