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 the 40/50 HP and 20 HP models.
| Identifier | WestWitteringFiles\K\June1923\ Scan81 | |
| 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 | ||