Description

Hitachi Sumitomo 330, 330LC, 350H, 350LCH, 370MTH Workshop Manual

You ever pull a swing motor off a 350H and find aftermarket torque values that are 30 ft-lbs off? I have. That kind of mistake costs you a seal, a bearing, and an afternoon. This Hitachi Sumitomo 330, 330LC, 350H, 350LCH, 370MTH Workshop Manual is the factory document. Not a summary. Not a reprint from someone who never touched a wrench. 752 pages of what Hitachi actually wrote for their technicians. If you work on these excavators, you need the real spec – not a guess.

Tightening Torque: Not a Suggestion

Section 1 of the manual devotes an entire subsection to Tightening Torque – TIGHTENING TORQUE SPECIFICATION, TORQUE CHART, PIPING JOINT, and PERIODIC REPLACEMENT OF PARTS. You get the numbers Hitachi stamped into the engineering drawings, not what some forum poster remembered. Torque on hydraulic fittings is not optional. Under-torque a pump discharge line and you get leaks. Over-torque and you crack the flange. The manual tells you exactly what to use for every threaded connection on the machine.

7 Major Sections Covering the Whole Machine

This Workshop Manual breaks down into seven main sections: General Information, Upperstructure (complete cab, counterweight, main frame, pump device, control valve, swing device, pilot valve, pilot shut-off valve, shockless valve, solenoid valve), Undercarriage (swing bearing, travel device, center joint), and more. Each section walks you through remove and install, disassemble and assemble, and maintenance standards. If you are rebuilding the control valve on a 330LC, you have six separate disassembly/assembly procedures to follow depending on the valve variant. That level of detail is why you buy the factory manual.

Pump Device Rebuild: Disassembly and Assembly Steps

The Pump Device chapter covers everything: remove and install the complete pump device, then tear down the main pump, the regulator, and the pilot pump. Every step is documented. You get the maintenance standard tables with wear limits and clearances. The manual does not skip the regulator – that little valve stack controls your pump output pressure. Miss a shim or mix up the springs and you lose power or overspeed the engine. The factory sequence prevents that.

Why Are There Different Procedures for Different Serial Numbers?

Hitachi updated the travel device design mid-production. The manual separates procedures for ZAXIS330, 330LC, 350H, 350LCH up to serial No.31357 and from serial No.31358 onward. Same for the 370MTH – its own travel device section. If you are working on a 350H with serial number 31360 and you use the earlier brake valve assembly steps, you will install parts that do not fit. The manual keeps you straight because it comes from the factory, not a generic aftermarket publisher. Related manual: HITACHI ZAXIS 330/350/370 Workshop Manual covers the same series with different binding.

Swing Device and Travel Motor Procedures

The Swing Device chapter includes removal/installation of the swing device, disassembly/assembly of the swing motor, and the parking brake release valve. The Travel Device chapter for the 370MTH has its own brake valve assembly steps. If you ever get into the center joint, that section is there too. Every hydraulic component – pilot valves (right, left, travel), pilot shut-off valve, shockless valve, solenoid valves – has a dedicated remove/install and disassemble/assemble procedure. The manual even splits pilot valve procedures by serial number and manufacturing date (before March 2003 vs after April 2003). That is what you call manufacturing-specific documentation. For additional reference, see Hitachi Sumitomo 330LC, 350H, 350LCH, 370MTH, ZX330 Technical Manual for troubleshooting and operational principle, and Hitachi Sumitomo SH330 SH330LC 350HD-3B 2006 Workshop Manual – Factory Specs for similar late-model coverage.

Safety and Source Validity – Why OEM?

This manual carries the Hitachi logo and manual number KM-1HH-E. It is part of a three-volume set: Technical Manual (Operational Principle), Technical Manual (Troubleshooting), and this Workshop Manual. The safety sections at the beginning use the standard alert symbol and strict handling instructions for component weights. Aftermarket documentation often skips the weight warnings because they are not liable. OEM manuals do not skip them. You want the real thing when you are lifting a counterweight or supporting a 1,200-pound swing motor. For context on why factory documentation matters compared to generic manuals, read about Manual Transmission rebuilds or any precision assembly – the difference is knowing tolerances versus guessing. Hitachi specified every torque, every clearance, every step. Use that.

FAQ

Does this manual include wiring diagrams?

No. Wiring diagrams and electrical troubleshooting are in the Technical Manual (Troubleshooting), sold separately. This Workshop Manual focuses on mechanical disassembly, assembly, and maintenance standards.

Will it work on a ZAXIS 370MTH?

Yes. The 370MTH has its own dedicated travel device chapter within this manual. All other sections apply.

What about the engine?

The manual references the Operation Manual of the Engine and Parts Catalog of the Engine separately. You get removal/installation procedures for the pump device and related systems, but engine internal repair is not covered in this volume. Use the engine manufacturer’s manual for that.

Is this a reprint or a PDF?

Digital access of the original factory PDF, 752 pages, full searchable text, vector diagrams. No reprints, no copy-paste jobs. You get the same file Hitachi distributes to dealers.

You have a choice: trust a forum post or use the actual Hitachi Sumitomo factory document. This manual gives you the data you need to pull a pump, rebuild a travel motor, or torque a swing bearing correctly. Access the Factory Manual and stop chasing phantom specs.