Need help (hydraulic on a smta)

If you want to install a valve you need to plumb it in the high pressure hose that goes from the pump near the distributor to the reserviour. the high pressure hose is the smaller one. The valve which could be a grieson or cross needs to have a relief of no higher than 1000 psi. If it is higher you run the risk of shearing a key on the distributor. the hose from the distributor goes into the inlet side of the added valve. from this valve, the hose then goes back to the reserviour. and the large hose which is the return hose does just that ,returns the oil from the reserviour to the pump . with this system you can use both the liftall valve and the added valve.No need to have one valve locked. the IHC 2 way valve does not have a relief but uses the single acting relief because when the 2 way vlave is used the single acting is locked in the up position. by the way the hydraulic pump could be warn because there was no filter usedon therse tractors.You may want to check pressure