Gears in Mechanical Transmission

Gears are among the most commonly used mechanical components and are widely employed in mechanical transmission devices. Perhaps the most important reason for their widespread adoption is the remarkable range of power transmission they can accommodate — from tiny gears used in timepieces to large gears for marine turbine engines, gears are capable of reliably transmitting power across this full spectrum.

By selecting different combinations of tooth counts, any desired and precise transmission ratio can be achieved. Additionally, by increasing or decreasing the number of gear pairs in a train, the relative positional relationship between rotating shafts can be freely altered. This enables their use in a variety of shaft configurations, including parallel shafts, intersecting shafts, and non-parallel/non-intersecting (skew) shafts.

Classification of Gears

Gears come in a wide variety of types, and the most common classification method is based on shaft orientation. Generally, they are divided into three categories: parallel-axis gears, intersecting-axis gears, and non-parallel/non-intersecting (skew-axis) gears.

• Parallel-axis gears include spur gears, helical gears, internal gears, racks, and helical racks.
• Intersecting-axis gears include straight bevel gears, spiral bevel gears, and zero-degree bevel gears.
• Skew-axis (non-parallel, non-intersecting) gears include crossed helical gears, worm gears and worm wheels, and hypoid gears.