Pneumatics · Rotary Spool Valves
4/3-way pneumatic directional control valves: choosing the right HDV series rotary spool valve
A 4/3-way directional control valve controls four ports across three switching positions – and the third one, the center position, determines how your system behaves when idle. STASTO supplies 4/3-way pneumatic directional control valves as rotary spool valves in the HDV series: manually actuated via a detented lever, with a pressure range of 0…12 bar and port sizes from 1/8" to 1/2". Here you'll find the key technical distinctions, a selection table covering all HDV variants, and a direct link to the product range.
HDV Series at a Glance
Why Series HDV
Four Features That Determine the Selection
The rotary spool valves of the HDV series cover the 4/3 way symbol purely mechanically – from center position to size to port orientation.
Two Center Positions in the Range
The blocked center position (HDV-4001, HDV-4002, HDV-4004) holds the actuator in place, while the vented center position (HDV-4101, HDV-4102, HDV-4104) makes it pressure-free. You choose the switching behavior, not a compromise.
Purely Mechanical – No Electrics
All 4/3 way valves in the HDV series are operated via a detented hand lever. For manual controls, setup operations, and adjustment stations, this means: no wiring, no control electronics, clear switching position.
Sizes 1/8" to 1/2"
Port threads of 1/8", 1/4", and 1/2" with DN 5, 7, and 9 mm and flow rates from 480 to 1050 Nl/min. This means the valve fits everything from small clamping cylinders to larger actuators.
Selectable port orientation
The "-I" version (bottom ports) and "-N" version (side ports) suit the installation location in the control panel, switch cabinet, or machine frame. Identical circuit diagram, different piping orientation.
Basics
4/3-Way Valve – Circuit Diagram and Operating Principle
The first number indicates the number of ports, the second the number of switching positions. A 4/3-way valve therefore has four ports – compressed air supply, exhaust, and two working ports – as well as three switching positions: two working positions plus the center position.
Rotary Spool Operating Principle
- Rotary spool element
- A rotatable spool element connects the channels with one another – the operating principle of the HDV series rotary spool valves.
- Detented hand lever
- The lever holds the selected position mechanically until it is deliberately changed. The switching position is visible.
- Momentary vs. spring-return distinction
- With momentary or spring-return hand valves, the valve returns to its initial position as soon as the operator releases it.
- Four ports
- Compressed air supply, exhaust, and two working ports to the actuator.
Blocked vs. Exhausted Center Position
- Blocked center position
- Both working ports are closed, trapping the air inside the actuator. Parts: HDV-4001-I, HDV-4001-N, HDV-4002-I, HDV-4002-N, HDV-4004-N.
- Exhausted center position
- Both working ports are vented to atmosphere, relieving pressure in the actuator and allowing it to move freely by hand. Parts: HDV-4101-I, HDV-4101-N, HDV-4102-N, HDV-4104-N.
- Pass-through center position
- A well-known symbol convention in directional valve technology. In the HDV range, only the blocked and exhausted center positions are available; please contact us directly for other circuit diagrams.
Type Code and Special Version
- 40xx / 41xx
- The digit sequence 40xx indicates the blocked center position, 41xx the vented center position.
- -I and -N
- "-I" stands for bottom ports, "-N" for side ports.
- HDV-4004-N-S01
- Special version 1/2", DN 9 mm, blocked center position, internal parts chrome-plated brass, hand lever and screws made of stainless steel. Price on request.
- Accessories and Spare Parts
- RE-HDV-4002-N (rotary spool element) and PC-HDV-4..2-N (plastic cover); further spare parts by size available on request.
Selection guide
All 4/3-Way Valves of the HDV Series Compared
Selection is based on three criteria: center position, size, and port location. "–" means: value not specified in the item master data, please inquire.
| HDV-4001-I / -N | HDV-4002-I / -N | HDV-4004-N | HDV-4101-I / -N | HDV-4102-N | HDV-4104-N | |
|---|---|---|---|---|---|---|
| Center Position | blocked | blocked | blocked | exhausted | exhausted | exhausted |
| Connection | 1/8" | 1/4" | 1/2" | 1/8" | 1/4" | 1/2" |
| DN | 5 mm | 7 mm | 9 mm | 5 mm | 7 mm | 9 mm |
| Flow rate | 480 Nl/min | 1050 Nl/min | – | 480 Nl/min | 1050 Nl/min | 1050 Nl/min |
| Pressure range | 0…12 bar | 0…12 bar | 0…12 bar | 0…12 bar | 0…12 bar | 0…12 bar |
| Actuation | Hand lever, detented | Hand lever, detented | Hand lever, detented | Hand lever, detented | Hand lever, detented | Hand lever, detented |
| Port orientation | bottom / side | bottom / side | side | bottom / side | side | side |
Product Range
4/3-way valves and matching categories in the shop
From the HDV series rotary spool valve to complementary directional valve ranges – find the matching sections in the STASTO shop here.
