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).
Specification sheet detailing speedometer speeds for 20 HP and Phantom chassis models based on axle ratio and tyre size.
Identifier | ExFiles\Box 50\4\ Scan177 | |
Date | 15th March 1928 guessed | |
20 HP. & PHANTOM SPEEDOMETERS. We give below the speeds of both chassis in miles per hour when the speedometers are driven at a speed of 600 revs. per minute :- 20 HP. Chassis fitted with 5-1/4" section Medium Pressure Tyres on 21" dia. rims. | Axle ratio. | M.P.H. of car at 600 revs. per min. of speedometer. | Revs. per mile | |-------------|----------------------------------------------------------|----------------| | 11/50 | 48.6 | 740 | 40/50 H.P. Chassis fitted with 33" x 6.75" Balloon Tyres on 21" dia. rims. | Axle Ratio. | M.P.H. of car at 600 revs. per min. of speedometer. | Revs. per mile | |-------------|----------------------------------------------------------|----------------| | 14/52 | 45.0 | 800 | | 15/52 | 48.2 | 747 | | 16/52 | 51.4 | 700 | | 17/52 | 54.6 | 659 | N.B. The figures for the 40/50 H.P. are the results of actual road measurements. Special 48.9 736.6 | ||