Description

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

If you are wrenching on any of these excavators — Hitachi Sumitomo 330, 330LC, 350H, 350LCH, 370MTH — and you don’t have this particular Workshop Manual open on the bench, you are working blind. That is not an opinion. That is what happens when a swing motor seal leaks and you start guessing which o-ring goes where. I have seen guys turn a two-hour regulator job into a full day because they used a third-party spec sheet and the pump compensator fought them the whole way. This is the factory manual. 752 pages. Written for experienced technicians. It assumes you know which end of a wrench to grab, but it does not assume you have memorized every torque value from memory.

Tightening Torque: Where Most Failures Start

Page 1 lists the manual number and volume. But the real meat is in Section 1 General Information, right where it says Tightening Torque. That section includes a TORQUE CHART, PIPING JOINT specs, and PERIODIC REPLACEMENT OF PARTS. You need the factory tightening Torque for every bolt on the control valve, swing device, and travel motor. Aftermarket manuals often round to the nearest five. That five lb-ft difference is enough to crack a valve body or strip an M12 into an aluminum housing. This manual gives you the exact spec. Use it.

Pump Device Disassembly: Don’t Skip the Regulator Sequence

Under Section 2 Upperstructure, the Pump Device chapter walks you through remove, disassemble, assemble — including DISASSEMBLE MAIN PUMP, ASSEMBLE MAIN PUMP, then the REGULATOR sub-assemblies. The regulator is where 90% of pump complaints live. If you skip the order of shims or mis-index the servo piston, the machine will not respond to load sensing. The manual separates DISASSEMBLE REGULATOR and ASSEMBLE REGULATOR with maintenance standards. Follow it exactly. No skipping steps.

Control Valve: 6 Sub-Sections for a Reason

CONTROL VALVE has six separate disassemble/assemble pairs — (1) through (6) — plus a STRUCTURE OF VALVES section. That is because the main control valve on these Hitachi Sumitomo machines is a stack of individual sections. Each spool, each relief valve, each check has its own sequence. The manual accounts for serial number breaks and production dates. For example, the Pilot Valve section splits procedures by serial number (up to 320880 and 320881 and up) because the internal porting changed. You do not want to mix parts between those groups. The manual tells you which applies to your machine.

Travel Device: Two Serial Number Splits for 330/350 and a Separate Section for 370MTH

Under Section 3 Undercarriage, the travel device gets three distinct sub-sections: one for ZAXIS330, 330LC, 350H, 350LCH (Up to serial No.31357), one for the same models from serial 31358 and up, and a dedicated ZAXIS370MTH section. Each includes REMOVE AND INSTALL TRAVEL DEVICE, DISASSEMBLE TRAVEL DEVICE, ASSEMBLE TRAVEL DEVICE, plus separate TRAVEL MOTOR and BRAKE VALVE procedures. The 370MTH brake valve is different internally — larger pistons, different spring rates. If you use the 330 spec on a 370MTH brake, you risk brake drag or complete lockup. Page 3 of the manual’s introduction explains the manual composition: three volumes — Technical Manual (Operational Principle), Technical Manual (Troubleshooting), and this Workshop Manual. This volume covers only maintenance and repair. It does not cover troubleshooting logic. You need the troubleshooting volume for that. But if you are pulling parts apart, this is the one.

Source Validity: OEM Factory Documentation vs. Aftermarket Knockoffs

I have seen reprints that claim to be “factory spec” but the TORQUE CHART on page 26 (of the original) is missing the pivot pin torque specs. This manual is a direct scan of the Hitachi Construction Machinery Co., Ltd. publication (Manual No. KM-1HH-E). It includes the SAFETY ALERT SYMBOL AND HEADLINE NOTATIONS (page 4) and the ADDITIONAL REFERENCES list directing you to the Operator’s Manual and Parts Catalog. Third-party manuals never include those references. They also skip the MAINTENANCE STANDARD TERMINOLOGY section, which defines terms like “standard” and “limit” for wear measurements. That terminology saves you from misinterpreting clearance specs. Do not trust aftermarket documentation on this. Get the OEM file.

Does This Manual Cover the Fuel System and Engine?

It covers everything on the machine except the engine internals. The engine operation manual and parts catalog are separate (referenced in the introduction). You get the complete upperstructure cab removal, counterweight, main frame, pump, control valve, swing device, pilot valves, solenoid valves, shockless valve, and pilot shut-off valve. Undercarriage includes swing bearing and travel device with brake valve assemblies. All hydraulic system disassembly is here. Torque specs for all hydraulic fasteners are in the TIGHTENING TORQUE SPECIFICATION subsection.

FAQ

Does the manual include torque specs for the swing motor mounting bolts?

Yes. The torque chart in Section 1 covers all hydraulic component fasteners, including swing motor bolts. Use the specification for each bolt grade and size.

What about the serial number splits for the travel device — how do I know which section applies to my machine?

The manual clearly separates travel device procedures into three groups: ZAXIS330/330LC/350H/350LCH up to serial No.31357, the same models from serial No.31358 and up, and a dedicated section for ZAXIS370MTH. Locate your machine’s serial number on the data plate (usually on the cab door frame or near the swing bearing). Compare it to the header in the manual. If you are working on a 370MTH, use the third section. The brake valve, travel motor, and center joint are all different. Using the wrong procedure can damage the brake valve piston or cause improper travel speed. The manual also includes separate maintenance standard tables for each group, so you get the correct wear limits.

Related manual: Hitachi Sumitomo 330, 330LC, 350H, 350LCH, 370MTH Workshop Manual – 752 Pages. For the troubleshooting companion, see Hitachi Sumitomo 330LC, 350H, 350LCH, 370MTH, ZX330 Technical Manual. Another variation: Hitachi Sumitomo SH330 SH330LC 350HD-3B 2006 Workshop Manual – Factory Specs. Also read about Manual Transmission basics if you need general drivetrain theory, and the external guide on Manual Transmission for clutch and gear concepts.

Access the Factory Manual — do not waste time with file-share copies that miss pages or have blurred torque charts. This is the real OEM PDF from AutoRepairManuals, verified factory specifications, complete 752 pages.