high chrome slurry pump 2024

Hydraulic pump- Major leak mystery (photos)

Senario

Small gear pump that powers automatic cold saw head up/down...plus 2 vises open/close... leaking like crazy thru the rotational seal...i.e. where the electric motor turns the pump..the seal that seals that pump shaft. Install new seal, blows the new seal immediately. Saw only a few years old, with aprox 400 hours run time.

Pump 2 draws fluid via hose 1, pressure line is 3, to pressure relief valve 4, then to manifold valve 5. The solenoids at manifold 6 control saw up/down, vise one open/close and vise two open/close.

The problem is either Hydraulic pump itself needs new internal seal kit (i.e. not the shaft seal but the special shaped seals inside)...or Pressure relief valve "stuck" somehow...or Valve no. 5 not working...either electrical malfunction or stuck.

The internal seals appear perfect...but maybe the depressions to receive these were milled a few thousandths too deep in manufacturing such that the slightest amound of flattening of the seals allows fluid to now leak from pressure side to the shaft side ?

Suggestions

Disconnect the discharge side of the pump, and secure/protect hose into a bucket,or container. Energise the pump, and see if your shaft seal still leaks, or weeps fluid. If possible add a flow control valve to raise pump internal pressure. After that, follow the trail downstream! You're right though, the schematic will assist in the troubleshooting.

Measure the clearances on all the parts inside the pump. In particular, worn shaft bushings: maybe .001" to .002" max diametral running clearance. Any more will allow excessive leak down the input shaft.

Also check the input shaft and the motor shaft for straightness and true concentricity. The latter can be difficult to determine, but if the mounting bolts are left slightly loose, a bent shaft/misaligned shaft condition will produce vibration when the thing is running.

What does that show when it is running? As long as your not exceeding that, the pump shouldn’t leak unless it has increased internal leakage. Making the pump the culprit yes? That relief valve # 4 should show the maximum pressure the pump sees. Provided the pressure on the gauge is less than 100 bar, I cant see a pump where that pressure would be exceeding its pressure spec.

If it blows the seal out then there is excessive oil pressing against the seal...A: A worn pump allowing pressure oil to get where it should be getting ie: against the seal B: excessive pressure in the pump.

Is there a drainback hole to return fluid that would pressurize the seal back to the inlet side? If so, drill it out larger. If there isn't one, maybe drill one.

That shaft seal shouldn't see any notable fluid pressure.

If pressure is building behind the seal and forcing it out, then either there is a clogged drain inboard of the seal, or it is leaking excessively across the HP seal internally. Root cause could also be oil contamination - leading to excessive internal wear in the pump. Or perhaps pump/motor alignment contributing to premature shaft/bearing wear and leakage.

I think you have the pump pumping against a closed valve or spool causing the discharge chamber to be overpressurised. The solenoid spool valves look as though they can be manually stroked, have you tried moving them against the spring to see if they are stuck?

The shaft seal must be on the suction side of the pump.

Most pumps i work with have the drain back port/passage/rifling that allows the leakage to make its way back to the suction side. it might be that there is something as simple as a piece of rubber hose caught in that port.

Replies

All functions worked perfectly for a few hours after obtaining it...then out of the blue, leak city.

The funny thing is I don't know because it's leaking so bad that I don't have time to look at the gauge before shutting the system down !

So you missed the part where I said it ran for 400 hours just fine, but now even with new seal it blows it instantly ? although my pump does have "E" seals similar to the ones pictured, my seals are mounted on the main housing rather than the end caps, and therefore impossible to reverse. Pump is not assembled wrong or reversed.

First you have a problem with pressure releif valve, if valve 5 not working releif valve should compensate so pump is not damaged. Check it's setting or if sticking. Oil has found escape route with least resistance.