Installation Procedure for the 371-7080 Thumb Gp {0679, 6547} Caterpillar

Excavator:

320D (S/N: DHE1-UP)

Introduction

This special instruction covers the installation procedure for 371-7080 Thumb Gp .

Parts

Illustration 1	g02355138

Illustration 2	g02333733
Assembled View of Thumb

Reference

• Reference Service Guide, SEBD0512, "Caterpillar Service Welding Guide"

• Reference Special Instruction, REHS1841, "General Welding Procedures"

• Reference Torque Specifications, SENR3130, "Torque Specifications for All Caterpillar Products"

• Reference Thumb Ordering and Matching Guide, GEJQ0212

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 procedures. Welds must be smooth and continuous. Do not undercut the welds. No overlap is allowed. Grind the ends of the welds to a smooth radius.

Prepare the metal for welding. Refer to ""Preparing the Metal for Welding" ". Refer to the illustrations in this Special Instruction for welding symbols and specifications.

Use AWS E7018 electrodes or equivalent electrodes to weld the guards to the work tool.

All electrodes must be dried completely. 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 following conditions:

• Electrode diameter

• Shielding gas

• Welding current

• Plate thickness

The following items also affect the welds:

• Geometry of welded joints

• Surface conditions

• Composition of the base metal and of the electrode

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.

All welds to the stick must be welded in the direction from the rear of the stick toward the front of the stick.

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

Preparing the Metal for Welding

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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.

All grease, paint, and foreign objects 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 foreign objects with a wire brush, a buffer, or a grinder. Shot blasting the appropriate areas will also remove foreign material.

Remove any oil or grease with a Caterpillar approved solvent.

Welding on Machines and Engines with Electronic Controls

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

Note: If you are welding on a work tool, Caterpillar recommends removing the work tool from the host machine before welding.

1. Turn off the engine.

2. Turn the Battery Disconnect Switch to the OFF position. If there is no Battery Disconnect Switch, then remove the negative battery cable at the battery.

3. 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 in order to reduce the possibility of damage to the following components:

• Bearings of the drive train

• Hydraulic components

• Electrical components

• Other components of the machine

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

Installation

Illustration 3	g00104545

Prevent the machine from movement. Park the machine on a level surface.

Attach a "Do Not Operate" warning tag or a similar warning tag to the start switch or to the controls before you service the equipment. These warning tags (Special Instruction, SEHS7332) are available from your Caterpillar dealer.

1. Ensure that the host machine is on a flat level surface.

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Illustration 4	g02334418
Location of brackets to be welded to the stick

2. Orient the stick of the host machine into a position suitable for welding brackets (5), and (6) .

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Illustration 5	g02334423
Reference dimension for bracket (6) (A) 1984.2 mm (78.12 inch)

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Illustration 6	g02334400
Weld Dimensions and Specifications (B) 294 mm (11.57 inch) (C) 40.6 mm (1.60 inch) (D) 315 mm (12.40 inch) (E) 1669.2 mm (65.71 inch) (F) 40.6 mm (1.60 inch) (W1) 8 mm (0.32 inch) Fillet Weld (W2) 8 mm (0.32 inch) Fillet Weld

3. Locate the correct position for brackets (5), and (6). Refer to Illustrations 5 and 6.

   Note: Brackets (5) and (6) should be centered on the stick. Use dimensions (C) and (F) as reference.

4. Tack weld bracket (5) and bracket (6) in place. Refer to Illustration 6.

   Note: Placement of bracket (5) and bracket (6) is critical in order to create a long service life for the thumb cylinder. Install the components of the thumb group then make functional measurements before fully welding bracket (5) and bracket (6) to the stick.

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Illustration 7	g02334816

5. Position cylinder assembly (3) underneath the boom of the excavator by using a suitable lifting device. The approximate weight of cylinder assembly (3) is approximately 93 kg (205.03 lb).

