Earthmover Techniques and Preparation
There are some keys to ensuring that preparations of repairs in tubeless, off the road repairs are successful:
- Skiving of the Plug and Injury Area: The objective is to remove a minimum area from the casing and, accordingly, rather than the “hourglass” type of skive, the injury should be prepared with a straight through the casing area with a slight bevel, both on the inside of the casing and the outside. There is equipment available that can improve the preparation of the plug area to ensure that there is good bonding and no glazing or burning of the material. A radial injury including side wall should likewise be prepared with a minimum elimination of the cord body of the tire.
- Liner: If the inner liner is solidly bonded to the casing, it is not necessary to remove the inner liner in the patch area, but it does have to be prepared for best adhesion. It is important, that any silicone or other mold release agents that are on the surface of the inner liner, be washed off from the patch area with material such as Siliclean. This ensures that the silicone or foreign materials are removed from the area prior to buffing and preparation, so that the silicone is not worked into the inner liner, causing potential failure of the patch bonding layer.
- The inside should be buffed slightly beyond the patch area but should not be burned or glazed to attain a good bonding and adhesion base.
- A small amount of cushion gum should be applied throughout the plug area for best flow and bonding, after which conventional rubber can be used either with an extruder gun, or strips can be stitched into the plug area. The patch should be applied very carefully on the inside, stitching from the plug area outwards to eliminate all possible air pockets.
- Vulcan-Vulcap recommends a layer of cushion gum on top of the edges of the patch to provide better sealing and flex characteristics.
- With Vulcan-Vulcap’S MV series Section Molds the patch and plug will result in an almost invisible repair with maximum adhesion values. If proper repair procedures are followed, repaired injuries can be guaranteed for the life of the tire, as a true vulcanizing repair is accomplished.
- Should an inner liner be separated in the injury area, it should be removed and with careful buffing to the first layer of the casing, the inner liner materials should be replaced with cushion gum prior to applying the patch. In the case of radial tires, the steel cord must be carefully prepared to eliminate all rust. It needs to be buffed until it is bright and shiny and then coated with cement.
It is the partnership between the skill and art of properly preparing and patching the area of the tire injury and vulcanizing it subsequently with the proper equipment that will guarantee a perfect repair consistently.