dumper / forklift hydraulics

[bangertrack]

Hi all,

I am putting a forklift mast on a liner dumper. I have the spool valve that was with lift mast. I am also going to fit a danfoss hydraulic steering valve. My question is this:-

Can I take the high pressure pipe to the steering valve, then the outlet of the valve to the mast spool valve then a return to the tank? My concern is that the once low pressure return from the steering valve has now become high pressure with the addition of the spool valve - and that will make a difference to the pressure relief operation in the unit????

The mast spool valve has 2 tank returns - but both flow oil when just turning the engine over (ie, the pressure relief valve is not operating).

I have a thwaites alldrive dumper with hydraulic pivot steer and looking at the pipework on that - the tip spool valve is fed from the pump, then feeds the steering unit, but the spool valve has a separate pipe ( 5 pipes in all) that splices into the return line which I assume is the pressure relief pipe.

I hope that makes sense - any advice appreciated.

[essexpete]

Ashamed to say that I have looked properly at the hydraulic circuitry on our old Thwaites 4000 but I do know that tipping and trying to steer can be difficult. It would make sense from what you describe with your Thwaites. Without getting into dual pumps or proportional valves would it not be best to stick to a similar layout on the forklift project. My gut feeling would be that on encountering a heavy load the pressure in the sytem might damage the steering valve or at least cause the steering RV to blow continuously if that is designed to run at less than you need for the f/lift. The forklift could also lack speed/power with a small dumper pump.

[bangertrack]

Thanks for the reply - I think I'm going to build it and see what happens! If there are problems then it will have a redesign or modify how it is driven.

The pump is only small on the machine, but I have had the mast hydraulics working and it lifts the forks pretty quickly (it is a small, 2 stage mast off a little electric lift). ##

I will keep you informed of progress and performance!