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).
Letter from Vauxhall Motors discussing theories on steering, understeer, and caster effects.
| Identifier | ExFiles\Box 170\3\ img131 | |
| Date | 2nd December 1937 | |
| VAUXHALL MOTORS Ltd CONTRACTORS TO THE ADMIRALTY, WAR OFFICE & AIR MINISTRY. LUTON. BEDS. TELEPHONE NUMBER 2600 LUTON TELEGRAMS CARVAUX. TELEX. LUTON WHEN REPLYING PLEASE QUOTE OUR REF. MO/KF YOUR REF. 2nd December 1937. Mr. Grylls, Rolls-Royce Limited, DERBY. Dear Gry{Shadwell Grylls}, Yours of November 22nd. Regarding my theory of a "critical point" where the centre of turn comes in line with the front wheel centres, the boys in Detroit have been trying to check this, and in one word their reply is "phooey." They dont find no such thing: The sponge in the steering coupled with the strong return tendency of the tyre itself and the caster effect is certainly a strong understeer effect when the steering measurements are taken at the steering wheel. In fact it looks as though the general steering wheel effect is like the attached sketch. The steering wheel angle line I makes an angle X. above the steering angle line representing sponge in steering coupled with total self centering torque. The turn over at A is due to the tendency of precession torque to reverse at high angles. (The steering effort curves show the same turn over.) If the caster is reduced "snappier" handling results, like line II, but the danger of reversal at higher lateral accelerations, i.e. at higher speeds on a given winding road, increases. A car with a very pronounced understeer like the 37 Pontiac can stand as much as 3º negative caster and then shows a steering angle curve like III and steering wheel curve like IV. We certainly have not paid enough attention to steering wheel angles, which is why I wrote you. Yours, Maurice Olley [Handwritten Notes] Top right: Oy Right side: FJH{Fred J. Hardy - Chief Dev. Engineer} Left margin: FJH{Fred J. Hardy - Chief Dev. Engineer} 22GVI | ||