HYDRAULIC SCRAPERS Tires Caterpillar

These scrapers are equipped with rock type tires known as "of-the-road" tires.

The use of the same tread pattern on the scraper as that on the drive wheels of the tractor is usually a good practice. This permits interchange-ability which affords greater tire economy.

Tires are available with two types of cord structure: standard cord and radial steel cord.

In conventional standard cord tires, the cord structure is composed of layers of cords, with the cords in each layer placed at an angle around the tire from bead to bead. The cord angle is reversed in each alternate layer. "Ply ratings" are a measurement of the load carrying capacity of standard cord tires.

In radial steel cord tires, the cord structure consists of a single layer of steel wire cord placed straight around the tire from bead to bead. The load carrying capacity of these tires is not related to "ply ratings", but depends primarily on inflation pressure, which is therefore even more important than in standard cord tires. Both types of tires are covered in the following topics.

Specifications: Rock Type, tubeless tires are standard equipment.

Optional: Michelin radial steel cord tires available are

Factors Affecting Tire Service: The ordinary hours of service that are built into the tires may be obtained and greatly extended if proper care and maintenance are given them. There are a number of factors affecting tire service which should be understood in order to give the care and maintenance that is required.

Tire Rating: Tires are rated as to load carrying capacity, inflation pressure, and speed. These three factors are so related that they cannot be considered individually. Therefore a specific tire has been selected to match this particular machine.

Inflation: For long trouble free service, tires should be correctly inflated for a given load at a given speed. The illustration shows the comparison of tire shapes assumed due to differences of inflation.

COMPARISON OF TIRE SHAPES
A-Correctly inflated tire. B-Underinflated tire. C-Overinflated tire.

The properly inflated tire (A) cushions the road shocks and allows all of the tread to contact the surface.

Underinflation (B) causes excessive strain on the tire, uneven tread wear, and greater flexing, which results in cord fatigue and breakage.

The overinflated tire (C) will not cushion shock and results in less ground contact area. Wear is uneven and tire body is in greater tension.

Maintaining correct air pressure in radial steel cord tires is important.

Because of the lack of stiffness in the sidewalls, the tire will always appear underinflated. An operator has no visual method of telling when the tire is properly inflated. Cold inflation pressure should be checked every morning.

For average operating conditions, inflate tires when cold to the pressure shown in the TIRE INFLATION CHART.

Increased inflation pressures may be desirable when operating loaded under extreme conditions of high speed and on long hauls over smooth, well maintained haul roads. Contact your tire dealer for correct pressures.

Reduced inflation pressures for flotation purposes may be permissible when operating in sandy conditions, relatively free from rocks and boulders, if smaller loads or lighter weight materials are handled at reduced speeds.

CORRECT POSITION FOR INFLATING TIRE

Show/hide table

For safe tire inflation self-attaching air chucks are recommended. An air chuck that can be fastened to the tire valve will enable tire inflations to be accomplished from behind the tread of the tire.

Haul Road Condition: The condition of the ground over which the scraper travels is important if full tire service is to be obtained. Chuck holes, depressions, sharp rocks, boulders and snags cause abnormal wear to the equipment as well as damage to the tires.

If a motor grader is not available for road maintenance, lowering the bowl of the scraper on the return to the cut clears away much of the debris and smooths the road. It is sometimes profitable to clear the road by hand.

Inspection and Care: Keep valve caps on to prevent dirt getting in the valve. Replace the valve core when it first develops a leak. Wipe off any oil or grease which may be on the tires. Inspect the tire daily for cuts, breaks and sharp objects which might work into the casing. Remove all foreign material. Repair at once all deep cuts which have penetrated into the cord body. Where a number of small cuts and snags have accumulated, the tire should be removed and repaired as soon as possible. When a bulldozer is used to push a load, caution the operator about allowing the bulldozer blade to catch on the scraper tires.

Tubeless Tires and Rims

Tires are heavy. Therefore, when it becomes necessary to remove and replace them, care should be taken to avoid personal injury. Suitable hoisting equipment and a heavy rope or chain will be required to lift the tire from the rim. Do not use a hook on the beads in lifting a tire.

Tires: Proper handling and correct procedure in mounting, servicing and maintenance are essential to obtain all the advantages of tubeless tires. The following information has been prepared for this purpose.

1. Tires should be stored and transported in a vertical position. Horizontal storing may make initial inflation difficult.

2. Do not lift the tire by the beads with hooks or forks unless forks are saddle type construction. Sharp hooks or forks may tear, cut or snag the tubeless tire beads and result in leaks at these points. The beads should be protected and tire handled with a chain or rope around the outside.

3. Any foreign material or moisture should be removed from inside the tire.

Rims: Tubeless tire rims perform an important function as part of the assembly air seal. Proper care must be taken not to distort or mutilate the rim parts because they must mate properly to form part of the basic air chamber. For proper rim care see steps 1 through 7 as follows:

1. Never lift the rim using the valve hole.

2. Never drop, tumble, or roll rim parts.

3. If rim parts are to be stored outside in the weather, it is recommended they be given a protective coat of good commercial primer paint.

