Usage:
225 Excavators, 227 Loggers
Reference: Special Instructions, Form SMHS7822, "Procedure To Repair Damaged Boom Tower Pin Bores" and Form SEHS8171, "Using Hydraulic Boring Machines".
Description of Change: Improvements have been made to the boom and upper frame to extend the service life of the pins, pin bores, and bearings. The improvements include:
... Higher tensile strength structural steel is used for the upper frame boom support plates.
... The pin bores in the boom support plates are line bored and held to closer tolerances.
... Coated bearings are used in the boom.
... New pins and pin retainers are used to attach the boom to the upper frame.
Earlier machines can be updated to include these improvements.
The upper frame boom support plates were changed to a higher strength structural steel and the boring process for the pin bores was changed to a line bore process effective with the product identification numbers shown in Chart A.
The pin bores in earlier machines can be bored oversize, rewelded and line bored to a closer tolerance to achieve a tighter, better aligned pin fit. Refer to the Special Instructions to bore the pin bores oversize and for line boring them. Bore the pin bores to a diameter of 89.03 mm (3.505") or larger before welding. Rebuild the oversized pin bores by welding with E7018 Electrodes or an equivalent. When the pin bores have been welded, line bore all four of them to a diameter of 76.28 ± 0.05 mm (3.003 ± .002").
Illustration 1. Installation of bearings.
The two new 7V8106 Bearings (boom foot bearings) are a direct replacement for the two former 8K533 Bearings. The new bearings have a manganese phosphate coating to aid in break-in. Chart B gives the effective Product Identification Numbers for the new bearings.
The new 7V8106 Bearings must be installed to a depth of 11.0 ± 0.5 mm (.43 ± .02"). See Illustration 1.
The new 6W5996 Pin Assemblies (boom pins) are a direct replacement for the former 2V1722 Pin Assemblies when used as shown in Chart C.
The new pin assemblies are effective with the Product Identification Numbers shown in Chart D.
When the new pin assemblies are installed, locate the two 6W5997 Brackets as shown in Illustrations 2, 3 and 4. Weld the brackets in position with E7108 Electrodes or an equivalent.
Illustration 2. 6W5997 Brackets viewed from front of machine.
Illustration 3. Location of right 6W5997 Bracket.
Illustration 4. Location of left 6W5997 Bracket.