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 the efficiency and friction coefficients for a torsion shaft, pin joint, and lever.
| Identifier | ExFiles\Box 13\1\ 01-page70 | |
| Date | 21th December 1934 | |
| -3- Torsion Shaft in 20/25 Front Axle. The efficiency of this component is 89%, and is apparently constant. This includes the two pin joints on it. Therefore for a Bowden cable to be as good as the 20/25 brake linkage system, it would have to have an efficiency of 87% - and preferably at all loads. Co-efficient of Friction in an R.R. Pin Joint. The octagonal apparatus of which a picture is attached has 8 working pin joints, all equally loaded. It has been tested over a range of loads, the velocity ratio remaining approximately unity. Its efficiency remains constant at 95.5%, the co-efficient of friction calculated from this comes out at 0.261. It is hoped to compare this with the efficiency of another type of pin joint now in course of preparation. The pins used were 5/16" pins: reducing them to 1/4" pins would increase the efficiency from 95.5% to 96.5%. Lever G.53637 (see photo attached). The efficiency of six of these levers was measured, the result being somewhat indicative of the result of using many levers of all kinds, bell cranks etc. in series. The pin joints in this lever are all different, and the co-efficient of friction being unknown for two of them, no accurate calculations can be made. However, treating them all as behaving similar to the central pin joint, the calculated efficiency assuming a µ of 0.261 is within 2% of the actual one. A reduction in the sizes of the pivots improves the efficiency. Hs{Lord Ernest Hives - Chair}/A.F. Martindale. | ||