Procedure to Replace the Bracket Assembly of the Boom Nose on Heavy-Duty Booms for 313D2 LGP Excavators {6501} Caterpillar

Excavator

313D2 (S/N: GAJ1-UP; RKN1-UP)

Introduction

This Special Instruction describes the necessary procedures to replace the bracket assembly of the boom nose on 313D2 LGP Excavators that are equipped with a heavy-duty boom. If you need more information to install the bracket assembly, consult your Cat dealer.

Do not perform any procedure and do not order any parts until you understand the information that is contained in this document. Refer to the appropriate Parts Manual, Operation and Maintenance Manual, and Service Manual.

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

Safety Section

Required Parts

Disassembly of the Bucket, the Stick, and the Boom

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Personal injury or death can result from improper lifting or blocking. When a hoist or jack is used to lift any part or component, stand clear of the area. Be sure the hoist or jack has the correct capacity to lift a component. Install blocks or stands before performance of any work under a heavy component. Approximate weights of the components are shown. Clean all surfaces where parts are to be installed.

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Hydraulic oil pressure can remain in the hydraulic systems after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to the section, Testing and Adjusting, "Hydraulic System Pressure - Release" before any fitting, hose or component is loosened, tightened, removed or adjusted. When possible, the bucket or attachment must always be lowered to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket or attachment have correct support. The swing lock (if equipped) must be engaged before service is started. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.

1. Move the machine to level ground. The ground must support the weight of the machine.

2. The removal of the bucket, stick, and the boom requires special equipment to handle the extreme weight. Consult your Cat dealer for the weight ranges of the assemblies.
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   Illustration 1	g00100836

3. Put the machine in the servicing position. The servicing position is attained by lowering the boom until the bucket is flat on the ground. The stick must be in the vertical position when the bucket is flat on the ground. Refer to Illustration 1.

4. While the machine is in the servicing position, remove the bucket from the stick. Refer to the applicable Disassembly and Assembly manual for your machine for the correct removal procedure

5. Remove the stick from the boom. Refer to the applicable Disassembly and Assembly manual for your machine for the correct removal procedure.

6. The work can be done with the boom on the machine or with the boom off the machine. Refer to the applicable Disassembly and Assembly manual for your machine for the correct removal procedure.

7. Remove all hoses and hardware from the boom.

Preparing for the Removal of the Bracket Assembly

Illustration 2	g01998133
(1) Lifting points (2) Bracket assembly

Illustration 3	g01998134
(1) Lifting points (2) Bracket assembly (3) Stand

Note: If the boom is not attached to the machine, use a stand to support the boom. Refer to Illustration 2.

1. Fasten an appropriate sized lifting sling and a hoist to the bracket assembly (2) before cutting.

2. Follow "Removal of the Bracket Assembly" to remove the existing bracket assembly.

Removal of the Bracket Assembly

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Personal injury can result from flame cutting or welding on painted areas. The effect of gasses from burned paint is a hazard to the person doing the cutting or welding. Do not flame cut or weld on painted areas.

Illustration 4	g01998313
(2) Bracket Assembly (4) Cut

Illustration 5	g03744978
(4) Cut (5) Backing plate

Note: Extra care must be taken when you cut the bracket off the boom to prevent any accident.

1. Gas cut the center of existing welding of four plates in the following order: bottom, both sides, and top.

2. Remove backing plate (5).

Preparing the Metal for Welding

Read the instructions from the supplier and understand the instructions from the supplier. Provide fresh air circulation to the welding helmet to avoid any illnesses that can be caused by long-term exposure to the welding fumes. The fresh air circulation will also remove any exhaled carbon dioxide that may be trapped in the welding helmet. Use proper eye protection, ear protection, and protection of the body while you are preparing the surfaces and while you are welding on the surfaces.

All grease, water, paint, rust, dirt, and scale must be removed before welding. Any of these materials will discharge gas which will cause porosity in the weld 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 or by buffing or grinding. Shot blasting all work areas will also remove foreign material.

Remove any oil or grease that is on the boom with a Caterpillar approved solvent.

Before you do any welding on the boom, remove all foreign material and paint a minimum of 50 mm (2.0 inch) beyond the area of the weld.

Cover all finished bores and threads. Finished bores and threads must be protected from all the following items: foreign material, welding, gouging, and paint spatters. Do not remove the covers until the boom is painted.

