422 



THE INDIA RUBBER WORLD 



March 1, 1921 



Repairing Giant Pneumatic Tires 



By Roy 



IN WRITINX an article on the repair of pneumatic truck tires it is 

 taken for granted that it is to be of interest to tire repair men 



experienced at least on passenger tires, and who desire infor- 

 mation on a new branch of the repair business about which, up 

 to the present time, very little has been written. Therefore, these 

 paragraphs will deal almost wholly with methods and equipment 

 for repairing truck tires, wherein passenger tire repair methods 

 and equipment will not apply, and details which are common and 

 understood by average repair men will be omitted. 



Generally speaking, the repairing of truck tires is a more im- 

 portant operation and requires the exercising of much more care 

 than that of passenger tires because of the originally high cost 

 of the truck casing, and because the failure of the repair will 

 usually result in the loss of the tire. All the common injuries 

 and many of those resulting from improper care and abuse may 

 now be successfully repaired, since equipment has lately been 

 manufactured to handle these tires. 



The outfit needed in a repair shop, in addition to the equipment 

 used for passenger tires, would consist of the following molds and 

 equipment : 



1 — 6-inch combination retread and section mold. 



1 — 7 and 8-inch adjustable combination retread and sec- 

 tion mold. 



1 — 9 and 10-inch adjustable combination retread and 

 section mold. It depends upon the locality whether 

 or not these molds are necessary. 



1— generator of sufficient capacity for above molds ; un- 

 less there is a sufficient steam capacity in the generator 

 already installed for passenger tire repairing. 



1— set combination steam and air bags. Steam hose and 

 connection to supply steam for the above bags. 



1 — pair giant bead spreaders. 



1 — flexible shaft buffing outfit. 



1 — 36 by 6 truck tube plate. 

 The above equipment eliminates the necessity of having 5 

 molds to take care of the 6, 7, 8, 9 and 10-inch truck tires since 



R. Raid' 



INSPECTING THE CASING 



Seven to Eicht-In-ch Combination .Retread and Section Mold 



the two larger molds in the outfit are adjustable to four sizes of 

 tires, and they are also manufactured as combination retread and 

 section molds, eliminating the necessity of having separate molds 

 for these two different classes of work. 



> Western Rubber Mold Co.. Chicago, 111. 



The first and most important consideration in the successful 

 repair of giant pneumatic tires is the careful examination of the 

 casing and for this purpose the giant bead spreaders should be 

 used so that a clear view of the inside surface may be had. Extra 



Seven to Eight-Inch .^djust.^ble Combinwtiox Mold 



care should be used in the examination of the exterior for tread 

 and side-wall cuts which if neglected will usually result in a sepa- 

 ration. If separation of cords is found to be local only, the repair 

 is justifiable, but if found to be general, a local repair would 

 result only in the failure of the repair. Watch carefully on the 

 inside for wavy appearances at the flexing point of the tire, which 

 indicate underinflation or overloading and cause separations. A 

 large probing awl should be used in making the examinations. 

 The side-wall and beads should also be carefully examined for 

 rim cuts, side-wall cuts and worn out or torn bead covers. 



The same care must be taken in preparing the job for rebuilding 

 as that given any pneumatic tire, regarding the cleaning of the 

 surface and buffing the old cords and rubber so that it gets a 

 correct annealment with the new material. 



REPAIRING SURFACE CUTS IN TRUCK TIRES 



Where no fabric is involved, surface cuts are repaired in the 

 same manner as passenger sizes except that the table of cures, 

 given in this article, should be followed closely. 



In tread cuts, where not more than half the plies of cord fabric 

 are involved, it is not necessary to make a lay-back of the tread. 

 Clean and buff and apply stock in and around the injury and 

 repair the same as passenger sizes, but clean out the inside of the 

 tire and reinforce with several plies of cord fabric, or a cord patch 

 of the right proportion, according to the number of plies of cord 

 cirt through. 



Where an injury Involves all the plies of fabric and is less 

 than an inch in length, it is necessary to remove only one group 

 of plies inside the tire, stepping them out diagonally, building 

 ihem in as removed and then reinforcing on top of this with 

 extra plies as described. Be sure to buff the tire well, inside and 

 out, before applying cement. A flexible shaft buffing outfit is best 

 for this purpose, as it can be carried to the tire and can also be 

 operated inside the casing. 



