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).
Comparison of R.R. Marles steering and La Salle steering, detailing design differences to understand performance variations.
| Identifier | ExFiles\Box 28\3\ Scan175 | |
| Date | 26th June 1935 | |
| To E.{Mr Elliott - Chief Engineer} & Da.{Bernard Day - Chassis Design} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} X1300 Hs{Lord Ernest Hives - Chair}/PJH.2/KW.26.6.35. SpectreCodename for Phantom III Marles Steering. We have, up to now, two R.R. Marles steerings on SpectreCodename for Phantom III cars - on SpectreCodename for Phantom IIIs II & III. Both these steerings are bad for joggles, though better than a standard Phantom, while the La{L. A. Archer} Salle steering on SpectreCodename for Phantom III I gives very good results. There is no major difference between the design of our gear and the design of the La{L. A. Archer} Salle so that we are obliged to consider details in an attempt to find the cause of the different performance. We give below a list of the known differences between the two gears, which may affect the transmission of joggles. (1) The La{L. A. Archer} Salle has a greater reduction in the box; 19.7 to 1 as against 15.1 to 1 for R.R. This is allowed for by a longer pendulum lever. The overall ratio is 16.5 for the La{L. A. Archer} Salle and 16.3 for R.R. The dia. of the cam is less in the La{L. A. Archer} Salle. (2) The helix angle of the La{L. A. Archer} Salle is greater than R.R., i.e., 7° 30' against 6° 35'. (3) The rockershaft on the La{L. A. Archer} Salle is overhung and is mounted on large dia. needle rollers. Our rockershaft is straddle mounted and is supported by parallel rollers in conical races. (4) The roller follower on the La{L. A. Archer} Salle is supported by ball bearings whereas ours is on parallel rollers in conical races. (5) The roller races on the cam have a much more acute angle on the La{L. A. Archer} Salle. | ||