Illustration 6	g02020093

1. Use a grinder, form a 25 degree groove on each cut face of the four plates on the boom.

2. Completely remove the cut particles. Remove any other foreign materials from inside the boom and clean the welded areas.
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   Illustration 7	g02020095
   5I-3266 Backing Plates (Top and Bottom) (L) 271 mm (10.67 inch) (T) 10 mm (0.39 inch) (W) 25 mm (0.98 inch)

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   Illustration 8	g03814436
   5I-3270 Backing Plates (Right and Left) (L1) 278.3 mm (10.96 inch) (L2) 275.1 mm (10.83 inch) (S) 1.6 mm (0.063 inch) (T) 10 mm (0.39 inch) (W) 25 mm (0.98 inch)

   Note: The plate material should be 40Kg/MM2 tension mild steel. The tolerance of the backing plate should be 1.5 mm (0.059 inch).

3. Weld a backing plate to a proper location on each of the four plates on the boom.

Alignment of Pins

Illustration 9	g01999359
(2) Bracket assembly (10) Boom boss pin (11) Boom foot pin

Note: Use the boom foot pin when the boom is lifted at the boom nose.

1. Insert the boom foot pin (11) into the holes of the fixed bracket assembly (2). The bracket assembly comes with the finished pin bore. By using a lifting sling and a hoist, put the bracket assembly in position to the cut nose of the boom.

2. Insert the boom boss pin (10) into the holes of the cylinder bracket on the top of the boom.
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   Illustration 10	g03810924
   Example of 312D 4.65m heavy-duty boom (2) Bracket assembly (12) Boom boss pin (13) Boom foot pin (L) 2434 ± 5 mm (95.8 ± 0.2 inch)

3. Put bracket assembly (2) in a position so that the distance from the center of the boom boss pin (12) and the center of the boom nose pin (13) are 2434 ± 5 mm (95.8 ± 0.2 inch). Refer to Illustration 10.
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   Illustration 11	g01999533
   (12) Boom boss pin (13) Boom foot pin

4. Check the boom boss pin (12) and the boom foot pin (13) for alignment from the back side of the boom. Make a final check for pin alignment with a level. Refer to Illustration 11.

5. After the pins are aligned and properly adjusted, perform tack welding on each groove.

6. Check the alignment of both pins after each tack weld. Make adjustments with the pins if alignment is not correct.

   Note: No cracks are permitted on the tack welds. Tack welding within 50 mm (2.0 inch) of a groove weld is not permitted.

Welding on Machines and Engines with Electronic Controls

Proper welding procedures are necessary to avoid damage to the electronic controls and to the bearings. The following steps should be followed to weld on a machine or an engine with electronic controls.

1. Turn off the engine. Place the engine start switch in the OFF position.

2. If equipped, turn the battery disconnect switch to the OFF position. If there is no battery disconnect switch, remove the negative battery cable at the battery.
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   NOTICE
   Do NOT use electrical components (ECM or sensors) or electronic component grounding points for grounding the welder.

3. Connect the welding ground cable to the boom.

4. Clamp the ground cable from the welder to the component that will be welded. Place the clamp as close as possible to the weld. Make sure that the electrical path from the ground cable to the component does not go through any bearing. Use this procedure to reduce the possibility of damage to the following: bearings of the drive train, hydraulic components, and electrical components and other components of the machine

5. Protect any wiring harnesses from the debris which is created from welding. Protect any wiring harnesses from the splatter which is created from welding.

6. Use standard welding procedures to weld the materials together.

Welding Requirements

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Personal injury or death can result from fumes, gases and ultraviolet rays from the weld arc. Welding can cause fumes, burn skin and produce ultraviolet rays. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing area. Wear eye, ear and body protection before working. 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 cause death. Read and understand the manufacturer's instructions and your employer's safety practices. Do not touch live electrical parts. See "American National Standard Z49.1, Safety in Welding and Cutting" published by the American Welding Society. American Welding Society 2501 N.W. 7th Street Miami, Florida 33125 See "OSHA Safety and Health Standards, 29 CFR 1910", available from U.S. Department of Labor. U.S. Department of Labor Washington, D.C. 20210

Welding quality is critical to the success of the installation procedure. Welds must be smooth and continuous. Undercutting and/or overlapping is allowed. Grind the ends of the welds to a smooth radius.

Prepare the metal for welding according to "Preparing the Metal for Welding". Refer to the illustrations in this special instruction for welding symbols and specifications.

Use LB-26 Electrodes (AWS E7016 or AWS E7018) or equivalent electrodes to weld the baffle plate and the reinforcement plates. Basic welding wire ESAB OK tubrod 15.00 with a 1.2 mm (0.05 inch) diameter can also be used. The basic welding wire must be the equivalent to AWS E70S with positive polarity. The welding wire must be shielded with CO₂ gas.

