A gear is a toothed wheel that engages another toothed mechanism to change speed or the direction of transmitted motion. Gearmotors will introduce you what are the types of gear. Gears are generally used for one of four different reasons:
- To increase or decrease the speed of rotation
- To change the amount of force or torque
- To move rotational motion to a different axis (i.e. parallel, right angles, rotating, linear etc.)
- To reverse the direction of rotation
Gears are compact, positive-engagement, power transmission elements capable of changing the amount of force or torque. Sports cars go fast (have to speed) but cannot pull any weight. Big trucks can pull heavy loads (have power) but cannot go fast. Gears cause this.
Gears are generally selected and manufactured using standards established by American Gear Manufacturers Association (AGMA) and American National Standards Institute (ANSI). This course provides an outline of gear fundamentals and is beneficial to readers who want to acquire knowledge about the mechanics of gears.
The gears can be classified according to:
- the position of shaft axes
- the peripheral velocity
- the type of gearsthe teeth position
According to the position of shaft axes
Gears may be classified according to the relative position of the axes of revolution. The axes may be:
- Parallel shafts where the angle between driving and driven shaft is 0 degree. Examples include spur gears, single and double helical gears.
- Intersecting shafts where there is some angle between driving and driven shaft. Examples include bevel and miter gear.
- Non-intersecting and non-parallel shafts where the shafts are not coplanar. Examples include the hypoid and worm gear.
According to peripheral velocity
Gears can be classified as:
- Low-velocity type, if their peripheral velocity lies in the range of 1 to 3 m/sec.
- Medium velocity type, if their peripheral velocity lies in the range of 3 to 15m/sec.
- High-velocity type, if their peripheral velocity exceeds 15 m/sec.
According to the type of gears
Gears can be classified as external gears, internal gears, and rack and pinion.
- External gears mesh externally – the bigger one is called “gear” and the smaller one is called “pinion”.
- Internal gears mesh internally – the larger one is called “annular” gear and the smaller one is called “pinion”.
- Rack and pinion type – converts rotary to linear motion or vice versa. There is a straight line gear called “rack” on which a small rotary gear called “pinion” moves.
According to teeth position
Gears are classified as straight, inclined and curved.
- Straight gear teeth are those where the teeth axis is parallel to the shaft axis.
- Inclined gear teeth are those where the teeth axis is at some angle.
- Curve gear teeth are curved on the rim’s surface.