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 of climbing capabilities for 40/50 HP and 20 HP models.
| Identifier | ExFiles\Box 113\2\ scan0039 | |
| Date | 16th April 1923 guessed | |
| COMPARISON OF CLIMBING CAPABILITIES 40/50 HP. and 20 HP. Guaranteed weights 39 and 55 cwts. Tyre dia's taken as 31.4 and 33 ins. ηP at rear wheels. 76 " 69 lbs.per sq.in. SPEED. | Gear Ratio. | Power available for hill climbing. lbs.per ton. | Equivalent gradient, surmountable. Good surface. Axle. | Axle. | Axle. 14 X 52 | 15 X 52 | 14 X 52 | 15 X 52 | 14 X 52 | 15 X 52 Top | 3.715 | 3.466 | 174 | 160 | 1 in 12.85 | 1 in 14 3rd. | 5.57 | 5.16 | 283 | 253 | 1 in 7.9 | 1 in 8.85 2nd. | 8.27 | 7.8 | 423 | 397 | 1 in 5.3 | 1 in 5.64 1st. | 12.7 | 11.8 | 650 | 617 | 1 in 3.45 | 1 in 3.62 SPEED. | Gear Ratio. | Power available for hill climbing. lbs. per ton. | Equivalent gradient, surmountable. Axle. | Axle. | Axle. 11 X 50 | 12 X 50 | 11 X 50 | 12 X 50 | 11 X 50 | 12 X 50. Top | 4.545 | 4.166 | 141.5 | 127 | 1 in 15.8 | 1 in 17.6 2nd. | 7.403 | 6.784 | 250 | 226 | 1 in 8.97 | 1 in 9.9 1st. | 14.43 | 13.22 | 515 | 470 | 1 in 4.35 | 1 in 4.76 | ||