Welding of the V-groove requires LB-52 (AWS E7018), or an equivalent electrode. Basic welding wire ESAB OK tubrod 15.00 with a 1.2 mm (0.05 inch) diameter can also be used.

Dry all electrodes before use. The electrodes can be dried by heating the electrodes to 300°C (572°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 (60°F).

Penetration characteristics may vary greatly depending on the electrode diameter, shielding gas, welding current, and plate thickness. Geometry of welded joints, surface conditions, and composition of the base metal and electrode also affect the welds.

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

Maintain a 3 mm (0.12 inch) minimum root opening on all cross welds and circle welds.

Allof the welds to the boom must be in the direction from the rear of the boom toward the front of the boom, unless the directions of the welds are otherwise specified.

For more information, consult the Caterpillar Service Welding Guide, SEBD0512.

Welding Procedure

The welder must be qualified for the welding method as specified by the Qualification and Routine Testing of Welding Operators, MC100-105 manual. If the welding operator is experienced, the welds can be completed on the machine. If the welding operator is less experienced, the boom should be detached from the machine.

Repair work should be reinspected to ensure conformance to the quality requirements.

Illustration 12	g01999793
(14) Left side plate on the boom (15) Bottom plate on the boom (16) Left side plate on the nose (17) Bottom plate on the nose

Note: The four planes of the four plates on the nose are higher than the four planes on the boom.

Illustration 13	g06021219

V Groove Weld Joints

1. Create a 12 mm (0.47 inch) weld for the top plate. Refer to the view of area D in Illustration 13.

2. Create a 15 mm (0.59 inch) weld for the right and left sides. Refer to section B-B in Illustration 13.

3. Create a 15 mm (0.59 inch) weld joint for the bottom plate. Refer to the view of area E in Illustration 13.

Longitudinal Welds

1. Create a 12 mm (0.47 inch) with 1.5 mm (0.059 inch) longitudinal weld of the bracket to the side plate on the top side of the boom. Refer to the view of area D in Illustration 13.

2. Create a 12 mm (0.47 inch) with 1.5 mm (0.059 inch) longitudinal weld of the bracket to the side plate on the bottom side of the boom. Refer to the view of area E in Illustration 13.

3. Create a 6 x 14 mm (0.24 x 0.55 inch) fillet weld to the end of the bracket. Refer to section A-A in Illustration 13.

For more welding information, consult the Caterpillar Service Welding Guide

Trimming of V Groove Welds

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Illustration 14	g01999928
(18) Remove this area.

1. Grind the weld until the top face is flush with both plates. Remove the portion (18) that is crosshatched from a butt weld.

2. Prepare the boom for painting. Refer to "Painting and Coating the Boom" for additional information.

Painting and Coating the Boom

1. Relieve the stress in all welds by needle peening. A wire brush or a grinder can also be used to clean the welded area.

2. Use Caterpillar authorized paint for painting the welds and reinforcement plates.

3. Cover all bores, threaded holes, and cylinder rods before painting.

4. Remove all protective covers from the bores and threads once the paint has dried.

5. Bores must be free of paint and grease prior to assembly of the bearings.

6. Apply the required amount of lubricant to the bores, bearings, and threads. Refer to the Operation and Maintenance Manual and the Service Manual for lubrication instructions and quantities.

Installation of the Boom, the Stick, and the Bucket

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Do not attempt to assemble this machine until you read and you understand the assembly instructions. Improper assembly procedures could result in injury or death.

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Personal injury or death can result from improper lifting or blocking. When a hoist or jack is used to lift any part or component, stand clear of the area. Be sure the hoist or jack has the correct capacity to lift a component. Install blocks or stands before performance of any work under a heavy component. Approximate weights of the components are shown. Clean all surfaces where parts are to be installed.

1. Prepare the machine and parts for reassembly. The weight of the boom, the stick, and the bucket is excessive. The correct equipment must be available to handle the extreme weight safely. Consult your Cat dealer for the weight ranges of the assemblies.

2. Reattach the boom to the machine. Refer to the Disassembly & Assembly module for the machine systems for your machine.

3. Reattach the stick to the boom. Refer to the Disassembly & Assembly module for machine systems for your machine.

4. Reattach the bucket to the stick. Refer to the Disassembly & Assembly module for machine systems for your machine.

5. Make sure that the machine operates according to the Operation and Maintenance Manual for your machine.