Machine drive shaft

[noel shelleyParticipant @noelshelley55608]

Oversize wheels/tyres overhanging the hub ! Male splines hardened so female splines likely to be soft and worn. Lock stops set to sharp. How long had you had it when the first shaft failed ? Thread run out groove bit deep. Check the fit of the splines ! if there is any/much slack then the nut/thread will never stay tight and eventually break. The hub may be the problem ? Noel.

[colin hamiltonParticipant @colinhamilton16803]

<p style=”text-align: center;”>It’s an awesome machine. CTM are the dealers who originally supplied the tractor back in 2000. It’s now obsolete and the parts are getting hard to source which is why I’m keen to see if I could make it.</p>

[Michael GilliganParticipant @michaelgilligan61133]

Understood … but now we know a little more about the machine, and the way you are using it; your real question should be “ could I make a replacement that is significantly better than the original part ? “

MichaelG.

[colin hamilton]

On colin hamilton Said:

The nut holds the hub onto the shaft. The tractor is used on very steep land (over 30 degrees). The dealer thinks that the loads on the lower wheel when turning at very steep angles with something heavy like a topper fitted could be causing very high loads. Especially if the wheel lock is set allowing the wheels to turn too far. Unfortunately I had to send the broken part off so they could identify it properly so will not be able to get pictures of the failure. The tractor has no suspension and my land is very rough so I do spend most the time bouncing around so everything takes a bit if a pounding.

Two things spring to mind although no help in sourcing a replacement part, a heavy topper normally is rear mounted ( ??? ) so reducing turning wheel loads unless you have a new fangled fancier front mounted topper.

You could make a replacement part last longer and your own life more pleasant by smoothing the land.

[colin hamiltonParticipant @colinhamilton16803]

I wish I could smooth the land out but if I could I wouldn’t need the alpine tractor:)

If I could make the part I would happily accept a lower life span than the original!!

[colin hamiltonParticipant @colinhamilton16803]

Yep – it’s definately a big ask for the tractor. This side is original (as far as I know) so is 24years old. The hub is still in good shape and fits snuggly on the new shaft. The threads are handed so on the nearside it’s a left hand I don’t duffer from the nut coming loose. I also mark them and check they are tight as part of my routine maintenance

[colin hamiltonParticipant @colinhamilton16803]

I do have a spare part for the tractor so it’s up and running. However, I am still really interested in the process of making the part. It’s all part of trying to learn machining. To be honest even if I did make the part I would think long and hard about fitting it (when the part fails the wheel comes clean of the tractor, which is interesting on a 30 degree hill that drops into a stream!!). So how do i go about revrese engineering it? I was going to start on the splines and then worry about the yoke end. I was hoping to somehow identify what the splines are and the just machine a length of shaft to see if I can get a nice fit.

[Michael GilliganParticipant @michaelgilligan61133]

Give us the best photo[s] you can get of the splines, and let’s see what the ‘collective brainpower’ can come up with.

If it gets really difficult, then sectioning an existing shaft would be the obvious approach … is there any chance of retrieving the broken part for that purpose ?

MichaelG.

 

[Ian PParticipant @ianp]

Are there any pictures is the handbook/workshop manual that shows the hub assembly?

I know you showed the failed part with a rule alongside but an idea of the shaft diameters and thread size would be helpful

Ian P

[David JuppParticipant @davidjupp51506]

ISO 14:1982 (and the identical BS 5686:1986) may be what you need for identification and for tolerance information of the splined part of the shaft.

[Michael GilliganParticipant @michaelgilligan61133]

Potential Red Herring time:

https://www.practicalmachinist.com/forum/threads/need-some-help-figuring-out-what-this-spline-is.315912/

MichaelG.

[colin hamiltonParticipant @colinhamilton16803]

Thanks everyone. I’m back down my field at the weekend so will take a load of photos. Just had a look through the red herring thread. One of the suggestions was to take a cast of one of the teeth and use it to grind a single point fly cutter, which sounds like a cracking idea to me

[colin hamiltonParticipant @colinhamilton16803]

 

Part 7 is the part i would like to make. Part 11 is a spacer, Part 1 – wheel bearing, Part 3-spacer, Part 4-wheel hub, Part 5 washer and Part 6 is the nut that holds the hub onto the shaft in question

[David JuppParticipant @davidjupp51506]

Having looked again at the photo of the end of the shaft, involute looks more likely than straight sided splines.  BS ISO 4156 is perhaps a better starting point.  Apologies for the earlier duff reference.

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