Elecrolux vacuum motor

[Andrew Gabriel]

Whilst visiting parents, I got called upon to investigate vacuum cleaner. Apparently, whilst being used, the motor started slowing down and giving off a burning smell. I was expecting a motor brush to have worn out, but on investigating, the brushes were fine. The commutator was a bit dirty, which I cleaned up with some fine sand paper, but there was nothing else obviously wrong with the motor. When I had the brushes out, the armature spun very freely in its bearings. Having reassembled it, I ran it for a few minutes without the brush bar belt, and the drive shaft had got hot enough to burn me, although the motor didn't slow down, so I'm not sure if I changed things by cleaning the commutator. Connected back the brush bar and used it for a few minutes -- smell of hot electrics, although it seemed to be working. I had also cleaned the internal filters, but they weren't heavily clogged, and the bag was only a 1/3rd full.

Any suggestions what might be wrong with it? If it's a gonner, would be good to get a new one while the sales are on.

[mrcheerful]

from your description, the motor has a dodgy armature. Check how many amps it is pulling, 5 for a 1000w is correct.

mrcheerful

[BigWallop]

This may have been caused by dirt in the carbon brush holder. If it gets to dirty in there it can cause the brush to stick and not to make full contact with the armature. This causes an arc to form across between them like a welders rod. It also explains the smell of electrical burning and the motor slowing.

If the carbon brush has been allowed to arc for a while it begins to heat the sections on the armature and can damage them to the point of causing a failure on the armature due to the enamel coating on the coil wire being burned off and a short forming across the windings.

The damage caused by an arcing carbon brush may also be the cause of the over heating you're getting on the vacuum motor now. The enamel itself may be at the point of causing a lower resistance path between the armature windings, but not quite at the point of causing a direct short that would probably blow a fuse or cause the motor to stop.

Look at the coil wires on the armature where they meet the brush sections. If the enamel looks to be discoloured, usually a darker brown than the rest of the windings, then the armature will need replaced. You might also see burning marks or lifting off (loosening) on the actual brush sections if they've been allowed to heat to long without remedial work.

[John]

I had an Electrolux upright (bagless) - it had an air cooled bearing! A tube connected to the bearing area to create a low pressure area so that cooling air would be drawn to the bearing area.

[Dave Plowman (News)]

Sounds like an internal short in a winding. Most likely the armature. Difficult to prove without specialist test equipment. Perhaps it's available as a spare?

[Ian Stirling]

may have replacement motor. It's not under guarantee is it?

[Andrew Gabriel]

I'll try that next time I visit, if the vacuum cleaner is still around;-) Didn't have the right tools on me last time.

[Capitol]

Disassemble the motor and separate bearings from armature. Friction between the bearings and the shaft can cause this effect. You can't feel it unless the armature is spun between the fingers. Remember the motor runs at over 10K rpm! The bearings on these units are sealed, try oiling them, takes patience, but can be done. Also check the shaft for burring. If present, remove the worst with a file and then polish with emery. If still a failure, it's probably easier and cheaper to buy a new £20 vacuum cleaner than to buy a new motor.

Regards Capitol