Massey Ferguson 50B - Movement between digger frame and tractor

[Tony Smith]

Hi,

I wondered if anyone had any suggestions for how to fix or improve this problem. On the 50B the backactor frame mounts to the "tractor" by two arms from underneath, and two from above. The frame rests on the lower arms, and is held down by the upper. The upper and lower arms are tied together on each side by a near vertical rod threaded for a very deep nut at the top. The diagram roughly shows it except that on my digger the upper arm (50) looks like its part of the chassis and not removable.


URL of the original image: http://i42.photobucket.com/albums/e320/GandyGoose/YBW/IMG_0789C_800.jpg

My problem is that there is movement between these, so the backactor frame can move relative to the tractor. To fix it, I assume the nuts on the vertical rods should be tightened, but so far I have been unable to move it. The nut looks to be peened in place, and even looks like a hole's been drilled to weld the nut. See picture..


URL of the original image: http://i42.photobucket.com/albums/e320/GandyGoose/YBW/IMG_0788_800.jpg

Given that the rod had the immovable nut on the top, and a fork at the other end, I can't even remove it altogether to try and sort it out in the workshop.

Any ideas? The movement worries me, it can't be right and I think it could even be dangerous.

Thanks in advance, Tony S

[FOWLER MAN]

Hello Tony
I see your problem.
If all else fails and the nut has been drilled and welded as you suspect, I reckon a good man with a lamp could possibly sort it. I'd have a go anyway.
It should be possible to cut an indent in the side of the nut and remove the weld, you would have to just nick the bolt to release the weld from the thread, but with care it could be re-usable.
You've nothing to loose anyway, the only other way I can see is to cut the bolt.
The thread looks like UNF so it should be possible to replace the nut, I would use a locknut too.
Fred

[Tony Smith]

Cheers. I take these parts wouldn't normally be welded up? I might try ringing round some places to see if I can get bits off a 50B that's being dismantled. I'm not totally happy about drilling or otherwise abusing the nut unless I'm confident I could replace the rod if that gets damaged.

I'll check the thread size, as you say if that's a standard thread then its going to be easier to find a general purpose replacement. A locknut sounds more sensible than welding it up!

[essexpete]

You could split the nut with a very fine cutting disc (small 4-4.5in). With care it is possible to salvage the thread. If you did cut out the weld and manage to shift the nut the damaged area might chew the thread.

[Tony Smith]

Hi, I was thinking about about that. Using a grinder with the disc vertical wouldn't be able to cut right down the nut without cutting into the frame as well. Maybe drill a series of holes to weaken it, then I'd need to work out how to fully split it.

Edit - supposing I could split the nut leaving the thread undamaged, would using ordinary steel nuts be strong enough? Say three nuts on each rod, tightened hard down on each other.

[martyn williams]

I would try the angle grinder method or better still,remove one and get new threaded bar and make one up,try it,if ok get the other one done.We did that on a 50B, never broke.
The thread is only to clamp it tight,the weight is mostly on the bottom.The trouble is if they are not fully clamped tight,the claws wear and get very slack.I fitted a new one on one machine,the parts were picked up from Kellands of Bridgewater.A machine shop will knock you up a new pair.
Martyn