INDUSTRY COMPONENT

Spool

Precision spool component for servo valves controlling fluid flow in industrial systems.

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Component Specifications

Definition
A spool is a cylindrical sliding component within a servo valve that precisely regulates hydraulic or pneumatic fluid flow by moving within a valve body to open, close, or meter ports. It converts electrical control signals from the servo valve's torque motor into mechanical displacement, enabling accurate control of fluid pressure, flow rate, and direction in industrial automation systems.
Working Principle
The spool operates on the principle of axial displacement within a matched bore. When the servo valve's torque motor receives an electrical signal, it generates torque that moves the spool via a flapper or direct linkage. This displacement changes the overlap between spool lands and valve ports, modulating fluid flow proportionally to the input signal. Feedback mechanisms (mechanical, electrical, or hydraulic) ensure precise positioning for closed-loop control.
Materials
Typically made from hardened alloy steels (e.g., AISI 52100, 440C stainless steel) or carburized steels for wear resistance. Surface treatments include chrome plating, nitriding, or DLC coatings to reduce friction and corrosion. Materials must exhibit high dimensional stability, low thermal expansion, and compatibility with hydraulic fluids (e.g., petroleum-based, synthetic, or fire-resistant fluids).
Technical Parameters
ParameterTypical rangeNotes & selection driver
Response Time<10 ms
Surface FinishRa 0.1-0.4 μm
Spool Clearance5-15 μm
Temperature Range-40°C to 120°C
Diameter Tolerance±0.002 mm
Operating PressureUp to 350 bar

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards
ISO 4401, DIN 24342, ISO 10770-1

Parent Products

This component is used in the following industrial products

Servo Valve

A precision electro-hydraulic control valve that regulates fluid flow in response to an electrical input signal.

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Pressure Control Valves

Valves that regulate hydraulic pressure within a die cushion system to control cushion force during stamping operations.

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Spool and Sleeve Assembly

A precision spool and sleeve assembly that controls fluid flow in a servo control valve.

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Engineering Analysis

Risks & Mitigation
  • Contamination leading to spool sticking or wear
  • Improper alignment causing leakage or reduced response
  • Material incompatibility with hydraulic fluids
  • Overpressure damaging spool lands
FMEA Triads
Trigger: Fluid contamination (particles, water)
Failure: Spool sticking, increased friction, or scoring
Mitigation: Implement filtration systems (e.g., 3 μm filters), regular fluid analysis, and use sealed reservoirs.
Trigger: Wear from cyclic operation
Failure: Increased clearance, leakage, loss of precision
Mitigation: Use hardened materials with coatings, maintain proper lubrication, and schedule preventive replacements based on operating hours.
Trigger: Improper installation or alignment
Failure: Binding, uneven wear, reduced valve efficiency
Mitigation: Follow torque specifications during assembly, use alignment tools, and conduct post-installation testing.

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
Dimensional tolerances per ISO 286, surface finish per ISO 1302, and pressure ratings per ISO 10770-1.
Test Method
Testing includes dimensional verification (CMM), leakage tests (ISO 6403), response time measurement (step input), and endurance cycling (ISO 10770-1).

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
Verify equipment lists, process limits, capacity, and representative production evidence.
Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
Check the legal entity, factory address, ownership, certifications, and direct contacts.

Compare the published product scope and source details, then include your specifications and quantity in an enquiry.

Manufacturers of Spool

Manufacturer profiles associated with Spool.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the primary function of a spool in a servo valve?

The spool precisely controls fluid flow by moving axially to open, close, or meter ports, enabling accurate regulation of pressure, flow rate, and direction based on electrical input signals.

How do you maintain a servo valve spool?

Maintain fluid cleanliness (ISO 4406 class 16/14/11 or better), monitor for wear or contamination, and follow manufacturer guidelines for inspection intervals. Replace if tolerances exceed specifications or scoring is visible.

Can spools be interchanged between different servo valve brands?

Generally not interchangeable due to precise dimensional and material specifications unique to each valve model. Always use OEM or certified compatible parts to ensure performance and safety.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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