The Cycle Industry/Chapter 7

From Wikisource
Jump to navigation Jump to search
 

CHAPTER VII

THE PNEUMATIC AND OTHER TYRES

The title of this chapter places the pneumatic tyre first, but before we begin to read how the pneumatic tyre revolutionized the cycle industry and made it what it is to-day, this book would be incomplete without a few remarks on the trials, tribulations and sufferings of those who rode bicycles with solid and cushion rubber tyres and still survive.

As we have seen in Chapter I, the first velocipedes had wheels shod with steel tyres; fortunately for their riders, the saddle was on a long spring, otherwise words fail to explain what they would have suffered.

The next innovation in the way of a non-slipping, elastic tread was to fasten strips of leather to wood felloes. Naturally, leather proved comparatively unyielding and india-rubber was tried. At first it was fastened like the leather in strips, then came the day of wire spoked wheels and solid india-rubber tyres fastened in V or U-shaped steel rims.

The common practice was to cement an endless band of circular rubber to the steel rim with a composition called "packwack," still used to attach perambulator tyres to their wheels. Naturally, the tyres refused to remain in place for long, particularly when wrenched against early-day tram lines, etc. Arrangements to overcome this trouble of the tyres coming out of the rim were patented, notably Hookham's patent wired tyre. A crimped or corrugated wire was inserted in the centre of the rubber tyre and held it in the groove of the steel U-shaped rim by contraction. Tyres in sections were also bolted to the U rims by T-shaped bolts moulded in the rubber, with the tail of the T passed through the rim, being nutted underneath the rim. The average size of solid india-rubber tyres was ¾ in., but sizes from ½ in., for racing machines, to 1¼ in. for roadsters were used. The larger sizes were, however, too heavy.

The Cycle Industry (1921) p65.jpg

Fig. 17
A ROADSTER SAFETY BICYCLE OF ORTHODOX PATTERN MADE BY RUDGE-WHITWORTH, LTD.


The first attempt to provide more comfortable tyres for cyclists was by the introduction of the cushion tyre. This was a hollow rubber tyre varying from 1¼ to 1½ ins. diameter, the hole through the centre varying from about ⅜ in. to ¾ in. If the hole was small the tyre was heavy and the machine ran "dead"; if large, the sides pressed hard against the edges of the rim and cut through. Some cushion tyres were more like a glorified thick garden hose, and various shaped rims were introduced to obviate the tendency there was to cut through at the sides. The expense of india-rubber resulted in great adulteration of cushion tyres, and although cycle makers of repute paid a fair price to obtain a good article, the makers of cheap shoddy bicycles often used cushion tyres that had very little india-rubber in their composition. The result can be easily imagined.

A tyre on the lines of a cushion tyre, because the air in the hollow part was not under compression, was Bartlett's original Clincher tyre. Bartlett was associated with the North British Rubber Co., Ltd., Edinburgh, big makers of rubber goods. They supplied the trade with quantities of solid and cushion tyres and he patented a tyre that fitted in clinches made by turning over the edges of a steel rim, so that if the tyre were moulded in a certain manner its edges would lock into the clinches and remain firm. The tyre was really just like a modern cover of a pneumatic tyre, but strengthened at the sides till it would support the weight of the rider and machine. The original Clincher tyre had no separate air tube, in fact no air tube at all; the air under it was at atmospheric pressure only.

Early Pneumatic Tyres. The introduction of the pneumatic tyre for bicycles came about in a strange manner known to most people, but repeated here for the benefit of the uninitiated.

In the suburbs of Dublin lived a veterinary surgeon named J. B. Dunlop; he was a cyclist and he had a rather delicate son. Naturally, he wanted the son to derive some benefit from riding a bicycle but he hesitated to allow him to ride a solid tyred bicycle owing to the vibration. The roads around Dublin are not of the best. Mr. Dunlop set to work, and like a lot of other inventors not connected with any particular manufacturing process, he thought out the very master idea that everybody had been looking for, that of insulating the rider at the point of contact of the wheel with the ground.

It will suffice to say that he made an experimental pneumatic tyre, in which the air was compressed in an elastic inner tube of rubber provided with a crude non-return valve for inflation and surrounded with a non-stretchable casing of canvas, the latter being covered with an india-rubber tread to take the friction of the road. The rim was very nearly flat in section, and to build the tyre the air tube was partially inflated and laid on the rim; around rim and tube was built the canvas casing by solutioning canvas strips to canvas already solutioned to the metal. Over it all more solution was rubbed in by hand and then came the fixing of the cover, which was also solutioned to the canvas casing and nearly encircled the rim. The edges were finally solutioned down with a thin piece of canvas, afterwards painted to resist the attack of water.

I was not privileged to see Mr. Dunlop's first attempt, but I saw one of the first of these very crude tyres made by the Dunlop Tyre and Booth's Cycle Agency, Dublin, on a tricycle ridden to Coventry by Mr. R. J. Mecredy, the editor of the Irish cycling and motoring papers and, of course, a renowned cyclist.

The tyres were quite unknown, and when the tricycle was left outside a hotel (not in the centre of the city) for ten minutes, a crowd of 400 or 500 people were found pushing each other to obtain a sight of it.

