Those of you with hydraulic splitters.......what is your relief pressure set at?

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JRHAWK9

Minister of Fire
Jan 8, 2014
1,691
Wisconsin Dells, WI
Have any of you threw a pressure gauge on your hose between the pump and control valve to see what pressure the relief valve is set at? I've read in numerous forums that most relief valves are set around the 2,500psi area. Assuming this is correct then most splitters are grossly over-rated in tonnage. I have a CountyLine 40 ton and it has a 5 1/8" cylinder. This means I would have to see 3,880psi in order for it to apply 40 tons of force. Manual states max PSI is 3,800 psi which would make 39.2 tons. I thought they were out of their minds.........

Anyway, I am assuming, based on everything I have read, I wouldn't be seeing anywhere near those pressures. It has both an adjustable relief and detent. I already adjusted the detent and I installed a 3,000 psi gauge. I was completely surprised as to what I saw when I went to test what the relief was set to. I still don't know because it maxed out the 3,000 psi gauge before I left off. I remember the ram slowing down as the pump hit the second stage and the engine digging in and next thing I know the pressure went pretty rapidly to burying the 3,000psi gauge before I lifted. It was probably around 3,200psi when I said that's enough.

Anyway, just curious what other's are seeing? I know I don't need it to be set that high and will probably adjust it down to the 2,500 - 2,800psi area. I don't think I will ever even encounter anything I need to split which will even require 2,000 psi (little over 20 ton actual force) seeing I split mostly oak.
 

Jags

Moderate Moderator
Staff member
Aug 2, 2006
18,259
Northern IL
My 5 inch ram is set to 3200 and my 4 inch is set at 3400. Both are set below the max rating of the weakest link in my hydro system (which is the 3500 psi hoses in the system).
 
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hedge wood

Burning Hunk
Mar 1, 2009
216
Eastern NE
I have mine set at around 2500 PSI on my homemade splitter with a four inch cylinder. I have it set that way because a lot of the time when we are splitting wood I wasn't the one running it. I am in the skid loader or doing other things. We split a lot of hedge and locust that is very tough and I want it to stall the hyd cylinder out and not tear up the splitter. If I was the one running it all the time I would have it set closer to 3500 PSI. If you watch the gauge most wood is split at 800 to 1000 PSI.
 
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JRHAWK9

Minister of Fire
Jan 8, 2014
1,691
Wisconsin Dells, WI
I threw a Wika 3,000 psi gauge on mine. I currently have my DCV (directional control valve) unloader set to around 3,300psi. I just interpolated a bit past the 3,000 mark on my gauge. Comes out to be around 34 tons actual force. My high pressure hoses are rated for ~4,600psi IIRC.


IMG_20210213_212703452.jpg

I also adjusted my pump's unloader valve. It adjusts the crossover pressure relief from the low pressure/high volume to the high pressure/low volume. Basically adjusts what pressure the pump goes to the second stage. Longer it stays in high volume/low pressure the faster you will be able to power through the splits....as long as you have the engine power to do so.

Some informative videos, for those, like me, who are new to how the 2 stage pump works and how to adjust the pumps unloader valve.


 

hedge wood

Burning Hunk
Mar 1, 2009
216
Eastern NE
Years back I used to pickup a fair amount of log splitters at sales that needed some work and repair them and sell them in the fall and winter and one of the first things I would do would be put a T and a gauge on the system so you could see how it was running. The splitter I use for most of my wood splitting has a 28GPM two stage pump on it and I have enough engine that I have adjusted the switch over to second stage at around 1200 PSI so it splits most wood without shifting down to the lower flow higher pressure stage.
 
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JRHAWK9

Minister of Fire
Jan 8, 2014
1,691
Wisconsin Dells, WI
It's hard to tell on mine when it actually does....although I have not tested it in wood yet. I just fully extend my ram and then engage it. I can't get a bead on when it goes to the second stage. It obviously does, as the motor keeps running and I'm able to get up to the DCV relief pressure.

I cranked the pumps switchover valve up quite a bit and the motor still doesn't sound like it's going to die when I run the pressure up to the DCV's unloader setting. Maybe I'll try to crank it fully in and see what happens. LOL
 

JRHAWK9

Minister of Fire
Jan 8, 2014
1,691
Wisconsin Dells, WI
In my case, I have a 25GPM pump, it's a CBDN 22/4, so my second stage is quite a bit lower flowing than a 28GPM's (CBDN 22/7 typically) second stage. So mine, on paper, would be only about ~10% slower during high flow/low pressure use....but will be ~43% slower in it's high pressure/low flow second stage.
 

hedge wood

Burning Hunk
Mar 1, 2009
216
Eastern NE
I think once you start splitting some tough blocks you be able to notice by sight and by the gauge when it goes to low flow high pressure mode on the pump. Having mine set a 1200 it normally doesn't shift down to the low flow mode. The two guys that normally run my splitter have no idea its even is a two stage and never notice it shifts down. All they want is it to keep splitting and to get the trailer full.
 

JRHAWK9

Minister of Fire
Jan 8, 2014
1,691
Wisconsin Dells, WI
I think once you start splitting some tough blocks you be able to notice by sight and by the gauge when it goes to low flow high pressure mode on the pump.

That's what I am guessing too. In the manner in how I'm going about it with "bench testing pressures", I guess the farther I can turn the pumps valve up while keeping the engine from sounding like it's lugging too much, the better. Ideally I would want it turned up to the point of giving my engine a load to where it's keeping my engine at peak HP rpm. If I had the pump performance data sheet and dyno of my engine I would know where to set it. ;lol

Those relief valves operate pretty smoothly. Makes sense seeing they are a spring activated by pressure, and are not an on/off type of deal.
When I first went to test what the DCV's relief was set to, the pressure increased pretty darn fast up to that 3,000psi area before I let off. I was like :eek:. After I adjusted it down, now the pressure rises fast to a point, then starts to slow down once the unloader starts to unload till the pressure gradually increases and holds it to the 3,300psi it's currently set at. Wherever it was set to before, I don't think the DCV unloader even started to unload yet at around the 3,000psi area. Now I can tell the unloader is starting to open much sooner seeing my pressure is not spiking as fast nor as high as it did prior to the adjustment.
 

Jags

Moderate Moderator
Staff member
Aug 2, 2006
18,259
Northern IL
Remember when setting relief pressure that it must not exceed the lowest rating in the entire system. Pump, hoses, valve, fittings, etc.