Pump gear what if?

[cosworth34677]

By now yall know I like the play around trying silly stuff, well I was thinking , if got two pinion gears that are the same size and pitch of the ones in my magom pump and just cut down or off the shank with the screw they should work to replace worn brass gear?

[sparkycuda]

It's possible. Precision is the key to pumps. Clearances between tooth-end to case and gear-end (side clearance) to case are the critical measurements - they must be as close as possible to prevent oil from "slipping" by. Since you are rebuilding a pump, there might be wear that must be compensated at both tooth-end and sides. Don't know the original specs for the Magom pump, but tooth-end to case is probably .001" - almost touching. Side clearance is probably similar. If your case is worn it could be reworked to clean up the tooth-end area (outer diameter of the gears) - again, a very precise operation. If side clearance area is worn, the end plate could be ground flat to give a good sealing surface, but precision is key.
Since pumps are normally hand fitted during assembly, I can't predict what your success will be. A few years ago, someone on the Forum built a gear pump from scratch (don't remember who) and had some decent level of success. Maybe your repair will work.
Forgot to ask - how badly worn is your original pump? Is it not pumping well? Low flow or pressure or both?

Good luck!

Ken

[cosworth34677]

Originally Posted by sparkycuda

It's possible. Precision is the key to pumps. Clearances between tooth-end to case and gear-end (side clearance) to case are the critical measurements - they must be as close as possible to prevent oil from "slipping" by. Since you are rebuilding a pump, there might be wear that must be compensated at both tooth-end and sides. Don't know the original specs for the Magom pump, but tooth-end to case is probably .001" - almost touching. Side clearance is probably similar. If your case is worn it could be reworked to clean up the tooth-end area (outer diameter of the gears) - again, a very precise operation. If side clearance area is worn, the end plate could be ground flat to give a good sealing surface, but precision is key.
Since pumps are normally hand fitted during assembly, I can't predict what your success will be. A few years ago, someone on the Forum built a gear pump from scratch (don't remember who) and had some decent level of success. Maybe your repair will work.
Forgot to ask - how badly worn is your original pump? Is it not pumping well? Low flow or pressure or both?

Good luck!

Ken

Well it will work but there is no lifting power, the pump is a older magom pump still has the brass gears , I know now they make all there gear harden steal . It's funny it more as like it's working fine but there is no power

[sparkycuda]

I believe the gear material has more to do with longevity and wear than performance, if all dimensions of pump housing, gears, tolerances, etc. are equal. Hydraulic pump efficiency is determined by measuring flow (gal/min, cc/min, etc)) at no pressure and then again under rated pressure: pressurized flow rate divided by free flow rate = % efficiency. Gears pump should be 85% or higher. If lower, it indicates that oil "slippage" is high - internal tolerances are beyond acceptable standards - you will see slow movement and/or low pressure when working and extended operation may cause oil heating.
If you want to test the pump, have a calibrated container to pump into. Fill the supply reservoir and run the pump at rated RPM for a specific time (maybe 30 or 60 sec). Measure how much flow was delivered at no pressure. Repeat the test but have a valve and pressure gauge in the output line. Run pump at same RPM as first test, but slowly close the valve until gauge indicates rated pressure of the pump, then collect and measure oil volume over the same time period as first test. A bit complicated but you will know what the pump is doing. If badly worn, pump may not be able to produce the rated pressure.
Note: while the system is still in your machine, be sure to verify the relief valve is functioning properly. You should be able to adjust and see if the performance changes. If you cannot adjust pressure, maybe the valve is defective or stuck. Does your machine have a pressure gauge on it? If yes, what pressure does it show when a cylinder gets to end-of-stroke?
If the pump tests OK out of the machine, something in the rest of the system may be at fault.

[cosworth34677]

Not in ths one, pump runs only when valves are open.

[sparkycuda]

It would be very difficult to flow test the pump in the machine, especially since the radio mixes the valve opening and motor on. Best to remove the pump/motor and wire directly to power source but that may not be easy to do. Possible that a valve is opening or stuck open that returns oil to the tank? That would account for low flow/pressure going to the cylinders.

[cosworth34677]

Well I was a little ambitious yesterday and took the pump out of my dozer, and put it in my loader. They are the same brand and model. Little younger and its worn to but it's just lifting the blade dosent need the power. But it will lift the arms and curl the bucket and lift a tape measure, (granted not a bench make but heavy enough to test ) easy but same problem with dirt it wont lift it all the way up. So I'm thinking it's the pumps. Both do anyone have a good cheap pump , other them magom? I dont know how they are now with the steel gears but it's a pain to keep replacing the pump gears every 5 -6 months.

[frizzen]

For a flow test, couldn't you just unhook the pressure output and route line to some kind of cup, then move the pump esc into a non-mixed channel at 100% epa.

For the mushy lifting, is there a way to verify you've bleed all air from the cylinders?

Gear damage that fast makes me wonder if flow between pump and reservor it too low and causing cavitation.

Any chance we could get pics of the pump guts?