Technical DataGearhead



A gearhead mechanism capable of increasing torque by reducing the motor speed. An approximate value can be calculated using the following equation. The reduction ratio has been established for each model. Please see the pages of products.

Motor speed/Reduction ratio =Speed of gear motor

Gearheads Structure

Gearheads are roughly divided into two types of structures.

Planetary Gearhead:Aiming for high torque
Spur type:Thin and quiet design is possible

Gear Efficiency

Gearheads have mechanical loss (gear meshing, bearing friction, etc.). Generally, for each meshing of one stage, an efficiency of 81% for planetary gears and 90% for spur gears is used in calculation. The gear efficiency, however, varies largely depending on such factors as motor torque and speed therefore is presented as a reference value. When used at a lower torque, the efficiency will drop significantly.

An example of calculation of efficiency

・Spur gear 3-stage meshing

efficiency(n)=0.9 ×0.9 ×0.9≒ 0.73(73%)

・Planetary gear 2-stage meshing



The amount of gearheads backlash depends on a play required for smooth meshing and a play between the shaft and the bearing. Note, however, it increases under load due to elastic deformation.