Skidder Articulated Hitch Pin Bore Rebuilding{7057} Caterpillar

Skidder Articulated Hitch Pin Bore Rebuilding{7057}

Usage:

518 (9HJ, 1CL, 50S, 55U, 94U, 95U) 518 Series II (94U2500-Up, 95U3200-Up) 518C (9HJ, 1CL) 528 (96C, 97C, 8SJ, 5BK, 51S, 78W) 528B (8SJ) 530B (5BK)

Introduction

This special instruction provides information for repairing 518 and 528 Skidder articulated hitch frames. Worn and elongated pin bores can be welded and machined to original dimensions. Successful repair depends on the extent of required repair, repair methods and repair quality.

Illustrations in this publication may look different from your machine. While the illustrations are typical, the dimensions are actual.

NOTE: All dimensions listed are dimensions for manufacturing and assembling a new machine.

Reference: Parts Manual, Operation & Maintenance Manual, Service Manual, and Caterpillar Service Technology Group (CSTG) Bulletin NEHS0513-02.

Do not perform any procedure, outlined in this publication, or order any parts until you read and understand the information contained within.

Cleaning Procedure

All foreign material (oil, grease, water, paint, rust, dirt and scale) must be removed before any welding operation. These materials displace hydrogen gas when in contact with intense heat. The gas causes weld porosity and weld deposit cracking.

Remove oil and grease with solvent and allow to dry. Remove paint, rust, dirt and scale with a wire wheel/brush or with a fiber flap wheel.

Inspection

Pin bores must be inspected prior to any weld repair. Crack inspection is necessary to prevent any further failure following salvage. Cracking will occur at the thinner sections surrounding the pin bores.

If external cracks are suspected, the part should be inspected using dye penetrant or magnetic particle. Inspection surfaces should be clean and any surface irregularities removed. Surface irregularities can mask indications of unacceptable defects.

Repairable defects should be cut or ground out 6 mm (.25 in) deeper than the original defect and repaired with weld material.

Machining Elongated Bores

Metal to metal contact of the pin to any frame member can result in material deformation. Deformed material can contain cracks and should be removed. Pre-machining provides for a concentric bore with a stable base material for weld build-up.

Preheat

If the surrounding temperature is less than 16°C (61°F), the bores and adjacent area should be preheated to 95°C (203°F) prior to welding to prevent cracking. If the welding process is completed in a reasonable time, no additional preheating should be required. To ensure good weld deposits, the material around the weld area should be 95° ± 10°C (203° ± 50°F) during the welding process.

Weld Process and Consumables

The 1U9600 Welding Group is a recommended tool for pin bore weld build-up. Automated welding results in clean and even metal deposition. Weld quality is improved over SMAW and semi-automated GMAW. The recommended weld comsumables are shown in the above chart.

If the 1U9600 Welding Group is not utilized, the bores may be built up to size using E7018 SMAW 3.18 mm (.125 in) diameter electrode, 1U5232, or by the GMAW process. Use the recommended consumables for the bore welder for semi-automatic welding.

NOTE: The 1U9600 Welding Group (60 Hz) is not sold in the COSA territory. The 1U9601 Welding Group (50 Hz) is sold in COSA only.

Weld Procedure

1. Pin bores must be free of all contaminants (oil, grease and paint).

2. Preheat the bores to 95°C (203°F) to eliminate hydrogen gas potential and to reduce weld stress.

3. Follow the recommendations for the 1U9600 Welding Group according to Caterpillar Service Technology Group (CSTG) bulletin NEHS0513-02.

4. Allow the welds to slowly cool following build-up of the bores.

5. When using SMAW or semi-automatic GMAW, outline the repair area, placing welds (A) and (B) as shown in the illustration. Make a series of transverse welds (C) to complete the build-up.

NOTE: If additional weld deposit is required, repeat the welding procedures for the appropriate processes.

Spot repairs of welds may be made by defect removal, preheat and welding according to the specifications.

Machining

If the repair is completed in a shop environment, a vertical or horizontal mill may be used for machining the bores to dimension. Single point tooling is used for cutting. Carbide tools recommended include C5 for roughing and C7 for finishing.

For field repairs, CSTG offers a 1U8660 Hydraulic Boring Bar with several attachments to complete machining requirements. The hydraulic boring bar can be mounted into the configuration allowing welding and machining from a single set up.