PASSENGER TRAVEL NEWS.
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The Latest Doings and Developments in the Bus and Coach World.
BRAKES AND THE MOTOR COACH.
A Vital Problem and Some Suggestions for its Solution. Reducing Running Risks. Power Braking versus Manual Operation. Giving the Driver a Chance. Fatigue and Fatality.
WE have on many occasions, in dealing with coach chassis design, referred briefly to the braking problem and its importance, and we now propose to consider this aspect of design at greater length. The subject of braking divides naturally under two headings :—(1) The type and efficacy of the retarding mechanism. (2) The method of bringing it into action. Both are of paramount importance, but, generally speaking, development seems to have taken place mainly under the first heading. There have been continual efforts made towards increasing the efficiency of brakes and braking surfaces, whilst the mode of operation, i.e., by means of hand lever and pedal, have become practically standardized. We wish to emphasize the fact that, as regards the motor coach, there are strong grounds for a complete reconsideration of the whole problem, and to offer some suggestions towards its solution.
Braking and Safety First.
The rapidity with which the public has acquired the "coaching' habit has hardly given the designers and makers and proprietors of these vehicles time to realize the great new responsibilities
they have undertaken. It is true that passengers have been carried in millions on bus routes for many years, and that, during that -time, existing braking arrangements have generally served their purpose satisfactorily.
But the coach presents an entirely different problem from the bus. By its nature it is a vehicle of exploration and adventure. It may be called upon to operate in valleyi or on mountains— wherever there are roads. The coach must be able to go wherever the pleasure-seeking laublie wishes to be taken. Now, the driver of a London bus has great responsibilities and incessant traffic problems to negotiate, but these problems are such that a man, by daily contact with them, becomes able to surmount them almost by instinct.. The coach driver, on the other hand, must always be prepared to encounter the unexpected, and, when he does so, the safety of his passengers must be ensured
Now, in the numerous letters received from coach drivers throughout the country in connection with The Commercial Motor coach competition more than a year ago, one fact that stood out with great prominence was that nearly every driver was hankering after some automatic form of braking—electrical, vacuum, hydraulic—no matter what. It was obvious that drivers were dissatisfied with existing methods of brake operation.
The Driver's Third Hand.
Now the driver's bugbear is obviously the side-brake lever. On the majority of vehicles it operates the brakes which he should use most fre
quently, yet, generally, he prefers to use his pedal-operated brake.
Take the case of a coach descending a tortuous mountain road. Probably the driver will find it necessary, for several reasons, to use both hand and foot brake intermittently during the entire descent. That leaves but one hand with which to steer the lives of 30 or more people along, perhaps, the edge of a precipice. It means that warning, at the curves and corners, must be given by frantic jabs at the horn bulb. Frankly, it is not good enough. Most coaches are not too easy to steer with one hand. Several entrants in the competition referred to maintained emphatically that they required two hands to manipulate their steering wheels in traffic and on awkward roads. Even a light car driver prefers to toy with two hands at his wheel, even if he does not really need them both.
Then there is the question of fatigue. The coach driver in the busy season works long hours. His work entails no inconsiderable fatigue to which the manual labour of constant braking must add considerably. It is not in the general interests of safety that drivers should be unduly tired at the wheel. It is on the way home, after a long and gruelling run and when the light has failed, or is failing, that accidents are prone to happen.
Power Braking Possibilities.
The great requirements in any system of power braking are that it shall be, firstly, as infallible as human skill can make it, and, secondly, of such design that the expense of manufacture does not add enormously to the cost of the vehicle. The second consideration is probably the reason that power braking has made so little headway in the automobile world.
What is wanted on the coach is not so much the supersession of the hand-brake lever Ind its accompanying mechanism B37
(it could still remain as a stand-by), but some power-operated means of putting it into action, controlled preferably by a button on the steering wheel. This implies electrical control, but not necessarily electrical operation. The operating ntedium might be oil' (as in tthe case of the four-wheel .braking system on the 14-16 h.p. Rolland-Pilain car), compressed air, or vacuum. In the case of the :Saurer design, we have compressed air braking (the engine brake) as an auxiliary.
Is the idea not capable of developmerit? Supposing the pneumatic tyre eventually achieved a wider popularity than at present, many chassis will be fitted with a miniature air compressor for intermittent use. Could it not be made of such a size, provided with a compressed air reservoir, and adapted to serve as part of a compressed air braking system?
It is not possible in an article such as this to do more than suggest possible lines Of exploration. Producing a simcessful design is, We are aware, quite another matter, and the files of the Patent Office would probably bring to light a host of undeveloped and unexploited notions. Our purpose is merely to invite the interest of manufacturers and designers in a problem which, sooner or later, will have to be solved in one way or another.
n28 The hand brake is a crude idea at hest, not far removed from the ideas of Pickwiekian coaching days. It seems to us rather remarkable that, with a heavy vehicle in motion, the momentum of which has to be reduced, it should be necessary to exert manual effort for that purpose.
The ideal system would be an electrical regenerative one. But, so far as we are aware, none has ever been successful, and, in any case, the cost would probably be prohibitive. 13ut a braking system utilizing the motion of the vehicle need not ne.cessaril7 be regenerative. On the Rispano-Sniza car a step
in this direction has been made already. Is this not afield of invention worthy of more investigation?
The Four-wheel Alternative.
More than once in these columns we have advocated front-wheel brakes for coaches, and on one design of chassis— the Burford—they have been fitted. The provision of brakes. pedal-operated simultaneously on both sets of wheels, should obviate the necessity for using a side lever except when it was niece convenient to do so. It should remove much of the bugbear of braking to which we have referred.