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Steering Column Switch

In message <Pine.HPP.3.96.971026051627.17896B-100000@lyra.U.Arizona.EDU> Robert W Obrien writes:

> On Sat, 25 Oct 1997, Phil Payne wrote:

> > Somewhere I've still got some Whitworth spanners.

> What measurement does a Whitworth pertain to? I've heard them in
> conjunction with "tea-bags,MGTCs,tweed caps" among the nostalgic US owners
> of really old British cars. I figure these are not metric, obviously, but
> are they a different scale than inches/fractions?

I don't think Whitworth ever made it as far as cars, but it represents
one of the first 'standards' for thread pitch and profile to become
widely used.  I also have some BSF spanners (British Standard Fine) and
some BA spanners (don't know the abbreviation, but used on old
electrical equipment.)

The bells in our local church have Whitworth threads, so one or two of
the spanners are still useful.  The most pervasive remnant of Whitworth
in the modern age is the idiosyncratic thread used in camera tripods -
1/4" Whitworth Coach Bolt - a few seconds' perusal will reveal how odd
it looks.

The major differences are not spanner (wrench) size but thread profile
and pitch.  As the quality of steels improved, it became possible to
cut and use much finer threads for the same or greater holding power.

 Phil Payne
 Phone: +44 385302803  Fax: +44 1536723021  CIS: 100012,1660