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 L.7 steering gear.
| Identifier | ExFiles\Box 28\3\ Scan062 | |
| Date | 13th November 1934 | |
| HS{Lord Ernest Hives - Chair} 1605 MECHANICAL EFFICIENCY OF MARLES TYPE L.7 STEERING GEAR FIGURES TAKEN AFTER GEAR HAD BEEN RUN FOR 7 HOURS ON RIG MID POSITION RATIO - 7:1 PEND LEVER - 10.15 Helix Angle 10 2° STATIC EFFICIENCY IN MID. POSITION LOAD AT END OF PENDULUM LEVER LBS MOBILOIL D MARLES OIL F/3/H 13/11/34 | ||