Skip to content Skip to navigation


How do I repair or replace a PPA actuator in my machine, RV, trailer or boat?

If you have determined that your linear actuator is either not functioning properly or requires partial or complete replacement, we recommend following these simple steps to identify and replace your actuator or its parts:

Contact the manufacturer of the equipment into which the actuator is installed for repair parts or actuator replacement.

If the manufacturer of your machine is no longer in business, you may attempt to match the actuator you are trying to repair with Thomson’s standard product line. Oftentimes, an actuator is modified or customized for an application such as yours and is available only to equipment manufacturers in large quantities. If that is determined to be the case, there may not be a current standard offering that will fit your application as a replacement.

PPA assembly

When attempting to identify your actuator, if you find that it looks similar to the model above, it is likely an Electrak® PPA. This model features a modular design consisting of a motor/gearbox and lift assembly.

Combinations of the various motor/gearboxes and lift kits create different actuators that have different load/speed, voltage, feedback and stroke lengths. If you find a 7-digit part number starting with "57" or "78" on the motor/gearbox, that applies only to the motor/gearbox.

Replacing the Motor/Gearbox

If you need to replace the motor/gearbox only, the 7-digit part number can be searched on to find a possible replacement. If the part number cannot be found for the motor/gearbox, it may be possible to match up the voltage and gear ratio to a current PPA actuator model.

To determine the ratio of the actuator, the travel rate or load capacity needs to be determined. It will either be 1.1 in/s (18:1 ratio, 750 lb capacity) or 0.37 in/s (58:1 ratio, 1500 lb capacity). If the speed isn't known or not possible to measure, the unit can be disassembled and the gear teeth counted. If the output gear is Delrin and has 52 teeth, then it has an 18:1 ratio. If it has 68 teeth, it has a 58:1 ratio. If the gear is steel, these ratios (17:1 and 55:1) are no longer used or available. However, the closest current gearbox can be used. If the output gear has 70 teeth, use an 18:1 ratio, and if the output gear has 91 teeth, use a 58:1 ratio.

With the voltage and gear ratio determined, use the links below to view available replacement motors/gearboxes:

If your actuator has an extra 2-in-long section at the back of the motor (see diagram below) the unit has sensor options. In this case, it is recommended that you purchase a complete actuator assembly. See the order code in the “Replacing the Complete Actuator” section below.

Actuator with 2” section for sensors.

Replacing the Lift Assembly

To identify the lift assembly needed for your actuator, the stroke of the unit needs to be determined. With the actuator retracted, measure the "B" dimension found below and refer to the table to obtain the stroke.

If the "B" dimension is significantly different than those in the table, the actuator may feature a special stroke and is not available for purchase. You may try a standard stroke unit, but Thomson is unable to provide advice on compatibility.

With the stroke determined, view available replacement lift assemblies at the following link: Lift Kits
To purchase a complete replacement actuator, the part number can be built using the order codes below:

Order code for DC versions

Order code for AC versions
Once you have a complete part number, you can enter it into a search at

The Thomson Electrak PPA installation manual can be found here: link
back to top