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).
Higher geared axle ratio tests carried out at Brooklands on two sales trials cars.
| Identifier | ExFiles\Box 182\M19\ img191 | |
| Date | 4th June 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to Ds. E.{Mr Elliott - Chief Engineer} c. to PN.{Mr Northey} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KT.4.6.31. X788 X7350 X7120 BROOKLANDS. HIGHER GEARED AXLE RATIO TESTS. Tests were carried out on Brooklands to determine whether it was possible to improve the Continental P.II. type cars, at present being sold, by fitting them with a 9% higher rear axle ratio. Two sales trials cars were used for these tests 26-EX and 129-GN. The first series of tests were made with both cars having 11 x 41 axle ratios. These were ballasted up to the same weight which was 5800 lbs. without passengers, or with two passengers say 6100 lbs. Side by side acceleration tests were then carried out which showed that there was no appreciable difference between the performances of the two cars accelerating from 10 MPH. upwards. The lap speeds of the cars were then measured. 129-GN. was not run with the cut-out open owing to the suspension being too flexible at these speeds with the bad state of the track. The lap speeds measured were as follows :- Lap Speed. 26-EX. C.O. closed 2 min. 7 1/2 secs. 78.1 MPH. C.O. open 2 min. 0.3/5 secs. 82.59 MPH. Lap Speed. 129-GN. C.O. closed 2 min. 6.1/5 secs. 78.9 MPH. The higher geared axle was then fitted to 26-EX and acceleration tests repeated. The loss in acceleration from 10 - 50 MPH. was noticeable, 26-EX being 3 or 4 lengths behind 129-GN at 50 MPH. We then removed the ballast from 26-EX car which brought its weight to 5340 lbs. and repeated the acceleration tests. Though the difference between the two cars was reduced considerably, the performance of 129-GN up to 60 MPH. was still better than 26-EX. This we should expect as the reduction in weight gives about 7 1/2% improvement in acceleration, whilst the axle reduces it 9%. | ||