I have a New Holland TL90A Tractor with 825TL Loader. Occasionally when I raise the loader fairly high and roll the bucket all the way back the bucket hydraulics seem to jam in the fully rolled back position. If I try to roll the bucket forward to dump it will move a little and then stop. The hydraulic lines seem to build up pressure and if I reverse the joystick to roll the bucket back again it jumps back as the line pressure is relieved. Sometimes I can get it to roll forward if I put the bucket under something very heavy and try to lift it while moving the joystick to roll the bucket forward. This doesn't always work and sometimes I have to let the tractor sit for a few hours or over night and then it will work alright. It seems to be happening more often - probably once every 2 or 3 weeks when it used to only happen once or twice a year.
The only thing I can think may be causing this is the hydraulic valve mounted on the loader frame cross member behind the bucket. All 4 lines for the loader arm and bucket cylinders from the joystick valve at the cab go into this valve. I think it is supposed to control the bucket rollback to prevent the bucket from rolling back too far and spilling material over the back when the loader arms are lifted all the way. If that is what it is supposed to do I dont think this valve has ever worked properly. If I have a full bucket I have to be careful and roll the bucker forward manually when the loader arms are lifted real high or else it will spill material over the back. My Case 580SM backhoe has a mechanical anti rollback linkage that does this very well. From the parts list the valve I am referring to is called a "Block Valve" - New Holland part number LDR10550510.
If this valve is the problem would a fix be to just remove this valve and connect the loader and bucket lines from the joystick valve to their respective cylinders directly so they are 2 independent hydraulic circuits. i realize I will lose the anti rollback function but I dont think it ever worked properly anyways. The older tractors I have had never had an anti rollback function so I am used to controlling the rollback manually. I use my Case backhoe for jobs that require a lot of loader work anyways.
I would appreciate any feedback from others who have experienced this problem and how they corrected it.
The only thing I can think may be causing this is the hydraulic valve mounted on the loader frame cross member behind the bucket. All 4 lines for the loader arm and bucket cylinders from the joystick valve at the cab go into this valve. I think it is supposed to control the bucket rollback to prevent the bucket from rolling back too far and spilling material over the back when the loader arms are lifted all the way. If that is what it is supposed to do I dont think this valve has ever worked properly. If I have a full bucket I have to be careful and roll the bucker forward manually when the loader arms are lifted real high or else it will spill material over the back. My Case 580SM backhoe has a mechanical anti rollback linkage that does this very well. From the parts list the valve I am referring to is called a "Block Valve" - New Holland part number LDR10550510.
If this valve is the problem would a fix be to just remove this valve and connect the loader and bucket lines from the joystick valve to their respective cylinders directly so they are 2 independent hydraulic circuits. i realize I will lose the anti rollback function but I dont think it ever worked properly anyways. The older tractors I have had never had an anti rollback function so I am used to controlling the rollback manually. I use my Case backhoe for jobs that require a lot of loader work anyways.
I would appreciate any feedback from others who have experienced this problem and how they corrected it.