   Note: The excavator boom will prevent an overhead lifting device from providing an adequate range of motion in order to position the thumb. The preferred practice is to utilize a surface mounted lifting device, such as an engine hoist or a fork truck.

6. Install pin (8) through bracket assembly (6) and cylinder (3). Secure pin (8) using bolt (12) and nut (10) .

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Illustration 8	g02334817

7. Position frame assembly (4) underneath the boom of the excavator by using a suitable lifting device. The approximate weight of frame assembly (4) is 198 kg (436.51 lb). Install pin assembly (7) through frame assembly (4) and the rod end of cylinder (3). Secure pin assembly (7) using bolt (13) and washer (11) .

8. Install pin assembly (7) through frame assembly (4) and bracket assembly (5). Secure pin assembly (7) using bolt (13) and washer (11) .

9. Connect the auxiliary hydraulic lines to the cylinder.

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NOTICE
Do not allow the cylinder to contact the thumb frame or any part of the stick. Failure to prevent contact will result in damage to the cylinder, thumb frame, and stick.

10. Slowly open and close the thumb four times to purge air from the system. Do not apply pressure to the thumb at this time. Ensure that the cylinder barrel does not contact the stick or any part of the thumb.

11. Make final adjustments to bracket (5) and bracket (6) in order to meet the conditions described below.
    • Cylinder (3) must not come in contact with the boom when the stick is fully curled.

    • Cylinder (3) must not come in contact with the stick during operation of the thumb.

    • The hydraulic cylinder (3) must maintain approximately 6 mm (0.24 inch) of remaining stroke when the thumb is fully opened in order to prevent damage to the hydraulic cylinder.

    • All pin assemblies must not bind during the complete range of motion of the thumb.

12. Either remove the hydraulic cylinder from the stick or take measures in order to protect the hydraulic cylinder from weld spatter.

13. Weld brackets (5) and (6) in place. Refer to Illustration 1.

    Note: Do not weld completely across the stick.

14. Allow the welded area to cool. Prepare the welded area for the application of paint.

15. Apply a coat of rust prevention and a finish coat to the work area that has been completed. Use Caterpillar authorized paint.

16. Tighten all fasteners to the proper torque specification. Verify that all of the pins are secured.

17. Verify that all grease fittings (1) have been installed. Apply grease to all fittings and pins.

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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

18. Start the engine of the host machine. Cycle the hydraulic controls and check for leaks.

Setting Flows and Pressures

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Check valves in the hydraulic system may allow pressure to exist in the hydraulic lines after the engine has been stopped. Pressure must be relieved prior to servicing the components of the hydraulic system. Failure to relieve pressure prior to servicing may result in personal injury.

1. Release the hydraulic system pressure.

   ReferenceRefer to your host machine service literature, Disassembly and Assembly, "Hydraulic System Pressure - Release" or Test and Adjust, "Hydraulic System Pressure - Release" for the correct procedure for releasing system pressure.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide"for tools and supplies to collect and contain fluids in Caterpillar machines. Dispose of all fluids according to local regulations.

2. Disconnect auxiliary hydraulic connecting lines from the cylinder.

3. Test and adjust the maximum flows and pressures of the auxiliary hydraulic system, as needed.

Note: If the pressure and flows are not tested at this time, purging air from the system will be needed again.

Requirements for the Thumb Circuit

The Caterpillar thumb is hydraulically operated through a three-position control valve. The center position blocks the cylinder ports. Clamping force is maintained when the control valve is not actuated. Both working ports must be protected by a relief valve and a make-up check valve.

The relief valves must be set at the provided flow and pressure settings, or at least a lesser value. Refer to Table 2 for the specified settings. The settings will allow the auxiliary hydraulic circuit to be over powered by the bucket circuit. The relief valves have the capacity in order to absorb 10 percent above the supplied auxiliary circuit flow. Make-up (anticavitation) check valves should allow the bucket to displace the thumb without causing cavitation on the rod side of the thumb cylinder.

Illustration 9	g02072635
Circuit Requirement (N) Pressure (P) Return (Q) Tank