Description

Komatsu PC300-7, PC300LC-7, PC350-7, PC350LC-7 Technical Manual

You rolled a rebuilt HPV125+125 pump onto the bench and you need to run it through a validation test before it goes into that PC300-7. This 31-page Komatsu PC300-7, PC300LC-7, PC350-7, PC350LC-7 Technical Manual is the exact procedure Komatsu uses at the factory. It gives you the test stand setup, the hydraulic circuit diagram, and the performance tables. There’s no room for a guy who skips the drain pressure check – that’s how you blow a seal on a $4,000 pump.

What You Get: 31 Pages of Factory Pump Testing

This manual is built around five sections. Test Method (pages 3-11) covers everything from pump installation on the KHT75-3 stand to the actual test sequence. The Test Hydraulic Circuit Diagram (page 12) shows you exactly how to plumb the lines, including the drain line routing. Performance Diagram and Standard Value Table (pages 13-28) gives you the flow curves and acceptance criteria for the HP125+125 pump. Finally, Names of Sections and Related Dimension (pages 29-31) lists the critical dimensions for the test jig. If you’re rebuilding these pumps for a PC300LC-7 or a PC350LC-7, this is your quality check sheet.

Does This Manual Cover Engine Overhaul?

No. This manual is pump-specific – it’s for the HPV125+125 (140+140 cc/rev specification) main pump only. If you need engine tear-down and reassembly for the same machines, look at the Komatsu PC300 PC350-7 2002 Workshop Manual”>Komatsu PC300 PC350-7 2002 Workshop Manual. That document covers the SAA6D114E-2 engine, injection timing, and head bolt torque sequences. The manual you’re looking at now is for verifying pump output after a rebuild, not for fixing a misfire.

Test Specifications at a Glance: Numbers You Can Rely On

Page 3 of the manual lists the test specifications in Table 1-1. For the HPV125+125 pump, the maximum input shaft speed is 1,950 rpm (standard test speed is 1,500 rpm). The maximum hydraulic pressure is 37.3 MPa {380 kg/cm²}. Suction pressure must be 0.98 ± 0.05 MPa {1.0 ± 0.5 kg/cm²} – get that wrong and you’ll cavitate the pistons. Drain pressure must stay at 0.98 MPa or less. EPC valve original pressure is 3.1 MPa {32 kg/cm²}. These are factory numbers, not a third-party guess. I’ve seen aftermarket copies that list drain pressure at 2.0 MPa – that will grind the valve plate in ten hours.

Safety: High Pressure Hydraulics Demand Respect

The manual opens with a blunt warning: “Since high pressure is produced during this HST pump test, great care should be taken when selecting the equipment, device, test jigs and components.” That means you don’t use a cheap hydraulic hose from the hardware store. You need certified lines rated above 40 MPa. Also check the universal joint connection – a loose U-joint at 1,950 rpm will throw a pump across the room. If you’re new to bench testing, read the test hydraulic circuit diagram on page 12 before you pressurize anything. You can also review general hydraulic safety from this Manual Transmission”>Manual Transmission article – the same caution applies to high-torque rotating assemblies.

Why OEM Documentation Matters

I have a rule: never trust a “reprint” that was scanned from a copy of a copy. The letters blur, the torque values lose decimals, and someone’s coffee stain covers the drain pressure spec. This manual is a direct factory PDF from Komatsu. The stamp on the nameplate reads 708-2G-00023 and 708-2G-00024. It’s for machines with serial numbers PC300/300LC-7 #400001~ and PC350/350LC-7 #200001~. That exactness is what keeps the pump performance curve inside the standard band. Use the performance diagram on pages 13-28 to verify flow at 1500 rpm and 34.3 MPa. If your flow is off, you don’t install the pump – you tear it down and find the leak. Period.

FAQ

What pump models are covered in this manual?

HPV125+125 (140+140 cc/rev specification), DR2 type, stamped 708-2G-00023 and 708-2G-00024.

Do I need the KHT75-3 test stand?

The manual says to use the Komatsu general-purpose hydraulic test stand KHT75-3 or an equivalent. Standard value testing requires a stand with the same performance as the production plant stand. Converted value testing can use the KHT75-3. You also need Komatsu genuine engine oil E010-CD or equivalent, and the oil must meet NAS10 cleanliness class. If your test stand can’t hold 37.3 MPa steady, don’t start the test. The manual gives the hydraulic circuit diagram on page 12 so you can rig a suitable equivalent.

Does this manual include wiring diagrams?

No. It covers the pump performance test and the EPC valve original pressure setting. There is no electrical schematic for the machine. For the machine’s electrical system, refer to the Komatsu PC300 PC350-7 2001 Service Manual”>Komatsu PC300 PC350-7 2001 Service Manual.

Where can I find the pump mounting dimensions?

Pages 29-31 list the names of sections and related dimensions of the test jig. If you need the bolt pattern for the pump-to-engine adapter, check the KOMATSU PC300LC-7 Hydraulic Excavator Product Bulletin”>KOMATSU PC300LC-7 Hydraulic Excavator Product Bulletin. Also, the test jig schematic is referenced in the manual but not printed – you may need to contact Komatsu for that drawing.

If you’re rebuilding the main pump for a PC300-7 or PC350-7, this 31-page technical manual is the only source that gives you the factory test procedure, standard values, and hydraulic circuit diagram. Access the Factory Manual now and keep it next to the test stand. You’ll use it every time.