Does fisher use 2 single acting cylinders, like meyers? If so you can just ad a relief valve somewhere on the plow between the hydralic hoses. if it angles to fast (which I found with my meyers blade) just ad a needle valve in each hose and adjust the flow to your taste. Both are available from surpluscenter.com a 1/4" npt needle valve can be had for $20 each. I was told my meyers plow was good to 3500 psi, so i never worried about the psi, but i did put in flow restrictor needles valves because it angled way to fast if the engine was above an idle. KenI was going to suggest using a relief valve, but after i thought about it, that would be a little too complex. You would need a relief vavle on both hydraulic lines and then you will need a vavle to allow the oil to by-pass when you reach your pressure..... It may be easier and cheaper to get another ram for it with a higher pressure rating. As long as the hoses are rated at the correct pressure.
I wish you luck!
after getting it all set up it turns out that with the hand aux on my relic with just a little movement on the stick the plow does fine I like it to go kinda fast anyway no blown seals yet JeffDoes fisher use 2 single acting cylinders, like meyers? If so you can just ad a relief valve somewhere on the plow between the hydralic hoses. if it angles to fast (which I found with my meyers blade) just ad a needle valve in each hose and adjust the flow to your taste. Both are available from surpluscenter.com a 1/4" npt needle valve can be had for $20 each. I was told my meyers plow was good to 3500 psi, so i never worried about the psi, but i did put in flow restrictor needles valves because it angled way to fast if the engine was above an idle. Ken