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).
Examination and summary of conclusions regarding a clutch design, focusing on friction, wear, and load distribution.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 97 | |
| Date | 4th August 1924 guessed | |
| -7- Examination of the working of an existing clutch of this type suggests that the loss from actual friction is inconsiderable owing to the effectiveness of the grip. If this conclusion is correct, then the principal cause of loss of energy in clutching and subsequent unclutching can only be the imperfect elasticity of the clutch, leading to the usual stress-strain hysteresis cycle. It must be borne in mind that it is impossible, in any conceivable clutch, to eliminate this completely, for the stresses are necessarily very great and no material is perfectly elastic. Apart from the use of specially resilient material, the only way of minimising this effect is by so distributing the loads that concentrations of stress are avoided. The clutch designed by Mr. Humfrey goes a long way towards meeting this condition, namely, the load is carried equally by all the rollers, and, with the modifications suggested in para. 5, it should be possible to obtain a more even distribution on each roller considered by itself. 7. RESISTANCE TO WEAR. From the point of view of wear, every part of the bearing surfaces and of the rollers being used, either simultaneously or in turn, a much longer life is to be expected than with a clutch in which the reactions are always limited to the same parts. 8. SUMMARY OF CONCLUSIONS. (i) As a simple one-way clutch for ordinary requirements, the Humfrey Clutch is entirely effective and its action is based on sound mechanical principles. It would be well suited, for example, to the "free-wheel" action of a bicycle. | ||