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).
The selection of springs, detailing poundage specifications and recommendations for Ph.III, 30 HP, and Bentley models.
| Identifier | ExFiles\Box 154a\4\ scan0019 | |
| Date | 15th December 1936 | |
| -3- It is recommended that springs be ordered to the. "Drawing Numbers" and the "Average Ideal Poundage", even if this figure is an intermediate poundage as 1375 lbs. Selection of Springs. On the Erection Card in order to get the intermediate poundages between the "types" or Piece Numbers", the following terms are used:- Plus - Minus - Plus Wide and Minus Wide. The spring makers' interpretation of "Plus Wide" is interesting, because for the 30 HP. front springs it is taken to mean 25 lbs. and for the rear springs 40 lbs. This is due to the fact that the 30 HP. front spring Piece Numbers or Types varying in 50 lbs. and those of the rear in 100 lbs. It is recommended that this scheme is deleted and that the ideal poundage is given on the erection card for each Chassis, with a limit of ± 50 lbs. for spring selection. This limit is far greater than what is used at the moment. In conjunction with the springs being ordered to the average ideal poundage a limit of ±50 lbs. will enable practically all chassis to have similar poundage springs. From the spring instructions of the week ending 12.12.36., it can be seen that :- Ph.III. 21 springs out of 22 total are within the limits of 1400 ± 50 lbs. 30 HP. All fronts are in the limits of 800 ±50 lbs. All rears are in the limits of 1150 ±50 lbs. Bentley All fronts are in the limits of 750 ±50 lbs. All rears are in the limits of 950 ±50 lbs. This means that for all our cars in this week's programme there is only one spring on Ph.III. that need be different in poundage from the other springs made to the same Drawing Number. continued | ||