closed center hydraulics 1

[jimbomo]

i have a massey ferguson tractor that has closed center hydraulics that i am converting to an open center system, i have an open center pump mounted and working but i know that it will not last long pushing the fluid through so many relief valves. would like to know if a power steering pump from a chevy pickup or car works on a closed center system. if it would work i'd plumb one into the steering and brakes and everything else i have to finish conversion. any help would greatly be appreciated.

 

[MikeHalloran]

AFAIK, power steering pumps are all intended for open center systems.



Mike Halloran
Pembroke Pines, FL, USA

 

[jimbomo]

do you know of any closed center pumps that i could run off a pulley to the front that would work?

 

[hydtools]

Look at Muncie products

http://www.munciepower.com/products/fluid-power/pf-ph-series-clutch-pumps/?class0=Fluid

Power&class0_0=9&query=Product Classroduct Type.eq.Fluid Power&back=Products

Ted

 

[MikeHalloran]

Such things exist and are available from many sources. They often come with an electric clutch so they can be driven by a belt. Some come with two-groove clutches, so you can piggyback an open center pump alongside the closed center pump. ... which seems to be where you are going. ... I think.

Maybe it's time to put down the wrenches and the credit card, and complete the system design before you buy any more hardware.

Mike Halloran
Pembroke Pines, FL, USA

 

[jimbomo]

the best thing is i work at a trash company and i already have most of the valves and pumps that i need just every thing i have is open center. all i really need is a small pump to operate the steering and brakes.

 

[hydtools]

You can make an 'open center pump' into a 'closed center pump' by adding an unloader valve to the pump outlet. If the directional valves are not integrated into the pump meaning you have a bare pump.

Ted

 

[jimbomo]

ive thought about that but was not sure it would work, have heard some say that it will build up too much heat

 

[hydtools]

jimbomo, that's how a closed center system uses a fixed displacement pump. The unloader valve directs pump flow back to tank at a low return pressure when the system demand is blocked.
The closed center system pump alternative is a variable displacement pump that is made to stop pumping when the system demand is blocked.

Ted

 

[MikeHalloran]

Put a cooler in the return to tank line so the unloader flow goes through it. That will remove whatever heat the pump put in.



Mike Halloran
Pembroke Pines, FL, USA

 

[bradleyelwood]

Years ago I added an EXTRA power steering pump to a Ford pickup to run a small open center hydraulic circuit. We increased the reservoir capacity by welding another tube to the reservoir. (We "borrowed" a second reservoir and welded two together).

You should calcuate the volume required for implement cylinders and be sure the reservoir is large enough.

I dont think it is a good idea to combine implement functions with steering and brakes.