[Bell Historians] Moseley St Mary

[Bickerton, Roderic (SELEX GALILEO, UK)]

-----Original Message-----
From: Bickerton, Roderic (SELEX GALILEO, UK) 
Sent: 23 May 2008 10:05
To: 'bellhistorians at yahoogroups.com'
Subject: RE: [Bell Historians] Moseley St Mary

 

-----Original Message-----
From: Bickerton, Roderic (SELEX GALILEO, UK)
Sent: 22 May 2008 10:53
To: 'bellhistorians at yahoogroups.com'
Subject: RE: [Bell Historians] Moseley St Mary

I am back on line from work!

The gudgeon cannot know what sort of baring is supporting it, so there
is no immediate difference.
The gudgeon is sensitive to where the load is cantered along its length.
The further out the load point from its support point, (the front of the
gudgeon plate if it is a plate gudgeon) the grater the bending moment.
A plane baring distributes support from its face to the beginning of the
back well, typically centred half way along the length.
Inevitably a pillow block will be a bit further out, because of the need
for the housing and seals.
If the ball baring centre line is 3/4 of the length of the gudgeon out
from the plate the bending moment will be up, nearly 50%.

So if safety margins are not to be eroded, a conventional pillow block
is not suitable.
A slim line block, with a sealed baring rather than a sealed housing is
what is needed, and it needs to be mounted as close in to the headstock
end as possible.
This is not possible with a clamped sleeve baring, as the tapers take up
to much space.

Its just as well that most gudgeons are generous enough to take extra
load and when they are not it is no big deal to drill out a gudgeon
plate to take a slightly bigger shaft or replace it with a modern high
spec steel shaft.

Thicker gudgeons are used with ball races, more to suite available
standard baring sizes, than because of shaft loading. Standard bearings
strong enough for bell use have a bigger centre hole than the shaft size
needed for the load. They are oversized further to provide a step to
position the baring on the shaft.

I have had to replace a broken gudgeon because Whitechapel turned down
the gudgeon to fit a standard sleeve and baring, o/k they did it more
than 50 years ago, and probably have not done it since, but turning down
a gudgeon is a real NO NO.
	

"It's a very long time since I did any engineering, but I seem to
remember that the dynamic load created by use of ball bearings is
considerable greater than that from plain bearings, which is why the
diameter of gudgeons on bells hung on ball bearings is usually
significantly larger than for those hung with plain bearings.   

Over the years there have been a number of gudgeon failures on bells
where locals have fitted ball bearings to original gudgeons that were
manufactured for use with plain bearings.

I'm sure some of our number who are current engineers will be able to
furnish a much more 'scientific' explanation than the above!

Richard"


SELEX Sensors and Airborne Systems Limited
Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS14 3EL
A company registered in England & Wales.  Company no. 02426132
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