631G
Senior Member
621B Wheel Tractor
Machine Serial Number - 8HC00010
Machine Build Date - 1985/07/04
We have a low hour 621B that has been running great up until this week. The operator was running across the fill dragging up and says that he suddenly lost all hydraulic function. According to the operator the machine had been running great all day and that there were no obvious strange noises, thumps, bumps, etc. to accompany the sudden loss of hydraulic function. The bowl, apron and ejector would not move but he could steer the machine. However the response on the steering was slower than typical to the machine. To get the machine out of the fill we backed it up over a small hump to push up the bowl and then let the cylinders hold it there. So I guess that says the valves are not stuck open/closed being we can lower and hold the bowl up/down?... Transmission still takes gear fine and pulls normally. (not sure if the two are related but there it is)
We got the machine up to "pit row" (same job where we've had the D8H go down) for a look at by the mechanic. We pulled the in tank hydraulic filters and found that one of them, the lowest one, was crushed and both seemed awfully heavy even after draining out. Good news is there was no metal to be seen anywhere in the filters after cutting them open, but they were dirty with filtered out dirt. Oil was clean and has no water or other obvious contaminates.
Thinking that maybe this was the issue we replaced with new filters and started the machine back up. No change. We could still steer the machine but no implement function.
Has anyone dealt with this before where you have no implements but do have steering? I am looking at service manuals but with our machine being ex-military, I am trying to sort out what is the closest standard serial number prefix to match our machine. Best I can see is that 45P seems to cover the year our machine was built. My goal is to find a pressure testing procedure for the hydraulic system. It would seem to me that if the pump let go that we'd have nothing anywhere. I would imagine that the steering circuit would require the same pressures as the other implement circuits would given the amount of push needed to move the tractor unit side to side.
Machine Serial Number - 8HC00010
Machine Build Date - 1985/07/04
We have a low hour 621B that has been running great up until this week. The operator was running across the fill dragging up and says that he suddenly lost all hydraulic function. According to the operator the machine had been running great all day and that there were no obvious strange noises, thumps, bumps, etc. to accompany the sudden loss of hydraulic function. The bowl, apron and ejector would not move but he could steer the machine. However the response on the steering was slower than typical to the machine. To get the machine out of the fill we backed it up over a small hump to push up the bowl and then let the cylinders hold it there. So I guess that says the valves are not stuck open/closed being we can lower and hold the bowl up/down?... Transmission still takes gear fine and pulls normally. (not sure if the two are related but there it is)
We got the machine up to "pit row" (same job where we've had the D8H go down) for a look at by the mechanic. We pulled the in tank hydraulic filters and found that one of them, the lowest one, was crushed and both seemed awfully heavy even after draining out. Good news is there was no metal to be seen anywhere in the filters after cutting them open, but they were dirty with filtered out dirt. Oil was clean and has no water or other obvious contaminates.
Thinking that maybe this was the issue we replaced with new filters and started the machine back up. No change. We could still steer the machine but no implement function.
Has anyone dealt with this before where you have no implements but do have steering? I am looking at service manuals but with our machine being ex-military, I am trying to sort out what is the closest standard serial number prefix to match our machine. Best I can see is that 45P seems to cover the year our machine was built. My goal is to find a pressure testing procedure for the hydraulic system. It would seem to me that if the pump let go that we'd have nothing anywhere. I would imagine that the steering circuit would require the same pressures as the other implement circuits would given the amount of push needed to move the tractor unit side to side.
