Why wont the MMM lock in the top position?

[radioman]

The thing that is puzzling is why would it do it all of a sudden? when you look at the adjustment rod it seems almost inpossible for it to get out of adjustment.

That what been puzzling to me too on mine and others.

 

[mozark]

Anytime that very heavy deck is not resting on the height adjuster or locked into the "top" position, it is supported by the adjustment rod. Watch the deck as you drive across something real rough and you can see how bad the rod gets hammered by all that weight bouncing on it. Although its not recommended, I mow part of my yard at 5" where the deck is resting just on that rod, I try to go slow enough to avoid putting too much stress on it.

 

[quarencia]

Why it gets out of adjustment. In the picture below, pin (60) holds the shaft (30) and lift arm (40) together. Over time the holes in the bracket and shaft tend to get a little wallowed out. The alignment of the bracket and shaft changes. This causes the tang on the shaft to rotate less than it did when the tractor was new. Once this happens, the top lock position on the dial will no longer engage.

IMHO, this is why Kubota went to the two bolt bracket shown below on the bx24 and later tractors. The newer design will take more stress/strain without permanent deformation.

 

[okie350]

Why it gets out of adjustment. In the picture below, pin (60) holds the shaft (30) and lift arm (40) together. Over time the holes in the bracket and shaft tend to get a little wallowed out.

Looking at the diagram I can see how that would happen. I wonder if I drilled part #30 & 40 and installed a larger diameter pin that would help. Probably not worth it and I should just try and adjust it out.
By the way, the diagram for the BX24 did not show up

 

[radioman]

ok- I have BX24 and i had to make two adjustments.. this year alone! Before that it was perfect. Right now it seems fine. HMM.. After typing this I wonder if there are 2 bolts bent or broken ? I guess I am gonna get down there and look.

 

[Mike11C]

Thank you! Isn't it interesting that your advice from 10 years ago is still helping people? The adjusting bolt on my BX2680 is exactly where you described. I fought with that tractor for two hours, in the Texas sun, before I Googled it. It only took five minutes after reading your post. I hope you're still on here.