The Pre-selection Debate Continues
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I MUST apologize for encroaching upon your space to continue the latest battle between the pre-selective and other types of gearbox, but some rather interesting points arose from the letters on this subject published in your issue dated July 20. • In the first place, the air-operated gearbox has the failingthat should the brakes cease to function, the gears also cannot be engaged, for the actuating medium is the same air supply as that to the brakes. Instances of this trouble are comparatively common in my district but, like certain other failures, occur • more often when the vehicles are new; Secondly, a hurried change with a crash-type box can cause objectionable noise, unless the driver be skilled in the art of making "fancy changes. On the other hand, a hurried change in the case of a preselective box gives the inevitable result of a violent jerk; which, is preferable is a matter of opinion. The fast idling speed, apart from causing "creep," would also result in the poor gear changing of which one of your correspondents on this subject complains.
I have heard drivers suggest that a pre-selective transmission is too easy, and that it tends to make them less alert or even sleepy. From the point of view of both the manufacturers and the passengers, I would say that the gear engagement should be designed so that it is less rapid and jerkless. This might be attained by introducing the operating air through a rotary valve or some other device of this nature.
Rochdale. J. M. SimPsom HAVE been following the discussion on pre-selective I gearboxes and fluid, transmission in "Opinions and Queries" with great interest, and would like to reply to Mr. C. G. Smith, whose letter appeared in your issue dated July 20.
In this he criticizes London bus drivers. 1 have had experience of heavy and light vehicles covering a period of over 29 years, and have recently joined London Transport. Here I have found, that the tuition is most comprehensive and adequate, whilst the examination is thorough and strict, but the ruling force is, once again, the human element.
If Mr. Smith takes into consideration that a bus is liable to stop eight times per mile over the whole period of a day's duty, coupled with normal London traffic conditions, -then he will find this work to be quite a different proposition from touring in Devon and Cornwall. Nevertheless, I and hundreds of others of my colleagues do endeavour to give the travelling public a comfortable ride without the neck-breaking jerks attributed by your contributors to some of the drivers 'of this big organization.
London, S.W.19. G. W. BYER.
VEHICLE driving has been my v life's work _after four years in a garage with some of the best tutors. Had I always been able to handle vehicles with pre-selective transmission, life would certainly have been safer, but duller.
This type I consider 100 per cent. safe with any old driver in any part of the British Isles, even when overloaded, provided that the man at the wheel does not expect anything that would be impossible with a crashtype box. My habit, for safety is always to drive with the selector in the second-gear position, except when using this.
As regards the safety of other vehicles, I think this applies more fully to those with six or eight wheels. In my view, vehicles with underfloor engines will require a good deal of alteration to make them really satisfactory. In continuous service of 16 hours, with standees at times, brakes are apt to become poor after the first two hours. Larger brake area, particularly at the front, and better cooling are needed, especially on double-deckers.
Sheffield W. CROOKES.
reasons, THE TON-MILE IN COSTING HAVE read with interest your article "'The Ton-mite I Factor" in your issue dated July 6, 1951. I have recently given considerable thought to this problem and, broadly, I have come to conclusions similar to your own.
The main virtue of a cost per ton-mile figure is that it affords a measure of comparison for vehicles of similar capacities.
I agree that true ton-mile costs are too involved for practical purposes, and certain broad assumptions must therefore be made. I have installed a system of costing for a large C-licence fleet of vehicles ranging from 10-cwt. vans to 10-ton lorries. The essential information available_ in respect of each vehicle is:—
For each period of three months—(A) days on the road; (B) total miles run; (C) tons carried (net); (D) cost E.
If the detailed calculations of true ton-mile costs are to be avoided, then the following assumption must be made: That on any day's run the net payload has been carried for the whole of the distance recorded on the speedometer.
The calculation is then:— – Cost per ton-mile.
The resulting costs can then be used for purposes of comparison when applied to vehicles of similar capacity.
Your article, for the purpose of simplicity, deals with a period of one week, whilst the above deals with a period of three months, and as such the number of days spent on the road is an important factor.
The basis of the cost per ton-mile can be simply stated as: Weight carried x distance x time divided into the total cost.
Blackburn. C. B. ALPE.
LIGHT PANTECHNICON OF REMARKABLE DURABILITY
WE are sending with this letter a photograph of a " pantechnicon which was first licensed in 1936. [This is reproduced.--ED.] Although this vehicle has a capa city of 1,000 cubic ft., the unladen weight when it was built was under 2i tons. We emphasize this point' because the chassis weighed 32-33 cwt., which left approximately 17 cwt. for the body, which is 17 ft. long behind the driver and 8 ft. 6 ins, high internally.
To keep the weight down, the timbers were spindled out wherever possible. This also applied to the bearers, which were reinforced with mild-steel plates. The rear was closed with doors and a serviceable tailboard, but the panelling had perforce to be of Masonite or some other hardboard.
The attention and thought bestowed on the factor of weight reduction were equalled by the care in design. Many improvements were found to be possible, and the durability of the body was estimated at five years. This was 15 years ago, and we were surprised when the owner, Mr. S. V. Robinson, of Aylesbury, invited us to survey the vehicle with a view to preparing an estimate for a thorough overhaul of the body. We were even more astonished, because we had assisted at the obsequies of many of its contemporaries and, as far as we knew, the decline had been general and uniform. However, this example was an exception.
The chassis bore a few honourable scars, but gave no sign of impending dissolution. Surely this result was the reward of years of care by the owner, and its driver, Mr.
J. A. Frost.
The history of the vehicle's many duties includes a period during the recent war when the van was on loan to the Govern ment.
The maker, Commer Cars, Ltd., has a right to be proud of the chassis. When it was new, the long wheelbase was considered to be a daring—almost reckless—innovation, but no doubt• its suc,cess was due in large measure to the pride of workmanship which has always been maintained as a part of the Commer tradition.
Having produced the body, we would be interested to know of any other vans which can challenge its record, which we believe to be outstanding. We might even suggest a competition, open to vans of equal capacity, cost and weight, the winner to receive' some suitable acknowledgement.
ALAN H. PERKINS
(for the Wokingham Pantechnicon). Wokingham.
SOME S.T.R. FIGURES CRITICIZED I IMAGINE that "Anxious," whose letter appeared in your issue dated June 22, under the title "Low Rates for Tipping Work," is more anxious than ever after reading S.T.R.'s reply published with it—in fact, to suggest that his vehicle should earn £10 8s. 8d. per "week" will no doubt drive him to distraction. Strangely enough, however, it is the odd 8d. that worries me. I am wondering how it cropped up, for 156 miles at ls. 4d. per mile seems to me to work out at £10 8s. Od. Has S.T.R. been caught out at last, or will you admit to two printer's errors?
H. J. JONES, Director, London, E.C.3. Burrows Transport, Ltd.
[We do not admit to either one or two printer's errors, but confess, on behalf of S.T.R., that you have caught him out. The figure given for earnings should have been for the day's work. As regards the 8d., possibly S.T.R.'s typewriter made a slip.—ED.1 STRONG WOMEN MAKE GOOD DRIVERS
WITH reference to the letter of your correspondent, " Mr. G. Prior, in your issue dated June 15 regarding women bus drivers, you will, I am sure, be interested to know that during the recent war this undertaking employed quite a number of women drivers and we still have two regular women drivers of troIleybuses. Our experience has been that women of suitable physique make very good drivers of such vehicles.
K. H. ADDLESEE, General Manager, Corporation Transport Department. Wolverhampton.
May .these worthy women continue to ‘set a good example to their sisters. We are left wondering what constitute, "suitable physique" for a driver.—ED.]