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).
Coil spring suspension systems, their benefits over leaf springs, and testing requirements.
| Identifier | ExFiles\Box 178\2\ img094 | |
| Date | 2nd February 1940 guessed | |
| - 2 - (6) contd. It loads the lower link rubbers however and on American cars of 1940 with present ideas of allowable maximum stress (approximately 130,000 lbs. per square inch without Wahl correction), there is not vertical height for the spring under the seat pan. Hence the spring is put on top of the axle and projects a bit into the trunk compartment. NOTE. It is possible to figure these springs rates with considerable accuracy. My notes on the subject are with papers at Vauxhall. The rate is not simply (Spring Rate) x (r)/(R) Allowance must be made for link forces, spring bending etc. Rates should always be checked by actual test on the car with a pull-down rig, as done at Vauxhall. (7) As compared with present Olds coil spring rear axle this offers - Less cost and weight. Less extension forward along the car. Better control of power and brake hop. Better control of tramp and sculling. Better control of understeer. Is better adapted for use on cars without X - members. (8) We must get rid of leaf springs because from the owner's point of view they are an expensive failure, never riding alike two days running. This is the most promising solution to date of coil spring suspension. In common with all other suspensions it requires intensive development on bump-rig and road to get it right for each individual car model. Common bump rig cams used for tests are 9" x 3/4" used 4 per drum on a 48" drum, with fine control of excitation frequency from 400 to 1500 cycles per minute. Rig should also have power absorption device of some sort for test of power hop. Oy. | ||