A gear rate reducer is a representative example of swiftness changers, and presently used products can be categorized by the kind of gears, shaft positions and arrangement of gears into (1) equipment reducer with parallel axes, (2) equipment reducer with orthogonal axes, (3) gear reducer with perpendicular non-intersecting axes, and (4) equipment reducer with coaxial axes.
Types and mechanisms of gear 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 planetary gearbox 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 offered. The overall 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 utilized for a long period.
Could be produced relatively cheaply as standardized gears are used.
Gear reducers with spur gears are used for increasing rate.
The sizes of gear reducers with spur gears are is generally large. Compared to worm gear reducers with the same rate ratio, their outer styles are huge, and the amount of parts increases resulting in constructional disadvantages. Therefore, it is utilized for machines with high rotation on the strain side, or which require higher output rotation compared to the prime movers (for increasing acceleration). The apparatus types are proven in Table 2.1.
The apparatus reducers with parallel axes usually use helical gears. They are found in steel services, ships, cranes, elevators, and conveyors. As for automation machines, these gear reducers are also known for geared motors which are equipment reducers with directly connected motors.