Glossary · Motion control and drives
Holding torque
Also known as: Static holding torque
German: Haltemoment
In stepper motor technology, holding torque is the maximum torque that can be applied to the shaft of an energized motor at standstill, with rated current in the windings, before the rotor is forced out of its position.
- Motion control
In one sentence
Holding torque is the maximum torque an energized stepper motor withstands at standstill with rated current before the rotor slips.
Example
A stepper motor with 0.45 N·m holding torque keeps the vertical adjustment of a camera mount in place while the axis is energized and stationary.
How it applies
- Engineering: Holding torque is the headline figure of a stepper motor datasheet, but usable torque falls with speed. Motor sizing uses the pull-out torque curve, not the holding torque.
- Commissioning: Standstill current reduction lowers the holding torque proportionally. Check that the reduced value still holds the load, especially on vertical axes.
- Operation: When the driver is disabled or the supply fails, holding torque disappears and only the much smaller detent torque remains; a vertical axis can drop.
- Documentation: State the condition behind the value (rated current, both phases energized). For vertical or loaded axes, warn that the axis is not held without power unless a brake is fitted, and describe the resulting hazard in the Instructions for use (IFU).
Holding torque vs. detent torque
Holding torque requires current in the windings. Detent torque is the small torque felt at the shaft of an unpowered motor, caused by the permanent magnets; see Cogging torque. Detent torque is typically only a few percent of the holding torque.