Introduction Of Heavy Duty Extended Life Undercarriage For Certain D8 Track-Type Tractors {4150, 4155, 4169, 4170, 4171} Caterpillar

Track-Type Tractor

D8N (S/N: 9TC1-UP; 1XJ1-UP; 5TJ1-UP; 7TK1-UP)

D8R (S/N: JR81-UP; DWJ1-UP; MEJ1-UP; RJM1-UP; 7XM1-UP; 9EM1-UP; T5X1-UP)

D8R Series II (S/N: AKA1-UP; 6YZ1-UP)

D8T (S/N: JJ51-UP; MB81-UP; J8B1-UP; FMC1-UP; MLN1-UP; FCT1-UP; KPZ1-UP)

Reference

Reference: Special Instruction, M0069972, "Procedure to Convert To Heavy Duty Extended Life Undercarriage With 218 mm Pitch Track On Certain D8N, D8R, And D8T Track-Type Tractors"

Reference: Service Magazine, M0085183, "D8 size Track Pins now have Smaller Diameter Oil Cavity and Rubber Stopper"

Introduction

A new Heavy Duty Extended Life (HD XL) undercarriage system is now offered for D8 size Track-Type Tractors. The system consists of a Positive Pin Retention (PPR) track link design with a longer link pitch ( 218 mm (8.60 inch)), a larger diameter track bushing, and a different sprocket segment.

The system is designed to extend the external wear life of the undercarriage in applications where bushing wear limits the total track wear life. The system is for field retrofit on machines with suspended track roller frames.

The D8 HD XL system is an optional factory attachment on certain Brazil built D8T’s, and will be available through the Cat® Parts system for field retrofit onto D8R/T machines. However, the existing PPR track with 215.9 mm (8.50 inch) link pitch will remain as the standard factory installed undercarriage for D8 machines. As previously, announced, D8 SystemOne® is discontinued in Parts and Factory offerings. D8 HD XL is the replacement undercarriage for D8 SystemOne®.

HD XL System Compatibility

The new link assemblies and sprockets are compatible with conventional D8 size track shoes, rollers, and idlers. The new link assemblies are compatible with either conventional or SystemOne™ major bogies, but specific idler mounting hardware and bogie shims are required for each bogie type. Table 2 contains a conversion summary. Table 3 contains a detailed part number list.

Reference: Refer to Special Instruction, M0069972 for detailed instructions.

Track and Link Assemblies

The new D8 HD XL system includes the new Cat™ Dura Link Track Link Assembly which contains 502-6149 Track Link (RH), 502-6150 Track Link (LH) and 5 mm (0.20 inch) larger diameter 502-6148 Track Bushing for improved external wear life.

The track pin¹, thrust rings, seals, shoes, and hardware are the same as in conventional PPR track. The new track is designed to allow a bushing turn or reseal at mid-life.

¹ See Service Magazine, M0085183, "D8 Size Track Pins Now Have Smaller Diameter Oil Cavity and Rubber Stopper"

Illustration 1	g06226469
D8 Dura Link (D1) 3 mm (0.12 inch) (D2) 218.25 mm (8.60 inch)

The new Dura Link has more steel in the center of the link rail to resist link scalloping from idler contact, improving ride and grade later in the wear life. The new link also has a longer track link pitch as compared to conventional D8 PPR links. The longer pitch allows straightforward conversion from either D8 SystemOne™ or conventional UC to D8 HD XL by reusing the existing major bogies. However, different idler mounting hardware configurations and bogie pad shims are required for each major bogie type (see Special Instruction, M0069972).

Due to the longer track pitch, the new link assembly also contains different master links than conventional master links. Do not use conventional master links in HD XL track.

Sprocket Segments

Due to the longer track pitch and larger bushing, the 278-2375 Sprocket Segment segments must be used. Depending on the sprocket and bushing wear rates, it may be necessary to install new sprockets mid-life before the bushing turn to achieve maximum bushing wear life. It is also recommended to install new sprockets at bushing turn, and anytime new link assemblies are installed. Worn sprockets running against new bushings will accelerate bushing wear.

Field Identification

D8 HD XL track links and sprockets will be marked with "218 HD XL" for easier field identification and compatibility.

Illustration 2	g06226473
502-6149 Track Link with part number and "218 HD XL" identifier

Illustration 3	g06226475
278-2375 Sprocket Segment with "218 HD XL" identifier

Service Tooling

The new link pitch and bushing diameter requires use of 517-8097 Saddle (V-block) to perform a bushing turn. This saddle is designed for Caterpillar Track Presses. The Caterpillar pin and bushing contact tools are the same as existing D8 PPR track.

Custom Track Service (CTS) Wear Charts

New bushing and sprocket wear charts are available via CTSi or CTS Pro. D8 HD XL utilizes existing wear charts for conventional links, shoes, rollers, and idlers.

Conversion Parts Compatibility Table

The following table shows required part numbers when converting between UC systems.