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Gearbox bearings

Submitted by andy_marks on Mon, 01/04/2013
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I've bought a complete set of new bearings to go in my dolls head gearbox and the roller bearings I had before had a lip on the edge to stop the rollers going all the way out the other side. I've just looked at the ones I have bought and the roller bearing does not have a lip. Does it matter? Will it cause problems with end float? Or cause the shaft to rub against the case? Are the new bearings I have useable or do I need to carry on shopping for a lipped version?

Submitted by andy_marks on Mon, 01/04/2013

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I've had a bit more of a look round at a few bearing suppliers and none of them seem to sell the same type as the original, with the rollers fixed on the inner race and a lip on the outer race. They do sell ones with the roller fixed into the outer shell and with a lip on the inner race. Would this do the same job?

Submitted by andrewmichael_… on Tue, 02/04/2013

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This sort of bearing will do the job http://simplybearings.co.uk/shop/p501804/NJ203+Budget+Single+Row+Cylindrical+Roller+Bearing+17x40x12mm/product_info.html

- not sure about the size as my vital piece of paper seems to have gone walkabout!!

A hot air gun is good for heating the casing and once up to ~100C the bearing outer should drop out with a sharp downwards impact of the case on a block of wood. Be gentle! Dolls-head cases are fragile and cost more than hens teeth.

Submitted by andrewmichael_… on Tue, 02/04/2013

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Previously wrote:

Cheers. I'll have to go shopping for some of them. Thanks

Andy

I think conventional wisdom (i.e. the experts!) say you only need to use a roller bearing (on the lay-shaft - opposite end to kick-start mechanism). The 2 bearings on the main-shaft should be ball races, with both shafts shimmed to have about 10-12thou free play. Ideally do the lay-shaft shimming BEFORE you fit the large main-shaft output bearing, so you can get your fingers inside the gearbox to check what you are doing, when the cover + k'start mech is fitted.

 


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