OPINIONS FROM OTHERS.
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The Editor invites correspondence on all subjects connected with the ose or commercial motors. Letters should be on One side of the pap2r only and, preferably, typewritten. The right of abbreviation is reserved, and no responsibility for views expressed is accepted.
The Littering of Streets with Bus Tickets. The Editor, THE COMMERCIAL MOTOR.
[2684] Sir,—This is a subject of personal interest to me. All tickets both on cars and omnibuses here in Burnley areCollected by the conductor, not for the purpose of preventing litter, but because it is the only effective method of preventing the missing of fares. The same system—and for the same reason—has been carried out by the railway companies for a hundred years.
Very serious losses mast occur on large undertakings with heavy traffic. The heavier the traffic the greater the loss from missed fares. The system has been in operation on the Burnley and district tramways since 1881.
It has always been a puzzle to me why such an elementary necessity of the proper conduct of a passenger-carrying undertaking is so universally neglected. The collected tickets are sold to paper manufacturers and well repay the cost of packing, etc. —1-Ours faithfully,
HENRY MozLEY, General Manager, Burnley Corporation Tramways and Onanibpses. Burnley.
New versus Reconditioned Vehicles, The Editor, THE COMMERCIAL PriOTOR.
[26851 Sir,—I have read with interest " S.T.R.'s " article this week on "New or Old Vehicles."
In principle I agree with him. At the same time it is quite possible to operate and to maintain a fleet of old vehicles successfully and economically. I have charge of such a fleet of nearly 50 vehicles. There are, certainly, a few vans among this fleet that are less than a year old. These are light vehicles and are more or less used only locally. The majority of the fleet, however, dates back to the 1917 and 1918 vintage I •
One is an old 1916 Ivy type Talbot van. This chassis did yeoman service as an Army ambulance. An 1919 it -was purchased by us and did many thousands of miles after reconditioning. It was thoroughly reconstructed in 1926 and fitted with a new body. Since then it has been in use every day, has cost nothing for repairs and will outdo many vans as many months old for speed and reliability.
I would point out that this vehicle has a wonderful engine. Thevalves, pistons and cylinders are the original. No bearing has ever run out, and the main bearings and crankshaft are the originals. Can any modern engine equal this?
My firm had to decide, some years ago, on whether they should incur heavy capital charges by the purchase of new vehicles, or should increase the maintenance costs by reconditioning the old vehicles. In view "Of the heavy capital expenditure in other branches of the business it was decided to adopt the latter course. I was not entirely in favour of this, but at the same time went wholeheartedly into the work.
I will give an example of one chassis. A CB Daimler was taken off the road in a very bad state. According to depreciation figures the capital value was nil. The chassis was stripped down to nothing. Every worn part, large or small, was replaced by new. Specialloid pistons were fitted. The old wheels were taken off and new ones fitted all round, with 36-in. by 6-in, pneumatic covers. A new body was built and fitted, this being a de luxe body with Sundeala panels.
When the whole work was complete the total cost was £375. A new vehicle similar to it would have cost round about 1850. The life allowed for this re
constructed vehicle was five years. One year has now gone, 20,000 miles having been run during that period. The tyres look goad enough for a further 20,000. There is no more wear and tear than there would occur with a new vehicle having run the same mileage. The average loads carried have been nearly 3 tons. Petrol over the 12 months has worked out at 10 m.p.g. Oil consumption is one gallon for 350 to 400 miles. Should one examine this vehicle close up or when passing on the road I guarantee they would not have the least idea that it was over 11 years old. This refers to only one of the fleet, There are many
As I have already said, I am not out to contradict your correspondent's statements, but to prove that, given proper reconditioning and maintenance, the old vehicles, even allowing the same amount for depreciation, can be run as economically as the new. Allocate the depreciation figures pro rata and the older vehicle will win. Therefore the whole matter boils down to not so much "new or old vehicles," but "efficient or inefficient maintenance."
