another basic hyd question

[brusew86]

say I have a PTO pump kit for a backhoe, where is the relief valve located? in the pump? in the valve? do gear pumps have a relief valve built in typically? the reason I ask is because I am building a PTO pump kit for woods BH 9000 and I'm wondering if I need a relief valve. the hoe has a relief valve in the valves set for 2400 is that all I need? Thanks!

 

[J_J]

You need at least one relief in the hyd circuit.

If the valve has a relief, that should be fine.

What is the pump max pump pressure?

The normal PTO pump has a working pressure of 2250 psi.

http://www.surpluscenter.com/item.asp?item=9-1047-2&catname=hydraulic

 

[brusew86]

the pumps I'm looking at are in the 3000 range. The typical tractor PTO pumps as you say are 2250 which isn't quite enough pressure for my application as the hoe takes 2400. I just wasn't sure if the relief on the hoes valves could be the sole relief. I thought it may be just a fine tune the pressure in case it's fed off a hydraulic source thats set a bit higher than 2400

 

[J_J]

You can adjust most any valve relief usually up to 3000 psi.

You can also gear up the rpm of the PTO output to meet the rpm requirement of a 3000 psi hyd gear pump.

Some tractors have more than one PTO speed.

Just for instance. if you need 10 GPM at 3000 psi, that would take about 21 HP to drive that pump.

A tractor with no attachments will usually have one relief and it is in the 3pt system.

If you add the FEL, the FEL valve is usually first in series and becomes the master relief.

If the BH is using the tractor hyd, you should set the BH relief to the tractor relief setting.