Product Overview

Part number 723-40-56302, also marked as 7234056302, is a critical unloading valve, also known as main relief or pressure safety valve, fitted on the main hydraulic control valve of Komatsu excavators. It automatically diverts oil from the main hydraulic pump back to the tank at low pressure when high system pressure is unnecessary, such as during idle conditions or when releasing control handles, which prevents pressure trapping, reduces hydraulic oil temperature and cuts engine fuel consumption. This high-precision metal valve cartridge weighs roughly 0.2kg and mounts directly onto the main control valve assembly. Built for heavy-duty construction sites with reliable wear resistance, it fits many classic 6-series and 7-series mid-to-large Komatsu excavators plus selected mobile crushers. The interchangeable part 723-40-56100 can serve as an alternative for certain older machine models during maintenance replacement.

FAQ

Q1: What common machine problems show this unloading valve needs replacement?

A: Common symptoms include weak machine power and slow movements, engine bogging down with black smoke, and abnormally high hydraulic oil temperature caused by stuck or worn valve internals.

Q2: Which Komatsu machines does 723-40-56302 fit?

A:

• Core excavators: PC200-6, PC220-6, PC300-6, PC350-6
• Other excavators: PC200-7, PC240LC-6, PC350-7, PC360-7, PC308USLC-3E0
• Mobile crushers: BR200S, BR380JG

Q3: Technical Specifications

Q4: What is the cross reference replacement part?

A: 723-40-56100 for selected older machine versions.