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).
Comparison table of hill climbing tests in North Devon for a 40/50 HP model and a Hispano Suiza.
| Identifier | ExFiles\Box 22\1\ Scan092 | |
| Date | 12th July 1923 guessed | |
| HILL CLIMBING TESTS - NORTH DEVON 40/50 HP. AND HISPANO SUIZA. Chassis specification. DETAIL | 40/50 HP. | HISPANO SUIZA. --- | --- | --- Turning circles. | R.H. 58½ ft. L.H. 59 ft. | R.H. 49 ft. L.H. 49 ft. Weight - fully equipped - no passengers. | 2 tons. 7 cwts. 1 qr. | 2 tons. 5 cwts. 1 qr. Gear ratio. | 1st. 11.81 - 1 2nd. 7.68 - 1 3rd. 5.14 - 1 4th. 3.46 - 1 | 1st. 10 - 1 2nd. 5.92 - 1 3rd. 3.365 - 1 Effective tyre dia. | 33.6" | 34" Wheelbase. | 150" | 145". CHASSIS PERFORMANCE. Gradients up to 1 in 4 measured by gradieometer. Steeper gradients - local intelligence obtained. Standing start (load 55 cwts. | 1 in 4 | 1 in 7 Gradient just surmountable, engine revs. falling off on steepest portion. Loads 55 cwts. | 1 in 3½ (approx.) Surface bad. Chains fitted. | 1 in 5 Surface heavy. Steering lock. | Shunting necessary for acute bends. | Reasonably good. Not tried on worst bend. Cooling. | Observed to boil. | No signs of boiling. | ||