Hiya my name is rob. I'm in Australia. I have a Fendt 712 with a Mcormack loader. Heres the prob. My crowd rams wont crowd back. But they will crowd up. If i run that circuit on the lift rams it works fine.Good pressure. Likewise the lift circuit wont crowd the rams back. I have changed the seals and glands on both sides (Hallite). There is no apparent leaking. 7 days later Im at wits end trying to solve the problem. My mate mentioned that maybe the shafts could be bent and that that could be the issue. How bent do they need to be to cause this? Also that maybe in the crimp there could be some rubber blocking the flow?? Any ideas thanks rob
Have you tried reversing the lines either at the cylinders or valve? if the shafts/rods are bent they *might* let air into the ram yet not leak noticeably as I have sen this on certain loaders, how long do you hold the lever for crowd in? before letting off.
So, the bucket will fall down but won't come back up, is that correct? If the shafts were bent enough to cause this kind of problem you would hear ugly noises and probably have oil shooting everywhere, just a guess. Have you tried just reversing the hoses? You say you changed the seals, you changed out the piston seals also? Look for any valve blocks in the lines to the cylinders, may be relief or lock valves somewhere is the only thing I can think of.
One other question... does it put a noticeable load on the motor when trying to crowd back?
Hi thanks boys for the help..well today i swapped over the short lift hoses to the crowd rams..Still same problem. When the shafts are fully extended there is a slight bend but not really that noticable. When i hold the joystick to the right (negative to fully extend shaft) yoiu can here the motor pumping but not making bad noises?? yeh the bucket will only crowd out if its in the air and falling under its own weight. Its a basic ram ie just line in and out. I changed all the seals including the main piston seal (DAS 300.225). Again today i swapped the two lines between valves (at the breakouts) and managed to lift the front of the tractor of the ground..so it seems to rule out the machine. Its such a mystery..
when i measured from the cap to the pin centre on both rams there was about a 15mm difference in measurement between the two rams? i have a fella coming tomorro morning aussie eastern time to run pressure guage on it so well see what he comes up with.. my temptation is to simply buy new rams but i dont wanna discover thats not the issue..theyd be ten years old and get a lot of work!!
Well after 8 days and a coupla hundred dollars later..heres the problem..a $25 breakaway/ quick coupla was fouling..i changed the females around but didnt fuddle with the males (??!!) and had i done i wouldve discovreed the problem doh!! thanks all