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).
Research into Marles steering for the Spectre project, comparing it with La Salle steering.
| Identifier | ExFiles\Box 28\3\ Scan053 | |
| Date | 16th November 1934 | |
| X4094 To Da.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to GWH.{George W. Hancock - Head Chateauroux} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}7/KW.16.11.34. SpectreCodename for Phantom III Steering. We visited the Works of the Adamant Engineering Co., where the Marles steerings are manufactured, with a view to obtaining any available information which would assist in the design of the SpectreCodename for Phantom III steering. Since your discussion with Commander Matravers at the Show he appears to have been in touch with the steering gear manufacturers in America, and admits that the double tooth steering is being very widely used over there, particularly since the advent of front wheel suspension. We are not yet entirely clear as to the advantages which the double toothed Marles has over the single toothed design, except that of compactness and greater angular movement of the pendulum lever shaft, which is certainly useful in that it removes the limitations as to the minimum length of pendulum lever arm that must be used. To illustrate the compactness we attach a sketch of the 20/25 size single follower compared with a "SpectreCodename for Phantom III" size "double" follower. We attach a report showing the forward and reverse efficiency of the Marles type steering which has been fitted to 21-G-IV for 10,000 miles, and also of the La{L. A. Archer} Salle steering which is fitted to the SpectreCodename for Phantom III. It will be observed that the La{L. A. Archer} Salle steering is considerably more efficient than the Marles, particularly in the reverse direction. In spite of this the La{L. A. Archer} Salle steering is remarkably good for absence of road shocks. We have therefore come to the conclusion that on this type of steering the instantaneous resistance to road shocks is largely independent of the static reverse efficiency. On the other hand, it would appear to be influenced by the helix angle which on the La{L. A. Archer} Salle is 7.4° against 10.2° on the Marles. We would recommend that on the SpectreCodename for Phantom III the helix angle is not greater than about 7.5°. | ||