The Needs of Modern Braking
Page 28
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ASIGNIFICANT remark by the author of the paper concerning the trend of brake design as it affects service (a resume' of which we published last week) was that as modern braking systems are, in many cases, more complicated than the mechanically operated, fixed-cam units which they replace, the emphasis will be on a proper educational programme to train maintenance personnel. Concerning the hand brake, the author said he had found that a large number of complaints regarding the lack of efficiency of these resulted from wrong setting of the linkage. Where the fault lies does not concern us at the moment, but that mistakes can easily be made even by moderately skilful mechanics unless they know exactly where adjustment should take place, is merely another indication that there is a need for what we may term 'continuation training" to bring maintenance men into line with the latest conditions.
The paper was read before a large number of members of the Institute of Road Transport Engineers, and no doubt they have noted, with interest, such useful practical points as these. Incidentally, there was again in the paper a call for the reintroduction of the transmission type brake. Specific reference was made to the drum and disc type, both of which are proving popular in America and on the Continent, and it would seem time that our P.S.V. Conditions of Fitness Regulations were amended to allow this modification. In the past there was, possibly, some foundation for the official view that transmissions did not possess a sufficiently high factor of safety to enable them to cope successfully and reliably with the additional stresses which might be imposed upon them by a brake acting through the propeller shaft and final drive, or, if mounted on the rear axle, through the final drive alone.
In the majority of modern vehicles, however, this extra loading could be discounted or, at least, allowed for in future designs. After all, the final factor is the adhesion between the wheels and the road, and a rather rapid engagement of the clutch is liable to result in practically as great a stress as would be caused by a transmission brake of moderate size.
Drivers would, however, require to be warned that such a brake, in its ordinary form, would be merely for parking or emergency purposes, as over-beating would be certain to ensue if a brake designed purely to meet these requirements were to be kept in use on long hills. No doubt a transmission brake, possibly of the hydraulic or electromagnetic type, could be fitted to cope with longer periods of application, but experience, so far, points to the fact that it would probably be larger and heavier than would meet with general approval. Important progress will, however, have been made if, as a first step, the law can be changed in this direction.