Question about whether this log splitter is working right

[kevin j]

Was it factory built, or owner built?
It's always hard to tell on a new to you machine if there is a design issue and it always did this, or if it ran ok in past but something is now wrong.

What is the pump? single stage or two stage? pics please.
If it is single stage, then the output flow is roughly constant. Required horsepower is simply volume times pressure setting (with some units in the math). Then either the engine torque is too low (which has been discussed) or the load is too high, which would be determined by the relief valve setting, usually in the main control valve as discussed.

However, if it is a two stage pump, there are two power limiting conditions: 1. low flow, high pressure , set by the relief valve as discussed. 2. both stages added together, operating at the highest pressure setting just before the large stage unloads, is another condition that could stall the engine.. If this unloading pressure is set too high, the engine can stall and adjusting the main relief would not have any effect because it is not the controlling device.

The unloading pressure (where the large pump section vents back to inlet at maybe 50 psi) is adjusted on the pump. There is usually a cap over it.

Step one, I would get a pressure gauge on the line between pump and control valve. Sometimes, rarely, there is a 1/4 NPT tapped port on the valve with a plug. Otherwise some tee and reducer adapters are needed. Do not use pipe fittings. Yes, they usually work at lower pressures, but at 2500-3000 psi they are dangerous.

Then, read the pressure when engine stalls. If it reaches 2000-3000, it is on the high pressure relief in the control valve, and that might have to be lowered (assuming engine is ok).

If the engine stalls in the 700-1200 psi range, it is likely the unloading setting in the pump.

All assuming two stage pump.

kcj

 

[moondoggie]

Sounds like your relief might be sat a tad high as well. I think what happens is the owners run into a stick of wood their splitters wont split and they start turning up the pressure trying to get more power. The engine pump combos can only produce so much power before the engine stalls. Bumping up the relief might give you a little more power at the ram, but sooner or later, if you keep bumping up the pressure, you reach the maximum power the engine can produce so the engine stalls. One needs to understand that its not just stalling the engine, its also overloading the coupling between the engine and the pump. Those couplings are designed to take just so much torque and if abused, its just a mater of time before you tear up the rubber insert, or strip the keyway out of the coupling. It might be years and cords of wood before this happens, and its hard to tell if the coupling failed because of just normal wear and tear or if it failed because it was being used beyond its designed parameters. At any rate, a splitter engine shouldnt stall at the end of the cyl's stroke or because the cyl stalls in a knotty piece of wood.

Thanks! Yes sir I replaced that coupling/rubber device about a year after I bought the machine. I will fiddle with it and see if I can fix it. The

 

[clydesdale6]

I checked and the machine does not have a hydro filter. Is AW32 a grade of hydro oil? Do I just drain and refill? I do not see a drain plug, but will look closer. Thanks

 

[muddstopper]

Was it factory built, or owner built?
It's always hard to tell on a new to you machine if there is a design issue and it always did this, or if it ran ok in past but something is now wrong.

What is the pump? single stage or two stage? pics please.
If it is single stage, then the output flow is roughly constant. Required horsepower is simply volume times pressure setting (with some units in the math). Then either the engine torque is too low (which has been discussed) or the load is too high, which would be determined by the relief valve setting, usually in the main control valve as discussed.

However, if it is a two stage pump, there are two power limiting conditions: 1. low flow, high pressure , set by the relief valve as discussed. 2. both stages added together, operating at the highest pressure setting just before the large stage unloads, is another condition that could stall the engine.. If this unloading pressure is set too high, the engine can stall and adjusting the main relief would not have any effect because it is not the controlling device.

The unloading pressure (where the large pump section vents back to inlet at maybe 50 psi) is adjusted on the pump. There is usually a cap over it.

Step one, I would get a pressure gauge on the line between pump and control valve. Sometimes, rarely, there is a 1/4 NPT tapped port on the valve with a plug. Otherwise some tee and reducer adapters are needed. Do not use pipe fittings. Yes, they usually work at lower pressures, but at 2500-3000 psi they are dangerous.

