Volvo EC300D

[RCP57]

Originally Posted by ihbuilder

Reg , dumb ? , do your valves turn with ease with no pressure ? Could be just a little lapping needed . I have a Robbe valve that is tight like that till I loosen up the top .

The valves turn with very little resistance with no pressure. They actually turn decent when their open too, it's just when you are trying to open them from the fully closed position or close them from the open position that they are too stiff. Have you had your Robbe valve apart? Does it look much different than what we're doin? I think that Ed is right and it is side loading the plug. I have some of my grandfathers hydraulic books and in them it says that rotary valves are hard to balance but there has to be a way!


Thanks for the help guys!

I just recieved some parts for my Tigercat so....

[ihbuilder]

Reg , the Robbe valve is exactly what your doing . I'm thinking you have more pressure then you need . do you have a pressure relief valve in somewhere ? If not , put 1 on the supply circuit after the valve . come out where the plug is ( assuming thats the supply side of your valve ) I haven't got to play with the stuff from Richard yet , but I plan to make a solid base for the valves much like the verio setup . they bring the supply from the pump through the valve into a pressure relief valve of some sort ( needle valve I think ) .

[RCP57]

Originally Posted by ihbuilder

Reg , the Robbe valve is exactly what your doing . I'm thinking you have more pressure then you need . do you have a pressure relief valve in somewhere ? If not , put 1 on the supply circuit after the valve . come out where the plug is ( assuming thats the supply side of your valve ) I haven't got to play with the stuff from Richard yet , but I plan to make a solid base for the valves much like the verio setup . they bring the supply from the pump through the valve into a pressure relief valve of some sort ( needle valve I think ) .

Thats interesting to know that they are the same. I do have a relief valve and it's set at about 28 bar. At 20 bar this machine doesn't have a lot of power but the valves do turn much easier. I would like to be able to dig firm ground with it so I think 25-30 bar is necessary. Do you know the diameter of the valve?

Thanks Reg

[ihbuilder]

the ports under the rotor are .320" center to center . the rotor is .510" dia the crescents are the same as the ports . I'm going to build a 385cl cat which is as big as vario's 850 deere . I'm not sure these Robbe valves are big enough the ports seem to small for the flow needed ( about 1 mm dia ) I may be making my own .

Stevie

[RCP57]

Thanks Steve, The valve block that I made is a little larger then but not much. The ports are just under 1/8 and the cresents are 1/8 because that was the smallest cutter I had. I would love to see what the Meinhardt valves look like on the inside that seem to be in a lot of the German machines. Flow was the main reason that my Father inlaw and I designed the valve he made for me so large but I guess the inside of the fittings are so small that maybe it isn't necessary? I use 5/32-10/32 push to connect fittings on the valve and rams. I did drill one out so that the ID of the fitting matched that of the hose and it still looks to be strong so I will drill the rest out and see if it makes a difference in flow or speed.

Thanks again for the help! I'll keep tryin! I have a lot more time and patience than money so I have to figure it out the hard way.

[RCKiwi]

Are you able to machine in a teflon shim on the back side of the rotary valve to help reduce friction? The larger you go with these part circular ways in the rotary head, the more force required to rotate it against the thrust created by a larger area in the circular ways. Sort of think that the circular ways or the "pressure in" way (when closed) is sort of a piston, and pressure here will cause the rotary head to thrust against the shoulder in the valve block - make sense?
ha - now Ive read it back I'm not sure it does - clear as mud!
Glenn

[ihbuilder]

now that Glenn mentioned it Right on , that my be an issue with the robbe valves I have , they're only designed for 10 bar max and have no way to limit friction between the rotor and head housing . 30 bar , 435 PSI is a lot of pressure