Procedure To Replace The Brackets For The Enclosure On A 973C Track-Type Loader{7257, 7263} Caterpillar

Track-Type Loader:

973C (S/N: 3RZ1-UP; BCP1-108)

Introduction

This Special Instruction contains the information that is necessary in order to replace the brackets for the enclosure on the 973C Track-Type Loader. The new brackets are used in order to provide increased reinforcement for the battery box.

Prepare the Area for Welding

Clean the area that will be welded. Make sure that the substances that follow are removed from the area that will be welded.

• Oil

• Grease

• Paint

• Dirt

If the temperature of the base metal is below 0 °C (32 °F), heat the base metal to a temperature of at least 21 °C (70 °F). Maintain the temperature of the base metal at 21 °C (70 °F) during the welding process.

Note: Heat distortion of the base metal is possible when you weld. Avoid excessive heating of the base metal.

Attach the welding ground cable directly to the base metal. Protect machined surfaces from sparks. Protect the machined surfaces from the weld splatter.

Weld Specifications and Qualifications

Show/hide table

Protect yourself and others; read and understand this warning. Fumes and gases can be dangerous to your health. Ultraviolet rays from the weld arc can injure eyes and burn skin. Electric shock can kill. Read and understand the manufacturer's instruction and your employer's safety practices. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area. Wear correct eye, ear and body protection. Do not touch live electric parts. Refer to the American National Standard Z49.1, "Safety in Welding and Cutting" published by the American Welding Society, 2501 N.W. 7th Street, Miami, Florida 33125: OSHA Safety and Health Standards, 29 CFR 1910, available from U.S. Dept. of Labor, Washington D.C. 20210.

Note: Personal breathing protection should be worn by the personnel that are welding. Personal breathing protection will prevent fumes from entering the lungs of the person that is welding. Use a 1U-8088 Type H Respirator for breathing protection.

Welders must be qualified for fillet welding and groove welding. The welders should be qualified in the use of the welding processes that follow: Shielded Metal Arc Welding (SMAW), Flux Cored Arc Welding (FCAW) and Gas Metal Arc Welding (GMAW). Refer to "American National Standards Institiute (ANSI)/American Welding Society (AWS) Specification D1.1, or Specification D14.3" for information that regards the qualifications for the processes that follow: SMAW process, FCAW process and GMAW process. The welders must have used the process at some time within the last six months. The welders must complete the process of certification if the welders have not used the welding processes for six months.

Proper Welding Procedure on Machines and Engines with Electronic Controls

Proper precautions are necessary to prevent damage to electronic controls. When you weld on a machine with electronic controls, use the steps that follow:

1. Turn off the engine. Put the key start switch in the OFF position.

2. If the machine has a battery disconnect switch, open the switch. If the machine does not have a battery disconnect switch, disconnect the negative battery cable at the battery.

3. Connect the ground cable for the welder directly to the actual machine component that will be welded. Attach the clamp for the ground cable as close as possible to the area that is being welded. This will reduce the chance of damage from welding current to the components that follow: bearings, hydraulic components and electrical components.

   Note: Do NOT use electrical components as a ground point for the welder. Do NOT use ground points for electronic components as a ground point for the welder.

4. Protect the wiring harnesses from the weld splatter.

Weld Specifications

Low Hydrogen Electrodes for the SMAW Process

The tables that follow list the mechanical properties of welds that are deposited by low hydrogen electrodes.

Low hydrogen electrodes must be stored in an electrode oven at 120 °C (248 °F). If low hydrogen electrodes get damp, scrap the low hydrogen electrodes or recondition the low hydrogen electrodes to the manufacturer's specifications.

The table that follows shows setting for the welding current for the electrode diameter.

Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The width of the weld should not exceed two times the electrode diameter.

As an alternative process, use the Flux Cored Arc Welding (FCAW) with E71T-1 H8 (ANSI/A5.20) welding electrode and the manufacturer's shielding gases that are specified for inside welding. The H8 implies that the electrode is designed to provide less than 8 ml/100 g of diffusible hydrogen in the weld deposit. The weld that is deposited by the flux cored welding electrode will have the following minimum mechanical properties:

Flux Cored Welding Electrode for the FCAW Process

The table that follows lists the mechanical properties of welds that are deposited by the flux cored welding electrode.

The table that follows shows setting for the welding current for the flux cored welding electrode that has a diameter of 1.3 mm (.051 inch).

Note: The settings for the welding current can vary due to the position of the weld. Also, the settings for the welding current can vary with the manufacturer of the welding electrode.

Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The fast freezing characteristics of flux cored welding electrode increases the possibility of evolving gas that is trapped in the weld. Control the size of the weld in order to reduce the possibility of evolving gas that is trapped in the weld. The volume of the fillet weld should not exceed 8.0 mm (.315 inch).

Arc Welding Electrodes for the GMAW Process

The table that follows lists the mechanical properties of welds that are deposited by the GMAW Process.

The welding parameters will vary with the position of the weld and with different electrode manufacturers.

Weld Inspection

The weld should not have any of the conditions that follow:

• Cracks

• Porosity

• Undercut

• Incomplete Fusion

In order to verify the quality of the weld, refer to"American National Standards Institiute (ANSI)/American Welding Society (AWS) Specification D14.3".

Required Parts

Replacement Procedure

Show/hide table



Illustration 1	g01062750
View of the battery box

1. Remove the battery and remove the battery box from both sides of the machine.

2. Remove bracket (1) from both of the battery boxes.

Show/hide table



Illustration 2	g01062791
(W1) 3.0 mm (0.12 inch) intermittent fillet weld (L1) Use 25.0 mm (0.98 inch) welds every 100 mm (3.94 inch). (W2) 3.0 mm (0.12 inch) continuous fillet weld (A) 41.0 ± 1.5 mm (1.61 ± 0.06 inch) (B) 3.3 ± 1.5 mm (0.13 ± 0.06 inch)

3. Install new bracket (2) .

   Note: Grind weld boss (3) or modify bracket (2) in order to avoid interference between the boss and the bracket.

4. Install the battery box and the batteries on both sides.

Show/hide table



Illustration 3	g01062827

5. Install brackets (4) with bolts (5) and washers (6) on each side.

   Note:

6. Torque bolts (5) to 100 ± 20 N·m (74 ± 15 lb ft).

Show/hide table



Illustration 4	g01063266

7. Install brackets (10) with bolts (8), bolts (11), spacers (7) and washers (8) .

   Note: Use brackets (12) on the other side.

8. Torque bolts (9) and bolts (11) to 55 ± 10 N·m (41 ± 7 lb ft).