EDIT: Dumb question. Never mind.
I reassembled the lift cylinder and fork on the bench and looked at how it moves. The fork only slides in the lift cylinder when the control spring is compressed. That was happening when I was plowing wet snow in reverse, as evidenced by the damaged back blade plow. The struts between the top link and lift pins collapsed when the blade dug in on the way back down the snowbank. The bank was about 6' high and pretty well packed. The blade must have dug in and caught on a chunk of ice.
The erratic movement has to be down to worn cylinders and/or sticky valves. The pump pistons look like they may be scored as seen from above, so it looks like a compete overhaul is on the to do list.
Here is the list of things that don't need attention:
The PTO cover.
Good grief, moving forward, I can't find anything else.
END OF EDIT
The lift was not running smoothly on my 2N. It would jerk as it lifted and tended to leak down pretty fast. When the lift was set to a certain height in neutral with an implement on it, the height would change when the tractor was in gear and moving.
Recently, I overloaded and blew a gasket. At that point, it was weak and after a short time could barley lift anything. It started to leak down too fast to shift into gear when there was a load on the lift.
I took off the top cover and removed the badly scored piston and cylinder. Half of the gasket around the fluid inlet to the cylinder housing was missing. The spring control fork (FO4 figure 206 #7 fork) is badly scored, maybe 10 to 20 mils deep. Scored cylinder, scored pistons, blown gasket; seemed like end of story until I had a good look at the fork. Get a new piston and cylinder (NAA O-ring type) and put it back together. Not a lot of sludge, little rust, so clean it up, change the oil and good to go, I hope.
The worn area on the fork, about 4" long, shows no corrosion or discoloration, so the wear is either recent or ongoing for a long time.The pictures don't show it, but the wear is uneven, like the fork was sticking and jumping as it moved. If it was just tight and moving steadily, the wear should be more even. It feels like there are 5-10 mil variations in diameter all along the worn area. The change in diameter in the picture is no optical illusion it steps down at least 10 mils at the start of the clean area.
I found several for sale online and all of the pictures seem to show similar, if not so much wear.
My impression is that the wear is not unusual, but in my case it is more severe than usual. All I can find in a forum search is some discussion of the spring not much about the fork. Maybe there was some binding somewhere that caused the lifts to work badly, but no specific indication that the forks were binding and causing the problems.
It looks like the fork rides in the holes in the cylinder. If it is binding, does that explain the jerky movement of the lift? It seems like the whole assembly is fairly flexible, so could the fork binding cause the valve to be operated erratically as the lift moved up? If that is the case, is the fork bent? Is there a way to prevent it from binding?
This post was edited by Dave G9N on 07/19/2023 at 09:53 am.
I reassembled the lift cylinder and fork on the bench and looked at how it moves. The fork only slides in the lift cylinder when the control spring is compressed. That was happening when I was plowing wet snow in reverse, as evidenced by the damaged back blade plow. The struts between the top link and lift pins collapsed when the blade dug in on the way back down the snowbank. The bank was about 6' high and pretty well packed. The blade must have dug in and caught on a chunk of ice.
The erratic movement has to be down to worn cylinders and/or sticky valves. The pump pistons look like they may be scored as seen from above, so it looks like a compete overhaul is on the to do list.
Here is the list of things that don't need attention:
The PTO cover.
Good grief, moving forward, I can't find anything else.
END OF EDIT
The lift was not running smoothly on my 2N. It would jerk as it lifted and tended to leak down pretty fast. When the lift was set to a certain height in neutral with an implement on it, the height would change when the tractor was in gear and moving.
Recently, I overloaded and blew a gasket. At that point, it was weak and after a short time could barley lift anything. It started to leak down too fast to shift into gear when there was a load on the lift.
I took off the top cover and removed the badly scored piston and cylinder. Half of the gasket around the fluid inlet to the cylinder housing was missing. The spring control fork (FO4 figure 206 #7 fork) is badly scored, maybe 10 to 20 mils deep. Scored cylinder, scored pistons, blown gasket; seemed like end of story until I had a good look at the fork. Get a new piston and cylinder (NAA O-ring type) and put it back together. Not a lot of sludge, little rust, so clean it up, change the oil and good to go, I hope.
The worn area on the fork, about 4" long, shows no corrosion or discoloration, so the wear is either recent or ongoing for a long time.The pictures don't show it, but the wear is uneven, like the fork was sticking and jumping as it moved. If it was just tight and moving steadily, the wear should be more even. It feels like there are 5-10 mil variations in diameter all along the worn area. The change in diameter in the picture is no optical illusion it steps down at least 10 mils at the start of the clean area.
I found several for sale online and all of the pictures seem to show similar, if not so much wear.
My impression is that the wear is not unusual, but in my case it is more severe than usual. All I can find in a forum search is some discussion of the spring not much about the fork. Maybe there was some binding somewhere that caused the lifts to work badly, but no specific indication that the forks were binding and causing the problems.
It looks like the fork rides in the holes in the cylinder. If it is binding, does that explain the jerky movement of the lift? It seems like the whole assembly is fairly flexible, so could the fork binding cause the valve to be operated erratically as the lift moved up? If that is the case, is the fork bent? Is there a way to prevent it from binding?
This post was edited by Dave G9N on 07/19/2023 at 09:53 am.