No cylindder pressure....

[mrcaptainbob]

The log splitter was working great until the cylinder wouldn't split the wood. It seems there's enough pressure to move the ram fore and aft and to cause the detent to work. Holding the lever at either direction to force a load does not change the engine rpm's or loading. The detent spring is not broken. It happened rather instantly. Was splitting oak and all was well until it got to a nasty. usually this 'nasty' part would not be an issue. Also, it sounds like there's a sort of vibration in the valve body. Is this a sign of:
* valve needing an 'O' ring kit?
* detent spring shims? (does not appear to be an adjustment. Just a cap over the spring with it's seal.)
* cylinder seals leaking?
* Pump issue? (Heaven forbid!!!)

I have no gauges to check pressures. It was recommended to squeeze one of the cylinder hoses and operate the cylinder to verify a bad cylinder seal. Also to slowly squeeze the pump output hose to see if it bogged the engine. Caution was given so as to not over squeeze and blow the pump. I did one of the cylinder hoses, but was reluctant to force it. Was concerned about lousing up the metal jacket and rubber and having to replace that, too. Didn't even try the pump output hose.

 

[oldnslo]

Do NOT squeeze any of the pressure lines to restrict flow. This will damage the hoses.

Splitting force is the result of pressure. Typically pressure loss is caused by relief valve stuck open, seals blown in cylinder or pump not turning under load.
Did the shaft key shear in one of the coupling halves? I.e. are you able to confirm the pump shaft is turning under load?

Cylinder seal test: fully extend the cylinder, remove the hose from the rod end of the cylinder. Plug the connection to the valve. Point the hose into a bucket and move the control valve to try and extend the cylinder little to no fluid should come out this hose. If you get significant oil flow the cylinder needs repair.

Relief valve: depending on the style you have it may be adjustable or shimmed. If adjustable you will need a gauge to reset the pressure. Most relief valves in directional spools are a simple spring on top of a poppet or ball. If a piece of debris gets stuck under this poppet or ball it will hold the valve open. Or the spring could also have broken.

good luck

 

[mrcaptainbob]

I like that idea, Oldnslo. I'll do that tomorrow. I checked the relief and it appeared clean. The spring is not broken. The pump shaft does turn. I'll verify that both sides are spinning the same. Thanks for the help.

 

[mrcaptainbob]

It took a while, but I extended the shaft fully. Disconnected the hose at the shaft end of the cylinder. Left all hoses connected to control valve. Did not plug cylinder end of hose. Started the motor and applied pressure as if to extend cylinder. No oil came from cylinder port. It also did not bog the engine. Reconnected h0ose to cylinder. l will verify again that the pump shaft is spinning in synch with motor shaft when under load. After this....do I try shimming the relief valve? Incidentally, Just before this all took place, it was difficult for the lever to stay in the detent position. Sometimes it did, sometimes it didn't. Until then, all was well. I fiddled with the detent control and got it to hold position. All was clean in there, too.

 

[J_J]

I am not even sure you can squeeze a hyd hose. Most times you feel the hose for pulses or vibrations.

If your valve is spring center to neutral, do you have equal spool movement when you push or pull the lever for flow, and you did say that the spool is complete and tight.

The relief valves purpose is to relieve pressure but there has to be some flow. If the work port has no flow, how can the relief valve relieve anything.

Where is the flow to make relief pressure.

If the pump is pumping there will be flow and it has to go somewhere, and if it is not flowing out through the work ports .

You might look at the load check valve for debris and or broke spring.

Did you switch hoses or QD's lately.

Lastly, check the coupling between the engine and pump. You may just have sheared the shaft key on one of the couplers.

To see if the pump is pumping the correct GPM's, remove the In hose on the log splitter valve and place in a bucket and time the flow.

If that looks good, reconnect the hose and remove the OUT hose to the filter and place in a bucket and opearate the log splitter and max out the cyl and see if the pump is still pumping the correct GPM flow.

 

[mrcaptainbob]

Thanks for the suggestion on checking pump flow, J-J. I just may do that. So far you all hit the mark. I managed to extricate the pump from the splitter. (This is a 'borrowed' unit. Breaks on my time, it's my dime...that's how I see it.) Had to use a puller to remove the Lovejoy type coupler from the pump shaft. It's aluminum and the set screw would not budge. The pump shaft is buggered up. Not sure what went on with it in the past, but it appears the coupler was sleeved. Removed the remains of the key from that and cleaned it up. The plan is to drill/tap for a new set screw. (One with plenty of Never-Seize!) Next is to Dremel a new key way in the pump shaft. The fit between the coupler and shaft is still pretty sound.
Thank you all so much for helping me and prompting me to investigate that pump shaft area. It was very well hidden behind some castings.

 

[mrcaptainbob]

Rats. That was not it! Although the key was split and the shaft ws in poor shape, I did manage to recover the situation. New key way, new key and two set screws later and...well, it's all the same. I guess I will be investing in a high pressure gauge to verify output of pump and cylinder pressures. As an aside....the unit was low on fluid. I replenished using hitrans, the stuff for hydraulics/transmissions. Would that cause issues? Should I drain it out and use straight hydraulic fluid?

 

[J_J]

Whatever the pump flow is, if you direct the flow into a bucket, do you have the advertise pump flow .

If the return filter new or clean?

If you have no flow, you can't check relief pressure.

The detent part of the log splitter is for the return stroke. Do you have cyl extension and can it go into relief?

 

[oldnslo]

Whatever the pump flow is, if you direct the flow into a bucket, do you have the advertise pump flow .

A word of caution on measuring pump flow in this manner on log splitters. Typically the reservoir on a log splitter is equal to or less than the rated no load pump flow so that in less than one minute the reservoir is empty.

 

[J_J]

That is true, however,

One gallon pumped in 6 sec = 10 GPM