Description

Komatsu HA250, HA270 1985 Workshop Manual

If you have ever chased a leak on a Komatsu HA250 because some aftermarket manual told you the wrong fluid, you know the cost. Thirty minutes of my life I will not get back, plus a quart of oil I should not have drained. That is what happens when you trust a PDF that some guy scanned from a copy of a copy. This Komatsu HA250, HA270 1985 Workshop Manual is the opposite. It is the original factory binder, 513 pages, printed in Japan in 1985. No guesswork. No reprints. Just the specs that Komatsu engineers wrote for their own technicians.

Torque Limit Table on Page 5 – Why It Saves Your Threads

Every fastener on these dump trucks has a number, and that number is on page 5. The torque limit table covers bolts from M6 to M30 in both standard and high-grade classes. I have seen guys snap a bell housing bolt because they used 150 ft-lb when the spec called for 96. That table is the difference between a solid rebuild and a cracked casing. The manual also lists tightening sequences for transmission and differential assemblies, so you do not warp a flange by going around in a circle. If you are pulling a torque converter, check the torque converter mounting bolts against that table before you reassemble.

Transmission Oil List on Page 44 – Get the Right Fluid

Page 44 is the transmission oil list. It tells you exactly which API classification and viscosity grade goes into the HA250 and HA270 gearboxes. Running 10W-30 when the manual calls for SAE 30 will cost you clutch pack life. The list also covers differential oil, hydraulic oil, and even the grease for the front reduction gear. Do not guess. Use page 44.

7 Systems Covered – Engine to Accessories

This manual splits into nine chapters: General Instruction, Engine, Transmission, Driveline/Brakes/Wheels, Air System, Hydraulic System, Electrical System, Front Chassis, Rear Chassis, and Accessories (includes an air conditioning fill instruction). That is every major system on the truck. The transmission section alone is 92 pages with 2.3 Disassembly and Assembly covering the torque converter, control valve, and interaxle differential. The air system section has full circuit diagrams for early and late serial numbers – that matters when you are tracing a four-circuit protection valve. I keep a copy of the hydraulic troubleshooting tables open whenever I work on the steering circuit. They list pressure checks and flow rates directly from the factory test stand.

Does This Manual Cover Both the HA250 and HA270 Variants?

Yes. The manual includes separate machine specification pages for the HA270-1 (page 0.0.32), HA250-1 (0.0.34), and the HA270-3 / HA250-3 (0.0.36). Performance charts and exhaust brake capacity diagrams are also given for each variant. If you own a HA250-3 with the later serial number, the air circuit diagram on page 4.1.4-1 applies to your machine. Do not rely on a generic manual that lumps everything together – this one tells you which page covers which serial break.

Understand the Air System Before You Touch It

The air system on these trucks is not complex but it is safety-critical. The manual devotes section 4.0 to structure and function, testing and adjusting, and disassembly. You get exploded views of the governor, moisture repellent injector, automatic drain valve, four-circuit protection valve, dual foot brake valve, and parking brake control valve. The standard values table on page 4.2.1 lists pressure settings for each circuit. If you are adjusting the parking brake, you need the parking brake chamber disassembly steps on page 4.3. If you need background on how a Manual Transmission works in general, that is separate knowledge – but this manual covers the specific transmission in this truck with full oil circuit diagrams and shifting point tables. For the driveline, the Manual Transmission section (actually the transmission chapter) includes the inductive transmitter adjustment and stall performance testing. Every adjustment procedure is written for a technician holding a wrench, not a textbook.

Why OEM Documentation Matters More Than Aftermarket Copies

I have flipped through aftermarket manuals that skip the torque limit table, omit the “Safety in Service Work Shops” section (page 0.0.6), or use generic wiring colors. This manual has none of that. It was printed by Komatsu in 1985 for their dealer network. The pages are numbered with the chapter-section-page system you see on the original binder: e.g., page 0.0.44 for the transmission oil list. Every test procedure references the correct special tool number. If the manual says you need a 2.3.92 special tool for the transmission, that tool exists and the manual shows you how to use it. No substitution.

If you are working on a fleet of these trucks, you already know that downtime from a misdiagnosis costs more than the manual. This is the only document that gives you the factory oil contamination standard (section 2.4) and the correct procedure for adjusting the interaxle differential lock. I would not start a transmission rebuild without it.

Frequently Asked Questions

What machines does this manual cover?

HA250 and HA270 dump trucks from 1985.

How many pages is it?

513 pages.

Does it include torque specs?

Yes. Page 5 has a torque limit table covering all major fasteners. The manual also lists standard values in each section for transmission, driveline, and air system components. You get factory numbers, not aftermarket guesses.

Is this a factory OEM manual?

Yes. This is an original Komatsu shop manual printed in 1985. No third-party reprints or condensed versions. It includes the full foreword, safety instructions, disassembly and assembly procedures, testing and adjusting, troubleshooting, and maintenance standards. Every page is scanned from the official binder. If you have seen cheap aftermarket manuals with missing diagrams or wrong specs, this is the opposite.

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Stop chasing bad information. Get the manual that came from the factory. Access the Factory Manual and put it on your shop tablet.