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28th February 2010 Modifications to the Bi-plane flyer...

Bearing
New bearing in place and sitting on a stack of washers

After it’s first outing at TIMS last weekend it was obvious that a modification was needed. Brass dust was evident at the end of the day so there was obviously something that needed some modification. The culprit was the main bearing – or should I say lack of it. The biplanes rotate around a central shaft that controls the rise and fall. This shaft runs through a double arm crank that is bolted to the plate that forms the platform on the top of the tower. Onto that the 57 tooth gear sits and is driven by a 19 tooth pinion. This friction bearing was wearing at a rate of knots.

What was needed here was some kind of small thrust bearing. One of Stuart Borrill’s really neat little ¾ inch diameter thrust pulleys (purchased at Skegness last year) was immediately pressed into action. The double arm crank was removed and replaced under the plate and a stack of five, ¾ inch diameter washers was used to support the bearing. This was topped with an eight hole wheel disc so that it will run on the bearing and support the bolt heads that pass through the 57 tooth gear above.

The planes now revolve nice and smoothly and there are no signs of dust. The model's next outing will be the SELMEC spring meeting in March.

Ralph.

 

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Bearing
Miniture engineering from Stuart Borrill
 
 
 
 
 
 
 

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