lift valve staff for XCMG ZL50G/ZL50GL Wheel Loader

product parameters

Product Name: Boom Spool
Part No.: None
Applicable Model: XCMG ZL50G, ZL50GL Wheel Loader
Matching Valve: D32 pilot multi-way valve
Material: Alloy structural steel, quenched and precision ground
Sealing Type: Clearance seal spool
Function: Control boom cylinder lifting/lowering and neutral holding
Nominal Port Size: 32mm
Medium: Anti-wear hydraulic oil for construction machinery
Working Temperature: -20℃ ~ +80℃
Inspection Items: Diameter check, concentricity test, notch profile inspection, pressure holding test, cycle durability test
Matching Parts: Valve spring, seal gaskets, overload make-up valve

Applicable Scenarios

Installed inside the boom section of D32 multi-way valve, it governs boom movement during shoveling, lifting, dumping and stacking. Widely used in heavy-duty working sites such as sand yards, mines, earthwork sites and cargo terminals.

• Manufactured according to original drawing, consistent dimension and notch profile for reliable interchangeability
• Quenched alloy steel with uniform surface hardness, strong wear resistance against particle erosion in hydraulic oil
• Pressure balance grooves eliminate hydraulic clamping, keep steady pilot operating force and smooth spring return
• Progressive flow notches provide linear speed control, no jerky boom movement, excellent fine positioning performance
• Precisely controlled clearance balances smooth sliding and low internal leakage, effectively prevent boom creeping down
• Cost-saving single-part repair solution; replace only the spool instead of the whole valve assembly
• Individual pressure and dimension inspection for consistent batch quality, low risk of stuck spool after installation
• Fully compatible with original spring, gaskets and overload valve, no trimming required during assembly

FAQ 

Q：What symptoms appear when the boom spool is worn and scratched?
A：Typical symptoms include boom creeping down, weak and slow lifting, jitter during movement, delayed return and abnormal flow distribution under compound operation.

Q：Does boom creeping always mean the spool is damaged?
A：No. Check overload make-up valve and cylinder seal leakage first. Exclude these faults before confirming spool wear.

Q：Can I polish and reuse the scratched boom spool?
A：Light dirt clogging can be cleaned temporarily. Scratched spool cannot be repaired by polishing, because it changes the clearance and leads to recurring leakage. New spool is recommended.

Q：Can boom spool and bucket spool be interchanged?
A：Not interchangeable. They have different notch shape and flow characteristic. Wrong assembly will cause abnormal speed control and safety risk.

Q：What should be noted during installation?
A：Clean valve bore thoroughly, lubricate with clean hydraulic oil, never hammer the spool. Replace gaskets and check return spring tension.

Q：What causes spool scratching most often?
A：Contaminated hydraulic oil and clogged filters are the main causes. High oil temperature and repeated high-pressure shock also accelerate wear.

Q：Do I need to readjust pressure after replacing the spool?
A：The spool itself does not set relief pressure, but pressure test is recommended after assembly to verify relief setting and boom holding performance.