sequence valve spool for XCMG ZL50G/ZL50GL Wheel Loader

product parameters

Product Name: Sequence Spool
Applicable Model: XCMG ZL50G, ZL50GL Wheel Loader
Matching Valve: D32 pilot multi-way valve
Matching Parts: Sequence valve seat, adjusting spring, O-rings
Material: Alloy structural steel, quenched and precision ground
Sealing Type: Clearance throttling spool
Function: Control valve opening/closing to realize hydraulic sequence control
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, cracking pressure calibration, pressure holding test, cycle durability test

Applicable Scenarios

.Installed inside the sequence valve seat of D32 multi-way valve, it enforces the sequence of boom and bucket compound operations. Widely used in mines, sand yards, earthwork and cargo terminals.

• Machined strictly per original drawing, consistent dimension and notch profile for reliable interchangeability
• Quenched alloy steel with uniform surface hardness, excellent abrasion resistance against contaminants in hydraulic oil
• Pressure balance grooves eliminate hydraulic clamping, ensure smooth spool travel and consistent response
• Optimized notches deliver precise cracking pressure, gentle opening and no hydraulic shock
• Precisely controlled clearance balances smooth sliding and low internal leakage, maintain stable sequence logic
• Cost-saving single-part repair solution; replace only the spool instead of whole valve section
• Individual pressure and dimension inspection for stable batch quality, low risk of on-site failure
• Fully compatible with original sequence seat, spring and seals, simple assembly and short downtime

FAQ 

Q：What symptoms occur when the sequence spool is worn and scratched?
A：Disordered hydraulic sequence, drifting cracking pressure, delayed or premature operation, spool sticking and unstable compound movement.

Q：Does disordered sequence always mean the spool is damaged?
A：No. Check spring fatigue and O-ring leakage first. Exclude seat damage before confirming spool wear.

Q：Can a lightly scratched spool be polished for long-term use?
A：Polishing is only for emergency. Modified dimension changes pressure characteristic and leads to recurring sequence fault. New spool is recommended.

Q：Can sequence spool interchange with metering or overload spool?
A：Not interchangeable. Notch shape and pressure response curve differ. Wrong assembly causes disordered sequence and operation risk.

Q：What should be noted during disassembly and assembly?
A：Clean the assembly thoroughly, protect seat passage, lubricate with clean oil, replace O-rings and calibrate cracking pressure after installation.

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