Saturday, July 23, 2011

Hatch Actuator Rebuild

     The engine room hatch lift mechanism is based on an electric linear actuator. I have read a few horror stories about these failing, so I thought it would be best to rebuild it before installing it in the boat. And it's a good thing I did, because when I opened up the gearbox, it was filled with water!
     What a mess. Fully disassembled, it looks like this:
     I took all the parts and washed them in my parts cleaner, and then assessed the gears and shafts for wear or damage. Fortunately, everything was in very good condition, with one exception. There is an override clutch built into the gearbox that uses 6 bearing balls, 2 dimpled plates, and a belleville spring for tension. When the actuator reaches the end of its travel, the override clutch allows the motor to keep turning, so that no binding or breakage occurs. It also emits a rather loud ratcheting sound, so the operator knows the travel limit has been reached. In my case, the balls in the clutch were no longer round, but had flat spots. Fortunately, I had a pack of 100 bearing balls from a previous project in stock, and they were the right size! (0.250" diameter).
     Once the clutch was rebuilt, I cleaned the housing and back plate:
     and reassembled the clutch:
     Then, I repainted all the components, cleaned and lubricated the gears, packed the housing with synthetic grease, and reassembled the actuator:

     Don't forget to also lubricate the screw and guide bushing at the top of the actuator, and replace the shaft seal. I also sealed the housing with a bit of silicone sealant, to keep the moisture out.
     As for the drive motor itself, I disassembled it, polished the commutator, lubricated the armature bearings, and reassembled it. It was clean inside, and the brushes had minimal wear, so nothing much had to be done here. Just need to install it now....


  1. Thank you for this great tutorial! Thought I might share this website I came accross which I found very useful to compare products and brands:

  2. Hi, i am not sure if your blog is still active, i just stripped down my actuator but could not get the main cog off that the clutch sits under.
    Can you remember how you dismantled it.
    Mine is working again but the clutch comes in far to early, i would like to replace the bearings.
    many thanks

  3. John,

    I don't recall exactly how I disassembled the clutch, but I do recall it was quite straightforward. If your clutch balls or plates are worn, that would induce the symptoms you are experiencing. It is also possible that the spring is worn or broken.

  4. need to resurrect this thread.. i have the same actuator and my clutch went bad on it ... grr... can u explain what u mean by spring in the clutch ??? i took mine all apart and no spring in there .. just plates that are cupped. the bearings , the plate they sit inside and another plate that has dimples in it .. i called around and they want want 90-150 for a new clutch ... i bout dropped over when they told me that... let me know of any solutions i can try to fix my clutch my self.. ohh i did think of adding shims to the top of the plates to put more pressure on them and the bearings.. let me know what u think... thanks in advance

  5. I ordered a new one for my 1998 330 and the mount that came with it was different it was at a 90 degree angle not sure how to fix this problem