Procedure to Reinforce the Frame Assembly Stabilizer{7222} Caterpillar

Excavator:

M320 (S/N: 6WL1-UP; 9PS1-UP)

Introduction

This special instruction provides the procedure to reinforce the frame assembly stabilizer.

The frame assembly stabilizer is reinforced by welding steel plates to the frame. The instructions for producing the reinforcement plates are included in this publication.

The information in this instruction should be read and understood before you begin the repair of the frame assembly stabilizer with the reinforcing plate.

Required Parts

Four reinforcement plates are needed to repair the frame assembly stabilizer (two left hand and two right hand).

Table 1 lists the different industry grades of steel that may be used in order to fabricate the reinforcing plates.

Welding Requirements

• Welding quality is critical to the success of the repair. All welds must be smooth and continuous. No undercutting is allowed. No overlapping is allowed. Grind the ends of the welds to a smooth radius.

• Prepare the metal for welding. Refer to ""Preparation of the Metal for Welding" " in this instruction in order to properly prepare the metal for welding.

• Use LB-26 Electrodes (AWS E7016 or AWS E7018) or the equivalent electrodes in order to weld the reinforcement plates to the frame assembly stabilizer. Also, basic welding wire EESAB OK may be used with a diameter of 1.2 mm (0.05 inch). The basic welding wire must be the equivalent to A5.20 E17T-5 of the American Welding Society (AWS) with positive polarity.

• Welding of the grooves requires LB-52 (AWS E7018), or an equivalent electrode. Also, basic welding wire EESAB OK may be used with a diameter of 1.2 mm (0.05 inch).

• All electrodes must be completely dry. The electrodes may be dried by heating the electrodes to 300 °C (572.0 °F). The electrodes must be dried for at least 30 minutes.

• Do not weld in windy conditions. Do not weld when temperatures are below 16 °C (61.0 °F).

• Penetration characteristics may vary greatly depending on the electrode diameter, the shielding gas, the welding current, and the thickness of the plate. The geometry of weld joints, the surface conditions, the composition of the base metal, and the electrode also affect the weld quality.

• A root pass should be applied before each weld is finished.

• For additional information concerning welding, refer to the Service Manual, SEBD0512, "Caterpillar Service Welding Guide".

Preparation of the Metal for Welding

• Cover all of the finished bores and all of the threads. Finished bores and threads must be protected from foreign material, gouging, and spatters of paint. Do not remove the protective covers from the finished bores or from the threads until the frame assembly stabilizer is painted.

• Be sure to remove the grease, the water, the paint, the rust, the dirt, and the scale before welding. Any of these materials will discharge gas which will cause porosity in the welds deposit. Water and rust will cause hydrogen embrittlement. Hydrogen embrittlement causes cracks in the weld deposit.

• Remove paint, rust, dirt, and scale with a wire brush, by buffing, or by grinding. Shot blasting of all work areas will also remove foreign material.

• Use a Caterpillar approved solvent in order to remove any oil from the frame assembly stabilizer.

• Use a Caterpillar approved solvent in order to remove any grease from the frame assembly stabilizer.

Fabrication of the Reinforcement Plates

Illustration 1	g00823858
The dimensions for the fabrication of the reinforcing plates are shown in Illustration 1. The thickness of the plates is 15 mm (0.6 inch). Reinforcement of the frame assembly stabilizer requires the fabrication of two left hand plates and two right hand plates.

Repair Instruction

Refer to Steps 1 through 5 in order to repair the frame assembly stabilizer.

1. Clean the frame. You must remove all foreign material and paint from the welding areas. Refer to ""Preparation of the Metal for Welding" " for additional instructions.

2. Check the frame for cracks. As you inspect the frame, also inspect the welds. Using a dye penetrant from Magnaflux makes finding cracks easier.

3. Repair any cracks that are found on the structure of the frame. Remove the full depth of the crack by air arc gouging or by grinding. Fill this area with the appropriate weld. Grind this weld flush to the structure of the frame. Refer to ""Welding Requirements" " for more details.

4. The repair of a crack in the weld requires grinding. Grind the crack to the full depth. Weld according to the specifications that are shown in Illustration 2. Refer to ""Welding Requirements" " for additional details.

5. Weld the reinforcement plates to the frame according to Illustration 3 and Illustration 4. Illustration 4 shows the reinforcement plates that are properly welded to the frame (chamfers to the welds on the frame).

Illustration 2	g00826936

Note: Horizontal welding is the preferred position. Vertical welding in the upward direction may be used if you are unable to weld in the horizontal position.

Illustration 3	g00827897

Start welding at point (B) in a clockwise rotation. Refer to Illustration 3.

Illustration 4	g00827969

Painting and Coating the Frame Assembly Stabilizer

1. Shot blast all of the welded areas. A wire brush or a grinder can also be used to clean the welded areas.

2. Paint all the welds, the plates, and the frame. Use a Caterpillar authorized paint.

3. When the paint has dried remove all of the protective covers from the bores and from the threads.

4. Prior to the assembly of the bearings, the bores must be free of paint and free of grease.

5. For information concerning lubrication requirements, refer to the Operation and Maintenance Manual, and also refer to the Service Manual.