Gears

Idler

Can be any size and changes the input and output so they rotate in the same direction.

Gears - definition and uses

Gears and gearboxes can be complex. Essentially, they are used to transmit rotary motion in various ways. Gears can be used to: Change direction of rotary motion, Change spindle speeds, Transmit motion through 90 degrees,

Gear Train - meaning

Gears that are linked together are known as a gear train. The simplest form is just two gears whose teeth mesh together.

Spur gear - definition

The most common type, they have straight teeth and are mounted on parallel shafts. Sometimes, many spur gears are used at once to create very large gear reductions.

Compound Gear Train

This type of gear train involves several seperate gear trains that mesh together. This could involove a number of gears positioned on the same shaft. These gear trains can significantly increase or decrease the number of possible rotation speeds.

Helical Gears

To reduce the noise and stress on the gear teeth, most of the gears in your car are helical.

Worm gear

Transmits forces through 90 degrees and are used where large gear reductions are needed (20:1 or even 300:1). The worm can turn the gear, but the gear cannot turn the worm. Useful for machines such as conveyor systems in which the locking feature can act as a brake for the conveyor when the motor is not turning.

Rack and Pinion

Used to convert rotation into linear motion. A good example is the steering system on many cars. As the gear turns it slides the rack to the left or right depending on which way you turn the wheel. Also used in scales to display the weight.

Bevel and Mitre gears

Used when the direction of a shaft's rotation needs to be changed. Usually mounted at 90 degress, but can be designed for other angles also. The have the same noise and stress issues as spur gears unless the teeth are curved.

Simple Gear Train

Uses two gears, if they are the same size with the same number of teeth, the input and output revolutions would also be the same. If one gear was larger than the other the rotational speed would be changed between each gear. The input and output are in different directions, unless an idler is used.

Involute

Mathematical curve that allows the teeth to mesh together properly and helps prevent jamming

Spur gear - applications

Simple gearboxes, washing machines, wind up alarm clock, Speeds can be increased or decreased, Direction of rotation can be changed.