Description

Komatsu D155AX-8, D155AX-6 Workshop Manual

If you’ve torqued enough head bolts to build your own engine block, you know the difference between a spec and a guess. This Komatsu D155AX-8, D155AX-6 Workshop Manual is the real deal—1146 pages pulled straight from the factory. I’ve seen techs lose a transmission because they trusted a third-party torque chart. That doesn’t happen when you have the OEM Workshop Manual open on the workbench. The Standard Tightening Torque Table in the foreword alone will save you from snapping bolts on the final drive. This isn’t a reprint of some aftermarket summary; it’s the actual binder Komatsu issued for the D155AX-80001 and up serial range.

1146 Pages of Factory Specs You Can Trust

You don’t buy a 1,146-page document for bedtime reading. You buy it because every page has a purpose. The manual is organized by section: 00 Index and Foreword, 01 Specification, 10 Structure-Function-Maintenance Standard, 20 Standard Value Table, and 30 Testing and Adjusting. Each section breaks down a specific system—engine cooling, power train (Part 1 and Part 2), hydraulic system, work equipment, cab attachments, and electrical. The index shows Form Numbers SEN00596-02 through SEN00721-01, so you can always verify you’re looking at the current revision. No guesswork about which version you’re using.

Torque Specifications: The Standard Tightening Torque Table

Page numbers matter when you’re under the machine with a wrench in hand. The Standard Tightening Torque Table sits in the foreword (Section 00) and gives you the correct ft-lb values for common bolt grades. Komatsu also includes a Conversion Table for metric-to-imperial conversions. If you’re replacing the track shoe bolts or the final drive sprocket, you’ll find those values in the Undercarriage and Frame chapter. I’ve seen broken bolts from over-torquing on a D155AX-6 because someone used a generic chart. This manual eliminates that risk.

Power Train System: Torque Converter and Transmission ECMV

Section 10 covers the power train in two parts. Part 1 includes the torque converter, PTO, lockup clutch ECMV, stator clutch ECMV, and the transmission itself. You’ll find the Main Relief Valve and Torque Converter Relief Valve specs, plus the Scavenging Pump and Lubrication Relief Valve. Part 2 goes into the HSS system, steering unit, brake control valve, brake ECMV, parking brake solenoid valve, and the sudden stop prevention valve. Each component has its own subsection with disassembly and assembly procedures. The manual shows you the exact hydraulic piping diagram for the power train, so you don’t route a hose wrong.

Testing and Adjusting: What You Need on the Job

Section 30 is where the real work happens—testing and adjusting. It’s split into four parts. Part 1 covers engine-specific tests: measuring intake air pressure (boost pressure), adjusting valve clearance, measuring compression pressure, and bleeding air from the fuel circuit. Part 2 deals with the power train: measuring oil pressures, adjusting brake pedal and parking brake lever, and the emergency escape method when the power train has trouble. If you ever get a sudden stop prevention valve failure on a D155AX-8, this section tells you how to test the brake ECMV. Tools required are listed for each procedure—no guessing what you need.

Does This Manual Cover the Electrical System?

Yes, and it’s not a generic wiring diagram. Section 10 includes the Electrical System chapter with engine control, deceleration potentiometer, monitor system, sensors, and the Palm Command Control System. The foreword explains how to read the electric wire code and how to handle electric equipment and hydraulic components. The troubleshooting section (Section 40) is six parts long, covering failure and error codes. If the monitor system throws a code, you cross-reference it in the table of error codes and follow the diagnostic steps. No flipping through third-party forums.

Why OEM Documentation Beats Aftermarket

I’ve used aftermarket manuals that omit the torque converter relief valve setting or list the wrong thread pitch for the hydraulic couplings. This Komatsu shop manual comes from the same source as the dealer’s service bay. The Organization List of the Shop Manual in the index shows every form number and revision status. You’re getting the latest version as released by Komatsu. The 1146 pages include factory dimension drawings, weight tables, and fuel/coolant/lubricant tables. The conversion table at the front lets you work in imperial units without mental math. If you need a dedicated Komatsu D155AX-8 Shop Manual for that specific serial number range, we stock it. You can also pair it with the Komatsu D155AX-6 Operation & Maintenance Manual for daily checks. For a deeper dive, the Komatsu D155AX-6 Workshop Manual – 1568 Page Factory Bulldozer Guide covers additional years. For background on how manual transmissions interact with torque converters, see Manual Transmission basics. And if you’re working on a separate vehicle with a standard gearbox, Manual Transmission repair principles apply.

Does this manual include torque values for the track frame bolts?

Yes. The Undercarriage and Frame section lists tightening torque for the track frame, idler, and track roller mounting bolts. Use the Standard Tightening Torque Table as a baseline, then check the specific subsections.

Can I use this manual for the D155AX-6 if my machine has a serial number below 80001?

The manual covers D155AX-6 serial numbers 80001 and up. For earlier machines, you’d need an earlier revision. The index includes form numbers for different serial ranges. If your machine falls outside that range, you risk missing updates to the transmission control valve or HSS pump specs. Always match the serial number range in the manual to your equipment. That said, the standard torque tables and many structure/dimensions are identical across later serial breaks, but the ECMV and wiring diagrams change. Check the manual’s foreword for the exact serial number applicability.

Access the Factory Manual. You need it open on the bench before you crack a single hydraulic line. The 1146 pages are all OEM—no aftermarket shortcuts, no missing torque values. This is the same book the dealer techs use. Get it obtained and print the torque table for your toolbox.