This is a blog relating to an advertising brochure published by the Wellworthy
company, in which are detailed some of the successes gained during 1951.
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| The choice of an expert |
Wellworthy
Piston Rings Ltd. was based in Lymington, Hampshire and manufacturers of
pistons, rings, cylinder liners and brake drums. They were also the exclusive
licencees of the Al-Fin process. This process was employed to produce a
bi-metallic component, usually consisting of a finned alloy muff surrounding a
cast-iron liner. This bi-metallic arrangement offered the best of both worlds,
the undoubted qualities of cast-iron as a bearing surface and the efficient
dissipation of heat through the alloy muff. There was also a considerable
weight saving over the traditional solid cast-iron component.
It was an
engineering solution that the racing world had long been waiting for and was
very eagerly adopted at the time. Primarily it was used in the production of
brake drums and engine cylinder barrels, both of which saw an immediate gain in
efficiency.
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| Al-Fin brake drums |
Al-Fin brake
drums were quickly accepted as the best available at the time and used by
leading race teams and drivers.
The following manufacturers specified and used
these drums throughout the 1951 racing season:-
Allard Frazer-Nash Jowett
Healey Connaught Aston-Martin
H.W.M. J.B.S. Kieft
Lester M.G.
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| Al-Fin motorcycle engine barrels |
Al-Fin
motorcycle cylinder barrels were used by Norton to win the World Championship in
1951.
They were also used by the following motorcycle manufacturers and
machines:-
J.A.P.
– 4B Speedway engine
Norton
– Manx/500T
Triumph – Thunderbird/T100
Velocette
– Venom/Viper/MAC
It is fair
to say alloy muffs had been fitted to iron liners on many occasions previously,
but this generally consisted of a machined alloy muff pressed or shrunk onto
the outer diameter of the liner. The interference fit that is essential for
good heat transfer clearly disappears as the temperature of the component
rises, as alloy has a coefficient of expansion four times that of iron. This can
result in local ‘hot-spots’, distortion and unpredictable behaviour, all of
which should be avoided like the plague.
The Al-Fin
process was a completely different animal and relied on the bonding of the two dissimilar
materials. This bonding process was a closely guarded operation and was covered
by the following:-Patent No.
599684 Patent No. 599725
Patent No.
606330 Patent
No. 652794
Applications:- No. 5859/48 No.
27437/50 No. 30264/50
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| Wellworthy Piston Rings Ltd. Ampress Works, Lymington |
The Al-Fin
process was originally developed by Fairchilds Engine and Airplane Corporation,
New York, USA. It consists of the formation of complex layers of inter-metallic
compounds common to both materials applied to the surface of the iron, on to
which the alloy is cast. This ensures that a true bond between the two
materials takes place.
