Jinma Hydraulic Pump - Failures

[Leejohn]

Could it be a case of just to much pump?

 

[Localmotion]

Could it be a case of just to much pump?

Good thought Leejohn - but if that was the case the pressure relief should have let the oil go before damaging the pump. Unless the bore of the pump "out" pipe is much greater than the tractors existing pipework, the extra pressure shouldn't be an issue.

Just be aware if you are stripping down the relief valves, you will definitely need a pressure gauge to re-set them - in my opinion it's too risky to simply rely on counting the number of turns...

On the same subject does anyone know who supplies off the shelf pressure regulators to fit the Jimna FEL's? We have a nightmare trying to get the replacements from China, and haven't so far had any joy getting matching parts locally...

 

[wdchyd]

Another time we had a customer who's pressure relief bypass valve on the fel failed. Because the Jinma loaders are generally in series (ie: the oil has to pass through them from the pump before servicing the back of the tractor) it overheated and cracked...

:

"Fortunately I had both the loader and the TPH in the raised position "

If indeed the FEL control valve is hooked up in series (with no power beyond) and the 3ph lever is maxed in full up position, then that hyd pump can see pressures of BOTH PRV pressures added together

having multiple relief valves in series with no reservoir drain, is pressure additive.....meaning if the FEL PRV is set at 2000 psi and the 3ph PRV is set at 1500 psi, then with both levers stroking the cyls to max that pump will see the 3500 psi

The OP needs to check to make sure there is a power beyond.......NOT in series direct to the 3ph

 

[Localmotion]

"Fortunately I had both the loader and the TPH in the raised position "

If indeed the FEL control valve is hooked up in series (with no power beyond) and the 3ph lever is maxed in full up position, then that hyd pump can see pressures of BOTH PRV pressures added together

having multiple relief valves in series with no reservoir drain, is pressure additive.....meaning if the FEL PRV is set at 2000 psi and the 3ph PRV is set at 1500 psi, then with both levers stroking the cyls to max that pump will see the 3500 psi

The OP needs to check to make sure there is a power beyond.......NOT in series direct to the 3ph

Maybe we're at cross purposes, as I'm not quite understanding your point...

The Jinma hydraulic circuit is as follows:

Reservoir - Pump - FEL - Spool Valves (if fitted) - 3pt Linkage - Reservoir...

There are pressure relief bypass valves fitted to the fel spool block, spool valve block (which is basically identical to the loader spool block) and 3pt linkage. If noting is being used (ie. the fel is not being tilted / crowded / lifted / dropped) then the oil passes through the relief valve onto the next item (spool block) and so on. A prime example is that the 3pt hitch will not normally lift on a Jinma if the fel is being used - however if the fel is static (even in the air) then there will then be pressure available to the 3pt. Likewise if using a spool, the 3pt will not work effectively until the spool is returned to neutral. This is not usually a problem - as any item will hold it's height / position if left in neutral while another item is being used.

This is a series circuit. If there was a separate supply from the pump to each item (fel, spool, 3pt) then it would be a parallel (or as you call it "direct") circuit - just like electricity.

:thumbsup:

 

[wdchyd]

assuming there is no power beyond (with no reservoir drain line), the valves are connected together in series

this only applies if the fel control valve is activated and going into full pressure relief (cyl at end of stroke) and the 3ph lever is in the full up position also in the full pressure relief

 

[RonMar]

Remember, the fluid must always flow. The Jinma does not have discreet return lines. The return/relief outflow passes down the main line to the next device till it gets to the 3PH and can pass thru that valve to the reservoir. The 3PH will work while the FEL is in operation. The system does it's best to maintain a constant flow. Since the fluid sent to one side of a cylinder also causes fluid to be pushed back from the other side of the cylinder, the FEL valve exhausts nearly the same ammount of fluid wether it is in operation or not. This fluid can then be used by devices downstream such as the 3PH. As Wdchyd stated, the loads on the pump are additive. This means that the work performed is divided by the two things being operated. This is usually not a good idea because as wdchyd mentioned, the pressures attained are additive and can exceed max pressure ratings if more than one device at a time is placed into relief/bypass...

This is rarely an issue as the controls are usually all on one side. I know I have to go out of my way to activate the FEL and the 3PH at the same time

 

[Gary Fowler]

"Fortunately I had both the loader and the TPH in the raised position "

If indeed the FEL control valve is hooked up in series (with no power beyond) and the 3ph lever is maxed in full up position, then that hyd pump can see pressures of BOTH PRV pressures added together

having multiple relief valves in series with no reservoir drain, is pressure additive.....meaning if the FEL PRV is set at 2000 psi and the 3ph PRV is set at 1500 psi, then with both levers stroking the cyls to max that pump will see the 3500 psi

The OP needs to check to make sure there is a power beyond.......NOT in series direct to the 3ph

I am not a hydraulics expert but do know a thing or two about multiple PRV in a closed system like steam boilers which in our case lets say the boiler represents the hydraulic pump. All boilers have safety relief valves (yes multiple valves) and each one is set at a different pressure. The lowest one goes off first then if pressure continues to build then the next lowest set one goes off and continues till the system design pressure is met at which time the last one goes off. Normally the lowest setting is the smaller valve and the size goes up incrementally till the biggest one relieves. At no time will the system see more pressure than the largest set valve and not the combination of adding the pressures of each. If properly designed this valve will relieve the maximum amount of steam that the boiler will generate. The tractors main hydraulic valve should be set to a design pressure, usually around 2200-2400 PSI at which time the relieve valve will open and circulate all the oil that the pump is capable of producing. If you have FEL and it has its on relieve the it must be set lower or same as the tractors main relief valve. At no time can the two pressures be added together to have the pump see more than the set pressures for each UNLESS the PRV fails to open and you dead head the output line. If that happens something is going to blow up because the pump is a positive displacement pump, if it turns then it is pumping oil and being a liquid it wont compress so if the pump keeps pumping and you dead head the system without a PRV or with a defective PRV either the pump or a weaker link like a hose but most times it is a pump that will blow.

 

[RonMar]

I am not a hydraulics expert but do know a thing or two about multiple PRV in a closed system like steam boilers which in our case lets say the boiler represents the hydraulic pump. All boilers have safety relief valves (yes multiple valves) and each one is set at a different pressure. The lowest one goes off first then if pressure continues to build then the next lowest set one goes off and continues till the system design pressure is met at which time the last one goes off. Normally the lowest setting is the smaller valve and the size goes up incrementally till the biggest one relieves. At no time will the system see more pressure than the largest set valve and not the combination of adding the pressures of each.

IT would add up if the outlet of the first boiler PRV fed into the inlet of the second PRV and so on...

The Jinma does NOT have dedicated relief/return ports. The combined outlet of one valve(relief and normal return) are fed to the input port on the next device... This is not normally an issue as only one device typically gets used at a time...

 

[Diamondpilot]

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

 

[wdchyd]

IT would add up if the outlet of the first boiler PRV fed into the inlet of the second PRV and so on...

The Jinma does NOT have dedicated relief/return ports. The combined outlet of one valve(relief and normal return) are fed to the input port on the next device... This is not normally an issue as only one device typically gets used at a time...

Exactly.....the boiler normally vents into the atmoshere right? not into the next boiler