R vs F vs K vs S geared motors: how to choose

The four modular series solve the same problem — reducing motor speed and increasing torque — with different geometry.

R series is coaxial helical: input and output shafts on the same axis. It is the first choice when space is tight along the drive axis.

F series is parallel shaft: input and output on parallel axes with offset. It suits high-torque applications where axial space is limited.

K series is right-angle helical bevel: the output axis is at 90° to the motor. It saves space where the drive direction must turn a corner.

S series is helical-worm: a right-angle configuration reaching higher ratios in a single unit, with efficiency falling at very high ratios.

Based on the internal selection database of the joint system, the modular series cover input power from 0.12 kW up to 200 kW depending on series, with typical ratios in the 3–300 range and higher for combined arrangements. Confirm the torque and service factor against your application before selection.