A gear rate reducer is a representative exemplory case of quickness changers, and presently used units could be categorized by the kind of gears, shaft positions and set up of gears into (1) gear reducer with parallel axes, (2) gear reducer with orthogonal axes, (3) gear reducer with perpendicular non-intersecting axes, and (4) equipment reducer with coaxial axes.

Types and mechanisms of equipment reducers with parallel axes
The apparatus reducers with parallel axes use spur gears, helical gears, or herringbone gears. Their input and result shafts are parallel. As for reduction ratios, 1/1 – 1/7 for one-stage shafts, 1/10 – 1/30 for two-stage shafts, and 1/5 – 1/200 for a lot more than three-stage shafts are commercially available. The general characteristics of equipment reducers with parallel axes are as follows :

For high precision gears, the transmission efficiency is very high. (98 to 95% for one-stage equipment reducer)
When correctly lubricated, it can be used for a long period.
Could be produced relatively cheaply as standardized gears are used.
Gear reducers with spur gears are used for increasing swiftness.
The sizes of gear reducers with spur gears are is usually large. In comparison to worm gear reducers with the same acceleration ratio, their outer shapes are large, and the planetary gearbox number of parts increases resulting in constructional disadvantages. Consequently, it can be used for machines with high rotation on the strain side, or which require higher output rotation compared to the primary movers (for increasing velocity). The gear types are demonstrated in Table 2.1.

The apparatus reducers with parallel axes usually use helical gears. They are found in steel facilities, ships, cranes, elevators, and conveyors. As for automation machines, these equipment reducers are also known for geared motors which are equipment reducers with directly connected motors.