A gear swiftness reducer is a representative exemplory case of quickness changers, and presently used products can be categorized by the kind of gears, shaft positions and arrangement of gears into (1) gear reducer with parallel axes, (2) equipment reducer with orthogonal axes, (3) equipment reducer with perpendicular non-intersecting axes, and (4) equipment reducer with coaxial axes.
Types and mechanisms of equipment planetary gearbox reducers with parallel axes
The gear reducers with parallel axes use spur gears, helical gears, or herringbone gears. Their input and output shafts are parallel. For decrease 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 obtainable. The overall characteristics of gear reducers with parallel axes are as follows :
For high precision gears, the transmitting efficiency is quite high. (98 to 95% for one-stage equipment reducer)
When correctly lubricated, it can be utilized for a long time.
Could be produced relatively cheaply since 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. Compared to worm equipment reducers with the same quickness ratio, their outer designs are 
large, and the number of parts increases leading to constructional disadvantages. For that reason, it is used for machines with high rotation on the load side, or which need higher output rotation compared to the primary movers (for increasing rate). The gear types are shown in Table 2.1.
The gear reducers with parallel axes usually use helical gears. They are used in steel services, ships, cranes, elevators, and conveyors. As for automation machines, these gear reducers are also known for geared motors which are gear reducers with directly connected motors.