120E Prentice swings erratically when I move stick boom up. The boom goes into full swing when I am raising the boom out and trying to feather the swing. In other words, I can't raise the boom and feather the swing at the same time. All of the spools are moving as they should. I have moved the hoses to other segments to see if one or more of the segments have internal cracks, but nothing changed - it still won't feather. I recently purchased this truck and it came with this loader. I've run a bunch of different loaders and I've never had this happen before. It looks like someone has tried to fix this in the past. Any help would be greatly appreciated!
Sorry there were no replies to your question on Prentice loaders they were good loaders I used one years ago and if I REMEMBER RIGHT took a little time to get used to the swing especially getting it to stop had to use the other pedal to slow and stop anyway perhaps some of the older guys will chime in .
Welcome to the Forestry Forum.
Mine is an old prentice FOBC, well overdue for the scrapyard. It does the same thing when I swing the boom out and have a foot on the pedal. Kind of backwards of what I'd expect. I was hoping one of the hydraulic guys would answer your question and I'd get to go to school on you.
Thanks for your replies hacknchop and Don P. My next step was to check for blockage on the return side to the tank. Anybody have an idea as to what that hydraulic pressure should be? I was thinking if the return pressure was too high, could it backfeed into the swing somehow.
I'm guessing that the loader has two separate valves, one on either side of the seat? I would also think that the lift function and the swing function are in the same valve. Most of those two valve systems have a double pump setup with a pressure line feeding each valve. I would think that the pressure should be anywhere from 2000 to 2500 PSI and 0 pressure on the return side. Pictures would help.
the first 120 didnt have a valve bank on each side. i dont think they used a swing break. the hood i had did. let off that and it stopped. dosent it have a cross over relief. could be the turn motor is worn out. it is old isnt it
Does that have a rackbar on a pinion for swing? If so, its proably the rackbar cylinder packings.
120 used a turn motor unless what he is calling a 120 is the 110 that had a 150 boom. ever only saw 1 of them around here. early 120's also had boom problems. i dont recall what it was. the new hood i bought in 83 was cheaper than a used 120 with the boom replaced