Check out some similar questions!

lairdkeith · Sep 16, 2010, 07:59 AM

Its hydraulic pump produces 12gpm at 2600 psi and 2600rpm.The main hydraulic loop has two valves 1) a 5" cylinder as a woodsplitter and a rotary motor that runs a series of rollers on a converted truck bed.This has run quite well in the past.BUT I recently teed in a hydraulic chain saw that requires 5 gpm and 1500 psi which I have run through controller. With the controlled flow to the saw and the overflow and the return of the saw into the main hydraulic loop. The saw runs well but not the other two things.The only time they will run is when I hold the saw trigger on and then activate one or the other valves and they will run. I am running the tractor at about 1200rpm. What am I missing here? Thanks Laird

smoothy · Sep 16, 2010, 08:14 AM

I woult look at the systen as you built it... and draw a detailed diagram and flow chart as you actually see it. If you look at the resulting diagram you may see how you hooked it up isn't how you thought you hooked it up and is causing the problem.

Basically it sounds like you put the saw in-line and not parallel to the other equipment and all flow is being forced through the saw. THat would explain the symptoms.

lairdkeith · Sep 16, 2010, 10:48 AM

Hi thanks for your interest: The Saw is parallel to the main loop running off tees from the main. May be I need to run the tractor at a higher rate than 1200rpm say 2000 to check it out? Laird

lairdkeith · Sep 16, 2010, 10:53 AM

Hi thanks for your interest: The Saw is parallel to the main loop running off tees from the main. May be I need to run the tractor at a higher rate than 1200rpm say 2000 to check it out? Laird

smoothy · Sep 16, 2010, 11:07 AM

Possibly I misunderstood what you initially said...

To get ANYTHING else to work, you have to have the saw running? (thats what I understood anyway)

If that is the case you didn't do a parallel loop like you thought. And the saw is acting like a gate valve on the system.

If you can clarify that a bit.

lairdkeith · Sep 16, 2010, 11:29 AM

You are right in that the saw is appearing to be the gate way valve but it is still in parallel with the main loop. Could there still be air in the system? Thanks Laird

smoothy · Sep 16, 2010, 11:50 AM

From my understanding of hyraulics... once the pump is primed the system will purge itself.

Also the fact the saw itself works proves the pump IS priming and working.

I can't think of any other explanation for what you are seeing other than somehow that saw in series and not parallel to everything else.

Unless, the saw bypasses all hydraulic pressure when its turned off internally... in which case the saw running provided enough resistance to hydraulic pressure for the other stuff to work. In that case you would need a restrictor to build a certain level of pressure when its not in use, but not enough to choke the saw or cause the line pressures to spike too high.