Reducing flow and pressure in hydraulic branch circuit

[Scooby074]

I need to reduce both the flow and pressure in a hydraulic circuit for the accessories on my wood splitter.

Pump is a 22GPH and relief will be at 3000 psi.

I need to reduce the secondary circuit to 2500 psi and about 2GPM to power my log lift and wedge lift. Both those cylinders are cheapie tie rod types, 6" stroke, 2.5" bore 2500psi max. THis circuit is controlled with a Prince RD522 2-spool valve that will have its internal relief set to ~2700 encase there are issues with the priority valve over pressurizing the secondary circuit.

I know that a 2/30 fixed (or adjustable) priority flow divider like the Prince RD405R with its internal relief set to 2500 ( Surplus Center - 3/30 GPM PRINCE PRIORITY FLOW DIVIDER W/RELIEF) will do what i want but theres the minor issue of constant flow to the secondary even when the secondary circuit isnt in use causing heat and wasting flow that could be going to the split cylinder.

Any way to do this circuit without those loses?

 

[aczlan]

What if you put the splitter AFTER the valve for the splitting ram (on the power beyond port)?
Then it will not affect the splitting valve.

Aaron Z

 

[Scooby074]

What if you put the splitter AFTER the valve for the splitting ram (on the power beyond port)?
Then it will not affect the splitting valve.

Aaron Z

good idea, but i should have clarified the only pb port i can use is on the 2 spool that needs the reduced flow and press. the split valve is a prince auto cycle without the pb option available,

if the split valve had pb id just use it first then reduce press on the 2 spool internal relief. flow would be reduced by using 1/4" hose to the cylinders

 

[J_J]

Would this valve not work.

2 SPOOL 25 GPM PRINCE LOG SPLITTER/LIFTER VALVE with PB

Surplus Center - 2 SPOOL 25 GPM PRINCE LOG SPLITTER/LIFTER VALVE

Why would want to reduce the pressure? Pressure is developed by the resistance to the cyl caused by the load in lbs.

If you are not lifting large loads all the time, the pressure should not be a factor.

You can also add an external relief just about anywhere.

This valve will provide max flow and pressure to the splitter spool.

 

[Scooby074]

JJ the valve you posted would be ideal, but its not the valve that i have. That valve has the option for PB, mine doesn't. The PB option valve isnt available locally.

Pressure reduction is necessary to keep the tie rod cylinders from self destruction. Theyre cheap cylinders only rated at 2500.I know that the pressure built in the secondary is related to load, but i can see these cylinders going to max stroke (and into relief) somewhat regularly. If im careful i can stop the cyls before they go into relief, but you know how it goes.....

I got them for about $70 each. A welded, threaded type cylinder rated at 3000 is about $140. So the upgrade to 2 good cylinders is about the same (or a little more) then adding the priority flow valve, and id still have the problem of excessive flow to deal with. Constricting the lines to the secondary circuits would help, but at the cost of a great deal of heat (line losses) and wear on components (high fluid velocity).

putting a relief on the work ports of the secondary might work as protection for the cyls... Id have to look at the plumbing and cost of the valves. Relief on the inlet side of the 2 spool would reduce system pressure.

The internal relief and PB on the 2 spool is useless really. I cant use it to drop the pressure as the splitter spool has to go second and i want it at system pressure

What im thinking about doing is coming off the pump with the priority flow. at the PF the relief will dump to tank, CF will go to the aux circuit (pressure reduced to 2500, 2 gpm) EF will then carry on to the splitter valve at 3000.

 

[aczlan]

JJ the valve you posted would be ideal, but its not the valve that i have. That valve has the option for PB, mine doesn't. The PB option valve isnt available locally.

What model is your auto cycle valve?

Aaron Z

 

[Scooby074]

What model is your auto cycle valve?

Aaron Z

Its a model RD523MMEE5A1A1 3/4 in and 3/4 work ports.

The model RD523MMEE5A4B1 is the one with PB

Heres a rough schematic of what i have planned. If anyone has recommended changes please let me know

 

[J_J]

Is there any reason that you can not return the valve you have and purchase the one from Surplus Hydraulics?

I really can't see the fluid heating up that much only using the wedge lift or log lift that often.

Is there any reason not to put the priority valve before the splitter valve for use by the secondary valves?

You are not normally using the wedge or the lift while splitting, so the EF fluid would go to the log splitter valve, and the fluid is only relieved in the priority circuit when using the wedge or the lift. So, with nothing in operation, the fluid is free flowing to the tank with no restrictions.

You didn't mention anything about another valve for the wedge cyl, unless you are going to use both cyl at the same time on one spool.

Your ideal valve setup would be a single spool auto valve total automatic operation, with PB connected to a two spool valve for the lift and wedge.

If you need someone loading while you are splitting, then the priority valve located before any spool valve would give the options you want.

 

[J_J]

Your diagram is exactly the way I was thinking. I didn't see the two lever valve before. There should not be any heat issues as you are not using the wedge or log lift all the time, plus the fact that you are not maxing out the cyl all the time .

 

[Scooby074]

My reasoning for the priority flow valve is as follows

1. to have the ability for someone to both load the lift and move the wedge in mid stroke. How often the later will happen, im unsure of.

2. i may add a conveyor in the future . I was going to use the CF to power it.

3. reduce pressure for the tie rod cylinders.

4. and probably the most important, reduce flow to the aux cylinders. a quick calculation shows a 0.3 second extend time for both the 6" cyls!!! can you say log catapult . 2 GPM into those cylinders gives me an extend time of 3.8 sec.

Flow reduction in the aux could be accomplished with needle valves but they are about $40 each, so no real savings and they wont accomplish some of my other goals.

Returning the valve and ordering from Surplus isnt really in the cards as shipping 30lbs of valve to canada and dealing with brokerage would make the valve too expensive.

I called another supplier to check on price and availability of the PB splitter valve and the prince 2/30 priority flow. I should hear back soon. Cost on the priority flow could come into play too. I cant see it being as cheap up here as Surplus has it in the states.