Selection
Three steps to the right 4/3-way valve
Center position, size, port orientation – in this order, you'll quickly find the right version.
Define behavior at standstill
Should the actuator hold its position? Then choose a closed center position. Should it be pressure-free and manually movable? Then choose a vented center position.
Determine size based on flow rate
Smaller actuators with 1/8" and DN 5 mm (480 Nl/min), larger loads with 1/4" (DN 7 mm) or 1/2" (DN 9 mm) and 1050 Nl/min. The valve flow rate must match the cylinder volume and piston speed – if you're unsure, we'll work through the calculation with you.
Choose port orientation and installation setup
Bottom ports (version "-I") for panel and front-plate mounting, side ports (version "-N") for piping along the machine frame.
In Practice
Typical applications
The following use cases are technical derivations from the switching behavior – common wherever a motion is deliberately actuated by the operator.
Manual control of double-acting actuators
Two working ports for extending and retracting, with the mid-position as a defined rest state. Typically used on clamping, pressing, and feed stations.
Setup and changeover operation
The vented mid-position depressurizes the actuator, allowing tools or fixtures to be positioned by hand.
Holding intermediate positions
With a blocked mid-position, an approached position can be mechanically fixed, as long as no leakage occurs.
Test stations and special-purpose machines
Suitable wherever the detented hand lever visibly indicates the switching position and a motion is deliberately actuated.
Manual Override for System Control
Manual valves are typically used as a manual level alongside the actual automated control system.
Workshop Setups and Fixtures
For simple setups without control electronics: one valve, one lever, three clearly defined positions.
Procurement
Ordering, availability, and consultation
Prices and availability can be viewed directly in the shop; for special versions and spare parts, our technical sales team will clarify your specific case.
Availability per variant
Availability and price are shown per item in the shop. Items without a valid list price – such as special versions – are marked "Price on request."
Special versions on request
HDV-4004-N-S01 with chrome-plated brass internals as well as hand lever and screws made of stainless steel is available on request. We're happy to discuss the feasibility of further special versions.
Spare and wear parts
Rotary spool element RE-HDV-4002-N and plastic cover PC-HDV-4..2-N are listed. Availability of further spare parts and seal kits per size available on request.
Technical specifications per variant
For further technical specifications per variant, please refer to the datasheet of the respective item or contact our technical sales team.
Frequently Asked Questions
FAQ: 4/3-Way Valves
Quick answers on schematics, mid-position, and how it compares to other directional valves.
What is a 4/3-way valve?
A 4/3-way valve is a directional control valve with four ports and three switching positions. Besides the two working positions for extending and retracting, it has a mid-position that determines how the actuator behaves at standstill. The four ports are the compressed air supply, exhaust, and two working ports to the load.
What's the difference between closed-center and exhausting mid-position?
With a closed-center (blocked) mid-position, both working ports are closed, air stays trapped in the actuator, and the position is held. With an exhausting mid-position, both working ports are vented to atmosphere, the actuator becomes pressure-free, and it can be moved by hand. Closed-center is available in the HDV-4001, HDV-4002, and HDV-4004; exhausting center in the HDV-4101, HDV-4102, and HDV-4104.
Is the HDV series also available with an open-center mid-position?
The HDV range covers closed-center and exhausting mid-positions. An open-center (through-flow) mid-position exists as a symbol in directional valve technology; for other schematics, please contact us directly.
What is a rotary spool valve?
A rotary spool valve connects the ports via a rotating spool element. In the HDV series, it's operated by a detented hand lever that mechanically holds the selected position until it's deliberately changed.
What's the difference between a 4/3-way valve and a 5/2-way valve?
A 4/3-way valve has four ports and three positions including a mid-position, while a 5/2-way valve has five ports and only two positions with no intermediate stage. 5/2 and 5/3-way valves to ISO standard can be found in a separate category in our shop.
Which body size do I need?
Sizing depends on the required flow rate: 1/8" with a 5 mm bore delivers 480 Nl/min, while 1/4" with a 7 mm bore and 1/2" with a 9 mm bore deliver up to 1050 Nl/min. Valve flow must match cylinder volume and the desired piston speed – we're happy to work through this calculation with you on request.
What do the suffixes -I and -N stand for?
“-I” denotes valves with bottom ports, while “-N” denotes valves with side ports. The circuit diagram is identical – only the piping direction differs: “-I” suits console and front-panel mounting, “-N” suits piping along the machine frame.
Are spare parts available for the HDV series?
Yes, listed items include the rotary spool element RE-HDV-4002-N and the plastic cover PC-HDV-4..2-N. Please contact our technical sales team for availability of further spare parts and seal kits per body size.
Also relevant
Overview
Complementary series and circuit diagrams for your pneumatic control system.
Next Step
Choosing a 4/3-way valve – we'll help with sizing
Whether blocked or exhausting mid-position, 1/8" or 1/2": tell us your application, and we'll work out size, flow rate, and port configuration with you.