The Editor invites Correspondence on all subjects connected with the
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use of commercial motors. Letters should be on one side aJ the paper only and typewritten by Preference. The right of abbreviation is reserved, and no resPonsibility for views expressed is accepted,
The £100 Works Runabout.
The Editor, THE COMMERCIAL MOTOR.
124801 Sir,—We welcome your invitation. for expresSims of opinion on the suggested petrol-driven works truck, and we would remark, in the fir/ place, that there are obvious reasons why such cannot be employed except in certain eases where they could be confined to yard work.
The fumes, noise and fire risk are sufficient to prohibit their use inside of any building, whilst upkeep on Such a machine kept constantly at work for, say, 10 hours per day would rapidly become very considerable. Reliability would become impaired and in many processes it is absolutely imperative that no stoppage should occur in tile transport system.
First cost is not the whole cost of any machine, and the electric truck is surely a paying proposition when it will repay its first cost in six to nine months. In the smaller trucks having a capacity of one ton, as you mention, a slow-speed motor with single chain reduction is most frequently employed, and we venture to suggest that nothing more simple or reliable can be found, nor is the first cost so much in excess of your figure as greatly to limit their use.
A one-ton truck of simple design can be obtained at prices ranging from £190 to £220, according to battery equipment, and, as the battery is really a consumable item that can be looked upon as a fuel charge to be Spread over a period of three or four years, the cost of the truck itself compares with what you have in mind.
We might instance a case of a fleet of 14 of our trucks which have all been in use for many years and which have averaged per truck under 10s. per annum for spare parts, and, as current costs only U. per day, we think it is obvious that tile battery truck has no equal for this sphere of usefulness and need fear no competition from a machine driven by an internal-combustion engine.—Yours faithfully, :C. G. C..0NRADI, Managing Direi?,/0T. ELECTROMOBILES, LTD. OtTey, Yorks.
Cork in Place of 'Felt for Washers.
The Editor, THE COMMERCIAL, MOTOR.
[21.81I Sir,—I read with interest the letter from Mr. R. S. judge, of Izegsight, Manchester; upon _ the question of cork in place of felt washers which, appeared in the issue of The Commercial Motor for April 6th. The questions which ,ze raises are serious, particularly in relation to the charring of the felt or' cork when not properly lithrica tecl. I myself, about 12 to 18 months ago, was badly up against the problem of oil, steam and -gas leakages from certain types of engine with which I was then dealing. I tried felt and found that, Under certain conditions, it got hard and charred, and it even wore the shafts badlyand very soon became ineffective. I tried lead wool and other packings, which never, for any length of time, seemed to get properly ,steam or gastight. I eventually came to hear of Langite and, being eager to test anything which looked at all likely, I tried it, and have had very few difficulties with this material beyond the fact that on ray early designs I had to fit sonic of these washers over a spline(' shaft and, naturally, the washer had to revolve with the shaft at moderately high speeds. They worked satisfactorily, but after:a time the splined parts tore away and rendered them inefficient. I then altered my designs to get a smooth surface on the internal bore of these cork washers. I may add that two surfaces which revolve and two surfaces which do not revolve are in contact with the washers. That means that the washer is free to rotate at half the speed of the -shaft if necessary, or any proportion thereof, according to Um frictional resistance between the rotating and non-rotating faces.
Since this change of design was made I have run an engine for long periods and at revolutions approaching anything up to 10,000 r.p.m., with not the slightest leakages, for many months past.
I mentioned steam and gas as well as oil because, in my case, these rings are fitted into a gland between a roller bearing and the cylinder of this type of engine, and prior to using these Langite washers I was always in trouble with the steam or gases blowing through from the cylinders into and through the roller races and escaping to the atmosphere. I have, certainly, great pleasure in recommending these washers, first, because there is little danger of over-compressing them and, secondly, because although the Cork Manufacturing Co., Ltd., do not recommend this cork material for steam, I can assure my readers that before I used these washers I was always in trouble with leakages through the bearings, no matter what jointing I used. Now I have no bother whatever in securing gas-tightness, and may say that the pressures in the cylinders are anything from 200 lb. per sq. in. tipward,s. When the engine was down last week for examination the Langite washers were found to be in perfect order, splendidly lubricated and clearly showing that they had been revolving, because they were polished on all faces and were squeezed down to about 80 per cent. of their original thickness, with no signs of charring.
