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).
Graph showing the mechanical efficiency of a Marles Type L7 steering column under different loads.
| Identifier | ExFiles\Box 28\3\ Scan125 | |
| Date | 12th October 1934 | |
| HS{Lord Ernest Hives - Chair} 1556 MECHANICAL EFFICIENCY OF MARLES TYPE L7 STEERING COLUMN. STATIC EFFICIENCY AT MID POSITION OF TRAVEL. GEAR LUBRICATED WITH MOBILOIL D.{John DeLooze - Company Secretary} PENDULUM LEVER 10.15" LONG. MID POSITION RATIO 15 : 1. 2 3/4 TURN CAM. HELIX ANGLE - 11.78° EFFICIENCY % LOAD AT END OF PENDULUM LEVER - LBS. FORWARD REVERSE F.A.H 12/10/34 | ||