Modify 2 stage pump?

[mikefromnh]

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.

Thanks for the explanation of how it works.

I assume (maybe wrongly) that since the pump has a spec'd adjustment range that turning the screw all the way would mean it would release the ball bearing at the upper end of the range? Otherwise there would be warnings to make sure the screw was always xx turns out in the manual.

Preventing the bearing from lifting until a higher pressure is what I want to do -- I'm not seeing the doom and gloom. The pump is designed to handle 3k psi and there is a relief in my auto cycle valve set at ~2250 psi.

I think my biggest concern is breaking something internally in the pump and getting debris in the system.

Obviously I realize this might not be ideal which is why I'm asking here. But I wouldn't be increasing the gpm or psi in the system so why wouldn't the rest of the components be up to the task?

 

[SPYDERLK]

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.

You have described a relief valve.

Thanks for the explanation of how it works.

I assume (maybe wrongly) that since the pump has a spec'd adjustment range that turning the screw all the way would mean it would release the ball bearing at the upper end of the range? Otherwise there would be warnings to make sure the screw was always xx turns out in the manual.

Preventing the bearing from lifting until a higher pressure is what I want to do -- I'm not seeing the doom and gloom. The pump is designed to handle 3k psi and there is a relief in my auto cycle valve set at ~2250 psi.

I think my biggest concern is breaking something internally in the pump and getting debris in the system.

Obviously I realize this might not be ideal which is why I'm asking here. But I wouldn't be increasing the gpm or psi in the system so why wouldn't the rest of the components be up to the task?

Does the manual designate that screw as the adjuster for the shift point? ... If so - and with adjustment you are coming to a sudden point where the engine stops quick rather than a lug down to stall, you have probably fully compressed the spring. ... The below applies:

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

 

[J_J]

2 stage manual.

Both stages are pumping when the pressure is under 450 psi.

https://www.northerntool.com/images/downloads/manuals/1012.pdf