Within a few months everybody in the city knew all about pneumatic tyres. The Du Cros brothers, an athletic family of Dublin, commenced to race on bicycles fitted with them, and very soon handicappers had to give racing cyclists on solid tyres a considerable start if riders of pneumatic tyred machines were entered. Within a year of the commencement of the serious manufacture of pneumatic tyres no racing man of any pretensions troubled to compete on anything else.

The firm responsible for the manufacture of the first tyres—the Dunlop Pneumatic Tyre and Booth's Cycle Agency—was a small concern in Dublin dealing originally in bicycles. They were joined by the late Mr. Harvey Du Cros, father of the racing cyclists, and his astute business management saw that the concern would have to move to the heart of the industry. Premises were taken in Coventry; previously bicycle manufacturers were compelled to send the wheels to Dublin.

At Coventry commenced an industry which has grown from small undertakings until now the Dunlop Rubber Co.'s factories, etc., occupy acres of ground in Birmingham, Coventry and elsewhere, and an enormous new works is in course of erection near Birmingham.

As at Dublin, owing to the special handling that the tyres required, the cycle makers had to send their wheels to the tyre factory to be fitted, and the Dunlop carts were soon careering about Coventry collecting the tyreless wheels and delivering them, fitted, to the various factories.

The repair of the original Dunlop tyre was a process that the average cyclist undertook with fear and trepidation. A puncture necessitated peeling back the solutioned tread of the cover, slitting the canvas across, withdrawing the air tube and fixing the patch, replacing the air tube, stitching up the slit in the canvas with needle and thread, re-fixing the rubber tread and re-inflating. Cyclists were not all neat hands at this job and wheels would be seen revolving with huge blobs on the tyres, where the amateur sewing and repairs were too weakly done to prevent the air tube bulging out the canvas and rubber cover. Result, inexperienced riders allowed the boil or blob to hit the forks time after time as the wheels revolved, until the friction wore away the retaining cover and bang went the air tube. In those days that meant the assistance of the railway to reach one's destination and oft times a long walk.

Experimenters had, however, been at work and an inventor named Welch brought out a tyre the principle of which is the one still mostly used on modern bicycles. This is now termed the “wired on” to distinguish

The Cycle Industry (1921) p69.jpg

Fig. 18
A "TRIUMPH" ROADSTER BICYCLE WITH OIL BATH GEAR CASE


it from the “beaded edge” or Clincher tyre which was Bartlett’s patent.

The "wired on" cover is now made of vulcanized rubber and fabric moulded, under Doughty’s process, on to inextensible wires which slip over the rim by reason of the diameter of the wires being so arranged in respect to the rim diameter that when one side of the cover is placed in the well of the rim the other side rises above the opposite edge and will pass over. Then inflation of the air tube draws the two wires, one up and the other down the sides of the rim, and they repose in ledges formed at about half way down the rim sides. There were modifications of the Welch patents, but the one used is one of the original ideas and upheld by the Dunlop Co. against a host of litigation that they were compelled to institute against infringers of their rights.

The names of tyre companies that made tyres for bicycles that were copies of the Welch patents would fill a page of this book and very, very few got through the Dunlop meshes. Many were very ingenious in the way they tried to overcome the master patents by means of hooks and pins and nuts, but gradually they were either bought up, forced to relinquish business by legal pressure brought against them by the proprietors of the patents, or died a natural death.

The original patents have run out now and all and sundry are free to make tyres, but there are comparatively few well-known makers.

In addition to the Dunlop, there are in the first rank the Palmer Tyre Co., who make a specially woven fabric outer cover knitted on a special machine which is a marvellously ingenious piece of mechanism in itself and well worth a study by those mechanically inclined. Then there is the North British Rubber Co., who make the Clincher tyre, Bartlett's original patent. W. and A. Bates, the Avon India-Rubber Co., the Midland Rubber Co., etc., etc.

All the firms mentioned have large works and a very complete sales organization.

I must not close this chapter without a reference to wood rims and single tube tyres. The introduction of single tube tyres in this country was due to Mr. Boothroyd, the inventor of the Facile bicycle referred to in Chapter I.

The simplest method of describing it is to say that it was a glorified hose pipe but thinner in the walls. It was repaired with rubber plugs which were inserted from the outside, and although a very lively fast tyre, it went out of vogue because of the difficulty of making satisfactory repairs. The U.S.A. makers supplied nothing but this type of pneumatic tyre for several years.

The Constrictor racing tyre is so constructed in the wall that the cover can be peeled back away from the fabric, allowing withdrawal of the inner tube and repair on the outside of the tube. Tyres of this description are only favoured by racing cyclists on account of the expert knowledge required to make a proper repair. It is, however, of interest to note that a "speedman" finds it an advantage to carry a spare tyre of this description in preference to using a thicker and heavier type, which requires longer to repair, than to change one of the lighter, thinner kind. The secret of the extra speed lies in the fact that a thin walled tyre is more resilient than a thick one, and when suitably inflated the rapid expansion of the tread, previously compressed by the rider's weight, does not retard the propulsion of the machine so much as a thicker one. A technical explanation of the why and wherefore of this must be sought in theoretical treatises on pneumatic tyres.