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).
Calculations and assumptions for developing road springs for the PII model.
| Identifier | ExFiles\Box 16\7\ Scan294 | |
| Date | 1st October 1930 | |
| x7410. POST OFFICE RECEIVED OCT 1930 Oy-3 October 1, 1930. Cc- Mr. Beaver Mr. Burton Mr. Ross Mr. Beck Mr. Caswell Rm.{William Robotham - Chief Engineer}) Mx.{John H Maddocks - Chief Proving Officer}) Derby Rolls Royce, Ltd., Derby, England. Attention: Mr. R.W.H. Bailey Heights and Road Springs - PII In attempting to develop the correct road springs required for the various body types on PII, the difficulty we are faced with is the essential difference between our practice and yours, and the fact that you appear to adopt some "conventions" on PII springing that we are unaware of. Practice. You build up from the chassis weight, which we do not know (but apparently about 3700 lbs.) Springs. We start with the springs, and from knowledge of the unsprung masses and the distribution of passenger load, we assign to each spring the car weight, front or rear, for which it is suitable. Thus:- Assumed Front Unsprung - 430 lbs. " Rear " - 780 lbs. Assumed passenger load - 4 passengers - 600 lbs. will be distributed - Front - 120 lbs. Rear - 480 lbs. F.S. = (Wp - 430 + 120) / 2 = (Wp - 310) / 2 or Wp = 2 x F.S. + 310 R.S. = (Wr - 780 + 480) / 2 = (Wr - 250) / 2 or Wr = 2 x R.S. + 250 (Continued) | ||