BEARING 8D8888 - Caterpillar

Wheel Loader: AllIntroduction
While buckets are being loaded, stresses are developed in the adapter welds. The most severe stresses are concentrated at the start of the welds on the two strap adapters. The points of stress are at the front of the base edge under the nose of the abrasion and flush mount adapters. Applications of the welds in these areas must be of the highest quality.Two methods for repairing adapter welds have been identified that offer improved weld quality and enhance resistance to fatigue cracking. The preferred method is a Tungsten Inert Gas (TIG) welding process. Another method is toe grinding (Burr Grinding) and does not require an experienced welder or specialized equipment.This special instruction outlines the recommended procedure for repairing welds on K Series adapters for large wheel loader buckets with early hour fatigue cracks. Repairing the welds on K Series adapters for LWL's with early hour fatigue cracks will increase service life.TIG Dressing of Fillet Welds for Improved Fatigue Life
Welding Material
The suggested welding equipment is as follows.
GTAW (TIG) Power Source (with variable amperage adjustment recommended) and a torch with a 200 Amp or greater capacity.
Tungsten electrodes (2.4 mm (0.094 inch) or 3.2 mm (0.125 inch) diameter preferred).
Tungsten grinder for safely and effectively sharpening the tungsten electrodes.
A gas flow meter with variable flow adjustment and a flow rate scale applicable to the scale referenced in the required Weld Procedure Specification.
100% Argon shielding gas of a suitable purity for GTAW (TIG) welding.
Radius gages capable of measuring the engineering required toe radius.
Fillet weld gages capable of measuring fillet leg length and throat size.
Undercut gages capable of measuring to at least a minimum of 0.5 mm (0.020 inch) weld undercut.
A grinder or a needle peening tool suitable for removing scale and silicates.
Degreaser suitable for cleaning prior to welding. Degreaser is required if oil or grease is present on or near the metal in the affected weld area.Preparation for Welding
Illustration 1 g02178773
(A) Electrode point should be two to three times the diameter of the electrode (1A) Example of a properly dressed electrode with striations, or marks, parallel to the axis of the rod (1B) Example of a contaminated electrode
Cleanliness and tungsten electrode preparation are the first steps to ensuring a proper TIG dressing. The fillet weld and surrounding base metal must have all contaminants thoroughly removed. Rust, dirt, oil, scale, silicate islands, and so on, must not exist. This cleanliness can be accomplished quickly via a grinder with a carbon steel wire attachment. Next, prepare a 2.4 mm (0.094 inch) tungsten electrode to the dimensions shown in Illustration 1. Grinding striations should run parallel not transverse.Dress the tungsten electrode with the grinding striations parallel to the axis of the electrode as indicated by the red lines on electrode (1A). Refer to Illustration 1. The length of the electrode point should be approximately two to three times the diameter of the electrode.If the electrode becomes contaminated after use, the electrode will produce