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).
Clarifying design points for the Marles Steering system on Phantom III, 25/30 HP, and Wraith II models.
| Identifier | ExFiles\Box 153\2\ scan0025 | |
| Date | 5th May 1936 | |
| X1300 To BY.{R.W. Bailey - Chief Engineer} Copy to Mr. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Mr. Hs{Lord Ernest Hives - Chair}/DLY. GRY{Shadwell Grylls} Marles Steering. ------- Certain points in connection with the design of our Marles type of steering have arisen in conjunction with the Phantom III, 25/30 H.P., and Wraith II, which we would like to clear up. 1) Angle of Axis of Cam Wheel relative to rocker shaft. The pitch angle of the worm at the centre has been given by ourselves and the Expl. Dept. for Phantom III and 25/30 H.P., and it is at this angle that the cam wheel has been set in each individual case. Since, however, the cam wheel does not bed at the centre but at its outer faces, the setting of the cam wheel relative to the rocker axis should be the pitch angle at the point of bedding. In the case of Wraith II the angle given on the scheme is the pitch angle at the bedding face. We give below a table illustrating these points:- | Car. | Pitch angle at centre of worm. | Pitch angle at bedding of cam wheel. | Angle of cam relative to rocker shaft axis as detailed. | Proposed correct angle for cam wheel relative to rocker shaft axis. | |---|---|---|---|---| | Ph.III | 6°35" | 5°55" | 6°35" | 5°55" | | 25/30 HP | 5°48" | 5°39" | 5°48" | 5°39" | | Wraith II | - | 6°59" | - | 6°59" | 2) Worm Attachment to Worm Shaft. We understand that the limits concerning the shrinkage fit for the worm to the worm shaft, which give a minimum interference fit of .003", have been derived as the result of experience on the experimental cars. It would appear necessary to ensure that the dimensions of the key and keyway are such that when the shaft is | ||