I should like to hear other people's opinions on this subject. —Yours faithfully, C. B. TALBOT. Newport, Mon.
Friction Clutches Behind Gearboxes.
The Editor, THE COMMERCIAL Murcia. [26861 Sir,—In the résumé of patent specifications in the issue of The Comntercial Motor for June 5th, referring to the above subject, it is stated that "the difficulty is that no friction clutch has as yet been made that will transmit the torque of the Tow gears, etc." This to me seems hardly in accordance with the facts. At the same time, it is quite true that few attempts have been made to introduce friction clutches behind the gears, but I submit there is really not the least warranty for supposing that a single or multiplate clutch, if of reasonably substantial design—not necessarily of large dimensions—would not work just as well behind as in front of the gears.
The first consideration In clutch design is, of course, the capacity to transmit the power developed by the engine, and this is provided bt-arranging the clamping pressure in relation to the number, dimensions and friction value of the contacting surfaces. The temperature evolved when the clutch is slipped is a consideration of comparatively minor importance. Taking, for example, two clutches of identical dimensions, both requiring to transmit the same horse-power, one running normally at 1,000 r.p.m. and the other at 250 r.p.m., it is only necessary to increase the unit pressure on the slow-running clutch four times to make both equally effective for the respective torques, and if both clutches be slipped for equal periods no difference in temperature will obtain, since the number of heat units evolved by slipping would be directly proportional to the work done.
Good-quality friction lining will carry safely very much heavier unit pressures than apply in general in plate clutches ; hence, unit pressure is relatively of minor importance.
The real difficulty where heavy torques have to be dealt with arises in laying out a simple system of levers for opening a clutch with a reasonably light pressure, without undue movement of the operating pedal. If a suitable release gear be provided there is no reason why the ordinary clutch, as fitted between the engine and gearbox, should not be fitted behind the gearbox, with clamping pressure in
creased to provide for the considerably greater torque. In the case of a single-plate clutch for an engine developing 20 h.p. at 1,000 r.p.m. (1,260 in.-lb. torque), with two friction linings 11 ins. o.c1., Si ins. i.d., clamping pressure 600 lb., the unit pressure would be approximately 16 lb. per sq. in. The same clutch would be equally effective running at 250 ramie., transmitting 5,040 in.-lb. torque with 64 lb. pressure per sq, in. on the linings provided the total clamping pressure of 2,400 lb. could be released conveniently—a matter that does not present insuperable difficulty, Alternatively, a multi-plate clutch with six linings 8 ins. o.d., 6 ins. 1.d., would carry 5,040 in.4b. torque at 250 r.p.m. with a total pressure of 1,000 lb, which gives a unit pressure
of 46 lb. per sq. in.—Yours faithfully, ' F. J. FIELD, Chief Engineer, • FERODO, LTD. Chapel-en-le-Frith.
Motor Taxation.
The Editor, Tan COMMERCIAL 1VIOTOR.
[26871 Sir,—One hardly knows whether to use the words " amazing " or " amusing " in comment on a letter over the signature of J. E. Allen, which was published in The Times on Friday last. It would be merely amusing and might be entirely ignored if one did not feel that it Was part of an insidious propaganda, designed to disparage the road transport induetry and to incite public sympathy for the railway companies in their pathetic fight against modern progress.
The public have an inherent regard for the ill-used, and if one can only touch its responsive heart with some plaintive cry, sympathy for the bottom dog will for ever after that keep reason out of its behaviour.
Here is the sort of nonsense Mr. J. E. Allen hands Out—
"Motor transport is the most heavily subsidized industry in England."
"These huge vehicles are no good to trade." "Motor transport is not cheap transport." What shall we do—laugh, or get annoyed? But when we hear Mr. Allen's only constructive pro
posal, surely we shall know what to do. This is it :— " Lorries weighing more than two tons ought to be prohibited unless they are fitted with special wheels and tyres, with engines which will not take them at more than 10 miles an hour."—Yours faithfully, London, E.C.1. CHAS. DUNCAbi.