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 gear ratios for O and Q Marles-Weller gears at various rocker shaft positions.
| Identifier | ExFiles\Box 28\2\ Scan065 | |
| Date | 5th May 1934 | |
| O AND Q MARLES - WELLER GEARS GEAR RATIOS AT VARIOUS POSITIONS FROM MID POSITION OF ROCKER SHAFT GEAR RATIO 18 17 16 15 14 13/1 1 5/8" PITCH 1 3/8" PITCH POSITION OF ROCKER SHAFT FROM MID POSITION MID POSITION 5° 10° 15° 20° 25° 30° 35° 5.5.34 C8/67 | ||