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).
Analysis of tyre failure due to heat generation, internal friction, and canvas construction.
| Identifier | ExFiles\Box 1\7\ B001_X15 20 46 50 59-page136 | |
| Date | 1st August 1920 guessed | |
| -3- had a long run; sometimes when a tyre has just burst out, it is impossible to put the fingers inside to take out the inner tube, so hot is the cover. DECREASE OF INTERNAL WORK. Such an elevation of temperature (thinks the reasoning observer) is petrol wasted; in fact heat is energy, and from what should the car take its energy if not from the engine? Now all the energy which is taken from the engine by the tyres in order to get hot is so much energy which should be devoted to the proper function of propelling the car. If the engine had not the tyres to heat it could propel the car forward at the same speed and at a lower expense, or it would propel the car quicker for the same price. From the economical point of view it is of great interest that the tyres should absorb as little energy as possible: they should generate as little heat as possible. Furthermore the elevation of temperature which is determined by the friction of the warp upon the woof, and of the layers of the tissue upon one another softens the rubber and renders it more easily cut by stones. Everyone has noticed that the cover deteriorates much quicker in summer time than in winter. Now this is the most serious point, the threads of the warp and the woof are constantly moving one upon the other, and therefore wear each other out. It is hard to acknowledge that the woof threads, the sole duty of which is to keep in their proper place the warp threads which they interlace, in the end gradually cut them to pieces. As soon as this cutting is done rupture takes place, and in a few moments the cover bursts out. THE "WARP" IN CABLES. THE "WOOF" IN SMALL THREADS. Figures 2 and 3 allow us to perceive the difference in construction between the cross canvas of the old covers and the "Cable" canvas belonging to the modern cover. We see that in the "Cable" - hence its name - the warp is no longer constituted by a thread, but by a cable, i.e. by several threads twisted together; this constitutes a reinforcement of the warp | ||