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).
The skidding characteristics of tyres and various road surfaces.
| Identifier | ExFiles\Box 158\1\ scan0083 | |
| Date | 1st March 1934 | |
| X20 COPY I.A.E. RESEARCH AND STANDARDISATION COMMITTEE Research Department, 5, Bolton Road, Chiswick, W.4. No.7048. Class 387, 530. March, 1934. Skidding Characteristics of Tyres and Road Surfaces -------------------------------------------- R.A. Moyer, Report of the Annual Meeting of the Highway Research Board, U.S.A. Dec., 1933. Oversea Mech. Transport Bull., April, 1934, p. 307. -------------------------------------------- In these experiments a two-wheeled trailer was used which, when measuring side skid forces, was connected to the towing vehicle at an angle of 15°. The main conclusions were as follows :- (1) There was a marked decrease in coefficient as the speed of the car increased on all wet surfaces except gravel and cinder. The same characteristic was observed on dry surfaces, although the decrease was at a much lower rate, and an increase in coefficient with speed was observed on gravel, brick and asphalt plank surfaces. (2) On wet surfaces at 30 m.p.h., the straight skid coefficient was 10 to 20% higher than the side skid coefficient. (3) Variation in load on the tyres or variation in tyre pressure had little effect on the straight skid coefficient, but a slight decrease in side skid coefficient was observed with an increase in load or a decrease in tyre pressure. (4) The same coefficient of friction was observed for two standard balloon tyres of the same size with with different tread designs. | ||