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 comparing the effect of drilled valves versus standard plain valves on rear axle movement.
| Identifier | Morton\M19\ img158 | |
| Date | 21th April 1931 guessed | |
| R.R. HYDRAULIC DAMPERS. EFFECT OF DRILLED VALVES ON REAR AXLE MOVEMENT. ETWALL HUMP BACKED BRIDGE. 25 EX CAR. LOW RATING ROAD SPRINGS. DAMPER LOADS. 90/90 LBS. NORMAL BUFFER CLEARANCE. ROAD SPEED (M.P.H.) 25 30 35 40 MAXIMUM REAR AXLE MOVEMENT. COMPRESSION REBOUND 8 6 4 2 2 4 6 8 NORMAL AXLE POSITION. H.P. VALVE DRILLED .055" DIA. STANDARD PLAIN VALVES. | ||