Neptune Labs

A moment on a lever arm is just another word for torque — the rotational equivalent of force acting on a bar or pivoted arm.

To calculate moments, we add up all the torques and use the principle of rotational equilibrium to determine unknown forces. In static systems, the sum of clockwise moments equals the sum of counterclockwise moments.

Example:
A gripper finger is applying 800 N downward at a point 6 mm (0.006 m) to the left of the pivot. The part being held resists the motion 100 mm (0.1 m) from the pivot. How much force is being applied to the part?

Using: F1⋅d1=F2⋅d2
800⋅0.006=F⋅0.1
4.8=F⋅0.1
F=48N

Convert to pounds-force:48 N≈10.8 lbf48N≈10.8lbf

✅ Result: The gripper is holding the part with 10.8 lbf of force.