Log splitter question

[Eyecatcher]

I've been re-reading all of the threads I can find on log splitters, but still have some questions I hope I can get some help with.
I have a log splitter that my son and I built many years ago. Never did get it to perform satisfactorily, too slow, so we forgot about it for many years. I found an electric powered splitter that was good enough for what I wanted to do and used it. Unfortunately, I loaned it out, and it was run out of oil, so back to the drawing board.
We rblt the original splitter a couple of years ago. It has a 4"X24" cylinder w/2" rod from Grainger (original), Hyd pump is also Grainger, and I have the paperwork from when I bought it, and it says it's either a 4Z450 (9.44gpm) or a 4Z703 (10.76gpm), drawings look identical, and I can't find a p/n on the pump itself. The control valve is a prince, that I took of my old fel when I converted over to a three spool to accommodate remote hydraulics. I intend to use the second spool for a log lifter at some point in time. Engine is a Chonda clone, 6.5 hp, which handles the pump well. I have a pressure gauge teed into the line on the closed end of the cylinder, and I never see any indication on it until it encounters an obstruction, then it will momentarily exceed 2500psi until it clears that obstruction (splits the wood). Run it to the end of the ram and hold it, looks like 2850psi. Does a great job of splitting, but just way too slow.
I have an 8hp Honda GX, and would like to purchase a 16gpm pump and install on this unit. Here's my questions:
(1) Is it possible that the old loader valve will not handle the 10 gpm now supplied? Will it handle the 16gpm flow?
(2) The fittings on the 4" cylinder are 1/2" MPT street ells, the passage through them is pretty small. Is this enough restriction to slow it down this much?
should I try to exchange them for fittings with larger opening prior to investing in the pump?
(3) The literature I read on the 16gpm pumps reccommend 8hp. Is this marginal?
(4) For a few extra dollars, you can purchase a CI body pump, vs Aluminum. Is this worth while, or is aluminum good enough?

 

[oldnslo]

I presume these are two-stage pumps. If yes what is the flow rate from each stage?

Fitting size: I would not worry to much about the fittings, just make sure the hose sizes are large enough to not cause severe restrictions.

At 9.4 GPM your cylinder should extend fully in 8.3 seconds.

 

[J_J]

Your pump appears to be a single stage pump.

Your old FEL valve will work , but will not have the auto return, and the GPM flow might not be adequate.

Your old valve might also have features you don't need, such as float and regen.

If your cyl ports are 1/2 in fittings, and your valve is 1/2 in , then use 1/2 in hose.

Now you are talking about a 16 GPM pump, Is that a 2 stage pump?

As far as HP, you can use whatever, but there is a HP requirement for full use of the pump.

A smaller HP engine, will stall out under a certain load.

Minimum engine HP is so the pump can develop the full pressure and volume..

A new log splitter valve with a detent return and auto kick out to neutral is only about $65

 

[Eyecatcher]

The pump I am using, is a 2 stage pump. I have adjusted the unloadeer valve setting from end to end, and either it doesn't go into hi speed mode, or the pump just doesn't supply enough volume to move the cylinder any faster. If I do install the 8hp and 16gpm pum, it will be a 2 stage.
The flow from the 9.44 is 7.46/1.98 & the 10.76 7.46/3.30

 

[J_J]

The unloading pressure should be around 650 psi.

The valve GPM flow should match the pump GPM flow.

This $65 log splitter valve will handle 25 GPM flow .

To check GPM, remove the base end cyl hose and place in a bucket and time it. If it can fill a 10 gal bucket, full in 1 min, then it is a 10 GPM pump.
-------------------5 gal-----------------30 sec-------------10
------------------5 gal bucket, 1/2 full 15 sec-------------10

 

[LD1]

When you say the splitter is slow....how slow?

Time it with a stopwatch (or just counting in your head), see how long it takes to FULLY extend and FULLY retract with NO load on the cylinder.

This will tell us if it is stuck in low-speed mode. Cause if it is working properly, a full cycle (out AND back) should be in the 15 second neighborhood. But if it is stuck in low speed, it will be closer to 60 seconds.

 

[J_J]

4 in cyl, and 2 in rod.

Extend speed using 10 GPM, would be 3.1 in per sec, and = 7.74 sec to fully extend a 24 in cyl in fast mode..

3.3 GPM = 1 in per sec, = 24 sec to extend in slow mode, which would be unusual because of the load.

The splitter should stay in fast mode most of the time, as long as the pressure is below about 650 psi.

 

[Eyecatcher]

Just had a chance to go down to the barn and run the splitter. With the oil cold, extend time is 35 seconds, ful cycle time is just over a minute. I guess from JJs calculations above, it's not even moving fast enough for slow mode. I can put a log on the splitter and observe the gauge. You never see any indication on the gauge until it jumps to 2500#+. It's 5K# gauge, maybe the low pressure cycle just doesn't show. I have adjusted the unload screw from end to end and it doesn't change. The unload spring an ball assembly looks undamaged, and the seat looks good. the only thing I can think of is the valve won't handle the flow. Maybe I should move the gauge over to the inlet side of the valve and see if it looks like there's pressure there with the valve centered.

 

[J_J]

Where do you have the gage now.

Are you using a tee?

The test gage can be anywhere from the pump outlet to the IN port of the log splitter valve, or in the cyl hose. The gage should be showing various pressure based on load. Somewhere you are putting med hard wood in the splitter. Try a piece of wood side ways, and slowly push the lever a little to extend.

 

[Eyecatcher]

Right ow, and all of these posts, the gauge is in a tee that goes to the closed end of the cylinder. It never moves until the ram engages an obstacle.