I know that for oil glands this material is being used extensively, instead of felt or lead wool, by most of the large engineering concerns, especially on motorcars and the heavier types of motor vehicle, and I am sure it is worthy of the consideration of steam engineers for joints as well as glands, because of its capacity for being squeezed up to the smallest dimensions without spewing out, in the manner rubber does, but it is essential that It be well lubricated.—Yours faithfully, SPEED. Leyton, London.
The Editor, THE COMMERCIAL MOTOR.
[24821 Sir,—One of your correspondents, in the issue of April 0th, raises the question of charring and disintegration of cork washers under heat, owing to friction, and remarks that, "of course, where oil is used this only tends to aggravate the trouble." The contrary is the case.
A feature of the Langite cork composition referred to is that it requires, and improves with, oil or grease, and, if well lubricated, will give no trouble whatever.— Yours faithfully, -ARTHUR COOTE, Director, CORK MA/VITFACTURING CO., LTD. South Chingford, E.4.
The Editor, THE COMMERCIAL MOTOR.
[24831 Sir,—I notice that in the letter of Mr. R. S. ;Fudge which appeared in the issue of The Commercial Motor for April 6th he asks what would be the effect of friction upon cork washers used for the purpose of retaining oil in bearings, as he seems to have had a rather bad experience of cork when used as inserts in brakes and clutches.
It would be unfair to compare the slight friction produced by the resiliency of the cork in the case of an oil-retaining washer with the very heavy friction induced in a brake or clutch, as we all know that the
greater the pressure between two surfaces that are in frictional contact, the greater the heat induced.
I have recently had an opportunity of -examining an experimental car that had been dismantled after it had covered ten thousand miles, and its cork washers were
as good as when new.—Yours faithfully, C.M.L. London.
Speed of Pneumatic-tyred Buses.
The Editor, THE COMMERCIAL MOTOR.
[2484] Sir,—We read with much interest Mr. Nixon's letter under the above heading in the issue of The Commercial Motor for April 6th, which, we think, having regard to the main points at issue, might, in your original editorial article, have been more aptly described as "Weight and Speed of Pneumatic-tyred Buses."
We agree that a 12 miles per hour limit for anything short of a heavy traction engine is absurd, and we know that, generally, no one observes the regulation any more than the private motorist observes the 20 miles per hour speed limit, and we take it that the proposed increase of the speed limit to 20 miles per hour for a bus on pneumatic tyres, weighing unladen 3f tons, is relative.
When, however, Mr. Nixon says:— "As to tare weight as a qualification for higher speed rating, why impose such a restriction on the designer and operator? What matters are the gross weight and the laden axle weights.
"In order not to exceed the 3 ton 15 cwt. limit, weight has been cut in many directions which are undesirable, perhaps not so much from the safety point of view as from those of smooth running, freedom from vibration, durability and consequent low maintenance cost of the complete ,bus."
We entirely disagree.
In the first place, it is generally recognized that, at a given speed and diameter of :tyre, the heavier the axle load the greater the damage to the road when the tyre hits a projection or a pot-hole.
The question of road damage has a direct bearing on the cost of bus operation and maintenance cost. Vehicles operating on a specified route, that wear out the road more quickly, deteriorate themselves more rapidly than would otherwise be the case, and so the vicious circle is completed.
In this connection it is interesting to notice on page 248 of the issue of April 6th that you report that complaints have arisen as to the speed and vibration of buses at Gravesend and that the operating company reply that they are putting on lighter buses to obviate the nuisance.
