Control Lever Repair

[aesmith]

This operates the diff lock on our tractor. On the left what I call the knuckle fits on a shaft sticking out of the transmission, when rotated a ramp pushes a control inwards. On the right is the lever, this threads into the knuckle. The lever is cranked because there's all sorts of stuff in the of a straight lever. When it's all assembled the crank offsets the lever to the right looking down. So pressing down wants to unscrew it from the knuckle. Which is what keeps happening until now the thread is shot.

Looking for repair ideas. I am thinking
(a) grind a bit off the end of the lever, recut the thread and put it back together as a bodge that will no doubt fail soon.
(b) remove the locknut, screw it together in the correct orientation, and weld it in place. I like this, but i think the knuckle is a casting, not sure if that's a problem or how to check.

Any suggestions appreciated.

 

[Screwdriver]

Couple of things you might consider. Drill and tap the knuckle for a sharpened grub screw. Weld a large washer on the arm and peen it over the knuckle to keep it in the correct orientation. Maybe also cut a feature into the knuckle which would trap the welded on washer iyswim.

I assume the thing is unwinding rather than merly being pulled out.

 

[tom2207]

take the lock nut off , shorten thread by same amount ,,, then set it in place and put a tac on it ,,,, take it off and braze it ,,, it will outlast you and me

 

[zzr1200]

Personally I would braze up the thread in the knuckle unit and drill/tap a new thread, also make a new control handle. When assembling the control use a lock nut and stud lock, not thread lock as this WILL require heat to remove the control handle.

 

[addjunkie]

Lock nut off, screw in, and drill, fit small rollpin

 

[Agroshield]

Clean it up and loctite.

Then if it ever needs to come apart again, you can heat it up.

I am not understanding 'cranked to the right so pressure causes it to unscrew' unless it has a left hand thread...

 

[Screwdriver]

Clean it up and loctite.

Then if it ever needs to come apart again, you can heat it up.

I am not understanding 'cranked to the right so pressure causes it to unscrew' unless it has a left hand thread...

Means the crank is offset to the right of the screw thread, pushing the knuckle down tends to lift the crank end up, hence rotate anti clockwise.

 

[aesmith]

Thanks. I'll do another photo assembled and in it's correct orientation.

To explain the unscrewing tendency, it's a normal right hand thread. The crank offsets the knob to the right of the bit that screws into the knuckle. Pushing down therefore tries to turn it anticlockwise as you look at the knuckle.

Hence it keeps coming loose and when it does the thread gets a hammering.

 

[Gareth J]

I expect it will weld up ok enough to hold everything in place.

But whether or not you want to do that depends...on if you'll ever want to remove it again... On the value of it less molested... On the obtain-ability and price of replacement parts.

Unless it's something very special, considering the whole assembly can be taken off with that roll pin, I'd probably just try welding it on.

 

[aesmith]

Thanks. I don't see the need for the two parts to be separate. The rod can't be screwed or unscrewed with the knuckle installed, so even as originally made you'd have to take the whole thing off to unscrew the lever.

 

[Turbo]

Thanks. I don't see the need for the two parts to be separate. The rod can't be screwed or unscrewed with the knuckle installed, so even as originally made you'd have to take the whole thing off to unscrew the lever.

In that case I'd braze it together. That way it can be disassembled again with lots of heat.

 

[aesmith]

I like brazing but haven't done any for decades and don't have the gear. Would a butane blow lamp be hot enough? Then I guess I need rods and Flux.

 

[Screwdriver]

Just file a flat on the knuckle, weld a washer to the crank (steel to steel) then peen it over so it can't move. Depends on the forces involved I suppose but seems a bit easier than the other options plus you get to vent your frustration with a hammer.

 

[Turbo]

There will be still a good thread on the locknut and that part of the crank.
Weld the locknut to the knuckle and use green loctite studlock to assemble it. Once it sets it will not move without heat but can still be taken apart in the future.

 

[aesmith]

Photo showing the orientation of parts when it's in service. Lever is roughly horizontal when it's engaged, raised up around 45° when released.

Regarding a fix, there's a little problem that we're not accessible by normal road vehicle just now. So there's going to be a long wait if I need to order anything like green Loctite or brazing stuff. I might be able to get hold of a die. Apart from that I either need to fix with what I have to hand, or wait a week or so.

 

[addjunkie]

Shorten remove lock nut, clean thread upwith a small triangular file, reassemble drill and use a small roll pin, or splitpin, or old bent nail

Superglue does as loctite if you are really struggling

 

[aesmith]

The thread might be beyond that.

 

[addjunkie]

The thread might be beyond that.

View attachment 527215

Eyyyy thats well cattle trucked

 

[wyn]

Cut the thread off and weld on a suitable bolt.

 

[oldbikedavey]

Soft solder, given sufficient surface area and preparation, can be plenty strong.....
Worth looking at for that one, I think.