Layshaft bearing

baz

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Opened up an atlas gearbox to check condition and found this bearing on the layshaft
It's obviously a conversion but not the same as I have seen before
Does anyone know if these are good?
Cheers
IMG_20191104_212923266.jpg
 

Burgs

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Hi Baz
Not sure a roller bearing would be good or not, but generally for a roller bearing everything needs to be inline, and shaft no bend under load, on the other hand deep groove ball bearings can handle a little bit of both.
If everything is inline and the shaft doesn't bend the roller would be better as the load carrying capacity is greater, but more costly.
The other thing is end loads/location, the roller no, DGB ok sort of, need to read a bearing manual for specific loads but they give good examples for reference.

Burgs
 

baz

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Yes I see what you mean about alignment
If the bush the other end of the layshaft were worn this could pull the roller out of alignment?
Cheers
 
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The layshaft is subjected to bending and twisting due to the force couple acting at the gear wheel flanks. In addition, bending of the mainshaft may affect the layshaft by shifting the action line at the gear wheels. Bearing resilience and clearance will increase deformation also.
Fitting a roller bearing may have been an attempt to impose a clamping condition at the layshaft's end support. This will not succeed. Rollers will misalign and wear will increase rapidly as line of contact becomes point of contact.
The best bearing arrangement is found in the AMC racing gearbox as used on the Manx, 7R and G50. Due to the absence of the K/S, the inner cover supported the layshaft by a ball bearing. I believe the standard inner cover can be machined to accept a ball bearing for those wanting to abandon the K/S. Otherwise, the racing inner cover has (had?) p/n 050125 with RGM.

-Knut
 

Tornado

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Mick Hemmings, in his gearbox rebuild d vd, recommends a DGB bearing on the layshaft drive side instead of the more popular roller for the reasons stated above. Having recently looked at an AMC layshaft in detail and seeing the grooves cut into the shaft at the 90 degree changes in diameter for oilways, I can see why they are prone to breaking under loading. I hear there are such things as 90 degree radiused shafts being made. Might me custom jobs or sourced? Just for racing?
 
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Fast Eddie

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That's interesting does he also use a bearing in place of the bush/kickstart shaft would you know?
I don’t know Baz. He rebuilt my box, but I’ve not looked inside since !
 
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RGM was supplying a needle bearing for the kickstart instead of the bush , you should ground the layshaft end to fit , tho it still remains some evidence of the previous scroll marks !!, it seems they do not supply it anymore ?
 

comnoz

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RGM was supplying a needle bearing for the kickstart instead of the bush , you should ground the layshaft end to fit , tho it still remains some evidence of the previous scroll marks !!, it seems they do not supply it anymore ?
They don't supply it anymore because the shaft was not hard enough to live with needle bearings running directly on the shaft. It was a neat idea that ended up destroying the layshaft after some miles.
 
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