Wheelhorse 520h Power Steering

[ctg332]

Hello, I am putting power steering on my old 520h garden tractor, run pressure line off charge pump forward, put tee in line, one line to input of hydraulic lift valve, other to input of ross 4 port steering valve- column, run return line with tee back to trans sump, other 2 ports on column to left and right for steering cylinder. Problem is with tractor running, steering has little hydraulic help- UNTIL --- you crack hydraulic lift valve open, then steering is ONE finger. Put a make shift ball and spring in return line so return from steering valve cant go back toward lift valve and it JUST about is good-little stiff yet PLEASE PLEASE help this will be an awesome rig if it will work Thanks in advance to any or all !!! Tom

 

[bigdeano]

It probably has an open center hydraulic system. You can't tee into a pressure line or the oil will just take the path of least resistance back to the tank thru the valve that's not being used. The valves would have to be hooked in series, which could be a problem if the lift valve doesn't have a power beyond port. You could hook the inlet of the steering valve to the tank port of the lift valve, but the back pressure may damage the lift valve, or it may work fine. It would be a gamble. If it damaged the lift valve you'd have to replace it with one with a power beyond port.

 

[ctg332]

Hey thanks so much for help!! The lift valve DOES have a 700 psi relief valve built in, would that help to keep things in check? I am not very knowledgeable about this stuff, Tom

 

[bigdeano]

No, because the relief valve dumps into the tank port, which would now have back pressure on it.

This brings up another problem. If the steering valve doesn't have a relief valve, and you turn the steering to the end of travel, it would deadhead the pump. I suspect the steering valve has a relief valve, but you should check it out, I'm not familiar with them.

 

[ctg332]

Hey bigdeano, it does have an internal relief inside steering valve according to the schematic, so by me putting ball and spring in tee where lines join to return, I added pressure to the line going into the steering valve, if I DID hook them up in series which better to go to first lift valve or steering valve AND what would actually happen if either did get " damaged" I don't understand, and I will leave you alone AND thanks so much

 

[bigdeano]

I doubt if the shaft seal on the steering valve would take 700psi if you put steering valve first. I would put lift valve first because it would be cheaper to replace if damaged by back pressure. The metal around the tank port passages in the lift valve may not be strong enough to withstand high pressure, as it was made to just go to tank. Some valves are strong enough, some aren't. It could split open, or it could work fine.

 

[ctg332]

Great THANKS so much have a good afternoon

 

[bigdeano]

I forgot to mention, you should adjust the relief valve in the steering valve to 700 if you're putting it after the lift valve. Otherwise when you turn the wheels to the stop the pressure will spike to the relief valve setting, which is probably higher than 700.

 

[oldnslo]

Normally steering has priority for safety reasons so the steering should be before the auxiliary valve. You will have to do some research to see if your steering valve allows power beyond. How many connections are on your steering valve?

Your existing charge pump should also have a relief valve so relief in your steering unit may not be required. Again you need to determine how your transaxle is designed.

 

[bigdeano]

Hooking them in series without power beyond, they would either both work or neither will work until one is released. I don't think the order would matter in that respect. It doesn't seem like a lack of steering for a few seconds is a big safety concern on a garden tractor. You could well be right on the pressure relief valve.

 

[oldnslo]

If neither component has power beyond the tank line must be capable of system pressure. Agree on a lawn mower loss of steering may not be a concern but definitely something the OP should know about and understand