combining two hydraulic pump flows

karl f · Apr 7, 2011

How do you combine the output of two separate pumps into one control valve or circuit?
My 656 Farmall is described in the operator's manual as doing this for the auxiliary (remote) valves when the 3 point is not using its oil supply. The hitch and valves are supplied by separate pumps on this tractor.

I'm wondering how you would do this for other tractors or equipment when doing custom add on hydraulic plumbing or making a system from scratch.

thanks

karl f

TractormanNC · Apr 7, 2011

Surplus Center DOT com used to have flow dividers that would work as combiners. Don't see them in their current catalog though.

As for the IH 656, the main pump supplies the power steering through a flow divider and the excess flow goes to the remotes with a relief valve set at 1600 psi. The hitch pump supplies the hitch when it is being used, but when the hitch is NOT in use, this flow goes through a check valve and joins the excess flow from the main pump to feed the remotes. The hitch circuit has a 2000 psi relief valve setting. Therefore, the hitch pump can feed into the remote circuit but the main pump flow cannot feed into the hitch circuit.

Clear as mud ???????

karl f · Apr 7, 2011

tractorman,
pretty clear explanation. I'm going to mess it up some

What about when you install the optional remote relief valve for loader use (typically found on the utility or industrials) that's rated around 2000 psi?
The equal pressures would seem to keep the check valve closed in theory if i'm thinking correctly.

karl f

FORD 1710 · Apr 8, 2011

If both pumps are turning at the same time, all you need to do is connect the outlets. If one pump can be stopped, a check valve at the outlets will be needed to prevent reverse flow.

Flow combiners can used to syncronize the return oil from two cylinders. ( and a flow splitter used to sync oil to cyliners). A flow combiner won't work with a positive displacement pump as you would be forcing a restriction on the higher volume pump.

As a side note. Two stage pumps ( like on a log splitter with rapid extension) couple the output of two pumps for rapid extension. As do some hydraulic punch presses. When high presure is needed, the output of one pump is bypassed to the tank.

Any specifics as to what pumps / systems you want to combine?

karl f · Apr 10, 2011

FORD 1710:
Generalized question.

thanks for reply
karl f

combining two hydraulic pump flows

karl f

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TractormanNC

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karl f

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FORD 1710

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karl f

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