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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Spring design, discussing weight reduction, material choices, and discrepancies with spring suppliers.

Identifier  ExFiles\Box 43\2\  Scan231
Date  14th November 1927 guessed
  
contd :-
-2-
thick leaf cantilever was eliminated on the rear of the 40/50.
Therefore the spring makers have gratuitously added 17 1/4 lbs.
to the car weight with no justification because it is certain
that we are at present well within the safe stress range and
maximum stress with our cantilevers.
We consider that this fact should at once be
brought to their notice and they should be asked to produce a
rear spring at least as light as the equivalent cantilever.
Probably with the latest American information a definite
reduction in weights over our present standard can be effected,
also so far our tests shew a much better life with Silico
Manganese than Chrome Vanadium, which, when we have had more
experience with it, may enable us to revise the rear spring
design as with our present material the rear spring factor of
safety is quite adequate.
The third discrepancy which indicates quite
clearly that the spring makers are not in the least concerned
about the weight of metal which they put in our springs has been
observed in connection with the Sports cars. One of our objects
in fitting stiffer springs instead of "stiffer stronger" springs
was to reduce weight. It is reasonable to expect that if a
spring has to support a load through only 75% of the deflection
of the standard type, it can be made with at least 20% less
metal than the standard spring for the same stress.
Actually as an example of the stiffer springs
we have already received, we have :-
2300 lbs. standard spring 87 lbs.
2300 lbs. 25% stiffer " 96 lbs. 6 ozs.

contd :-
  
  


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