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).
Car spring selection, adjustment, and weight considerations.
| Identifier | ExFiles\Box 16\7\ Scan295 | |
| Date | 1st October 1930 guessed | |
| - 2 - F.{Mr Friese} Spring - 1050 1100 1150 WF 2410 2510 2610 Range of WF - 2360 to 2460 2460 to 2560 2560 to 2660 R.{Sir Henry Royce} Spring - 1100 1200 1300 1400 WR 2450 2650 2850 3050 Range of WR - 2350 to 2550 2550 to 2750 2750 to 2950 2950 to 3150 On the front springs we can adjust to the nearest 50 lbs. On the rear springs we can adjust to the nearest 100 lbs. (This is similar to PI except that on the rear of PI we can adjust to the nearest 90 lbs. - i.e. 180 lbs. range). (In case of cars coming on the division line - i.e. 2460 front, 2750 rear, we always assign the lighter springs, i.e. 1050 and 1200) Car Weights. Having thus arrived at the front and rear complete car weights for which certain springs are to be assigned, we have to find out in advance as near as we can, what the front and rear weights of various types will be. We find from experience that we can do this with sufficient accuracy to avoid all but an occasional spring-change after completion. (See tables below). However, every complete car is weighed (front, rear and total - the three readings forming a check on the weigh bridge and the accuracy of weighing) and a form is filled out like the attached. It is the duty of the final car tester to see that correct springs are used for the actual weight of the car and not for the previously assumed weights for each body type. The assumptions made on the spring charts for PI are 4 passengers and 200 lbs. of baggage equivalent to 70 lbs. on front springs and 730 lbs. on rear springs. This assumed rear load which is much heavier than the average, is necessary to prevent bumping with our very soft "long" rear springs. On PII with 20% stiffer rear springs we feel that we can afford to neglect the possibilities of additional rear load and spring for four passengers only 120 lbs. front and 480 lbs. rear, as above. (Continued) | ||