Hydraulics / lift question
- Thread starter rinms
- Start date
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So here's the result of the work:
I removed the rear plate of the hydraulic cylinder, the one that has the mount for the center link, as well as the front plate, the one through which the arm "stop" wheel is threaded (NOTE - this is the wheel that blocks the flow of hydraulic fluid, thereby keeping the arms in the set position - it is the large knurled wheel facing forward under the seat). At first, it seemed that perhaps the piston had come so far rearward that the split ring on the piston had come out of the cylinder and was preventing the piston from returning forward into the cylinder, allowing the arms to lower. So I removed the assembly and inspected things. What I found was that when the tractor sat up, some light rust had formed on the rearmost portion of the cylinder and when the piston moved to its rearmost position, it became stuck in this less-than-ideal cylinder wall condition.
I remedied the situation by a careful cleaning and brass-brushing, followed by a flooding with cleaner. I then reassembled everything and the arms now work properly. Based upon _this_ tractor - which is to say that since this is the only YM1700 hydraulic cylinder I have ever seen, much less worked on - there would have been no way that the "piston rod" could have slipped out so far so as to have become disengaged from the piston. There was not enough clearance.
In any case, should anyone else have such a problem - the arms not lowering, especially after a long sit-up - I'd recommend the following, based solely upon the premise that all YM1700 systems are essentially the same:
1. Remove any implements and remove the lower 3-point arms from the lift arms.
2. Make sure that the wheel under the seat is in the open
3. Remove the coverplate through which the wheel threads.
3. Remove the rear coverplate, the one to which the center link attaches. It will be attached with 4 bolts. You can see the piston, the piston rod, etc. If the piston cannot be pressed forward with a controlled pressure, proceed to 4. If it can, replace both plates, place control lever in the "lower" position, start tractor, and attempt to raise and lower arms with the control lever. If it cannot, remove hydraulic assembly by removing the 6 bolts attaching it to the transaxle (this is not a difficult job).
4. Once removed, _GENTLY_ tap on the arm (the large casting that you see with the rear coverplate removed) that impinges on the piston rod. I'd recommend a deadblow. This will drive the piston toward the front of the assembly. It will reach a point at which you can use a socket extension or other long tool to simply push it out of the cylinder.
5. Once out, carefully inspect and clean the piston and cylinder. Don't use power tools, etc. Take care to simply polish/remove any surface rust. If the piston, rings, etc., are damaged beyond cleaning, replace.
6. Reinsert the piston _from the front_ of the assembly. It should slide in with a gentle force, compressing the plastic/teflon??? splint ring as it does.
7. Reverse removal process to reassemble.
8. If everything goes right, the lift should work as intended.
I hope this helps others with similar problems.
I removed the rear plate of the hydraulic cylinder, the one that has the mount for the center link, as well as the front plate, the one through which the arm "stop" wheel is threaded (NOTE - this is the wheel that blocks the flow of hydraulic fluid, thereby keeping the arms in the set position - it is the large knurled wheel facing forward under the seat). At first, it seemed that perhaps the piston had come so far rearward that the split ring on the piston had come out of the cylinder and was preventing the piston from returning forward into the cylinder, allowing the arms to lower. So I removed the assembly and inspected things. What I found was that when the tractor sat up, some light rust had formed on the rearmost portion of the cylinder and when the piston moved to its rearmost position, it became stuck in this less-than-ideal cylinder wall condition.
I remedied the situation by a careful cleaning and brass-brushing, followed by a flooding with cleaner. I then reassembled everything and the arms now work properly. Based upon _this_ tractor - which is to say that since this is the only YM1700 hydraulic cylinder I have ever seen, much less worked on - there would have been no way that the "piston rod" could have slipped out so far so as to have become disengaged from the piston. There was not enough clearance.
In any case, should anyone else have such a problem - the arms not lowering, especially after a long sit-up - I'd recommend the following, based solely upon the premise that all YM1700 systems are essentially the same:
1. Remove any implements and remove the lower 3-point arms from the lift arms.
2. Make sure that the wheel under the seat is in the open
3. Remove the coverplate through which the wheel threads.
3. Remove the rear coverplate, the one to which the center link attaches. It will be attached with 4 bolts. You can see the piston, the piston rod, etc. If the piston cannot be pressed forward with a controlled pressure, proceed to 4. If it can, replace both plates, place control lever in the "lower" position, start tractor, and attempt to raise and lower arms with the control lever. If it cannot, remove hydraulic assembly by removing the 6 bolts attaching it to the transaxle (this is not a difficult job).
4. Once removed, _GENTLY_ tap on the arm (the large casting that you see with the rear coverplate removed) that impinges on the piston rod. I'd recommend a deadblow. This will drive the piston toward the front of the assembly. It will reach a point at which you can use a socket extension or other long tool to simply push it out of the cylinder.
5. Once out, carefully inspect and clean the piston and cylinder. Don't use power tools, etc. Take care to simply polish/remove any surface rust. If the piston, rings, etc., are damaged beyond cleaning, replace.
6. Reinsert the piston _from the front_ of the assembly. It should slide in with a gentle force, compressing the plastic/teflon??? splint ring as it does.
7. Reverse removal process to reassemble.
8. If everything goes right, the lift should work as intended.
I hope this helps others with similar problems.
California
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After seeing what is inside - do you think simply loading a lot of weight on the 3-point arms would have pulled the piston out of the rusty region and got it working again?
Anything is possible, but I'd not try that and I'd advise others not to try it. If one attempted to force the piston back by forcing the arms down with a lot of weight, at the very least, you would be risking a sudden release that could bring the weight crashing down. As I mentioned, the piston has an o-ring and a plastic/teflon??? split ring and you could easily damage the rings and/or the cylinder by forcing the piston, not to mention the equipment or yourself.
IMO, since we are talking about an hour's (or two, depending on experience, general mechanical skill, etc.) worth of pretty straight-forward work to do it properly (or if not to factory instructions, at least safely), and it can be accomplished with simple hand tools, I'd say disassemble and actually fix it rather than forcing anything.
