McClean: RollerDrum BrushReplacement

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So the roller drum has stopped doing what it does so well---that is, roll around a bunch of tubes. Why oh why is this happening? First thing to check (thanks to the all-knowing Dr. Silverman for letting me in on this) is if the motor brushes need to be replaced.

What, you ask, is a motor brush. The motor brushes transfer power to the motor's commutator. They do not, in fact, look anything like a brush. Some basic explanations can be found in the links below.

The are made of graphite, and push against the commutator. They are made to wear down, so they need to be replaced.

The worn brush at the bottom of this picture caused the roller drum to stop spinning. Contrast with the new brush at the top of the image.


You will need the following to change the brushes in the lab roller drums:

  • New brushes (Menards #66722 Brushes)
  • Philips head screwdriver
  • Flat head screwdriver
  • 7/16 in. combination wrench (Can be checked out from the student shop)
  • Beaker or similar to collect screws as your remove them

Everything is available in our lab's toolbox, except for the brushes and the combination wrench. The combo wrench you can check-out from the student shop with your Green Pass, or similar. The brushes are in the "spare parts" drawer, or you may need to order more.

You will need the items shown here except for the Hex keys. I was just too lazy to take a new picture without them.


  • Begin by removing the back cover of the roller drum. There are four screws to remove using the philips head screwdriver. Throw them into a beaker or something else so that they don't go rolling away.
  • Once the screws are removed the cover should come off easily. Remove it gently so that you don't rip off the (green) grounding wire.
Green wire is grounded to the back cover. If you are careful you can work around it.
  • Inside you will find the motor at the bottom, attached to the belt that drives the wheel.
  • We need to loosen the motor by undoing the two screws that hold it to the casing. You will do this using the 7/16" wrench. See the pictures to locate the screws.

  • Once the motor is loose, remove the belt. Find where the two brushes are located (see picture). The are directly across from each other and one is much easier to reach than the other. In fact, if you are lucky and only need to change the "front" one, you won't need to undo the motor from the housing. Use the flat-head screwdriver to remove the cap covering the brush.
This is one motor brush hidey-hole. There is another one directly opposite it at the back of the motor.

  • Remove the old brush. If it is worn down, replace it with a new brush. Replace the cap.
The spring on the brush should pop out and make it very easy to remove the old brush.
  • Replace the belt. Reattach the motor to the housing. Use the wrench to tighten the two screws holding the motor to the housing.
  • Replace the back cover.
  • Voila! If it was the brushes, your roller drum should roll once more.

Helpful Links


Please feel free to post comments, questions, or improvements to this protocol. Happy to have your input!

  1. List troubleshooting tips here.
  2. You can also link to FAQs/tips provided by other sources such as the manufacturer or other websites.
  3. Anecdotal observations that might be of use to others can also be posted here.

Please sign your name to your note by adding '''*~~~~''': to the beginning of your tip.

*Megan N McClean 17:11, 7 May 2015 (EDT): This is a bit of a greasy job as you can see from my fingers in the above pictures. You might want to wear gloves. I preferred to just get greasy and then wash my hands, because it was easier for me to grab screws, etc without gloves on.


or instead, discuss this protocol.