August 1, 1919.] 



THE INDIA RUBBER WORLD 



623 



Tire Rebuilding and Repairing — IT 



TIRE REPAIRING OPERATIONS. 



TiRE-BuiLDiNX Lasts or M.\ndrels 



REMOVING THE TREAD. 



THE WORN TREAD, breaker strip and cushion stock down to 

 the fabric are completely removed with a sharp knife, and 

 the exposed edges of the side-wall gum are skived or bev- 

 eled, care being taken to avoid cutting into the fabric. The side 

 walls are allow- 

 ed to remain in- 

 tact unless de- 

 fective, in which 

 case they also 

 must be re- 

 moved in the 

 same manner, to- 

 gether with the 

 chafing strip. If 

 the tread is so 

 badly cut that it 



is difficult to skin, a buffing machine equipped with a rotary 

 rasp will be more effective than the knife. The casing is next 

 reversed to expose the inside and carefully examined for weak 

 places. For small inside repairs two tire jacks or "reversers" 

 will hold the beads open while the work is being done and ob- 

 viate the necessity of reversing the entire casing. All fabric, 

 bead, and side-wall damages are then treated by the usual meth- 

 ods of tire repairing and vulcanizing, quite irrespective of the 

 retreading to follow. 



BUFFING. 



When the fabric or cord repairs have been completed, all 

 particles of old rubber and dirt are removed from the outside 

 of the casing by means of a buffing machine equipped with a 

 rotary wire brush which also roughens the surface of the fab- 

 ric. All rubber dust and loose fabric particles are dusted off with 

 a whisk broom or fine hand-brush, when the casing is ready for 

 retreading, unless recovering of one or both side walls is necessary. 



RECOVERING. 



If the side walls of the casing are damaged to such an extent that a 

 small local repair after the 

 well-known manner is not 

 sufficient, the damaged 

 side wall or walls and cor- 

 responding bead or chaf- 

 ing strip will have been 

 removed with the tread, 

 and the casing must first 

 be recovered. Two or 

 three coats of vulcanizing 

 cement are applied to the 

 well-buffed fabric of the 

 carcass as needed, each 

 coat being allowed to dry 

 separately. The bead strip 

 is first replaced with an 

 8 ounce fabric frictioned 

 two sides, lapping 1 inch 

 on the outside and V/i 

 inches on the inside. The 

 side walls are next ap- 

 plied, using one ply of 

 black, white, gray, or red 

 unvulcanized gum of 

 proper thickness — usually 1/16 



HL LAbII\(_ 



Tools Used in Tire Rebuilding 



3/32-inch — and wide enough 

 so that the tread when put in place will overlap 1 inch. Care- 

 ful rolling to eliminate all air blisters it essential. 



'Continued from The India Ro8»e« Would. July 1, 1919, pages SS2-5S3. 



RETREADING. 



There are at the present time four principal methods of re- 

 treading tires in common use. They are as follows : 



1. Building up the tread of unvulcanized rubber, wrapping 

 and curing in a 



pot heater or 

 kettle vulvaniz- 

 er. If a ribbed 

 tread is desired, 

 the cure is ef- 

 fected in a re- 

 tread mold. 



2. Using a 

 " camel back 

 I r e a d gum 

 specially pre- 

 pared in one 

 piece to proper 

 thickness, and 

 then curing in 

 a kettle. 



3. Applying 

 endless semi- 

 cured retread 

 bands with 

 beaded or non- 

 skid treat designs, filling around the raised parts of the tread 

 with soap-stone mortar, or using a negative wrapping pad, wrap- 

 ing and curing in a kettle vulcanizer. 



4. Supplying a new tread by any of the foregoing methods 

 and vulcanizing in sections by three or four cures in a cavity 

 retread mold. 



BUILDING UP AND APPLYING THE TREAD. 



To the buffed outside surface of the casing two or three coats 



of vulcanized cement are applied as needed, permitting each to 



to dry thoroughly. From 



one-half to one hour must 



H! H _^ be allowed for the first 



^Sl ^ m L '^'''^^ °^ coats and from 



B W W FH S3mC> two to five hours for the 



K jl '' ' ' last coat. A longer time 



■ ^^g j j ,»j is required in cold damp 



uk^P V/ U L^ II /) weather than in warm 



dry weather. 



Cord fires require not less 

 than three coats of cement, 

 each being allowed to 

 dry separately. The first 

 coat should be a thin so- 

 lution that will soak into 

 the roughened cords, the 

 second and third coats 

 medium heavy solutions. 

 The first two coats must be 

 allowed to dry at least one 

 hour and the third coat 

 from six to twelve hours. 

 Over night is usually 

 convenient and sufficient. 

 When the cement is thoroughly dry, a strip of cushion stock, 

 usually 1/64 or 1/32-inch in thickness, and wide enough to 

 cover the cemented surface completely or within an inch on 

 either side, is applied. 



Repa 



