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second shaft and gear cluster

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second shaft and gear cluster Empty second shaft and gear cluster

Post  elwood-59 Thu 30 May 2019, 9:44 am

Hi,

Just back from workshop after fighting with the second shaft and gear cluster for ages. installing gear cluster (the package of 1st 2nd and 3rd gear) onto the second shaft stub => gears run freely and spin easily. When I add the ceter piece with second shaft it still runs good with LH bushing installed until I start to tighten down the 10 bolts that connect the universal joint to the gear cover things then start to go amiss.

As the joint is centerd only by the screws M5 so as soon as I start to tighten any one the shaft locks up. I now use only 4 bolts to ease the assembly hoping to have the parts to settle in relation with each other while being spun with loose bolts but as soon as I tighten the bolts (just touching no real torque), the shaft binds. Sometimes you feel it‘s only one spot but I cannot put my finger to it.

Tried to change orientation of universal joint vs gear cover to a different position => no change.

What do I miss?  

Thanks

Elwood
elwood-59
elwood-59

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second shaft and gear cluster Empty Re: second shaft and gear cluster

Post  lynnr Thu 30 May 2019, 10:56 am

Hi

If I remember correct and get what your after.

Looking at my build sheets. The 2nd Shaft Gear Cluster boss. BS42211 with the big washer holding it on the shaft .

When you tighten up the bolts holding the centre on to the gear cluster BS42210 it all binds up.
If this is the case the bearing inside has a radius on it and I think your binding on the radius of the 2nd shaft casting.

The only other place when I was building Crystal was the depthing of the gear teeth on to the crank gear set. Mine were too deep and the flange on either 1st or 2nd gear had to be ground down to fit and I fitted a shim under the crank bearing to just ease the fit.

I do not see any other place that would cause the issue.
lynnr
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Post  elwood-59 Thu 30 May 2019, 1:37 pm

Hi Lynn,

Just been out again and tried to follow your reasoning.

Checked with second shaft bearing, nope, there is enough space, the radius on the boss is 3,5mm whereas the bushing had a radius of 2,5 mm so plenty of room. And the binding also occurrs when the gear cluster is not completely pushed in.

Played around with the bolts again, when turning there is a tight spot, i.e. half of the turn is easy, then it binds and finally locks up. If I loosen the bolts I can feel movement of center vs. gear - just the play or gap of bolts in the holes. It seems to get better or at least different, but still not good!

All bolts loose => easy turn, bolts tightened less than lukewarm, shaft binds.

Looking at the cross section of second shaft ´housing, all i can see is a possible switch of centreline of second shaft box BS41010 and tube BS41011 but I think to remember that both were set against each other positively. If they are amiss than the LH bushing will not be (completely) on the same axis as the RH bushing, which would explain the issue. Loose bolts allow the shaft to adjust, tightening the bolts will lead to solidifying the cluster and shaft, making it bind due to bushing misalignment. Does that make sense?

Don‘t know, called it a day for now, no good use of the free time at Bank Holiday today Embarassed  

Cheers

Elwood


Last edited by elwood-59 on Thu 30 May 2019, 3:44 pm; edited 1 time in total (Reason for editing : misspelling)
elwood-59
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Post  Capricorn1 Fri 31 May 2019, 7:07 pm

There are a few issues around the 2nd shaft which would benefit from a slight re-design.
1. the 2 sections of the shaft housing do not locate on a spigot so some miss-alignment of the bearings may take place.
2. the 3rd shaft pinion shaft keyway is not the same length as the keyway in the gear.
3. the overall length of the shaft is shorter than the overall width over the gears, so if the retaining plates / washers are tightened up without shims, the assembly locks up.
4. the shaft is made from a length of BDMS, this has a "skin" caused by the drawing process which has stresses, when the keyways are cut the shaft will bow slightly.
5 the reduced diameter and short keyway at the cluster end is a weak point, the shaft could be made parallel with a longer keyway at the cluster end to transmit the drive.

I recently found the 2nd shaft cluster had moved outwards, on investigation and measurement I found the keyway at that end was far too short to provide an adequate drive and the torque / shock loading had resulted in the centre working loose on the shaft. After taking a few measurements I re-drew the shaft to make the final drive gear keyway longer, increased the length of the shaft and fitted longer keyways to both gears, this is now fitted and once an over lasting house move is over and done with, will be put to the test.


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Post  elwood-59 Sat 01 Jun 2019, 8:56 am

Hi Capricorn1

Yes, was thinking about the 2nd shaft housing myself, but was not sure about the fiiting of the two in relation to each other. Might give it a try and loosen the bolts (if I can get to them), try to spin the shaft/custer assembly and see what happens. Just today I am occupied elsewhere, have to postpone until Monday I‘m afraid.

Your other reasoning on the shaft and keys are logical, but I don’t remeber reading of anybody reporting a shaft failure due to fatique crack which I could imagine looking at the difference in diameter on the gear side of second shaft.  

On the other hand lots of others have built their engines with the same parts as I do and seem to have managed to assemble the shaft & gear cluster satisfactorily.

So what is different here or what do I do wrong? Question

Thanks

Elwood
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Post  elwood-59 Sun 02 Jun 2019, 1:48 pm

Little update,

Loosened the 8 bolts between second shaft box and tube => no change...

Last thing before mounting my wheels Sad

Cheers

Elwood
elwood-59
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