Arm on a pivot
Calculator 2
Where the arm's load goes
Example inputs; the calculator updates these with yours. Imperial first, metric in parentheses.
Example inputs from the calculator defaults. Losses ignored.
What the arm looks like
A gearbox at the pivot lifts the arm; gravity is worst when the arm is level.
Schematic, not to scale.
Available torque stays above gravity across this sweep
Failure line appears once the allowable is verified.
Weakest link: lift at horizontal. 3.9x stronger than it needs to lift at horizontal
Show all numbers
How this works
An arm's worst load is at horizontal, where gravity has the longest lever. The tool checks whether the motor can lift it there, what current it takes just to hold, and whether the gearbox and hub survive a stall or a hit.
Gravity torque = mass × g × pivot-to-CG × cos(angle).
A mechanism can be fine at rest and overloaded mid-swing. Gearbox ratings are per stage, and the last stage carries the most torque.
Hang a weight on a test arm, read holding current at three angles, and compare it to the prediction.
Estimates for learning. Losses are ignored. Verify the numbers before relying on them.