Modify 2 stage pump?

[mikefromnh]

Any way to modify/adjust an 11gpm 2 stage pump to stay in low pressure/high flow mode until 1750psi?


The pump I have is preset at 650 and is adjustable from 400-900. I'd like to use it with a Chonda 420cc to speed up my log splitter cycle times.

1750*11/(1714)85 = 13 hp

Right now I have a honda gx 160 and with a 4 way wedge it spends most of the extend cycle in high pressure/low flow with a resulting real world cycle time in the 40 second range.

Most every piece of wood splits at about 1000 psi, a few trip the auto cycle return at 1500psi. And 1 or 2 have needed the full 2000 psi that I have the relief set at.

So if I could move 11gpm at 1750 by only replacing the engine and adjusting the pump I'd be happy. My real world cycle time would almost always be 16 seconds.

 

[oldnslo]

May be as simple as a spring change in the sequence valve IF the pump drive shaft and components will take the extra torque / pressure.

 

[mikefromnh]

I'm willing to see if it will hold up to the increased load. It's either that or buy a bigger pump.

The spring would be under the adjustment screw?

As it is now turning the screw in increases the pressure that the pump unloads at -- all the way in and it stalls my current engine. 1.5 turns out and it works fine. I assume if I could some how turn that screw in further it would increase the adjustment range... Maybe add some shims?

Without a schematic I've been hesitant to tear to far into it.

 

[J_J]

Any way to modify/adjust an 11gpm 2 stage pump to stay in low pressure/high flow mode until 1750psi?


The pump I have is preset at 650 and is adjustable from 400-900. I'd like to use it with a Chonda 420cc to speed up my log splitter cycle times.

1750*11/(1714)85 = 13 hp

Right now I have a honda gx 160 and with a 4 way wedge it spends most of the extend cycle in high pressure/low flow with a resulting real world cycle time in the 40 second range.

Most every piece of wood splits at about 1000 psi, a few trip the auto cycle return at 1500psi. And 1 or 2 have needed the full 2000 psi that I have the relief set at.

So if I could move 11gpm at 1750 by only replacing the engine and adjusting the pump I'd be happy. My real world cycle time would almost always be 16 seconds.

Why do you think you can get 1750 psi and 11 GPM out of a 5.5 HP honda 160 engine.

You need 13 HP for those figures.

That pump can develop up to 3 psi, but at 3.4 GPM and 5.5 HP.

 

[mikefromnh]

Why do you think you can get 1750 psi and 11 GPM out of a 5.5 HP honda 160 engine.

You need 13 HP for those figures.

That pump can develop up to 3 psi, but at 3.4 GPM and 5.5 HP.

I'm well aware of that read my post you quoted and try again

 

[J_J]

Yep, I read it and to get more, you need more as in larger engine or smaller cyl.

Have you considered a regen circuit. More speed, and less force.

 

[mikefromnh]

I'm looking for the cheapest way to speed up my cycle times. Right now 80% or more of the time the pump is in low flow on the extend.

I can get a cheap 13-17 hp engine. What I'm looking to do is re use the pump I have and take advantage of the increased HP by increasing the psi at which the pump switches to low flow.

I'd basically be using my 2 stage pump as a ~1 cubic inch single stage. And hopefully be moving 11gpm at 1750--2000 psi.

 

[bigdeano]

The worst that can happen is it breaks. You'll probably need a stiffer spring, or maybe put a second spring inside the one that's there. Let us know how it works.

 

[SPYDERLK]

You may not have enuf spring to do what you want - nor enuf room for another spring that will. After making the adjustment the spring may be so compressed it doesnt have enuf travel left to allow the shift. The nested spring idea above is a way around this. Sometimes the coils will interleave tho unless the springs are counterwound. 1 left the other righthand coiled.
larry

 

[hydriv]

The screw you are adjusting is putting force against a coil spring that is in turn putting force against the ball bearing that sits against a hole in a conical seat. When the system pressure rises higher than the spring pressure, then the ball bearing is unseated and oil is allowed to bypass back to the low pressure return line.

If you crank that adjuster screw all the way in, then you are compressing the spring until the coils of the spring are binding against one another. That situation prevents the ball bearing from lifting off its seat and allowing oil to bypass. In other words, you just defeated the whole purpose of having a pressure relief valve. Fortunately for you, the engine you have is lacking HP and it just stalls. If you had a higher HP engine, then you would be here asking why your hydraulic pump split open and is now a piece of scrap metal.

Your splitter was designed in accordance with proven hydraulic engineering principles and the components were selected on that basis. My suggestion to you is simple. SELL IT. And then go buy a splitter with faster cycle times. As J_J pointed out already.... you have the wrong engine and the wrong pump in order to achieve what YOU deem to be satisfactory cycle times.