4. Like parts should be stacked neatly to prevent distortion.

5. Babbitt or lead hammers should be used in assembling rims instead of steel hammers.

6. O-ring seals for tubeless tires should be carefully stored in a cool, dry place and where they will not become damaged.

7. Valves should be stored in a cool, dry and clean place.

Tire Removal: Tire removal may be accomplished with the wheel either on or off the machine.

1. Before attempting to remove a tire, completely deflate the tire by removing the valve core.

2. Loosen the tire beads from the bead seat band and rim by using a 9F5194 Hydraulic Tubeless Tire Tool. See your AVSpare dealer to obtain this tool.

3. After the tire beads are loose, remove the lock ring, O-ring seal, bead seat band and the rim outer flange.

4. Lift the tire from the rim with a hoist using chain or rope slings.

Tire Installation: This topic covers tire installation with the wheel off the machine. However, the tire may be installed in a similar manner without removing the wheel.

Clean dirt and corrosion from all rim parts and particularly in the groove and adjacent to the groove where the O-ring seal seats. If excessive corrosion exists, paint the rim base and rim parts with a good anti-corrosive paint.

Valve Installation:

1. Install the valve spud (5) through the grommet (6) and into the hole in the rim.

2. Install the nut (4) and tighten to a torque of 6 to 7 pounds feet.

3. Inspect the seal on valve core housing (3) to be sure it is in good condition and not damaged, then install the valve core housing into the valve spud and tighten.

4. Install the valve core (2) and cap (1).

RIM AND VALVE ASSEMBLY
1-Valve cap. 2-Valve core. 3-Valve core housing. 4-Nut. 5-Valve spud. 6-Rubber grommet. 7-Rim. 8-Rim inner flange.

Standard Cord Tires:

1. Before installing the tire on the rim, block the rim (7) up approximately 6 inches above the floor being sure the blocks do not extend beyond the rim flange.

2. Place the inner flange (8) on the rim making sure the lug on the flange is aligned with the notch in the rim.

3. Using a hoist and chain or rope sling, place the tire on the rim.

4. Place the outer flange (10) and the bead seat band (9) on the tire and rim as shown.

5. Install the lock ring (11) on the rim with the lug on the lock ring fitting in the notch in the rim.

6. Align the notch (13) in the bead seat band with the lug on the lock ring, and the lug (14) on the rim outer flange.

7. Lubricate the O-ring seal (12) with a thin solution of high grade soap flakes and water or equivalent (do not use a soap with mineral or chemical base) and place in the groove under the lock ring.

TIRE INSTALLATION
9-Bead seat band. 10-Rim outer flange.

TIRE INSTALLATION
11-Lock ring. 12-O-ring seal. 13-Notches in bead seat band. 14-Lug on rim outer flange.

After installation, it is necessary to inflate the tire to 75 pounds pressure to assure proper seating of the tire beads. The tire should then be deflated to the recommended pressure.

When inflating a tire in the horizontal position it may be necessary to lift the tire upward to effect a seal between the bead seat band and the O-ring in the rim base.

Radial Steel Cord Tires:

Radial steel cord tires must be removed and installed in a vertical position and a jack or inflatable pad is used under the tire to center the beads on the rim.

In addition to the O-ring seal (11), radial steel cord tires use flange flange seals (2) and (5) to prevent air leakage. Always use new seals. When installed, all seals should be dry, clean, and free of cuts or tears which will allow air leakage.

1. Place the rim inner flange (1) on the rim, and the rim outer flange (6) on the bead seat band (7), making sure the lugs on the flanges are aligned with the notches in the rim and bead seat band.

2. Using a mild, soft type bar soap, fill the rim serrations (8) and bead seat band serrations (10), then coat the serrations and the tapers (3) and (4) with tire lubricant. Also lubricate the surface of bead seat band (7) which will contact O-ring seal (11).

3. Install the inner flange seal (2) on the rim and the outer flange seal (5) on the bead seat band, and wipe dry the surface on each seal which contacts the tire bead.

4. Position the tire on the rim base (9) with the arrow on the tire pointing in the direction of forward rotation on drive wheels, or in the opposite direction on free rolling wheels.

5. Install the bead seat band on the rim, with flange and flange seal, then install the O-ring seal (11) and lock ring (12), making sure the lug on the lock ring is aligned with the notches in the rim and bead seat band.

6. Center the tire on the rim, move the bead seat band out to contact the O-ring seal, and move the flange seals in against the tire beads to provide enough air seal for initial inflation.

7. Inflate the tire to 80 PSI pressure and then deflate as necessary to the recommended tire pressure shown in the Tire Inflation Chart. See the WARNING in the topic, TIRE INFLATION. During inflation, be sure the flange seals are correctly positioned as they move up the taper.

INSTALLING RADIAL STEEL CORD TIRE
1-Inner flange. 2-Inner flange seal. 3-Taper. 4-Taper. 5-Outer flange seal. 6-Outer flange. 7-Bead seat band. 8-Rim serrations. 9-Rim base. 10-Bead seat band serrations. 11-O-ring seal. 12-Lock ring.