Then, read the pressure when engine stalls. If it reaches 2000-3000, it is on the high pressure relief in the control valve, and that might have to be lowered (assuming engine is ok).

If the engine stalls in the 700-1200 psi range, it is likely the unloading setting in the pump.

All assuming two stage pump.

kcj

I didnt think it was possible, but I am going to disagree with you about the unloading valve. If the pump is only building the 700-1200-psi this shouldnt stall the engine as the engine should have enough power to supply that amount of pressure.
While it is possible The engine has the power it needs to build the 700-1200psi, it might not have to power to pump that amount of pressure at a higher flow rate. The low pressure numbers given would be in the range of a normal 2 stage pump in low pressure high flow and at that point the pump should unload and just run off one set of gears to build high pressure/ low flow, By not unloading, the pump should continue using both set of pump gears and continue to build pressure at high flow. This would most likely cause the engine to be over powered and stall. So I guess in a way I do agree the pump could be stuck in the low pressure high flow mode, or that pressure setting could be set to high, but I think the pressure would build above the suggested 700-1200psi range, or at least spike above that range before stalling the engine. This would be hard to tell without a gauge installed. Without a gauge, I think I would still just lower the relief on the control valve until I reached a point that the engine didnt stall. A little engine can move a lot of fluid as long as it is at low pressure, which would be accomplished by reducing the relief valve settings. If I found that reducing the relief setting the engine still stalled, or didnt have the power to actually split wood, then I would start looking at the pump and I highly suggest a gauge be installed before messing with the pump settings.

I am editing this post for two reasons, first I reread what Kevin has written and I think I more or less echoed what he said, I just said it different. Second, my statements about engine not stalling out was assuming the splitter had the little 11gpm 2stage pump. The 9hp engine should pull the pump at 11gpm, full flow at 1200psi before stalling the engine. Going over the 1200psi should spike the pressure above that number before stalling. Now if the splitter has a 13gpm or 16gpm two stage pump, then the 1200psi number isnt obtainable with the 9hp engine and the engine would stall at a lower pressure reading. Thats what I get for not reading clearly and making assumptions.

 

[muddstopper]

I checked and the machine does not have a hydro filter. Is AW32 a grade of hydro oil? Do I just drain and refill? I do not see a drain plug, but will look closer. Thanks

Why not post up a pic of your machine, it might help to know just a little more about it. Things such as brand of splitter, type/size of pump. Is the splitter homemade or factory built.

AW32 is a type of Hyd oil. Not having a hyd filter is something I would consider adding once you get it working right. there should be a drain on or near the bottom of the tank, but you might have to remove the suction line from tank to drain the oil if there isnt any drain.

 

[Big_Eddy]

Way I read it - the splitter splits fine - which suggests to me any 2 stage pump is kicking down from high to low flow as it should.
I'm assuming a standard splitter valve. Manual forward. Detent retract. These valves contains 2 pressure "reliefs'. First is a system-wide relief that opens when the pressure in the system exceeds a set value in either direction. Second is the retract-relief, which kicks out the retract, typically at a slightly lower pressure when the cylinder hits the end. I believe his system-wide relief in the valve is not operating, or is set higher than the maximum output of the engine. On normal operation the retract-relief kicks out the return stroke as it should, but if the OP manually overrides, the max pressure exceeds the engine output and it stalls. Likewise - put a huge crotch on it, or continue to hold it extended past the end of the forward stroke, and the system relief doesn't open when it should. Load exceeds output and it stalls again.

He needs a pressure gauge in the system, and needs to check / adjust the system-wide relief valve. Typically they are set at ~2000-2500psi.

Note: I didn't catch the pump size. If the pump is oversized for the engine, or the engine is not running at full speed (or is worn out) then stalling can occur even with a correctly set relief valve. Post us the engine, pump and valve details.