PC1800 Front Shovel (1/12)

[DADSGARAGE]

Finished working on the hydraulic fitting....took longer than I thought...lol

Next will be another test run with 4 cylinders using a new motor and belt drive, need to find out if there is enough volume when running the pump at 1200 RPM

[IMG]

[IMG]

[IMG]

[IMG]

[DADSGARAGE]

Did some more "high tech" testing of the hydraulics....turns out it does work but not as planned...lol...the open center valve is not the best for running more than one function at a time, live and learn, need to convert it to a closed center which will mean the PRV will be bypassing all the time when the controls are in neutral instead of free flow back to tank when using an open center valve.

Started testing with 20 lbs and then added another 20lbs to see what it would do with the 40 lbs....the extra weight made little to no change in cycle times or pressure

[IMG]

After running it with the 40lbs I noticed the 1/4" threaded rod was bending under the load, so went back to using only 20lbs for the "wire and wood" testing...lol

[IMG]

The motor and belt drive seems to work well, using a small adjustable pulley on the pump so the RPM of the pump can be changed a bit while using the same input RPM of the motor

[IMG]

[RCP57]

That's a shame about the valve bank but I'm sure you will get it sorted out. Looks like a good simple setup. I say just paint the plywood and get digging.lol

[Supermario]

With all valves in neutral and flowing back to tank what kind of pressure is in the system? I'm just wondering, some systems use a slow return check valve for the oil returning to tank. It keeps the valve in a more charged and ready state. Using a flow control you could restrict return flow to a point and not generate excessive heat. Let's say you have 50psi in a free flow state right now, using the flow control you could increase that to maybe 75 or 100 psi and see if the functions improve? Also, your prv would need its own dedicated return line to tank and not tee into the valve bank return line.
It may be something to experiment with before going through the hassle of converting to closed centre system?

[DADSGARAGE]

Originally Posted by Supermario

With all valves in neutral and flowing back to tank what kind of pressure is in the system? I'm just wondering, some systems use a slow return check valve for the oil returning to tank. It keeps the valve in a more charged and ready state. Using a flow control you could restrict return flow to a point and not generate excessive heat. Let's say you have 50psi in a free flow state right now, using the flow control you could increase that to maybe 75 or 100 psi and see if the functions improve? Also, your prv would need its own dedicated return line to tank and not tee into the valve bank return line.
It may be something to experiment with before going through the hassle of converting to closed centre system?

Funny you should ask that...lol....because the more I restrict the return line the better it works....lol....(the return pressure was about 60psi) but this is only helpful up to a point....if all the valves are open and the return line is too small the sytem pressure goes way up and beyond the PRV setting, which is what should happen because the PRV valve uses the same return line and there is no place or volume left over in the return line to dump the flow and or unwanted pressure.....but like you say if the PRV had its own seperate return line before the valve body the pressure in the system while in neutral could be increased but never allowed to go above the PRV setting.

From what I understand changing this valve to a closed center should be easy......need to change out one fitting.....the closed center simply uses a plug to block the center port flow to the return line port....when the plug is installed and the controls are in neutral (center position) all the flow must pass through the PRV and back to tank. I'm sure you already know much more than I do about hydraulic systems and don't need to learn anything from what I am sharing as I slowly learn more on the subject, I'm sharing this more for others who might also be interested in learning more on this subject. We can all be thankful and learn from the skills and knowledge shared here on this forum....like Joe says "the more you share, the more you get"

So....Thanks guys for sharing what you know with those of us that don't !!