1. Core Valve Introduction
Relief Valves（溢流阀）
As key pressure protection components in the excavator hydraulic system, relief valves limit the maximum working pressure of oil circuits. When system pressure exceeds the preset threshold, they open to discharge excess hydraulic oil, shielding hydraulic pumps, main control valves, cylinders and pipelines from overload damage, and maintaining stable pressure of the whole hydraulic system during heavy-load digging, lifting and slewing operations.
Holding Valves（保持阀）
Installed on boom, arm or bucket cylinder circuits, holding valves lock the oil chamber of actuators tightly when the operation stops. They prevent the working arm from sinking due to load gravity or internal leakage, sustain the position of attachments reliably, improve operation safety and positioning accuracy of the hydraulic system, and avoid accidental dropping of heavy loads.
2. Applicable Volvo Excavator Models
- Medium-duty series: Volvo EC200D, EC210, EC250D, EC290
These mid-size excavators adopt matched Kawasaki hydraulic main valves, widely used in earthmoving, road construction and municipal works. Relief valves and holding valves need to match the original pressure parameters and mounting dimensions to keep the hydraulic system consistent with factory performance.
- Large-duty series: Volvo EC360, EC460
Heavy-duty large excavators face higher impact pressure and heavier loads. Specially calibrated relief valves provide high-pressure overload protection, while heavy-load holding valves enhance anti-sinking performance for deep excavation and hoisting scenarios.
3. Kawasaki KMX15RA / KMX15RB Main Control Valves Matching Features
KMX15RA and KMX15RB are mainstream multi-way main control valves produced by Kawasaki, perfectly compatible with the above Volvo excavator fleet:
1. Both valve models adopt modular integrated structure, with independent oil circuit stations for boom, arm, travel and slewing functions. Relief valves are embedded in each valve section for individual branch pressure regulation; holding valves are mounted on the executive port of the valve block.
2. KMX15RA is the base specification, and KMX15RB is an upgraded version with optimized flow distribution and shock absorption. Their valve cavity mounting interfaces, thread sizes and pressure setting ranges are unified, so relief valves and holding valves can be interchanged for matched models.
3. Matching parameters: Relief valves support preset pressure ranging from 24MPa to 35MPa to fit different working branches; holding valves adapt to high backpressure conditions of large-displacement cylinders, effectively reducing hydraulic system leakage under long static load.
4. Matching & Installation Notes
1. Select relief valves strictly according to the branch rated pressure of KMX15RA/RB valves; mismatched pressure settings will cause weak digging force or frequent overflow heating of the hydraulic system.
2. Holding valves must be installed in the specified direction marked on the valve body; reversed installation will lead to failure of load holding and serious safety hazards.
3. Replace the matching sealing kits during overhaul, and clean valve cavities thoroughly to avoid particle blockage leading to valve sticking and hydraulic system malfunction.
5. Application Advantages
- Direct interchange with OEM parts for Volvo EC series excavators and Kawasaki KMX15 series valves, no modification to the original hydraulic system is required.
- Optimized valve core wear resistance adapts to harsh construction site oil pollution, extending the service cycle of the hydraulic system.
- Independent pressure adjustment for each circuit facilitates on-site debugging for different construction working conditions.
