AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

How Tyre Mileage is Wasted

8th January 1943, Page 31
8th January 1943
Page 31
Page 32
Page 35
Page 31, 8th January 1943 — How Tyre Mileage is Wasted
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

No. 14.—Inadequate Repairs and Neglected Injuries

w Certain Classes of Damage Can Be Effectively Repaired if Taken in Time, and the Methods to Employ To Ensure

' Good Results

0 F the many minor injuries to which a tyre is susceptible there are few which are not . repairable if they be taken in time. Tread cuts, casing cuts, small concussion breaks, chafes, etc., can mostly be effectively dealt with by vulcanizing There are certain limits to the repairing process, however, even in cases where the injury might be described as being of a minor character. Casing damage very close to the bead, for instance, is often beyond repair because it is impossible to get an adequate area of repair material around it. Most injuries to the bead itself are also beyond repair. Then, of course, all major injuries, such as large concussion bursts, cord detachhient due to underinfiation, tread separation, etc., are out of the question for, such treatment.

From this, it may seem that the vulcanizing process is of very limited application, and is capable of dealing with only a small proportion of tyre injuries. This is not true, however. By far the greatest number of injuries falls into the " minor " class and can be repaired with absolute satisfaction.

The best judge of whether a tyre is repairable or not is, the repairbr himself, assuming, of course, that he is a qualified repairer by the vulcanizing process. The man whu " sticks a patch in to get you home " is not a repairer at all, although his services certainly ha v e value in emergency.

This question -of leaving it to the repairer cuts two w a y a. Some operators bring all sorts of wrecked tyres along to the repair depot and practically insist on their being vulcanized, despite the fact that the expert says it is impossible. qn the reverse side, there are many, people who, so soon aa their tyre sustains a,slight injury, fling it aside and fit a ner one. That may not be so easy, nowadays, as it used to be, but I feel sure that in operators' " dumps" all over the country there are many good tyres which could be ,rendered serviceable by proper repair. The reason for this wholesale scrapping of tyres which have suffered only minor damage is that there are spme users who are pre judiced against repairs and regard them as a potential cause of subsequent failure. This is a hang-over from the days when tyre repairing was a much less satisfactory process than it is to-day, and the bad name which it earned for itself in those times is still fresh in the memory of those who experienced it.

Against this, I can say quite definitely that present-day repairing by an experienced vulcanizer is absolutely reliable; and is usually accompanied by a full guarantee. If the damage be properly treated the life of the tyre is unaffected. It will give its normal mileage and the repair will be just as sound, when the tyre is worn out,, as on the day it was done.

I suggest, therefore, that except in . cases of total collapse, the operator should submit all his injured tyres to the repair depot for inspection, and abide by the expert's decision as to whether they are repairable or not.

The most vitally important point about repairing is that it shall be carried out so soon as the injury is discovered. Damage to a tyre is like an open wound:--if it be neglected it gets worse insteadof better. It may start with a simple tread cut, such as is sometimes caused by a piece of glasior a sharp flint. Probably the casing is uninjured and therein lies the danger. Because there is no injury to the casing, the tyre will continue to run without, apparently, giving trouble. The operator may be well aware of the cut, but, as it does not appear to call for immediate action, will force the tyre io con tinue to work in its damaged condition, What happens? Grit enters the inlury and enlarges it. Ultimately the cord foundation is reached and rain and-grit now start to attack the casing. The cotton framework of the tyre is far less suited to withstand this kind of thing than is rubber, and it rapidly deteriorates.

The worst of it is that, once the rubber is penetrated, the actions of these foreign bodies are not confined merely to penetration in a radial direction. They extend circumferentially, as well. Consequently, in a short time, -diem' is a general weakening in the whole area for two or three inches around the original point of entry.

What is Indicated by a Slight Bulge

This weakness is sometimes indicated by a slight bulge, which is a sign that the area has so deteriorated that it is incapable of withstanding the internal air pressure and , has yielded to it. In other wo'rds, the tyre has "stretched" locally. Such a condition may, in certain cases, be repairable, but it is impossible to reduce the distortion which has been caused. The "bulge" will always be there and, although reinforced by .the repair process, is always liable to premature collapse.

Personally, I regard slight injuries; such as deep tread cuts, as being More wasteful of tyre mileage than rather larger injuries which involve casing damage as well.

• In the former case the tyre is capable of Carrying on, despite the damage, and it is often made to do so. This results in an ultimate damage which is far out of iiroportion to the original injury.

In the second case, however, where the cut extends right through to the -casing, the operator is forced to put the repair in hand at once,

because the tyre will not continue to • run until 'something has been done . about it.

The danger of a tread cut lies, then, not in the cut itself, but rather in the emtensive injuries which result from it. There are two methods of dealing with it. The best, because it is the most certain and the most permanent, is to remove the tyre and have it properly vulcanized. This, however, involves the loss of the use of the tyre for a day or two, which may be inconvenient.

