Spool Valves: An Overview

Introduction

Spool valves are used across various industries for different tasks.
Utilized in both hydraulics (oil as energy source) and pneumatics (air as energy source).
Control the flow direction of the energy source by switching paths for oil or air.

A spool valve is a cylinder inside a sealed outer case.
Ports: Chambers drilled through the case from one side to another.
Function: Spool moves within the sealed case to block or open ports based on spool position.
Movement Methods:
- Manually (button or lever)
- Control system (solenoid actuator)

Pushing the spool within housing opens or blocks the pathways between ports.
Examples of operational methods:
- Solenoid at each end
- Spring return mechanism

Ports Configuration:
- Port 1: Inlet (air supply)
- Port 2: Pneumatic cylinder extend connection
- Port 3: Exhaust
Normal State:
- Actuator not operated → Spool blocks air flow at Port 1
- Cylinder retracted (Ports 2 and 3 connected)
- Air escapes through exhaust (Port 3)
Working Position:
- Actuator operated → Spool position changes, cylinder extends
- Air flows from Port 1 to Port 2, blocking exhaust (Port 3)
- Valve Type: 3/2 valve (3 ports, 2 spool positions)

Different configurations: 4/2, 5/3 valves, etc.
Standard outer casing with different spool profiles.
Lands: Blocking parts of spool raised above the core; altering configurations changes port pathways.

Spool valves control hydraulic or pneumatic components by managing the flow of energy sources.
Energy sources/components connect via ports in the valve's outer casing.
Multiple operational methods: button, lever, solenoid.
Nomenclature: 3/2, 5/3 etc., where numbers indicate ports and spool positions.