Volvo EC300D

[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

[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

[doodlebug]

Ok, so you guy's have seen the valve innard's Now the question that I have is How can they be "pressure balanced'' to make accuation easier (less force)? Something to consider.
I've heard of pump's being "pressure balanced" as far as the seal's are concerned.

Just another brain cramp

Cheer's, Neil.

[Lil Giants]

0.3ml/rpm

2200rpm = 660ml

You running 3s lipo currently in your dumper Elliot with the Damitz pump?

You can run the pump from the gear switch and mix it. Set the rpm low when switching it on and the "mix" will speed it up when you activate the valves.

[RCKiwi]

Alloy rubbing on alloy, even with a snifter of oil, never lasts. I'd opt for a plain old mild steel or brass rotary valve in an alloy housing.
Also, the back of the valve does not need to be in full surface contact with its shoulder in the block - try say reduce the rubbing shoulder area (smaller diametre step) as the amount of friction will be a result of such a large surface area. Having a smaller "rub area" will result in less friction but a downside may be higher wear rates - another good reason to add a anit-friction washer.
The bearing would be a good idea if say you are operating the valve by push rods, etc so to alleviate side load - if you're mounting servos inverted, direct inline as is popular with commercial, it may be additional un-needed machining.

Keep plugging away at it - there's a fix here I'm sure

[Vanisle]

In regards to elliot330's comments about his Jung pump versus the Damitz pump. The Jung pump in the ADT's is the IP1Z-HR3 (4001) .18cm3 pump which pumps 520ml/min at 20 bar and 3000rpm. This pump is the IPZ1-HR5 (4002) .30cm3 pump which pumps 890ml/min at 20 bar and 3000rpm. It is the same one in the Vario excavators (and the same one others have used in 1/8 scale).

As for the discussion about the valve design, no idea how to fix it but hopefully Reg can figure it out. We want to see this things working!

[RCP57]

WWWOOOOOOOOOOOOOOOO-HHOOOOOOOOOOOOOOO! It's alive!

It took a couple months longer than I had planned but it finally works!!!!!!!

Sorry I'm a little excited. Big thanks to my father inlaw for making another valve block for me. I haven't taken it out of the shop yet to dig any dirt and I'm here by myself so there isn't any video yet. It seems to have good power at 25 bar but I won't know until it's in the dirt I guess.

Here's a couple pics of the valve installed. I still need to get a filter and a couple other things.

Reg

[doodlebug]

Way to go Reg! look's great!
Cheer's, Neil.

[RCKiwi]

Good stuff- what was the plan in the end to fix your valve block problems?

[RCP57]

Originally Posted by RCKiwi

Good stuff- what was the plan in the end to fix your valve block problems?

HAHA.. Secrets... No just kiddin, We just made everything smaller. He went off of my basic design but made the bottom out of steel and the rotors slightly smaller. We also decided to put the cresents in the top of the rotor instead of the bottom. I'm not sure if this actually did anything or not but it didn't hurt it either. The top of the valve body is also the sevo mount on this one too.

Thanks for lookin

Reg

[RCKiwi]

Good stuff - very nicely made indeed. Thank you for sharing. Good bunch of jokers on this site there is!

[modelman]

Looking good!! All that plumbing would drive me CRAZZY Nice work

[RCP57]

....and the moment you've all (and by you've all I mean I've) been waiting for!

Still has some bugs and I'm not happy with my skills at this point but its working.

http://youtu.be/IF7e79S3X10 http://youtu.be/8OVJV29FAd0

Thanks for watching

Reg

[steamer]

Reg, she looks fantastic. I don't know why your complaining you should see me at the controls.
Rob

[doodlebug]

IT'S ALIVE Great job Reg! Let the fun begin

Be patient, your's skill's will grow with time!

Cheer's, Neil