If' so, the second method can be used. It consists of cleaning out the' cut as well as possible and forcing into it, by Means of a screw-type pressure gun, enough rubber "tread gum" to fill the injury.

Outfits for this purpose can be obtained from the usual sources. They consist of a gun with a pointed nozzle for insertion into the cut. The gun is loaded with a cartridge of "tread gum," whicia.can be forced under pressure into the injury, but first, of course, the cut should be well probed to see that it is clear of foreign bodies. This method has very definite limitations. It is ideal for deep penetrations of small external diameter, such as are caused by the entry of screws, etc., but it is naraiy suitable for the long gash illustrated in Fig. 1..

" The reason for its failure in the latter type of injury is that the pressure cannot be maintained: the gum escapes to the sides. Thus, one can never be quite certain that, the cut is properly filled. It is important to remember that this method is incapable of dealing with any form of internal injury.

As I said before, internal injuries simply demand immediate repair because, unless this be done, they will nip through the tube every' day of so. If, by any chance, they are neglected, the damage will extend in just the same " way as I have previously described. Even if there be no external cut to admit destructive agents e.mere fact that the tyre is being worked, with all the movement that this involver, will cause aggiavation,and extension of the injury.

Proper Vulcanizing the Only. Cure The only effective method of dealing with internal damage is to have it properly vulcanized. The vulcanizing process consists, briefly, of cutting away all injured material, carefully padding all exposed edges and filling the resultant gap with cushion gum, then vulcanizing a gaiter into place. The gaiter is a substantial affair, which is strong enough to make up for the number of plies of the original casing which 'have been affected by the injury.

The outstanding feature of this process is that every part of the affected area is welded into a solid whole. It does not Merely cover up the injury as the ordinary type of adhesive gaiter does. The most that an adhesive gaiter cando is to act as a buffer between the injury and the tube, thus preventing the latter from chafing. But -the edges of the injury are still free to work about, because they are not protected by cushion gum. consequently, the gaiter itself is ultimately chafed through (Fig. 3) and the job has to be done again.

The danger, then, is movement due to the working of the tyre. The vulcanizing process prevents movement by achieving a complete, union of the whole repair area, and, in doing so, prevents aggravation and chafing. The repaired part of the tyre, • given normal working conditions, is as good as any other part. • I would like to etreSs these Words " given normal working conditions." Already, in this series, we have seen what can happen to 'perfectly sound tyres when they are subjected to unfavourable' conditions of use. Obviously, a repaired tyre, no Matter how good the repair may be, is even less capable of withstanding misuse than one which is sound.

Do Not Illtreat Repairs

Once again overloading and underinflation crop up. Either of these conditions will. •'quickly find any weakness • in the tyre and catise failure (Fig. 8). To offset this, many operators use their repaired tyres an, the front wheels. This is quite a good plan up to a point, but I cannot' help feeling that if the operating conditions be as they should be it should not be necessary.

The main purpose of this article, so far, has been to drive home the two major points connected With repairable tyre injuries. First, the damage should be put right immediately, before it extends beyond the point where it can be repaired. Secondly. it • should be done by a proper, permanent process, such as vulcanizing—not by .a temporary get-you-home method, such as the use of an adhesive gaiter.

From . the first point there is no deviation; it really is most important. The second point, how= ever, is to some extent subject to circumstances. If an injury be sustained, it , may not be possible to spare the tyre for the period required for vulcanizing—usually two or three days, but often longer in these difficult trines: In the circumstances it is excisable to resort to the less satisfactory, -but much quicker, • method of fitting an adhesive gaiter. This can be done in half an hour and the tyre is ready for service again: This Should be regarded as only a temporary measure, however.

Only a Temporary Measure So soon as the tyre can be spared the gaiter should be stripped out and the injury properly vulcanized. The trouble is, of course, that after this temporary method has been used it is forgotten. The tyre continues to run until it ultimately fails'.

There is one other condition under which the adhesive gaiter is justified, i.e., in the caie of a tyre which is so 'far worn that it is not worthy of an expensive repair. Vulcanizing of the smaller sizes of tyre may cost anything from 8s. 6d. upwards; lorry sizes usually range from 25s. upwards, If A tyre be so far worn that such expense is unjustified it is qtrite in order to use the cheaper' method. It is probable that, with luck, the repair will outlast the tyre.

Repairs are more important to-day than ever they were. The vulcanizing process makes possible the effective use of tyres which would otherwise have to be consigned to the scrap heap. Millions of vital tyre miles are saved every year in this way. It is a pity that there are still many operators who are not making proper use of the modern repair facilities which are available at most of the Authorized Tyre Depots.

The repairer is ready to do his part of the job, but he cannot do it without the co-operation of the tyre user. All that is required of the operator is that he shall conform with these few suggestions. L.V.B.

Tags


comments powered by Disqus