How to Replace a Mando Alternator Brush Used on StarTrac Fitness Equipment

This procedure demonstrates how to change the brushes of a Mando alternator that is used on StarTrac fitness equipment such as bikes and steppers. It is not necessary to remove the alternator from the machine to remove/install the brushes

  • To replace or inspect the brushes you must first remove the brush cover as shown in the video. It is attached with two nuts and a screw. Remove them and then remove the cover as shown in the video
  • Once the cover is removed you will notice the black rubber seal, this should be included with your new brushes. If not it can be re-used
  • You will still have two screws holding the brush assembly in place. Remove them and then you may need to use a screwdriver to pry up on the brush assembly as shown in the video to get it to come loose. The brushes shown in the video are new; This is not what a used pair of brushes will look like. Worn brushes will have a rough surface as well as being shorter than this pair. Generally, worn brushes will also leave quite a bit of carbon dust in the alternator which can increase resistance between the brushes and the commutator. Therefore it is always a good idea to use a commutator stone as shown in the video to clean up the surface of the commutator before installing a new set of brushes
    • Note: Using forced air to blow the carbon dust out of an alternator is not good practice. It can release the powder carbon into the air and inhalation of this can be harmful. Use of a vacuum with small attachments is the only safe option
  • First, locate the surface of the commutator by noting the surface the brushes rub against when installed. Focusing on one side of the surface at a time, spin the alternator pulley a few times while holding slight pressure against the commutator with the commutator stone. Doing so will clean and prepare a fresh surface for the new brushes to make contact with
  • There are two versions of the Mando alternator brush assembly
    • The version one brush assembly has a 1/4" height from the base where the rubber seal sits to the top of the brush housing as shown in the video
    • The version two assembly measures 13/32" from the rubber seal seat to the top of the brush housing, which is also shown
  • To reinstall the brushes place them as shown in the video and hold them in place while replacing the screws in the brush assembly
  • Now place the cover over the brushes and re-install the screw and two nuts. Once the cover has been replaced the procedure is complete
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