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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).
Letter from the Springfield, Mass. factory detailing the standard of springing, including front and rear spring stiffness and weight calculations.

Identifier  ExFiles\Box 43\2\  Scan264
Date  12th December 1930
  
x3900
ROLLS-ROYCE
OF AMERICA, INC.
SPRINGFIELD, MASS.

[Stamp: POST RECEIVED 22 DEC 1930]
[Stamp: RECEIVED DEC 16 1930]
[Handwritten: W]

Btn- 1
December 12, 1930.

Rolls Royce, Ltd.,
Derby, England.

Attention: MR. E.{Mr Elliott - Chief Engineer} Hives

Re: Springfield Springing

I quite forgot to give you our standard of springing at Springfield.

For the front springs - we use only one weight of spring of a stiffness 315 lbs./in.

For the rear springs - this is done in accordance with chart A-14835 of which I attach a copy. This chart is divided into two sections:

1. Original assembly - sprung in accordance with body types.
2. After mounting body - the rear end is weighed and springs are checked against the right hand side of the chart. This, of course, is merely a check to make sure that correct springs are fitted after making allowance for all sorts of extras. It is very seldom that it becomes necessary to change any springs.

Note. We have entirely eliminated the term "camber" of the springs because the load deflection curve is very far from being a straight line, especially when working with the high deflections and particularly on cantilever springs we have got into difficulties through assuming that it was straight.

Derivation of stiffness from weight.

1. Front
Weight on tires 2670 lbs.
Less weight of axle 430 "
-------
2240

Add allowance - 4 passengers
and 200 lbs. of luggage 70
-------
2310

or 1150 lbs. each side.

(Continued)
  
  


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