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).
Apparatus built to determine power losses in tyres.
| Identifier | ExFiles\Box 158\2\ scan0015 | |
| Date | 17th May 1939 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} c. to Ds. d.{John DeLooze - Company Secretary} to Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}15/JH.17.5.39. POWER LOSSES IN TYRES. The following apparatus has been built, and is being used in the determination of tyre power loss. The rear axle is mounted on ball bearings as shewn in the accompanying photograph, and a torque arm is attached to the differential housing. This arm extends behind the axle, is 2 feet in length, and exerts a force on a 1 sq.in plunger operating vertically in a hydraulic cylinder. The latter is connected to a gauge calibrated 0 to 500 in 5 lb. divisions. Hence given the gauge reading and the rear wheel r.p.m. the crown wheel H.P. may be obtained, and this is taken as being very nearly equal to the hub horse power. The axle has been installed in the road wheel dynamometer chassis 3.B.IV. Hence hub H.P. and dynamometer H.P. have been measured simultaneously, the difference between these two when corrected for dynamometer loss giving the tyre loss. The chassis is loaded to approximately the same weight as a B.V. with two up. When running, the gauge reading ranges from about 200 to 260 lbs.sq.in. This means that the rear axle is lifted by the same number of pounds, thus altering the power loss which is directly proportional to the loading. To allow for this an additional 200 lb. has been added to the ballast. A high speed range is obtained by using 11 x 41 axle gears and a Wraith overdrive gearbox. | ||