BP Boss spindle speed air motor

[jderou]

Anyone know the manufacturer for the spindle speed changer air motor? I need a rebuild kit for it and their are no markings on it.

[machintek]

I will look in the maintenance manual and parts manual to see if it is listed. There is a section in one of those books that has items such as the way lube pump, air regulator and oiler etc. I hope there is something on the air motor. GAST for some reason rings a bell. BPT never had a rebuild kit. As long as the air oiler was working, we did not have a problem with this unit. Have you removed it, shot some oil in the ports, and tried an air hose into each port a couple of times.

George

George

[rboeser]

I'm thinking GAST is correct. If memory serves, Grainger sells GAST. However, I would dismantle the motor and clean it up. All that is in it are vanes sliding in a rotor around an ecentric housing, a very simple design. Really very little can go wrong with it if it has been lubed on occasion and nothing has been run through it (chips, dirt, ect.)

One caution when dismantling, pay attention to the thin film gaskets used on each end, you don't want to tear one. They are plastic film and come in varying thickness to set the side clearance. Just reuse the same ones if they are not torn.

I used to rebuild a larger version of this air motor, it is a simple design, you can fix it.

[jderou]

The main thing is one of the bearings is shot, I figured if I can get a rebuild kit I might as well do it while its apart. I might just try replacing the bearing and see what happens. How long do the vanes typically last? When the rotor is in the housing the vanes do not touch the housing on the side with the most clearance. Is this normal?

[rboeser]

I'd replace the bearings. I have no specs on what is normal, or what the tolerance is. I do know if the vane wears, the power output will go down and the air loss do to the short vanes will be noticable. Eventually you will reach a point where all air is bypassed and the motor will not rotate. I have seen this condition, but it was on a motor used for hours on end every day.

I used to but rebuild kits for the GAST in the larger model. From memory they have only a few basic models that all took the same parts. The difference was in the mounting and shaft options, the insides were the same.

I did make a set of vanes once for an emergency repair. I used UHMW and milled them to size, then used sand paper to round the edge that rides in the outer housing. Also, side paper the sides for a smooth slip fit in the rotor.

[rboeser]

A quick search on Grainger found the following:

http://www.grainger.com/Grainger/rp_...es&from=detail

Make certain that the motor size is correct, my memory has been leaving me lately.

[jderou]

Thanks man!

[rboeser]

Happy to help out, best of luck!