Lift arms issue

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JohnM
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Lift arms issue

Post by JohnM » Fri Oct 04, 2019 6:40 pm

I have spent several hours today freeing off the lift arms and hydraulic operating levers on an old 10/60 that I have left out in the rain for far too many years. I had to press out the cross shaft that carries the arms and have a question about the correct method of holding the casting with a cup on it that moves the shaft. It has a slot for a key but it also has what the manual describes as a "set screw" which locates into a hole in the shaft to prevent the casting from sliding crossways along the cross-shaft.
I am not sure what this set screw should look like and wonder of mine had been "bodged"
All I had was what looked like a 7/16 UNF bolt screwed in with the head cut off. This bolt was bent and I had to weld a bar onto the end of it to get it out.
The problem is that I cant see how it is meant to be held in, ie what stops it from unscrewing itself? should it have a hole for a split pin which locates in the groove?
I hope that Rick will read this as his video about the locking plunger and the dangers of the pin coming out allowing the con rod to then break the housing almost shows it but not quite.
If anyone can be bothered to look it is on page 238 in the workshop manual downloaded from here (many thanks) number 17 listed as the cross-shaft set screw.



Rick Cobley
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Re: Lift arms issue

Post by Rick Cobley » Fri Oct 04, 2019 9:22 pm

Hi, I have a casting somewhere, will take a look tomorrow and let you know.

Regards Rick Cobley

JohnM
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Re: Lift arms issue

Post by JohnM » Sat Oct 05, 2019 6:12 pm

Thanks Rick, just to get the cover back on before a wet day forecast tomorrow I machined the end of a bolt down to fit in the hole in the shaft. I didn't realise this is smaller than the threaded hole. I drilled a hole through the top of the bolt so a split pin fits in the grove. I milled a square onto the top of the bolt (to screw it in) as I had to cut off the original head to hold it in the lathe as I couldn't be bothered to put an independent jawed chuck on.
It seems to be OK but I am slightly anxious about how much of the top of the bolt should stick out, this may or may not catch on the rod that the piston operates? So if you do get time to have a look at one I would much appreciate it.

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JohnP
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Re: Lift arms issue

Post by JohnP » Sat Oct 05, 2019 7:04 pm

Remember to liberally coat both ends of the connecting rod with "Molykote" grease, this is very important!
JVP

If it ain't bust don't fix it!

JohnM
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Re: Lift arms issue

Post by JohnM » Sat Oct 05, 2019 9:03 pm

Thanks for the advice, I have not heard of Molykote grease! most of my stuff goes together with ordinary general purpose grease straight from the bucket, that includes all the bolts as I have nightmares about them seizing solid again.

Rick Cobley
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Re: Lift arms issue

Post by Rick Cobley » Sun Oct 06, 2019 9:35 pm

Hi, Remembered today to take you a picture


Image

As you can see its pretty much as you said you have done, drill setscrew and pass split pin through to prevent it unscrewing.

Regards Rick Cobley

JohnM
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Re: Lift arms issue

Post by JohnM » Mon Oct 07, 2019 8:05 am

Many thanks Rick, I will need to cut the top off my bolt though after seeing this as I have left the top of the bolt protruding.
This was where I machined a square to be able to screw it in with a spanner and was concerned that the top could hit the con rod. I will cut it off and put a screwdriver slot in as your picture shows. Thanks again for your help.

Majorman
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Re: Lift arms issue

Post by Majorman » Mon Oct 07, 2019 11:10 am

About the Molygrease, in the early days of the Ford 5000 up to 1968 the lift connecting rod was held in by a pin and split pin to the housing on the lift cross shaft. When using a Ransomes TS84 plough it was common for the retaining pin to break, the con rod drop out and the cross shaft housing to punch the con rod through the rear axle housing. After a spate of rear axle housing replacement Ford instructed us to fill the whole cup and con rod pin hole with Molybdenum Grease when re-assembling them. Problem solved, no more pin breakages and no more damaged housings.
Kind Regards,
Brian

JohnM
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Re: Lift arms issue

Post by JohnM » Mon Oct 07, 2019 3:13 pm

Thanks Brian, I am a bit confused as to how the pin would break as in the Nuffield case it only seems to hold the connecting rod in the top cup if the arms are lifted externally and not by the ram. You would think that there would be no real force on it as the ball end of the rod would take the pressure against the cup. In the video posted by Rick the rod on his tractor was held in by a split pin whereas mine has a roll pin which you would think were tougher. Sounds like the Ford had belt and braces with a pin plus a split pin, do you think the lack of grease on this would eventually wear it enough to break?
Edit just had a thought, perhaps the lack of grease between the ball and cup allowed these to wear which in turn would put strain on the pin. This is probably what you were getting at but only just sunk into my thick head!

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JohnP
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Re: Lift arms issue

Post by JohnP » Mon Oct 07, 2019 3:41 pm

Yes, lack of lubrication will cause sever wear on the ball end and lever cup, sufficient to shear the pin/split pin.

On a Leyland with a 3 5/8" diameter piston with 2600PSI oil pressure the force acting against the connecting rod is very nearly 12 tons!!
JVP

If it ain't bust don't fix it!

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