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The method of using the pressure pad in making a repair on a defective tire bead is shown at Fig. 448, B. The side wall and bead mold is shown at C, while the appearance of a repaired portion of a casing having a long rim cut and blown side wall is shown at D. Retreading may be also easily accomplished by the dry cure method. The appearance of a tire needing retreading is clearly shown at Fig. 449, A. This is only practical if the layers of fabric are in good condition. The old tread is stripped off as previously de
Fig. 448.–Molds for Use with Dry Cure Process of Vulcanizing.
Fig. 449.—Showing Molds, Clamps and Pad Used for Retreading a Tire scribed and the new tread cemented on and vulcanized by the use of a retreading mold which is shown at Fig. 449, C. The retreading molds are 26 to 28 inches in length and heat approximately onethird of the circumference of the tire at one time. The molds are hollow, allowing steam circulation from one end to the opposite and have an opening at the lowest point to exhaust the products of condensation. The sectional view of the mold with the clamp and casing in place shown at Fig. 449, B, shows the construction of the mold and the method of applying the new tread very clearly. The appearance of a retreaded tire after the new tread has been cured on is clearly shown at D. Sectional molds, which are the forms previously described are simply short retreading vulcanizers. They are used for curing the tread portions where the injured section is not long enough to call for the use of the retreading mold shown at C. Sectional molds are the forms to use for surface cuts, sandblisters, stone bruises, short patches of loose tread and other defects confined to a specific area of the tire.
by the Dry Cure Process.
Reconstructed Tires.-A new method of tire salvage has been recently devised by which two old casings may be combined to form a new casing, this being especially desirable when one of the casings has a good bead but a poor tread while the other one may have a good tread but be defective at the bead. This process is called reconstruction to distinguish it from retreading as it consists of stitching the two tires together in such a way that they cannot separate, using the one with the best bead for the inside member. The entire feature of the repair lies in the stitching process, and as this is not an easy one a number of firms are in existence which have special machinery for doing this work. Sometimes the process includes adding a special layer of calendered fabric to the surface of the inner tire. Another process includes the addition outside of the second tire of a non-skid surface composed of steel studs fastened into a special fabric, this being firmly cemented to the casing.
The appearance of reconstructed tires is shown at Fig. 450. In one process the procedure is substantially as follows: the cover is first subjected to examination and if found satisfactory for repairing is transferred to the stripping machine which strips the whole of the remains of the old rubber tread from the canvas base. Any cuts, bruises or bursts are then cut clean and built up with fresh fabric and rubber and the cover is then treated to a process that forces a rubber compound under heavy pressure into the spaces between the layers of canvas where movement between them has produced separation. To the whole of the inside of the cover one or two layers of specially prepared canvas are applied, the cover
Fig. 450.—Method of Combining Worn Tires and New Material to Pro
duce a Reconstructed Casing Capable of Giving considerable Addi. tional Service.
being put into a special sewing machine which covers it with a network of stitching which runs through the entire carcass, this reducing the internal movement of the layers relative to each other to a minimum. A final lining of friction canvas is attached to the inside over the stitching. The stitching and treatment up to this point form the basis of the patent which protects the manufacturers repairing by this process. The illustration at A indicates the stitching of the inner cover before the outer cover is applied. The view at B shows the completed unit with the other tread in place and fastened to the inner cover. In this view A indicates the old cover with its tread removed, B, the cross sewing, C, the