Description

Komatsu HD985, HD785 2006 Workshop Manual

You’ve got a Komatsu haul truck down with a brake drag or a transmission that won’t hold lockup. The aftermarket manual you bought last month gave you a torque value on the final drive that stripped three bolts. I’ve been there. That’s why you need the actual OEM publication – the one Komatsu printed in 2006, 1392 pages thick, covering the Komatsu HD985, HD785 2006 Workshop Manual for the HD785-5 and HD985-5 models. This is not a reprint or a third-party compilation. It’s the original factory document that Komatsu issued for dealers and shop floors.

Every section in this manual is written for a mechanic who wants exact numbers – not “tighten until snug.” You get the full spec table from the GENERAL chapter (section 01), including the weight table and the list of lubricants and coolants. The SA12V140-1 engine is covered in the companion engine manual, but the truck systems are all here: torque converter, transmission, axles, brakes, steering, suspension, air and hydraulic circuits, and the full electrical diagnostics.

Torque Converter and Transmission: Hydraulic Circuit Schematics

Go to section 10 and you’ll find the complete power train skeleton – output shafts for both the HD785-5 and HD985-5, the torque converter valve, lockup solenoid valve, and the ECMV. I’ve rebuilt enough Allison and ZF units to know that a misread hydraulic diagram costs a shift solenoid. This manual gives you the actual circuit diagrams and schematics for the torque converter and transmission hydraulic piping. Need the charge pressure range? It’s in the TESTING AND ADJUSTING section 20. No guesswork.

Komatsu HD985 and HD785 2006 Workshop Manual: Torque Specs and Fluid Capacities

The MAINTENANCE STANDARD section (40) lists every fastener torque for the front and rear brake chambers, the slack adjuster, the differential lock, and the final drive. I’m talking about the exact ft-lb values for the brake chamber mounting bolts and the wheel lug nuts. The LIST OF LUBRICANT AND COOLANT in section 01 tells you what oil goes into the transmission, the differential, and the hoist hydraulics. Don’t trust the internet forums – use the factory data.

Does This Manual Cover the SA12V140-1 Engine?

The shop manual references the engine separately. On page 1 of the OCR excerpt, it clearly states: “HD785-5 and HD985-5 mount the SA12V140-1 engine. For details of the engine, see the 12V140-1 Series Engine Shop Manual.” So if you need piston ring end gaps or injector timing, you’ll want that companion manual. But everything else – the drivetrain, the brake system, the transmission, the air piping, the suspension, the payload meter, the automatic shift control – is here.

3 Critical Systems Documented: Brakes, Transmission, and Final Drive

Brakes: front brake, rear brake, parking brake, brake valve, emergency brake control valve, ratio valve for the front brake, brake chambers, slack adjuster. There’s a whole subsection on the air piping and circuit diagram. Transmission: torque converter, transmission valve, ECMV, lubrication relief valve. Final drive: both HD785-5 and HD985-5 versions, plus the axle support and wheel sections. If you’re pulling a differential or overhauling a drum, you need the exploded views and the tightening sequences that are only in an OEM manual like this one.

Get the Right Torque Data for Your Komatsu

I’ve watched guys snap axle housing bolts because they relied on a generic chart. This manual gives you the OEM torque for every threaded fastener on the truck – from the steering cylinder rod end to the hoist valve mounting. The TESTING AND ADJUSTING chapter (20) also includes the hydraulic circuit pressures and the brake oil cooler flow checks. You can’t adjust the demand valve or the crossover relief valve without those specs.

One more thing about authenticity: this is a genuine factory publication. The PDF you get is a direct scan of the printed Komatsu shop manual, with the same content as what the dealer techs used. Aftermarket manuals often combine data from multiple models and years, and they don’t tell you when they took shortcuts. This one has the original part numbers, the revised page marks (you can see the revision table on page 00-2-1 with marks like “b 00-1 (17)”), and the official Komatsu copyright from 2006. It’s the only way to be sure you’re not working with edited or missing information.

For related equipment, check out KOMATSU HD985 Dump Truck Parts Catalog if you need OEM part numbers, or the KOMATSU HD785 Dump Truck Workshop Manual for the companion engine manual. Also see the Komatsu WA65-5 WA70-5 WA80-5 2005 Workshop Manual for wheel loaders if that’s in your fleet. For a broader understanding of how these hydraulic systems work, Manual Transmission theory can help, and the same goes for Manual Transmission fundamentals in heavy equipment.

Can I use this manual for the HD785-5 with serial number 4000 or earlier?

The manual covers serial numbers 4001 and up for HD785-5, and 1021 and up for HD985-5. If your machine is older, some sections may still apply, but you should confirm with your local Komatsu distributor.

Does the manual include wiring diagrams for the automatic shift control system?

Yes. Section 10 has the full electrical circuit diagram for the automatic shift control system, including the transmission controller, connector signals, shift lever switch, and the self-diagnostic function. There’s also a separate AUTOMATIC SHIFT CONTROL SYSTEM subsection with system drawings and sensor details.

Stop working with half-right specs. Get the official document that Komatsu built for their own shop floors. Access the Factory Manual from AutoRepairManuals and put the right torque on every bolt.