It all began with a customer purchasing this used machine and wanted a thumb installed. No problem I said-famous last words. It had an auxiliary spool in the main control valve not being used-I just had to plumb it. Did so with a remote solenoid valve activated by an electric handle to control the pilot pressure thru to the signal control valve (which has the provisions for the aux circuit but were plugged off) and then to the main control valve to control spool operation. I installed OEM port reliefs in the main CV that again were plugged off, and ran lines down the boom/stick for the newly installed thumb with a 3-ways on each side (provisions for a breaker). Also on the one work port line (B) I had teed in a ball valve that dumps straight to tank (breaker provision). Fired it up and found the pump was not stroking when activating the aux circuit. Turned out I needed to cap off the line that was going to tank from the SM port of the signal control valve. Now the pump is stroking normally and the machine idles up from auto-idle when trying to use the thumb. Here lies my problem-when the spool is activating in one direction and directing pressure to the one work port (A)-its not dumping the pressure from the other work port (B) and vise-versa. Its not allowing the oil to return back to tank. So I will see the pressure build in one line when activated, go to activate the other line and the pressure builds in that line, but the pressure remains in the first line. I am watching this with gauges plumbed into the lines for the breaker provision at the stick end with the thumb cylinder out of the equation. There are no quick connects. I have verified the problem is in the main control valve by: 1.backing off the port relief in the main CV to dump the pressure in either work port line or 2.opening the ball valve back to tank in the one work port (B) I have verified the spool is moving freely and the pilot pressure to control the spool is building and dumping correctly as commanded on each side. I've never seen this before. I pulled the spool in desperation, reaching for an answer I'm starting to think the spool might be wrong and covering the return to tank section, but this seems crazy. What am I missing..............
What dash do you have, 2, 3? You are plumbed directly to the control valve and not through a selector valve, correct?
I believe its a dash 1. Tag just says ZX225US SN- HCM1GF00E00115554
What are your specific pressures on the pilot caps (top and bottom) measured simultaneously when activating one way, then the other way? Also post a picture of your remote solenoid valve. Do the lines from the solenoid valve go through the pilot signal manifold (into ports M and N and out of ports 13 and 14 to pilot caps)? A picture of the control valve where your main lines are plumbed as well.
So I tracked down a sister machine and yanked the spool and found they are different, FML. Looking at the original spool, when its shifted there is no relief cuts in the spool to feather the return oil and looks like the section that opens to tank is too long and blocks the path of oil Why-o-why would you want to send oil out but not have it return?
Hi I’m working on a zx225 just was wondering what ports did you use to put your aux circuit in for the valve body. Thanks