hydraulic pump psi
- Thread starter jdj257
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lens12
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- ford 9700, tw30, massey, jd2030 jd4010, yanmar F60d, ym330d, ym276d,ym226d,ym186d, ym2000, ym155
The hydraulic pressure of the system is determined by the relief valve. It is not made to adjust without disassembling it. It would take different springs or shims to change it. Raising the the pressure would increase your lift capacity , but not your rate(speed) of lift. To increase the rate, one would need a larger capacity pump. There is a good chance that i could supply a larger one. It would probably increase the volumn by around 25%.
JC-jetro
Elite Member
jdj257 said:Is there a way to turn up the hyd psi on a 165d? I would like to get a litttle more out of it. thanks
The pump pressure is function of gear design, case design , fluid capacity, rpm that the pump is ruining and the back pressure that is caused by piping, restriction and load being carried on the hyd system. The relief valve makes sure you do not dead head the pump (meaning running a pump that is positive displacement or others types where the flow is restricted to zero). At dead head flow (zero) the pressure will be tremendous causing all sort of problem with the system. System pressure can be pushed up or down by removing shims ( less sys pressure) or adding shims (more system pressure). on some you can adjust the spring pressure without needing shims. The problem is you will loose some flow and flow is what you need at desired pressure. At any given rpm you will have certain flow at varying different pressure by restriction (constantly changing) on the system in the forms of fittings, piping and load on Hyd system.
JC-jetro
Elite Member
jdj257 said:
Relief assembly off of hydraulic pump discharge. Some are adjustable and some are fixed as it is depicted. Adding shims increases pressure for relief and taking shift off reduces the relief pressure. Again increase pressure does not result in more flow. When you set the pressure higher effectively you’ll reduce flow at given rpm
.
Flow control valve assembly with another relief to avoid shock loading of the lift piston. Notice shim #14 which is basically a small flat washer. Each shims adds about 50 PSI of head resistance by making the spring #13 tighter
The shim on my picture is not shown since it was inside #16 spring guide bolt.
I hope this shed some light for you. Again pressure and flow go hand to hand . you can not increse pressure without reducing flow or increasing flow without reducing pressure for a given pump and rpm running at the time.
Probably shimming a bit will allow you pick up the weight and perhabs a bit slower. The caveat is not to damage the piston seal
This is what happens when you shim thing too much. You will then accelerate the demise of your piston seal, although not too difficult to change.
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JC-jetro Thanks for all the great information and the detailed pics. I realize that being a positive displacement pump it will keep making pressure until something comes apart (the weak link), hence the reason for the relief valve. My lift raises more than fast enough for me so I figure I can sacrifice a little there.
Again thanks for all the great info.
for all the great information and the detailed pics. I realize that being a positive displacement pump it will keep making pressure until something comes apart (the weak link), hence the reason for the relief valve. My lift raises more than fast enough for me so I figure I can sacrifice a little there. Again thanks for all the great info.
JC-jetro
Elite Member
jdj257 said:JC-jetro Thanks
Again thanks for all the great info.
My pleasure. I think all will be well as long as you do not stress out consumables such as O-rings, pistons seals and such. It is hard to find info on how much pressure seals can stand as they age. I reckon mine was 26 year old original seal and was exposed to extremes and gradually gave up taking many years. even with the conditio you saw, my 3 pt would lift all but could not stay up after the engine was shut off for obvious reason.Not bad at all for 26 year seal. A piston seal under $10 and at most couple of hours of sweat equity can remedy it and you are back to business for hopefully many years. That ain't bad at all.