Earthmover Tire Repair

When major damage or a blowout occurs or normal wear limits have been reached, the tire must be removed. Size alone makes the removal and replacement of earthmover tires difficult. Additionally, the nature of the terrain over which they operate often cause conditions to be far from ideal. Certain tools are necessary to change these large tires. The hydraulic bead breaker is specifically designed to break the giant beads for easier removal of the tire. BEFORE ATTEMPTING TO REMOVE THE TIRE, MAKE SURE THE WHEEL HAS BEEN JACKED UP AND THE EQUIPMENT PROPERLY BLOCKED FOR MAXIMUM SAFETY. After the equipment has been safely cribbed, deflate the tire completely by removing the valve core.

The clamping device is used to aid in unseating (breaking) the tire beads. Attached to the rim flange, it holds the hydraulic ram and shoe assembly. When securing the clamping device (fig. 3-34) to the rim, release the primary clamping device to permit full opening of the jaws. Hold the clamping device in a vertical position, as shown. Then hold the clamping device in place with one hand and tighten the large clamping screw lightly. Swing the reaction screw, as shown, until it is approximately perpendicular to the side of the rim flange. Turn the reaction screw in to bring the clamping device perpendicular to the rim. Tighten

Figure 3-34.-Clamping device.

Figure 3-35.-Hydraulic cylinder and shoe.

the primary clamping screw firmly by hand. When the clamping device is secured in place, turn the handle on the bottom of the reaction screw. This handle swivels up and down to permit maximum movement of the clamping device side arms to ease hooking the ram cylinder into place.

The hydraulic cylinder and shoe assembly (fig. 3-35) are actuated by a pump. The pump applies hydraulic pressure that forces the ram with the attached shoe down between the rim flange and tire bead. This action separates the tire bead and rim.

When securing the ram to the clamping device, place the ram and shoe assembly between the arms of the clamping device where the bracket of the cylinder is secured into the notches of the clamping device side arms, as shown in figure 3-35.

Applying pressure to the hydraulic cylinder forces the shoe down over the clamping device, as shown in figure 3-35. The jaws of the clamping device acts as a guide for the shoe. The convex side of the shoe bears against the sidewall of the tire, forcing it inward between the tire bead and rim flange, thus breaking loose the bead from the rim.

Figure 3-36 shows how the wedges are placed on each side of the shoe assembly to hold the bead of the tire away from the rim flange so that the shoe assembly can be easily removed. After the shoe has been forced between the tire bead and rim flange and freed from that portion of the tire bead, the wedges are inserted to keep the tire bead separated from the rim. Pressure is then removed from the hydraulic cylinder slowly. The hydraulic cylinder and clamping device are then removed from the rim and the clamping device is placed approximately 90 degrees from the wedge. This process is continued until the tire bead is completely free from the rim flange.

Cold Patches

Cold patches are used to repair punctures and small breaks or holes in tubes. The procedure for applying a cold patch is accomplished by the following steps:

Figure 3-36.-Operation of hydraulic cylinder and shoe.

1. Buff or roughen the tube surface to be patched for at least 1 inch around the hole. Then clean it with solvent. When a buffer is not available, use the perforated cover of the kit as a scraper.

2. Apply a thin coat of rubber patching cement evenly over the roughened surface and allow it to dry.

3. From the kit, choose a patch of the proper size that is about 3/4 inch larger than the hole in the tube from the kit. Remove the protective covering from the sticky side of the patch; place the patch over the hole, and rub it down firmly.

4. Inflate the tube with enough air to check for leaks. If you cannot hear or feel air escaping from the patch, you can make another check by inserting the patched area in water. If no escaping air bubbles are noticed, the tube may be dried and replaced in the tire or stored.

Hot Patches

Hot patches consist of a slow burning block of fuel held in a notched metal pan on the bottom of which is a patch of uncured rubber. To apply a hot patch, follow the manufacturer's instructions on the kit.

Although methods of applying patches vary with the clamping devices provided and the shape of the patch, you clean and roughen the tube just as you did in applying the cold patch. When the patching unit is placed in the notches of the patch and clamped to the tube, the burning material is ignited, allowed to burn, and then removed after cooling for at least 5 minutes. After this, examine the completed patch to see if the edges of the patching material are attached securely to the tube. Then install the valve core and test the tube. Hot patches of assorted sizes are supplied in kits similar to the cold patch kits. You will also find pressure clamps and roughening tools in the hot patch kits.