kilogram-force centimeter

The kilogram-force centimetre is the torque unit of the hobby servo, and its virtue is that the rating reads as a lever. A servo marked 10 kgf·cm can hold 10 kilograms on a 1 centimetre arm, or 1 kilogram at 10 centimetres, and since a servo drives an arm of known length, the datasheet number converts to lifting capacity by mental arithmetic alone. That is why radio-control, robotics and camera-gimbal catalogues have never given the unit up: a standard-size metal-gear servo runs around 10 kgf·cm, which is 0.98 N·m, almost exactly one newton metre.

Torque screwdrivers and small motor catalogues in Asian markets use the same unit one trade over, following the kgf·m of the automotive service literature one decimal place up. The conversions worth keeping at hand: 1 kgf·cm is 0.098 N·m and 13.9 ozf·in, the ounce-inch being what North American catalogues print for the same class of machine, so the two markets' datasheets describe identical hardware with numbers a factor of about fourteen apart.

The motor torque-power-speed solver in this site's power transmission catalog accepts kgf·cm directly, which makes it the quickest check of whether a servo or gearmotor can actually turn the load its datasheet implies, once the caution on this page about stall ratings has been taken seriously.