Hi folks,
We have an L4150, 4x4, hydraulic shuttle, loader tractor for odd jobs around the farm. It doesn't get used much compared to the larger equipment - really just feeding out round bales and blowing snow in winter. Last night it developed a problem with the three-point hitch: When any load is on it, it only lifts when wound up to quite a high RPM, and as soon as you idle down it drops. The loader and hydraulic shuttle work fine.
I didn't have much time to diagnose, and all my hydraulic testing paraphernalia is at our other farm, so I didn't get a chance to do any proper analysis. I made some crude assumptions based off some (very) quick and dirty testing methods and a glance over the hydraulic schematic. Wondering if you folks would agree/disagree:
If you raise the hitch, then completely close off the down-speed adjusting valve while it's raised, it will hold the load indefinitely. To me, this indicates the cylinder and cylinder safety valve are OK. The shuttle shift working fine seems to indicate the priority valve is ok. I didn't have any pressure gauges handy, but I hooked the remotes up to a pretty heavy field disc, and it lifted/held it just fine. This seems to indicated relief valve and remote valve are ok. I'm not sure how the loader is plumbed, but I'm assuming hydraulic flow is routed to the loader valve, which has power-beyond capability, with the remote valve down-stream? Either that or it's routed to the remote valve first (with power-beyond), then off to the loader. In either case, the remotes and loader working also indicate the loader valve and power-beyond functionality is working ok.
This leaves either the draft control valve or 3-point position control valve. I suspect there's a bypass/leak in one of these two. The draft control has never been touched - it's always used in position mode (I made sure to check it hadn't been moved). For this reason, I'm inclined to think the draft control valve is unlikely to have developed a problem, and the issue is more likely the hitch position control valve.
Am I completely out to lunch? Any thoughts/opinions are greatly appreciated.
We have an L4150, 4x4, hydraulic shuttle, loader tractor for odd jobs around the farm. It doesn't get used much compared to the larger equipment - really just feeding out round bales and blowing snow in winter. Last night it developed a problem with the three-point hitch: When any load is on it, it only lifts when wound up to quite a high RPM, and as soon as you idle down it drops. The loader and hydraulic shuttle work fine.
I didn't have much time to diagnose, and all my hydraulic testing paraphernalia is at our other farm, so I didn't get a chance to do any proper analysis. I made some crude assumptions based off some (very) quick and dirty testing methods and a glance over the hydraulic schematic. Wondering if you folks would agree/disagree:
If you raise the hitch, then completely close off the down-speed adjusting valve while it's raised, it will hold the load indefinitely. To me, this indicates the cylinder and cylinder safety valve are OK. The shuttle shift working fine seems to indicate the priority valve is ok. I didn't have any pressure gauges handy, but I hooked the remotes up to a pretty heavy field disc, and it lifted/held it just fine. This seems to indicated relief valve and remote valve are ok. I'm not sure how the loader is plumbed, but I'm assuming hydraulic flow is routed to the loader valve, which has power-beyond capability, with the remote valve down-stream? Either that or it's routed to the remote valve first (with power-beyond), then off to the loader. In either case, the remotes and loader working also indicate the loader valve and power-beyond functionality is working ok.
This leaves either the draft control valve or 3-point position control valve. I suspect there's a bypass/leak in one of these two. The draft control has never been touched - it's always used in position mode (I made sure to check it hadn't been moved). For this reason, I'm inclined to think the draft control valve is unlikely to have developed a problem, and the issue is more likely the hitch position control valve.
Am I completely out to lunch? Any thoughts/opinions are greatly appreciated.
