Volvo EC300D

[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

[elliot330]

Wow 30 bar is a lot of pressure... what are you're hoses rated at?

Another option is mixing your pump to your valves in the radio.

Run the pump at 1/4 to 1/2 speed when the valves are closed, then when you operate the boom, stick or bucket the pump ramps up, in most digital radios you can program this.

Are you using the 0.3 or 0.46 Jung pump?

Elliot.

[RCP57]

You guys are right about the friction issue for sure. The valve my father inlaw made has 1 3/8 plugs. I haven't figured it out but at 28 bar thats a huge amount of force! Another problem with it is that it's all aluminum and even with oil in it starts to score itself under that pressure. The one I made is so much smaller (plugs are .680)and with the plugs made of brass seems to be a little better but my machining skills are not that great so it leaks down too much. My father inlaw is coming over tonight so that I can show him what I've made. Hopefully he can make something similar on the cnc at work.

We were tossing around the idea of running a bearing in the top of the valve body to help with the side load on the plug but I think maybe a shim washer of some kind as mentioned may be easier. I think I will ask him to make this valve from steel as well so that it wears better. Weight is not an issue anyway here.

The pump is a 0.3, and my hoses are rated at around 300psi working pressure, 1200psi bursting pressure. I think the pump is a little small for the size of my cylinders. I'm picking up a larger, higher rpm motor from the hobby shop today so we'll see if that picks up the volume. I'm using a DX8 but I had planned on running the pump off of the gear switch because it's the only channel left. Can I still mix the pump if I do that? It will probably help if I can.

Thanks for all the help guys! I really appreciate it!

Reg

Thanks