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).
Technical memorandum discussing the springing, deflection, and stiffness of springs for various car models.
| Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan12 | |
| Date | 22th January 1926 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to PN.{Mr Northey} CWB. c. to OY. ORIGINAL Hs{Lord Ernest Hives - Chair}2/LG22.1.26. SPRINGING. X840 X540 X8840 We have sent by rail addressed to you at Le CanadelHenry Royce's French residence a 1600 lbs. rear spring for 7-EX car. The springs at present fitted to your car are definitely weak according to the std. schedule of springing. The springs on 7-EX car (1700 and 1800 lbs.) are the weakest standard springs we stock. We attach particulars of the standard schedule of springing both for 40/50 HP. and 20 HP. cars. It will be seen that different methods are used for arriving at the correct springing on the 40/50 HP. compared with the 20 HP. It will be seen that relatively the 20 HP. car is more stiffly sprung than the 40/50 HP. The deflection on the 20 HP. rear springs is 5.2" for normal camber - on the 40/50 HP. there is a 6" movement at the end of the spring for normal camber (.5" negative). Owing to the various allowances, the actual movement of the spring on the 40/50 HP. is now 8". The 20 HP. which you had at Le CanadelHenry Royce's French residence last year (5-G-11) was fitted with 900 lbs. rear springs (equal to 1800 lbs. canti-lever) which means that it had stiffer rear springs than those on your present car. The relative deflection on 5-G-11 was 5.2", on the present car (7-EX) it is 8.5". The periodicity of the springing on the 20 HP. car contd :- | ||