Volvo EC300D

[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

[elliot330]

FYI...

I've seen the inside of a Damitz valve and they are approx 8mm in diameter.

I recently changed my pump to a Damitz brushless pump (flow rate 450L a minute), Mr Damitz explained to me that its not about pressure, but about volume... albeit you still need pressure to lift a heavy object. ( I know very little about hydraulics :-) )

As an example, the release valve in my dumper is set to 10 bar, the steering is quicker than is was with a Jung pump running at 16bar, yet it'll still tip my daughter out the back and she weighes 17kgs aka 40lbs.

Without checking the flow rates of the Jung, I assume 0.3 equals 300l a minute?

With regards to the gear channel, you'd need to check whether you can mix that channel in your radio.

[RCP57]

At 1500rpm and 20 bar this pump is supposed to move 440ml, it ruffly doubles at 3000rpm. I'm running a double planetary(at least 6:1) so my pump speed is pretty low. I think with the motor I plan to buy today and my current reduction I should be able to spin the pump at around 2200 max. With the relief set at 28 bar it has a fair amount of power so if I can get the volume up it should be OK. If need be I'll have to turn the pressure down but at 20 bar it will only drag itself across the smooth concrete until the stick is at 90 degrees. This machine is about the same size as a Vario so it requires a lot of juice!

Reg