Gear

Mechanical transmission elements used to transfer motion and power between machine components, Depending on the design and construction of the gear pair employed. Geared devices can change the speed, torque, and direction of a power source. Gears of different sizes produce a change in torque, creating a mechanical advantage, through their gear ratio, and thus may be considered a simple machine.

• By using gear trains, large velocity ratio can be obtained with minimum space.
• Gears are mechanically strong, so higher loads can be lifted.
• They are used for transmitting motion over small centre distance of shafts
  They are used for large reduction in speed and for transmission of torque.
• Gears require only lubrication, hence less maintenance is required.
• Using gear systems, we can transmit motion between non-parallel intersecting shafts.
• They are used for positive drive, so its velocity ratio remains constant.
• They have long life, so the gear system is very compact.