Air compressor slows down then belts squeal

by b vecchoini
(chesr va)

when air compressor is running just before pressure is reached it starts to slow down, then the belts star to squeak and the motor hums, have to shut it off to keep from burning off the belts?

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Nov 13, 2018
Squealing belt
by: Bill

Belts are a friction drive device, designed to allow separate sheaves on a drive train to link together, to be misaligned slightly and still work, and to slip when one part or another of the drive is lugging.

In your case it seems to me that the motor is OK since I infer that your belt is slipping on the pump shaft sheave.

What I think is happening is as the load on the pump increases with air being compressed into the tank, and making the pump work harder, your pump is slowing, rather than overcoming the increased load. This, in turn, because the two sheaves are connected with the belt, is trying to slow the motor.

The motor isn't designed to be slowed, so it's trying to keep rotating at its design speed.

Your pump continues to slow as the back pressure increases, the motor has to work harder to overcome this slowing, this is overloading the motor, and ultimately, something has to give. In your case, the motor drive force breaks the friction between the belt and the pump sheave and the belt starts to slip. This heats the belt too, and can soon cause a belt break.

To me, this points to an advancing compressor pump failure.

If your compressor pump is oil lubed, do you have sufficient oil in the sump?

There is normally little that can impede the flow of compressed air from the pump to the tank. There is a check valve at the tank end of that line, and if, somehow, that check valve becomes blocked, or becomes difficult for the compressed air flowing from the pump to the tank to force open, that might, and a very slight might, account for the pump slowing as the pressure builds.

I'm guessing you've got a mechanical problem in your pump. Could be valves, but I suspect it might be more serious than that.

Good luck, and keep us posted, if you will.

Nov 13, 2018
Husky belts keep burning off
by: Nev

Hi I have Rockworth powertask 1.5LT. I have bought good quality belts never get more than three months out of belts before burning off.

I think they are stretching, then start to slip.

No tensioners on these compressors.

If any one knows a cure please let me know as belts are not cheap.

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