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

Anyone rebuilt a gear pump?
 

On 1/6/2011 6:05 PM, Jim Wilkins wrote:
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

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.

Anyone rebuilt a gear pump?
 

On Jan 6, 5:05*pm, Jim Wilkins wrote:
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

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

Anyone rebuilt a gear pump?
 

On Jan 7, 4:40*pm, wrote:
On Jan 6, 5:05*pm, Jim Wilkins wrote:





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

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

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