I have a John Deere 326E. Every time i curl or dump the bucket until is dead ended and try to lower the boom, the boom is actually raising. If the the bucket cylinders are not dead ended, the boom will lower but as soon as the bucket cylinders dead end, the boom will start raising. Is this normal?
I had a similar situation with a mustang skid steer. Turned out there was a partial blockage of the line from the valve to the tank. It took some time, fittings and gauges to figure it out. Once the blockage was removed, everything worked perfectly again.
Yes. The control valve on that machine is a series control valve and when one function is operated there is no flow to the next function except the return oil from the first function. In your case, the bucket spool reaches the end of the stroke, stopping all oil flow, and with the boom spool being before the bucket spool the rise in pressure from the dead headed oil, and design of the control valve boom spool return oil to the bucket spool, creates equal pressure on both sides of the boom cylinder, causing it will stop and start to raise because the surface area of the piston is greater on the barrel end than the rod end. I'm curious, when the boom stops while holding the bucket over relief, does the boom raise about 4 inches, then start to lower again? IIRC, I think that is what will happen. Either way, the solution is to not hold any function over relief when operating.
It totally makes sense looking at the schematic. But if only one function would work at a time … how come i can control any 2 functions without any problem before hitting relief (boom lowered or raised over relief, does not effect bucket or aux functions, problem only shows when bucket or aux goes over the reief). I am suspecting, will find out Monday, that the return line is having some resistance and redirects oil to boom spool. The boom does not stop. It goes all the way up. Regards!
Because of the passages shown below. They make multi-functioning possible, until you dead head.