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Anyone rebuilt a gear pump?

I'm trying to fix a worn Parker D17AA2A hydraulic gear pump for my tractor. As bought (for $20) the max pressure was less than 200 PSI. I found the aluminum end plate opposite the shaft worn away 0.010" by the gears. The bronze plate on the shaft end looks pretty good(???).

I milled the end plate smooth, routed the O ring groove deeper and shortened the gears by about 0.0007" with fine sandpaper, so the shaft still turns by hand when I bolt the housing together. A sandpaper donut removes close to 0.0001" when squeezed between the endplate and the spinning gear, in the mill.

Does that sound right? This sleeve-bearing pump only needs to work until I make and harden another involute splined broach to fit a new steel pulley onto my other pump.

jsw

Reply to
Jim Wilkins
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With that much wear on the end you may have a lot of play in the bushings. So the gears cut into the center section and leak oil between the teeth and housing. the only fix for that is a new pump.

Reply to
Ralph

Air-cooled VW oil pumps are quite the same, although not nearly as high pressure. What you've outlined is the basic overhaul for one. Remove grooves from the end plate, make the housing zero-clearance with the gears endwise and shim the cover with a gasket to get free running. If the gears are chewed up, replace with a new set. If the housing is chewed up, replace the pump. The way most guys did the gears and housing was to get a sheet of fine wet-or-dry, put it on a flat surface, a table saw would do, and sand until the gears and housing had the same pattern of scratches. Done. I've built a couple of new ones this way with no problems.

As the other poster said, check your shaft and bushing for wear, same with gears. I suppose you could bore and sleeve the shaft bearing with an under-sided sleeve and maybe grind the drive shaft down, but how much time do you want to spend on what's really a fungible item?

Stan

Reply to
stans4

Thanks. The end wear was all I saw, elsewhere the gears and shafts have a mirror polish, including the other end which presses against a bronze plate.

I can usually figure out how to make something broken work again, but in this case I have no experience to predict how long it will hold up, or how much clearance is right.

I have resleeved and bored a pump before, which taught me that the play in the quill of my mill increases as it extends, IOW it bores a slight taper. The knee feed fixed that.

jsw

Reply to
Jim Wilkins

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