March 1, 1921 



THE INDIA RUBBER WORLD 



417 



Substitutes for Rubber Tires 



The following shows German interest in almost any possible substitu 

 the \rar, the belief persists that solids or semi-solids made of an infini 

 Diplom. En^neer Jahr, Berlin-LJchterfelde, and appeared in "fCunststoffe." 



THE bristle tires which have come to notice recently were in 

 the market more than twenty years ago and mostly in the 

 form of cushion tires. Fig. 1 represents a tire patented in 

 1896 in England, the bristles of which are set in a base of wood, 

 caoutchouc or other material b, which is mounted on the concave 

 wheel rim / to increase the elasticity. According to an American 

 patent the bristle tufts o are closed in rubber k and are united 

 by vulcanization. Fig. 2. A German patent provides a cover of 

 steel rods upon a suitable base which is embedded in an elastic 

 ring to ease the pressure. Fig. 3 shows a more modern way of 

 securing the bristle tufts a. These are wound around a bolt q, 

 which is fastened in the rim. Other known examples of the same 

 principle arc those where the bristle tufts are wound around 

 rings running parallel to the base of the tire, Fig. 4; and an- 

 other one which is shown in Fig. 5. The strong tufts of wire 

 are connected in groups by wire fastenings screwed down below 

 the rim and the lowest layers of the wire bristles are con- 

 nected by short wire fastenings d in Fig. 6. An example of a 

 cushion tire is given in Fig. 7. The casing is filled with a coil 

 of bristles a, which are fastened to a spiral wire center. To give 

 more resiliency to the bristles the vacuum between the bristles 

 is filled with a light elastic material, preferably the pith of 

 plants. The filling of this material is effected while the bristle 

 coil is covered with a light cover of linen to prevent the filling 

 falling out. 



FIBER TIRES 



The principal material for these tires, which arc mostly made 

 in the United States and England, is fiber of all kinds in the 

 unspun state. Plant, mineral or animal fiber can be used. Pre- 

 eminently coconut fibers, jute, kapok, ramie and manila hemp 

 are in use. Lacking these, straw, turf and other materials can 

 be employed. The fiber is either wound around the rim or 

 placed in layers upon it. Or they are put perpendicularly upon 

 it, which is the newer method. The elasticity of the tires is 

 increased by alternating the fibers with strips of canvas or linen. 

 It has also been found useful to separate the individual layers 

 with metal strips or rings', which, incidentally, will aid in fasten- 

 ing the tire to the rim. The fiber may be arranged also in up- 

 right tufts or rows and set in a bed of caoutchouc. Or the 

 whole may be connected by enclosing it in a bed of tar, asphalt 

 or resin until it forms a complete tire, which is supported by 

 rings. To make the tires still stronger they have been subjected 

 later to strong pressure and sewed together with string. In the 

 case of a new English method the fiber bristles are treated with 

 a rubber solution and placed upright side by side. The fiber 

 then is cut to measure and vulcanized. This tire is made stronger 

 by interlacing it with strips of material made out of coconut 

 fiber or any other similar material. The space between the fiber 

 and the strips of material, which are also placed upright, is filled 

 with tar, balata, gutta percha, resin or any similar material and 

 the whole is subjected to hydraulic pressure. A U-shaped rim 

 is generally used for this kind of tires. 



VARIOUS EXAMPLES OF FIBER TIRES 



Fig. 8 demonstrates a fiber tire of American make. The tufts 

 of manila hemp f are placed upright upon the rim, and impreg- 

 nated with tar, asphalt or resin and subjected to high pressure 

 that produces a compact tire body which can still be sewed to- 

 gether if necessary. This tire is fixed upon the wheel by annular 

 rings which grip over the sides of the rim. Fig. 9 shows a tire 

 with metal protection, the fiber layers f of which are made of 

 braided hemp and pressed between strong bands of metal, m. 



te for the rubber pneumatic tire. Forced to do without rubber during 

 te variety of compounds mAy still be successfully used. The article is by 



The metal protection may be part of the rim. In this case the 

 fibrous material is inserted between the metal strips as shown 

 in Fig. 10. 



CORD TIRES 



The material used for this kind of tires as a rule is hemp, 

 as it gives the most strength and resistance. A substitute is raffia. 

 There is, however, little known about the practical use of this 

 tire. The hemp or any other material is spun into yarn, which 

 in turn is made into a strong cord. For the manufacture of the 

 tire several cords are required which are placed upon the rim, 

 side by side or cabled around each other. In some cases the 

 coid is wound around a hollow tube. Five or six cords also 

 may be used as a filling for an ordinary tire cover. Protection 

 has to be given the cords against stretching and deterioration. 

 The resistance of these tires can be increased by impregnation 

 nr by any other similar protection. 



EXAMPLES OF CONSTRUCTION 



A comparatively simple cord tire is shown in Fig. 11. The 

 cord s is fastened on the rim f and carried around it. The other 

 end of the cord is stretched by a chain or spring pulling device 

 which insures ihe cord being tight. Xo less simple is the con- 

 struction shown in Fig. 13. A wooden tire foundation h is 

 placed in the U-rim f. The ropes .s are then placed upon the 

 wooden tire, the surface of which is provided with a profile for 

 that purpose. The ropes s are packed tightly beside each other 

 and connected by hooks and hoops b or by means of screws and 

 plates to prevent the slipping of the outside ropes. To produce 

 greater elasticity, the center of the wooden tire It can be fitted 

 with a flat caoutchouc tire. To keep the tire surface concentric 

 to the hub springs b are inserted between the ropes and the rim 

 which can be adjusted if required, as shown in Fig. 12. 



Fig. 14 shows a cord tire v.ith an inner metal tube r around 

 which a hemp cord .? is wound which is covered by another cord. 

 Anti-slipping bolts are fitted upon the second cord, which also 

 may be made of wire. The connection between the ends of the 

 rope is usually made by easily closing connecting links. Fig. IS 

 shows a similar arrangement where three stronger cords are 

 connected with three thinner ones. The cable obtained in this 

 manner is enclosed in a rubber tube 6 and finally inserted in a 

 cover of leather / and another of rubber h. Finally a tire may 

 be mentioned where the rim is covered with short pieces of wire 

 cable placed crosswise upon the rim. Fig. 16. To prevent the 

 unwinding of the short pieces of cable the cable ends are welded 

 together with the cable center p. Fig 17. 



FELT TIRES 



F~elt is a material produced from animal hair. Not all hair, 

 however, is suitable for the manufacture of felt. The finer the 

 hair the better and more elastic is the felt. As a rule only pure 

 wool felt is used for tire making. The strips of felt are rein- 

 forced and impregnated. Care is taken that the inner layers of 

 felt are looser than the outer layer so as to retain a greater 

 degree of elasticity. Felt tires appear in different types. These 

 are: Tires made directly from the raw material during the 

 felting process; tires made from felt rings and felt strips; tires 

 made from felt disks entirely or in connection with leather, 

 rubber, canvas, or other filling materials. 



To the first-named group belongs an older felt tire, Fig. 18, 

 where a thin rubber tube g is covered with a felt ribbon in suc- 

 ceeding layers. This is done entirely by hand. When one layer 

 is applied the tire is cut to length and the whole is subjected 

 to a new felting process. The two ends of the tire are finally 



