Linear Actuator Troubleshooting: Causes & Fixes

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Problems on this page:

Actuator not reaching its position Actuator moving slowly or stalling Noise or vibration during travel Rod seal leaking or contamination getting in Overload or overtemperature faults Homing failures Vertical load dropping on power loss Wrong actuator after replacement

Actuator not reaching its position

Hits OEE: Quality

Symptoms: The actuator stops short of its target, or positions vary from cycle to cycle.

Load higher than the actuator rating

Check the force needed against the actuator rating, including friction and gravity on vertical axes.

Feedback encoder or position sensor fault

Check the feedback signal and its cable.

Mechanical binding from misalignment with the guided load

Check the alignment between the actuator and the load guide; side loads make it bind.

Position settings changed in the controller

Compare the positions with the saved configuration.

Prevention: Position accuracy checked at the start of each shift on critical axes.

Actuator moving slowly or stalling

Hits OEE: Performance

Symptoms: Moves take longer than the cycle allows, or the actuator stalls mid-stroke.

Screw or nut dry or worn

Lubricate the screw as the maker specifies and check the nut for play.

Supply voltage low at the drive

Check the supply under load.

Current limit set too low

Check the drive current limit against the motor rating.

Debris on the rod or seals

Clean the rod and check the wiper seals.

Prevention: Move times trended from the controller.

Noise or vibration during travel

Hits OEE: Availability

Symptoms: The actuator rattles, squeals or vibrates while moving.

Ball screw or nut wearing

Check the screw for play and plan the replacement.

Coupling or belt between motor and screw loose

Check the coupling or belt drive between motor and screw for play.

Bearing at the screw end worn

Check the end bearing for play and noise when turning the screw by hand.

Mounting bolts loose

Tighten the actuator mounting bolts to the maker torque.

Prevention: Noise checked during planned maintenance.

Rod seal leaking or contamination getting in

Hits OEE: Availability

Symptoms: Dust, coolant or washdown water gets inside the actuator.

Wiper seal worn

Replace the rod wiper seal before dirt reaches the screw.

Protection rating too low for the area

Check the IP rating against the washdown or dust conditions.

Bellows or cover damaged

Replace damaged bellows or covers over the rod or slot.

Breather blocked or missing

Check the breather fitting, since a blocked breather pulls in water through the seals.

Prevention: Seals inspected on the maintenance plan.

Overload or overtemperature faults

Hits OEE: Availability

Symptoms: The drive trips the actuator on overload or temperature.

Duty cycle higher than the rating

Check the number of moves per minute against the actuator duty rating.

Mechanical end stop hit

Check the soft limits so the actuator never drives into its end stops.

Load jammed

Check the guided load for jams.

Motor brake not releasing on vertical axes

Check the brake supply and release.

Prevention: Trips recorded per axis.

Homing failures

Hits OEE: Availability

Symptoms: The actuator does not find home or homes to a different place.

Home switch dirty or loose

Clean and secure the home switch.

Homing by hard stop with the wrong current limit

Check the homing current and method.

Encoder count lost after power cut

Check whether the actuator needs absolute feedback for the application.

Homing settings changed

Compare the homing settings with the backup.

Prevention: Homing checked after maintenance.

Vertical load dropping on power loss

Hits OEE: Availability

Symptoms: A vertical actuator lets the load drift or drop when power is removed.

Holding brake missing or worn

Check that vertical axes have a holding brake and that it holds the load; a falling load is a safety hazard.

Brake wiring fault

Check the brake control wiring.

Screw type back-driving under load

Check whether the screw lead allows back-driving.

Brake not tested

Test the brake holding force at set intervals.

Prevention: Brake holding tested on the schedule the risk assessment sets.

Wrong actuator after replacement

Hits OEE: Availability

Symptoms: A replacement actuator moves wrongly or faults.

Different lead or stroke

Check the screw lead and stroke against the original.

Drive parameters not updated

Load the parameters for the new actuator.

Motor wiring or encoder type different

Check the motor and feedback type.

Mounting position changed

Check the mounting and teach the positions again.

Prevention: Spare part numbers checked against installed actuators.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: stepper motor · servo motor · pneumatic cylinder · encoder · servo drive

Stop the same fault coming back

Recurring linear actuator stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover