The 803000115 is a balance valve (also referenced as a balancing valve core, model SBPHC260) used in the hydraulic system of XCMG truck cranes. It is primarily associated with the boom telescoping circuit on QY25K series models .

1. Installation Location
This valve is installed in the hydraulic circuit of the boom telescoping cylinder. On the QY25K series, it functions as a hydraulic lock (гидрозамок) for the boom extension cylinder, mounted directly on or near the cylinder to control oil flow during telescoping operations .

2. Function
The balance valve serves as a load-holding device, preventing the boom from drifting or retracting unintentionally due to gravity or external load when the control valve is in neutral. It maintains controlled back-pressure in the return line, ensuring smooth and stable boom retraction and extension. This is a critical safety function for telescoping operations on truck cranes.

3. Maintenance and Service
The valve is a precision hydraulic component and is not user-serviceable internally. If the boom fails to hold position, drifts during operation, or retracts too quickly, the balance valve should be inspected for internal wear, contamination, or seal damage. The assembly is typically replaced as a complete unit if a fault is confirmed. Before removal, fully depressurize the hydraulic system.

4. Important Notes
Always verify the part number 803000115 matches the original specification for the specific crane model (QY25K-II, QY25K5-I, QY25K5A, etc.) before installation . Confirm compatibility with the SBPHC260 valve core reference where applicable. After replacement, test the boom telescoping function through its full range to confirm proper load-holding and controlled movement.