Gears

Gears

are used in tons of mechanical devices. They do several important jobs, but most importantly, they provide a gear reduction in motorised

equipment. This is key because, often, a small motor spinning very fast can provide enough power for a device, but not enough torque. For

instance, an electric screwdriver has a very large gear reduction because it needs lots of torque to turn screws, bu­t the motor only produces a small

amount of torque at a high speed. With a gear reduction, the output speed can be reduced while the torque is increased.

Another thing gears do is adjust the direction of rotation. For instance, in the differential between the rear wheels of your car, the power is

transmitted by a shaft that runs down the center of the car, and the differential has to turn that power 90 degrees to apply it to the wheels.

Gear Ratio

The gear ratio is the relationship between the numbers of teeth on two gear that are meshed or two sprockets connected with a common chain

Spur Gears

 Spur gears or straight-cut gears are the simplest type of gear. They consist of a cylinder or disk, and with the teeth projecting radially, and although they are not straight-sided in form, the edge of each tooth thus is straight and aligned parallel to the axis of rotation. These gears can be meshed together correctly only if they are fitted to parallel axles.