Jinma Hydraulic Pump - Failures

   / Jinma Hydraulic Pump - Failures #21  
I did away with my quick connects for this very reason. My Jinma 284 uses 1/2 fittings so I just put in swivel unions.

Chris

QC's just downsteam after a positive displacement pump (dumb pump) makes me nervous, anything bad can happen
 
   / Jinma Hydraulic Pump - Failures #22  
I can't think of any reason to have QC's off of a pump pressure feed to the 1st relief.
 
   / Jinma Hydraulic Pump - Failures #23  
I can't think of any reason to have QC's off of a pump pressure feed to the 1st relief.

Other than to make it easier to remove the FEL:)
 
   / Jinma Hydraulic Pump - Failures #24  
I forgot about some loaders the valve goes with the loader. But doesn't pump go to the main relief first or they just use the 3pt relief when loader is off?
 
   / Jinma Hydraulic Pump - Failures #25  
I forgot about some loaders the valve goes with the loader. But doesn't pump go to the main relief first or they just use the 3pt relief when loader is off?

I believe the main relief valve is located in the FEL valve stack.
 
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   / Jinma Hydraulic Pump - Failures #26  
Those quick disconnects are usually the culprit on those jinmas causing the backpressure problem splitting the case on pump, also check the loader valve for the problem as mentioned, we have seen that cause the pumps to fail as well, those two things are usually what causes the pump failures on the chinese units.

Ben
Circle G Tractor Sales, inc.
Jinma Tractor Parts, Farm Pro Tractor Parts, Farmpro, Nortrack, Agracat
 
   / Jinma Hydraulic Pump - Failures #27  
My 1st pump (factory one) failed after my brother decided it was greasy and pressure washed it sending 3500PSI water into the pump body seals from the wrong side. :( well I bought a rebuild kit for it along with a NEW pump from Tommy. I rebuilt the Factory Pump and re-installed it but could not get he pump to spin over. The end plates may have been warped or? in any case the pump would not turn by hand or by engine. I simply tossed it aside and installed the NEW pump and went back to working. These things are not complicated, as stated quick disconnects are #1 pump failures either by accident (brush knocking them apart) or by owner disconnecting them while engine was running. That is usually pretty dramatic failures or they can blow the shaft seal and pump crankcase full of hyd fluid. I bought & sold a few and one of the NEW owners of one's DAD did this splitting the pump side pretty bad. I had a spare pump at that time & gave it to him to get him back to running.

Mark
 
   / Jinma Hydraulic Pump - Failures
  • Thread Starter
#28  
Hi guys,

Thanks for the interesting comments, I am always learning something new. When clearing snow using both the TPH snow blower and the FEL, it is normal for both to be in the raised position when moving from one place to another. I have done that for years and don't think that is the cause of the pump blowing. Having said that, the TPH blower isn't raised any higher than needed, whereas the FEL is used as needed. Obviously when blowing snow the blower is on the ground and the FEL usually a couple of feet off the ground - high enough to clear the newly cleared snow edges of the driveway/road.

I am thinking that the cause was probably the QD's connects though I will never know for sure.

To add to my other comments, I have now installed a pressure gauge and the original Jinma QD's have the internals removed and are now open.
I will put in an extrenal relief valve along with a dedicated dump line back to the hydraulic oil tank. I still have to make up my mind on where to connect the relief v/v return at the tank - either at the drain or at the top of the tank.

Thx

Jim
 
   / Jinma Hydraulic Pump - Failures #29  
Replacing a 14ml/r pump with a 20ml/r pump, an almost 50% increase in volume without increasing hose and/or fitting internal diameters. Has anyone else done this? I've never tried so I'm curious of the results. It would be ok at low rpm but I'm thinking oil flow at high rpm through the loader hand control and quick disconnects would be restricted. Restricted enough to cause pump damage?
 
   / Jinma Hydraulic Pump - Failures
  • Thread Starter
#30  
Circle D - I think you are on the right track. I did not have the extra direct relief valve installed when I put the 20ml/r pump on. Thinking about it, I am sure that the original system would be marginal at best, but with higher engine RPM, failure would most likely occur quickly. That is what happened in my case I am sure.
I should mention that when the QD are removed from the pump outlet (pressure side), you will see the hose to the FEL valve block has a smaller internal dia - maybe 5/16" dia at most. The short pump discharge hose has a bigger ID of around 1/2" The relief vales in the valve blocks may not be too efficitient IMO.

I have since added a 10gpm external relief valve in hyd.pump discharge line and set it to open at 1800psi (18 bar). For what I need the 1800 psi pressure is adequate. I have the hose from the relief valve returning to the hydraulic tank. Set up seems to work well so far. Will try to attach a couple of foto's (taken just a day or two ago) to show what I have done - very similar to what other owners have done also.

Without the extra relief valve it will become expensive - the external relief valve is essential IMO.

Cheers

Jim
 

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