3pt hitch drops too low, gets stuck.

[shaeff]

Ok, well now that we've had our first snow, about 4.5", I had the opportunity to give my MF35 Utility a shakedown with the snow plow on the 3pt hitch. Everything was going very well, plow lifts up and drops perfectly, but if I crest a hill and the 3pt hitch drops too low, it gets stuck. It goes so low that the right side manual adjuster on the lift arm touches the axle housing. The problem is that when it gets that low, it gets stuck there and no amount of moving the Position Control lever will make it move again. It's like the control valve is binding, but ONLY when the hitch drops too low. I've never had this problem before because the other implements I use don't allow the hitch to drop that far no matter what kind of terrain I'm traversing.

So, is there any way to limit the amount that the 3pt hitch drops?

My current solution was to pull the side cover (losing a good bit of oil into a bucket) and manually operate the control valve until I feel it pop, then the plow raises up no problem. But even if I spend time feathering the Position Control lever, all it takes is just the right hill to drive over, the hitch drops and gets stuck again.

Cliff notes:

Adapted snow plow from truck to 3pt hitch. When I crest a small hill, the rear of the tractor rises, the plow drops and the adjustment on the right side lift arm contacts the axle housing. When this happens, the 3pt hitch will not raise until I manually operate the control valve and feel it pop back out. Then all is back to normal.


My temporary solution is to create check chains to prohibit the plow/ hitch from lowering too much. I'd run them from the top link attachment area on the tractor down to the plow frame, kindof in an upside down V shape.

 

[coldsteelva]

Can you fashion a simple bump stop to keep the lift arm high enough to prevent lockup even when fully suspended in air? Just find out how low it can go without binding and make the bump stop taller than that.

 

[shaeff]

Can you fashion a simple bump stop to keep the lift arm high enough to prevent lockup even when fully suspended in air? Just find out how low it can go without binding and make the bump stop taller than that.

That's a good idea too, basically mirrors the check chain idea to limit downward travel. Thanks, I'll have to look into one or the other this weekend. I'm just curious if there's an adjustment I missed which is allowing the hitch to lower too much in the first place. I can't imagine that the hitch is ever supposed to touch the axle housing!

 

[coldsteelva]

I imagine there may have been a physical stop in/on the lift arm at one point that may just not be there any more. I know on my Mitsu and Massey, I can stand on the lift arms (with no implement) and they just stop their travel without contacting anything externally.

 

[shaeff]

I imagine there may have been a physical stop in/on the lift arm at one point that may just not be there any more. I know on my Mitsu and Massey, I can stand on the lift arms (with no implement) and they just stop their travel without contacting anything externally.

I wonder if there was one at some point. I can't get the hitch that low when I stand on it either. This only happens with the snow plow, presumably because the lower attachment points are very low to the ground?

My flail mower and rotary brush cutter don't physically allow the hitch to get that low, so I'm wondering if it's a design flaw with my home-brew snow plow?

 

[Leejohn]

Are you plowing backwards?

 

[shaeff]

Are you plowing backwards?

Indeed. Here are a few pics of my setup:

 

[Ford850]

you might be able to extend your top link enough to solve the problem. By extending the top link you will lower the blade, and limit the amount it will need to drop when you crest the high humps.

 

[shaeff]

you might be able to extend your top link enough to solve the problem. By extending the top link you will lower the blade, and limit the amount it will need to drop when you crest the high humps.

I'll give that a try. If I can't get enough length out of it I can extend the chain that raises the plow, too.

You're thinking that by keeping a bit of hydraulic pressure in the lift cylinder it'll create a "natural" stop point?

 

[Ford850]

I was thinking that by lowering the plow's edge, you would in turn raise the arms. The lower that plow's edge sits, the less the arms have to lower.
The issue could be that by having a flexible top link (chain) the plow is still pulling down with it's weight on the arms, down much lower than any implement normally would lower. If that's the case, you can slide a pipe over the chain, just a little shorter than the length of the chain. That allows some flex, but jams on the pipe when the blade is pushed up too far. I don't think you need the chain on there anyway, and a solid arm might be the solution. The chain flex isn't needed since the arms can be pushed up and float the blade over ground contours. I think your check chains are a good solution too.