OPINIONS FROM OTHERS.
Page 25
Page 26
If you've noticed an error in this article please click here to report it so we can fix it.
The Editor invites correspondence on all subjects connected with the use of commercial motors. Letters should be ort one side of the paper only and typewritten by preference. The right of abbreviation is reserved, and no responsibility for views expressed is accepted.
Safety on Hills.
The Editor, THE COMMERCIAL MOTOR.
[2260] Sir,—We note an interesting article in your issue of the 10th inst. dealing with the question of braking of vehicles on hills. You refer to the Saurer patent engine brake as a good example of this type. We feel, however, that the action of the engine brake is not understood by the general public, and would be glad if you would publish the following facts.
Safety on greasy roads, to which reference is made in the article, is absolutely ensured by the use of the engine brake, as the rear wheels are never locked while the brake is in operation, the braking being effected by the rotation of the wheels against the • engine compression, which is increased by an alteration of the position of the camshaft.
Fittings, such as hydraulic and air-pressure attachments, merely increase the power applied to the brake-operating gear and do not assist in solving the question of skidding. On the contrary, the application of increased power is, in our opinion, more likely to lead to the locking of the rear wheels, with .consequent danger of skidding, as the driver has not the sensitive control that he has when power is applied manually. As regards the reduction of labour required on the part of the driver, all that he has to do when using the Saurer patent engine brake is to push the throttle lever into the reverse position, when a graduated braking effect can be obtained, as is required by the circumstances of the gradient, etc. .There is no danger of overheating when this brake is in use, as the engine, temporarily functioning as a powerful air compressor, is water-cooled, and the heat generated by braking is carried off by the cooling water just as when the engine is driving the vehicle.
, The practice of drivers of having to release brakes and re-apply them when the wheels skid is quite unnecessary when the engine brake is used, as continuous and graduated braking can be employed throughout the entire gradient. It is well known that when the wheels are locked the braking effect is reduced and, as you state, the retarding effect is dependent on the adhesion between the tyres and the road. With the engine brake, this adhesion is never lost, as the wheels are constantly turning at a reducing velocity.
We demonstrated some 2; years ago the efficiency of the engine brake under R.A.C. observation, taking a &riser over the steepest hills in North Devon, such as Lynmouth, Parracombe and Countisbury, and throughout the entire trial, except for traffic emergencies, the engine brake only was used. This brake is additional to the friction brakes which are supplied with the chassis, These are controlled by pedal and hand lever and operate on the rear wheels, and either of these brakes is sufficient to hold the vehicle on any hill, so that, in the event of a breakage in the transmission between the wheels and the engine, the vehicle is still fully eouipped so far as brakes are concerned. There are numerous other advantages of the patent engine brake, such as economy in fuel and tyre consumption, absence of wear and tear due to braking and absence of carbon deposit in the cylinders, all of which increase the efficiency and utility of this fitment. —Yours faithfully, THE SAURER COMMERCIAL VEHICLE CO., LTD., RALPH E. WILSON.
London, N.W.I.
Front-wheel Brakes a Necessity.
The Editor, THE COMMERCIAL MOTOR.
[2201] Sir,—I have been interested in the views expressed in your journal onthe question of frontwheel brakes as applied to commercial vehicles. It would be well, again, to state that H. G. Burford and CO. had on their stand at the Olympia Show held in the year 1921 a char-h.-banes chassis fitted with front-wheel brakes, believing then that it must be absolutely right for the country roads which chars-k-bancs are now called upon to negotiate.
Whilst theory or expense may be against this extra brake, practice and experience confirm the views which the writer held some two or three years ago that passenger-carrying service vehicles must be fitted with four-wheel brakes. The justification of the polity adopted then is borne out by a letter received, dated June 12th, from Messrs. J. P. Arthur and Sons, of Smithfield Garage, Oswestry, who give their experiences, the chars-à-banes referred to having run close upon 20,000 miles in service, under conditions which are exceedingly severe. I think the letter is worth publishing in full and I attach a copy of the communication received, as I believe not only the need for the safety of the passengers, but for the general safety of other users of the road, will demand brakes being fitted to four wheels.
In the course of the past 25 or 26 years during which the writer has been engaged in the development of vehicles for commercial use a large number of the devices which are common to-day, have been fitted to vehicles for which H. G. Burford and Co. have been responsible, and it is gratifying to the writer that a purchaser and actual user confirms the ideas for which we were responsible.—Yours faithfully, London, &W.1. H. G. BURFORD. (Copy of letter referred to by Mr. Burford from J. P. Arthur and Sons, Smithfield Garage, Oswestry, to Messrs. 11. G. Burford and Co., Ltd., 24, Haymarket, London, dated June 12th, 1924.) Dear Sirs,—Re Tours of the 3rd instant, we regret not having given some attention before, The char-it-bancs referred to in your letter has now done close on 20,000 miles, most of it in about as bad a part of North Wales as possible, some of the roads travelled over being as steep as 1 in 5 for a mile or so at a time, so you will appreciate our meaning.
For example, during last week we transported one day about 300 people to Lake Vyrnwy, Montgomeryshire, over what is called the " Flirnant Pass,' and the road being extremely steep and narrow it was somewhat of an adventure. During the ascent of the steepest part one of the charsaha.ncs, being in first speed at the time, jumped out of gear ; the driver applied the brakes, but s40 same were of no avail, the char--banes ran backward and was "ditched," but not before having frightened the whole of the passengers and almost turning over. In our opinion, it was a very narrow squeak. Yow, if we had had front-wheel brakes on this vehicle we do not think for a moment that there would have been any trouble.
We have no hesitation whatever in stating that we consider the vehicle supplied by you with front-wheel brakes is a very much safer proposition than any others we have had experience with. • Trusting that these remarks will be of some avail.—Yours faithfully, (Signed) S. R. ARTHUR.
i-Many users of commercial motor vehicles are anxious for light or. the question of the practicability (under service conditions) of front-wheel brakes. We shall be glad to publish letters on the subject. —ED. CAL)
Coach Equipment for Bad Weather.
7'he Editor, THE COMMERCIAL MOTOR.
[2262] Sir,—The article on " Converting the Coach for Spring Traffic" in the issue of The Commercial Motor for February 26th must have been very interesting and instructive to many commercial body builders, as the providing of a fixed top for winter use makes a char-6,-bancs double its utility, because for six months in the year the vehicle is laid up and naturally is not earning anything for its owners, whereas if the removable top is ready there are surely many trips such a vehicle would be able to undertake. Of course, the all-weather type is gradually improving, and frameless glass windows, either operated by hand or winding mechanism, are taking the place of side curtains, etc,
The Beclawat char-h-bancs frameless carriers are a step in the right direction, as the folding fitting carries felt-lined channels back to back aiad provides a run for the adjacent light. The fittings for the doors are made in a complete unit and only have to be screwed to the body side, so it is not necessary to do any boxing out for glass runs. An ordinary Cape-cart hood is at present suggested for use with the above fittings and the head material is secured to carriers by press buttons.
Further developments are rapidly taking place and metal headwork of easy manipulation and not requiring much space (that is as regards height at the back) is being experimented with, and no doubt a very satisfactory and efficient all-weather char-kbanes will be the outcome. It appears that the cost of such an equipment will be practically negligible when taking into consideration the increased annual mileage of which an all-weather coach is capable.— Yours faithfully, H. WOODHALL. London.