# Basic intuition for motor torque

when shopping on digi-key or other electronics distributor, I can see the Torque - Holding spec, given in oz-in and mNm.

I understand Nm in a torque context when the force is applied as a lever at a distance from the rotation point (for instance when applying 1 N force on a wrench, 20 cm from the rotational point, would give 0,2Nm).

But what does it mean when we are talking about motor torque? It seems to me that it is like opposite: the motor is applying force at the rotational point, so the distance is always 0.

Does it mean motor specs are always measuring the force the motor is applying 1 meter away from it? I am trying to have a good intuition of what Nm mean when looking at motors, because tutorials online only talk about wrenches or other cases when the force is applied away from the ration point.

Thanks a lot!

• How would you calculate the torque if there was a gear of diameter 5cm on the end of the shaft? Commented May 5, 2020 at 5:21
• G=10 (close enough :-) ). Work in kg.m say 100 Nm = 10 kgm. Visualise a 10 kg mass on a 1 marm. You can se the effects of the torque by the bend in a suitable dimentioned arm and measure it with load clls on the arm - or by the ability to make a clamp at the hub slip or ... numberous ways. If you now twist that arm rotationally on a plane at right angles to gravity you will again induce a bend or measured strain or slippage. The same effect results from the same torque. A useful approximation is watts = kg.m x RPM. ie power = torque x rotational speed. ... . Commented May 5, 2020 at 9:33
• ... The above is derived from: "power = force x distance per second" and the units just happen to cancel nicely. |Summary - torque is "twisting power" It doesn't matter how you produce it. Commented May 5, 2020 at 9:33