Thanks for the reply...
I have to get back with the owner and get more details on exactly what the problems are he is experiencing...
It seems the hydraulic control levers are are doing more than they are supposed to...i.e., lifting boom lever also causes it to swing etc...
from what little I have been able to find from other sources it could possibly be "circuit relief valves"...does that sound plausible?...does each spool have its own relief valve? I understand that they can stick?
I only looked at it long enough to get the numbers off the control valve cover to start doing some basic research I did not remove it.
I will contact the owner this evening and find out as much more as I can
thanks again for the reply...
The control valve does not have relief valves, it does have check valves to hold the pressure to the cylinder when the handle is released The spool allows pressure to be applied to one side of the cylinder while it allows pressure to release from the other side simultaneously when you pull or push the handle.
I Rebuilt my control valve, and the controls, each cylinder has it's own spool. The control handles and pivots which there are a total of 12 tend to freeze on the rods after years of dirt and moisture cause rust. The upper rod can spin freely so if 2 handles or more are frozen on the rod, it can allow one handle to move 2 or more spools operating several cylinders with one handle.
The upper and lower rods are 1/2" in diameter, The bushings are in the handles on the top rod, and the pivots on the lower rod, they are nylon with a 1/2" ID and a 1.25" OD and 1-3/8 in length
The lower rod with the pivots that operate the spools is a fixed rod, on one end it has a flange that has a bolt hole to mount it to keep it from turning.
Each spool has it's separate ports so if you are getting reactions from 2 or more cylinders while pulling one handle, the upper rod is turning moving other spools which their handle(s) are also stuck to the rod. Messicks.com has a breakdown, type in the search 19-481 and it will show the parts breakdown and the part number and prices. The nylon bushings measure 7.72mm ID x 15.98mm OD x 34.8mm L, or 1/2" ID x 1.1/4" OD x 1 3/8" Long. The price was $18.64 for each bushing which was insane, especially when you need 12.
I have a small lathe so I bought a 3/4" x 2 ft long nylon rod on Ebay and made my own bushings, 12 bushings for $16.00. Then I had to turn 2 steel rods on the lathe down to 1/2" diameter because my old rods were worn and rusted. Now it works like new.
The control valve is easy to rebuild, it only uses o rings as seals, the sizes are shown on Messicks, most are either 1/16 or 1/8" standard o rings, the odd sizes are ORB O rings for O ring Boss connectors. With a chart that shows the measurements of ORB rings you can determine the rings you need, Messicks only shows measurements, they don't give you fraction sizes or ORB sizes, so you need a chart for both fraction to decimal, and a chart showing decimal measurements of ORB o rings. Ordering the rings from oringsandmore is cheaper than Messiks.
