4608478 396776 Main Relief Valve Pressure Relief Valve Safety Valve ZAX60 ZAX70

Product Specification

4608478 396776 Main Relief Valve Pressure Relief Valve Safety Valve ZAX60 ZAX70 EX60-5 ZX75 ZX85 HD307 Excavator Parts

Product Description

The GVO excavator relief valve, compatible with Hitachi excavators, is a key pressure control valve in the hydraulic system. It regulates hydraulic pressure, releases overload pressure, protects core hydraulic components such as the main valve and hydraulic pump, and ensures stable operation of the entire machine.

This relief valve is precision-machined from high-quality steel and undergoes overall quenching treatment. Equipped with oil-resistant and high-pressure-resistant seals, it boasts excellent sealing performance, impact resistance, and wear resistance. Suitable for the high-pressure hydraulic conditions of excavators, it effectively prevents internal leakage, pressure loss, operational instability, and vibration.

Product Introduction

This GVO cartridge-type main relief valve is a dedicated distribution valve and main pressure protection accessory for Hitachi's classic small and medium-sized earthmoving excavators. It is perfectly compatible with five mainstream models—ZX60, ZX70, EX60-5, ZX75, and ZX85—which have a large market presence. It is a 1:1 replica of the original factory valve bore size, thread specifications, cartridge stroke, and valve core pressure adjustment structure, making it an indispensable core component for overload safety protection in the hydraulic system of small excavators.

This series of Hitachi excavators, ranging from 6 to 8.5 tons, is widely used in urban and rural infrastructure trenching, landscaping renovation, municipal pipeline excavation, rural homestead leveling, interior demolition, small-scale earthmoving backfilling, and fishpond and river dredging—all involving fragmented and high-frequency reciprocating operations. During operation, the frequent bucket action on hard soil and rocks, along with the frequent arm retraction and braking, causes frequent pressure fluctuations in the hydraulic circuit.

The relief valve can dynamically monitor the main pump's output oil pressure in real time. Once the system pressure exceeds the rated safety value, it quickly opens to relieve pressure, guiding excess hydraulic oil back to the oil tank. This fundamentally avoids a series of costly repair failures such as wear and tear on the main hydraulic pump plunger, damage to the distributor plate, damage to the multi-way valve orifice, high-pressure oil pipe rupture, and internal leakage in the travel motor. At the same time, the relief valve directly determines the maximum pressure of the entire system, directly affecting the digging force, speed, and coordination. Many older ZX60, ZX70, ZX75, and ZX85 machines on the market suffer from common problems such as weak digging power, uneven digging, engine stalling and speed drop under heavy load, slow boom descent, high hydraulic oil temperature, and sluggish and weak movements. The root cause of most of these failures is the wear of the original relief valve core and the fatigue failure of the pressure spring, which leads to a decrease in the locking capacity.

Packaging & Shipping

We use high-strength, environmentally friendly paper export packaging, which is reinforced, cushioned, and moisture-proof, suitable for long-distance international logistics transportation, and meets cross-border freight and environmental protection standards. International transportation adopts formal cross-border logistics, with full tracking of logistics information and supporting customs clearance documents to ensure smooth customs clearance and timely delivery of goods overseas.

Company Introduction

The GVO brand is a manufacturer of hydraulic components. We mainly produce the most comprehensive range of pilot pumps, gear pumps, relief valves, hydraulic pumps, electrical components, hydraulic parts, engine assemblies, traveling assemblies, rotating assemblies, distribution valves, and other components.

We are factory direct sellers without any middlemen profiting from price differences. The quality is definitely the best for you because we are the ones who produce them. We cannot tarnish our reputation. The prices are also the most favorable for you. There is a stable delivery speed.

We value every customer and provide you with the best service. We offer pre-sale, in-sale, and after-sale guarantees. Any problems will definitely be resolved for you. We are always available to serve you.