Linear Actuator Holding Force

A linear actuator’s holding force is defined as the ability of a linear actuator to hold position typically without power to the motor. Holding force capability for a linear actuator depends on many variables:

Ball Screw or Modified Acme Screw

A ball screw is capable of much higher precision, however, it is not likely to be able to provide holding force unless continuous motor torque is being applied. However, with the selection of a specific lead/pitch of a modified acme screw, the linear actuator’s holding force can be maintained because the angle of the threads provides locking leverage preventing axial rotation of the screw.

Vertical or Horizontal Orientation

A vertical position requires the linear actuator’s holding force to provide additional resistance of the gravity/load combination, whereas a horizontal orientation removes the gravity element.

The Lead or Pitch of the Screw

As noted above, applying the correct lead/pitch selection with the screw allows for a self-locking mechanical advantage.

Axial Loading

The holding force consideration requires the amount of load to be taken into consideration

Mechanical Efficiency of the Screw

Efficiency here refers to how accurate the lead screw and the Nut are matched so that there is minimum play in the system, thus transferring more force and less loss to the axial movement of the actuator.

Motor is Energized or Power Off

If the motors can maintain power in a holding position, then many of the above variables may not be as important because the holding torque of the motor is, in effect, locking the system in place.

Belt or Lead Screw

Using a belt drive versus a lead screw changes the inertia greatly of the system. With a belt drive, either the motor or a braking system must be used to apply the holding force.

Use of Brake

Applying the use of a brake will allow for most variables noted above to be of little concern because the brake will prevent the system from moving in either a vertical or horizontal orientation.

For more information about linear actuator holding force, stepper motor linear actuators, or to discuss your needs for your specific application, please contact our team.