Unusual Methods in
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Tyre Maintenance
A Rational System of Dealing with the Servicing of the Tyres of the Large Fleet of Vehicles Used by the Great Western Railway' Company
AAINTENANCE methods which are idisuitable when operating three or four vehicles require revision when the number of machines has risen so high as to justify the application of the term " fleet." This fact is widely recognized so far as care of the mechanical parts of the chassis is concerned; schemes of unit maintenanCe, provision for periodic overhaul and so on are customary.
The care of tyres, however, is a proHem concerning which there is as yet no generally agreed scheme.. This fact lends additional interest to a rational and economical method of dealing With the subject, which has been evolved by Mr. W. Chas, Bolton, and is in operation in connection with the fleet of the Great Western Railway Co.
The G.W.R. Maintenance System.
It is necessary, as a preliminary, to make brief reference to an article which appeared in our issue dated May 10, in which the methods of chassis overhaul employed by the G.W.R. were described. We must re-. mind readers that three classes of maintenance are comprised in that Scheme of opetations: " S.P.," relating to a dock overall which every vehicle undergoes once in six weeks; " L.P.," to the complete overhaul taking place approximately every two years; and " E," to emergency repairs.
The first feature of note in Mr. Bolton's method of dealing with tyres is rather a startling one. He has taken the somewhat daring step of dispensMg with the use of spare wheels on the vehicles in his charge. Actually, one spare is kept at the depot for each group of four vehicles.
One advantage of this scheme jumps immediately to mind, namely, the considerable saving in initial outlay. In a fleet of 600 vehicles there is a saving of the cost of 460 spare wheels and tyres.
A Risk of Delay?
rs there a disadvantage which might bring into question the wisdom of this step: In particular, is there no delay as the result of punctures occurring while vehicles are on the road, perhaps some distance from the depot?
Obviously, the risk of that contingency arising must, to a large extent, depend upon the care with which the tyres are maintained. On that score, it is of interest to note that exhaustive and careful records show that the average of delays on account of tyre. trouble is less than one per week, although no fever than 3,000 tyres are concerned, It is actually a fact, again demonstrable by reference to records, that any delay on the road, due to a puncture, is diminished as the result of the absence of the spare wheel. When a spare wheel is available on the lorry various difficulties arise which make for excessive loss of time.
In the first place, it should be noted that the drivers, although each man is specially trained for his task and must pass an examination, are not, on the whole, mechanically minded. As the result, nine times out of ten a man will find himself unable to remove a wheel in order to replace it by the " spare," and has to telephone headquarters .for aid. Even that condition is subject to the wheel-brace and jack still being available on the vehicle.
A Result of Efficiency.
Actually, as an outcome of the efficiency of tyre maintenance, resulting in infrequency of tyre trouble, recourse to either the brace or the jack is so rare that, when it is wanted, it has been found to have been kit at some outlying depot. Again, with hydraulic jacks—the most popular type—infrequently used, there is sometimes a shortage of oil, so that a jack will not operate. Once more the telephone is used and the aid of headquarters requested.
Incidentally, the absence of the necessity of a jack and wheel-brace on each vehicle is a further source of economy.
In view of the foregoing difficulties, it has actually been found to be quicker and more economical to keep a small van ready at headquarters to answer any telephone message. The driver of that van, instead of 'being called upon to go out to show a man how to remove a wheel, or to replace or put right an ineffective jack, runs to the job equipped with brace, jack and the appropriate spare wheel and tyre.
One detail of organization is brought into prominence hy this scheme, and that is the need for accurate knowledge of the types of wheel on each make and model of chaSsis.. This, particularly in
a fleet of such a varied nature as that operated by the G.W.R., is a task.' requiring considerable exactitude.
Records are kept of this information and there is a double check, one a consecutive number of the vehicle itself, and the other a code number allotted to each type of vehicle, under which all expenditure for maintenance is debited.
An incidental advantage of this scheme is that all details of tyre troubles are, perforce, reported at once. Without it, there is often considerable delay, sometimes becoming serious, such as when a driver has had tyre trouble and has changed a wheel, without taking steps to have the faulty tyre-repaired. As it is a part of the seheme of maintenance that an immediate record of tyre trouble shall be made, this point is of considerable importance. The fact that the faulty tyre receives immediate attention has resulted in a considerable saving of time and money.
Testing for Pressure.
Every tyre in the whole fleet is tested for pressure once per week and inflated, if necessary. Any tyre which sbows drop of 20 per cent. in pressure for two consecutive weeks is immediately removed, replaced and returned to headquarters for attention.
At headquarters—the Alfred Road (London) 'depot of the G.W.R.—there is a comprehensive tyre-repair department, with provision for vulcanizing and all repairs.
At every " S.P." interval, the tyres are replaced, but net in the same position on the vehicle. A regular circular movement of these tyres takes place; from off front to near front, near front to near outer, near outer to near inner and so on, a spare wheel and tyre being brought into the sequence on every such occasion.
The tyre which is removed is thoroughly examined, all flints and stones being taken out of the tread. If a certain stated minimum of tread wear be exceeded, the tyre is discarded.
Compressing Air in Cylinders.
Lacy Hulbert equipment is used to provide air for inflation. The air is compressed at high pressure into steel bottles and those are circulated throughout the various depots. This system, besides affording means for inflation at outlying depots, without the need for air-compressing plant, is also convenient for inflating tyres on the road, cn the rare occasions when that becomes necessary.
The well-known B.E.N. tyre key is used to facilitate the checking and inflation Of tyres. Mr. Bolton has effected one Modification to this equipment. Which, as purchased, embodied a catch to hold down the inflation lever, the object being to allow the operator to put down, the device while the tyre
was being inflated. In Mr. Bolton's experience, this led to the risk of a tyre being over-inflated and be removed the trigger, so that the operator is compelled to hold the key until inflation is complete.