Hydraulics and PSI

[benkapitanec]

I've had my home built logsplitter for about 15yrs. and for the most part it has done what it was intended to do. On occassions I would get into some crotchety pieces and it just couldn't get through them. It had a 4" cylinder with a 11.5gpm pump powered by a 8hp
engine. I have since changed to a 5" cylinder and a 16gpm pump and same engine although I am looking to upgrade to a 10-12hp motor just for ***** and giggles. I have not tampered with the detent valve. I have also added a pressure gauge to the high pressure side of the system, between the pump and the detent valve. My question is, what should be the correct pressure reading to maximize my splitting force. I've heard that the pressure should read 600-650psi w/no load (just cycling the ram). Like I said I've never messed with the detent valves and just assumed that they were already preset with no adjustments required. If anyone has any experience with this, I'd like to hear your advise.

Ben

 

[SPYDERLK]

I think you mean relief rather than detent valve. Your relief is probably set around 2500psi. Are your pumps 2 stage, shifting automatically to lower volume at hi pressure? Im guessing so .. because 8hp wont drive 11gpm at the ~2500psi required to give you [almost] enuf force with a 4" cyl. If the 16gpm is 2 stage the 8hp engine will be near maxed out at 2500. But, with the the 5" cyl you will seldom need that much pressure even on the toughest splits.
larry

 

[AKKAMAAN]

I've had my home built logsplitter for about 15yrs. and for the most part it has done what it was intended to do. On occassions I would get into some crotchety pieces and it just couldn't get through them. It had a 4" cylinder with a 11.5gpm pump powered by a 8hp
engine. I have since changed to a 5" cylinder and a 16gpm pump and same engine although I am looking to upgrade to a 10-12hp motor just for ***** and giggles.

If your 2-stage pump is a Haldex-Barnes, it is probably adjustable between 650-900 psi. To measure this low pressure is hard, because if you stall the cylinder, it will show the HIGH pressure setting on your main relief valve....2500-3000psi?? So you need to run the cylinder through some logs and monitor at what pressure pump kicks into high pressure-low flow....
Your 8hp engine will do OK up to 800-850psi low pressure-high flow setting.

I have not tampered with the detent valve. I have also added a pressure gauge to the high pressure side of the system, between the pump and the detent valve. My question is, what should be the correct pressure reading to maximize my splitting force. I've heard that the pressure should read 600-650psi w/no load (just cycling the ram).

Pressure will depend on load.....at just cycling the ram, you should read less than 650psi....maybe 25-50psi or so....little higher on retract than extend...

Like I said I've never messed with the detent valves and just assumed that they were already preset with no adjustments required. If anyone has any experience with this, I'd like to hear your advise.

Your main relief valve is inside the control valve (you named it detent valve), and it's pressure setting was set by manufacturer, right!!??
Check the high pressure by stalling the cylinder at end of stroke!! Use a 3000psi liquid filled gauge.

 

[benkapitanec]

I just want to make sure I understand you correctly....To maximize my splitting capacity I need to run cylinder under load or preferably run to stall engine and take a reading at the gauge. Tune or make adjustments to the valve accordingly so that the gauge reads within the specs of the cylinder? I quess what I'm asking is, what is my PSI supposed to be if I am near stall? Can I just run the ram into my wedge? just so that you know, that would not be at full extension of the cylinder, if that makes any difference. Do I make adjustment to the valve while I'm in operation or do I make adjustment in increments during idle until I reach the desired result. I hope I am not confusing matters. I just want to simplify the process. I do appreciate everyones advice.
Ben

 

[AKKAMAAN]

I just want to make sure I understand you correctly....To maximize my splitting capacity I need to run cylinder under load or preferably run to stall engine and take a reading at the gauge.

Not stall engine just the cylinder....LOL

Tune or make adjustments to the valve accordingly so that the gauge reads within the specs of the cylinder? I quess what I'm asking is, what is my PSI supposed to be if I am near stall? Can I just run the ram into my wedge? just so that you know, that would not be at full extension of the cylinder, if that makes any difference.

No difference. If the splitter is designed right you should not be able to hit the wedge with the ram push plate.....but piston will still stop at the end of the cylinder, and then keep pushing while reading the pressure of the gauge....

Do I make adjustment to the valve while I'm in operation or do I make adjustment in increments during idle until I reach the desired result.

Either way can work, but I prefer to adjust while in operation, because then I have better control.....turn screw clockwise will increase pressure....so always start counter clockwise very care fully (max 1/16 of a turn at the time), to make sure that will lower the pressure, then turn clockwise to set the new pressure. Starting counter clockwise will tell you how much of a turn will change the pressure! (ATTENTION! Even if it is very rare, there are some very uncommon relief valves that increase pressure on counter clockwise)

The low pressure, 650-900psi, can not be adjusted with a stall on the cylinder. It has to be adjusted while in low pressure (650-900psi) motion.

I hope I am not confusing matters. I just want to simplify the process. I do appreciate everyones advice.
Ben

You are not confusing! Just not experienced with the proper hydraulic terms....:thumbsup:

I figured that your "detent valve" was meant to be the pressure relief valve....LOL....thx SPYDERLK!!