Good morning guys........ I have a little situation here that has turned out to be a bit of a brain teaser for me. At the end of last years soil season my screen feeder/yard loading machine developed a problem with the bucket slowly curling down by itself,at times after dumping a bucket load of material it wouldn't curl back without jazzing the control a couple of times. So being the end of the season and it was not a chronic thing we decided to address it now as we are servicing and repairing everything for the upcoming season. What seemed to me to be a simple problem in the pilot control has turned out to be something a bit deeper. We took the pilot control apart: All the springs,seats,o-rings and plungers look brand new. That led me to the manifold for the boom/bucket: Took it apart and other than a very small amount of barely visible scratches on the spool for the bucket curl everything including springs look new. So then came a leak down test for an internal leak on the bucket cylinder,which is on a Z-bar. I really doubted that it would be the problem as the cylinder is totally extended when the bucket is curled and after extending the cylinder,bracing it and plugging it and letting it go,the cylinder proved to be fine. Any new ideas on this would be appreciated,as when we put everything back together yesterday......the bucket still is slowly curling down. The machine otherwise is in excellent shape,tight as a drum with zero oil leaks anywhere.
I would put the bucket flat on the ground and the use the dump to raise the machine and see if it drifts in the other direction. If it only drifts in one direction most likely it is port relief, both directions could be spool or hairline crack in valve housing I would check the port relief for leakage, easiest way is to switch it out with the one for the dump side. if the valve is hard do get at try switching the hoses so the dump now works with the lever in the curl position.
Thanks for the reply oldseabee. I'm going outside right now and give that a try. Seeing as this is the unit I spend 12 hours a day 6 days a week throughout the spring til the middle of August I need it right and that drifting thing was driving me nuts.
Hi mate, I agree with oldseabee, does your loader seem to power the function or does it just creep. If it only creeps it could be either a broken spool spring or leaking shock valve. If it seems to power the function check for residual pilot pressure at either side of the affected spool. Cheers Yatesy
Thanks yatesy,it was only creeping down and after doing the bucket test oldseabee suggested I decided to check the port relief valve. Sure enough,after finding a tiny nick on the seat and smoothing it out,that was the problem and the bucket held position all night. Thanks to you both for your help.