Secondly, the reaction of the impact on the vehicle is also proportional to the load, and that these shocks On the vehicle do have a serious determining effect on the cost of maintenance will, we think, hardly be disputed.
Thirdly, for the same carrying capacity, other things being equal, increased weight of the vehicle means increased consumption of petrol and increased cost of tyres, etc. _ Fourthly, the tare weight—i.e., the weight unladen— is a determining factor on the number of passengers which can be carried for a given laden weight, or axle weights, and surely, this is of prime importance to the operator, as it directly influences the earning capacity of the vehicle.
in short, from every point of view, it is desirable to eliminate unnecessary weight.
We should like to ask you, or your correspondent, specifically to enumerate in what manner weight has being cut out of certain makes of 32-seater bus, which come within the 3 tons 15 cwt. limit, which has proved undesirable?
'As we pointed out in our previous letter, costs of operation of our buses show, an appreciable advantage compared with the heavier types and, as regards c46 smooth running and freedom from vibration, we make bold to say that the Guy bus compares favourably with any on the market, whether heavier or lighter.
The whole modern development of motorcars, aeroplanes and other forms of transport has been on the lines of a higher power-weight ratio. Why should not the same improvement apply to motorbuses, and, if one wishes to attain this desirable end in the most economical manner, surely it is best done, where practicable, by reducing the weight rather than increasing the power?
In conclusion, we would say that if it be desired to carry a heavier load at a high speed, without undue damage to the roads and the vehicle, what about increasing the number of axles and thus reducing the axle load?
Our opinion is that the future development of motorbuses and goods-carrying vehicles will be along the lines of reduced weight for the load carried and with particular regard to the axle weights, and all on pneumatic tyres,—Yours faithfully,
SYDNEY S. Guy, Managing Director. For Guy MOTORS, LTD.,
Wolverhampton.
A Point that is Sometimes Overlooked by Designers.
The Editor, THE COMMERCIAL MOTOR.
[2485] Sir,—Owing to my absence from town I have only just had the pleasure of reading the letter from "C.M.L." in the issue of The Commercial Motor for March 30th under the above heading. This letter is particularly interesting to me, as the point is one which has certainly not been, overlooked by the designers of the Gotfredson chassis.
All Gotfredson chassis are tested out by users under actual service conditions before being put into production, and, in the same way, when changes are suggested in the design of any component, the new type components are fitted to a number of existing chassis used by customers on various classes of work, and are left with them for a considerable period before the changes are finally incorporated in new chassis.
It is evident that changes of design, either of components or complete chassis, so tested and tried, must be satisfactory in service ; whereas new designs tested by a manufacturer's own staff, are, in the very nature of things, not expoAed to half the abuse to which chassis are very often subjected in actual service. Certainly no self-respecting test driver or mechanic could neglect lubrication as it is neglected in, I think I can safely say, the majority of cases in ordinary daily work. —Yours faithfully, BONALLACR AND SONS.
IL P. BRADLEY, Sales Manager. London, E.1.
Economizing Oil Consumption: The Editor, TEE COMMERCIAL AIOTOR.
[2486] Sir,—We have a fleet of ten Ford ton trucks and one 1-type Daimler lorry and ar'e wondering if any of your readers know of any device that will help us to cut down the oil consumption on both types of lorry. On the Fords the only means of telling the oil level is by the two taps on the back of the crankcase. This we find rather extravagant. Our lorries only average about 30 miles per day, but as this is a very hilly district; 'to be on the safe side our drivers like to see the oil running out of the tap tap. „In the opinion of the writer this is not necessary Is there a device, such as a tube, similar to a water gauge or a dip rod, to tell how far the oil is above the level of the bottom tap on the crankcase? We have tried one or two devices, but they have been unsatisfactory.
. In the ease of the Dahnler, the only means of telling how much oil is in the sump is-by looking through the filler cap, which makes it more or less guesswork.—
Yours faithfully, INTERESTED. Bristol.