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 discussion on the Phantom III hand brake, addressing issues and comparing performance with other models.
| Identifier | ExFiles\Box 92\4\ scan0090 | |
| Date | 19th September 1935 | |
| SECRET. Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} E.3/HP.19.9.35. c. By.{R.W. Bailey - Chief Engineer} Mx.{John H Maddocks - Chief Proving Officer} Da.{Bernard Day - Chassis Design} Hdy.{William Hardy} Phantom 3 Hand Brake. With regard to the seizing up of the hand brake on SpectreCodename for Phantom III 4, Mx{John H Maddocks - Chief Proving Officer} rather attributes this to the brake being too closely adjusted. When, however, we tried this car this morning with a slacker adjustment it was possible to pull the hand brake lever on to the stop. So far as we are aware the overall ratio on SpectreCodename for Phantom III 4 is at least 80 to 1 and may even be more than this - 95 to 1. GWH.{George W. Hancock - Head Chateauroux} has been running with 40 to 1 but Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} says that this gives insufficient braking. We, therefore, propose to try 60 to 1, but at the same time we should like to have some data on the amount of spring we use on Phantom 2 and 20/25, and we should like this compared with the amount of spring on the SpectreCodename for Phantom III, the test to be carried out on a chassis fitted with the stay to the crossmember carrying the brake counter shaft. With regard to the geometry, we say this is no worse on the SpectreCodename for Phantom III than on Phantom 2, and the 20/25 chassis is inferior to either of these, being nearly twice as bad. By shortening the last lever on the chassis to obtain 60 to 1 overall ratio we shall further improve the geometry. With regard to the adjustment, the normal type of R.R. hand brake adjustment is fitted to SpectreCodename for Phantom III and is just the same in principle as that on the Phantom 2, 20/25, and Bentley chassis. This adjustment does not automatically fix the shoe clearance, and such a refinement is not considered necessary since it is practically never necessary to adjust the hand brake. We propose to increase the length of the pull up hand lever even if this comes above the seat when fully on its stop as this will indicate that the brake needs adjustment. As previously indicated, however, we want to know how the SpectreCodename for Phantom III flexibility compares with what we have always used so as to reduce this if necessary to make the most of the pull up lever stroke. CONTINUED:- | ||