Full Rotation Pin Grabber Thumb Links may Crack Around the Welded Tube Joint or the Retaining Bolt for the Link Pin may Break{6513, 6547} Caterpillar

Excavator:

330B (S/N: 6DR1-UP)

330C (S/N: JAB1-UP; B1K1-UP; B2L1-UP; B3M1-UP; B4N1-UP; DKY1-UP)

330D (S/N: KAB1-UP; C5K1-UP; L2K1-UP; JJM1-UP; LEM1-UP; MWP1-UP)

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.

Problem

Links may crack around the welded tube joint or the retaining bolt for the link pin may break at low hours during operation of the thumb.

Solution

Correct installation and positioning of the 306-4186 Stop Plate is critical. The stop plate should engage the frame of the thumb when the stick is extended in a horizontal position and the weight of the thumb is pulling the thumb away from the stick. If the stop plate does not contact the frame of the thumb with the stick in this position, reposition or build up the stop. The linkage guide on the thumb linkage should not make contact with the stick in this position. Replace the broken links with similar parts. Add the thumb stop if the thumb stop is not currently installed. Review the installation of the entire thumb if links continue to break. Verify that the links do not bind through the entire rotation of the thumb.

Illustration 1	g01621453
(1) Stop Plate (2) Linkage Guide