Product Overview

The Bosch Rexroth Z2S10-2-3X/ is a pilot operated check valve in sandwich plate design, engineered for hydraulic actuator locking, position holding and controlled release.

The Z2S is a releasable check valve designed to provide leakage-free blocking of one or two actuator ports, including during extended machine standstill. Free flow is permitted in the defined direction, while reverse flow is blocked until the control spool hydraulically releases the check element.

For Z2S10-2-3X/:

• Z2S: Pilot operated check valve, sandwich plate
• 10: Nominal size NG10
• -: Leakage-free blocking in channels A and B
• 2: 3 bar cracking-pressure configuration
• 3X: Component series 30–39

Bosch Rexroth’s official NG10 selector identifies cracking-pressure configurations of 1.5, 3, 6 and 10 bar. Therefore, version 2 corresponds to 3 bar.

For OEM replacement and retrofit projects, the valve can be engineered for in-place interchangeability based on the original configuration, mounting interface, cracking pressure and hydraulic circuit, followed by 100% simulated working-condition testing before shipment.

Technical Specifications

Z2S10-2-3X/ — R900421985

• Manufacturer: Bosch Rexroth
• Material Number: R900421985
• Model: Z2S10-2-3X/
• Product Type: Pilot Operated Check Valve
• Design: Sandwich Plate Valve
• Nominal Size: NG10
• Component Series: 3X
• Blocking: Leakage-free blocking of both A and B channels
• Cracking Pressure: 3 bar
• Maximum Operating Pressure: 315 bar
• Maximum Flow: 160 L/min in the indexed material-specific product record
• Flow Function: Free flow in the permitted direction; pilot-released reverse flow
• Control: Hydraulic pilot-operated control spool
• Pre-opening: Yes / standard
• Mounting Pattern: ISO 4401-05-04-0-05
• Seal Material: NBR
• Hydraulic Fluids: HL, HLP, HLPD, HVLP, HVLPD, HFC
• Approx. Weight: 2.66 kg
• Plug Screw: SW30
• Plug Screw Torque: 40 + 5 Nm
• Mounting Screws: ISO 4762 M6, 4 pieces
• Installation: Vertical stacking / sandwich mounting

Z2S10A1-3X/ — R900407424

• Manufacturer: Bosch Rexroth
• Material Number: R900407424
• Model: Z2S10A1-3X/
• Product Type: Pilot Operated Check Valve
• Nominal Size: NG10
• Component Series: 3X
• Blocking: Channel A
• Spool Symbol: A1 → A2
• Cracking Pressure: 1.5 bar
• Maximum Operating Pressure: 315 bar
• Maximum Flow: 120 L/min
• Mounting: Sandwich Plate
• Mounting Pattern: ISO 4401-05-04-0-05
• Pre-opening: Standard
• Seal: NBR
• Approx. Weight: 2.64 kg
• Control: Mechanical control spool / hydraulic pilot release

Z2S10B1-3X/ — R900407434

• Manufacturer: Bosch Rexroth
• Material Number: R900407434
• Model: Z2S10B1-3X/
• Product Type: Pilot Operated Check Valve
• Nominal Size: NG10
• Component Series: 3X
• Blocking: Channel B
• Spool Symbol: B1 → B2
• Cracking Pressure: 1.5 bar
• Maximum Flow: 160 L/min in the currently indexed material record
• Mounting: Sandwich Plate
• Mounting Pattern: ISO 4401-05-04-0-05
• Pre-opening: Standard
• Seal: NBR
• Approx. Weight: 2.64 kg

The currently indexed Bosch Rexroth product record specifies 350 bar for this material-specific listing, while the current official NG10 3X selector shows 315 bar for the series. The exact material-number datasheet revision should therefore control the final commercial specification.

Z2S6-1-6X/ — R900347495

• Manufacturer: Bosch Rexroth
• Material Number: R900347495
• Model: Z2S6-1-6X/
• Product Type: Pilot Operated Check Valve
• Design: Sandwich Plate
• Nominal Size: NG6
• Component Series: 6X
• Blocking: Channels A and B
• Spool Symbol: A1 → A2, B1 → B2
• Cracking Pressure: 1.5 bar
• Maximum Operating Pressure: 315 bar
• Maximum Flow: approximately 60 L/min
• Mounting Pattern: ISO 4401-03-02-0-05
• Seal: NBR
• Approx. Weight: 0.96 kg
• Control: Mechanical control spool
• Pre-opening: Optional depending on special version

Z2S6-40B Verification Status

The supplied Z2S6-40B does not map cleanly to the current Bosch Rexroth 6X ordering structure.

Third-party documentation lists:

• Nominal Size: NG6
• Design: 40
• Maximum Working Pressure: 31.5 MPa
• Maximum Flow: 60 L/min
• Opening Pressure: 0.15 / 0.3 / 0.7 MPa

However, these figures are not treated here as current Bosch Rexroth official specifications. The currently accessible Bosch Rexroth NG6 selector uses the 6X series structure.

For commercial publication:

Z2S6-40B — Legacy / Revision-Specific / Verification Required

is the safer designation.

Z2FS Series — Separate Product Category

The original title also includes Z2FS Throttle Check Valve, which should be separated from Z2S.

Bosch Rexroth officially defines Z2FS as a:

Double Throttle Check Valve

For example:

Z2FS6-2-4X/1QV — R900481623

is specified as:

• Nominal Size: NG6
• Maximum Flow: approximately 80 L/min
• Maximum Operating Pressure: 315 bar
• Throttle Check Valve: Both A and B sides
• Adjuster: Setscrew with locknut and protective cap
• Flow Version: Fine adjustment / pilot-flow limitation
• Seal: FKM
• Series: 4X

The /2QV configuration provides the standard main-flow limitation version.

Therefore:

Z2S = Pilot Operated Check Valve

Z2FS = Double Throttle Check Valve

These should be separate SEO entities.

Displacement, Maximum Speed and Peak Pressure

These are hydraulic valves rather than pumps or motors.

• Displacement: Not applicable
• Maximum Speed: Not applicable
• Z2S10-2-3X Maximum Operating Pressure: 315 bar
• Z2S10-2-3X Maximum Flow: 160 L/min in the indexed material-specific record
• Cracking Pressure: 3 bar
• Peak Pressure: No separate verified model-specific peak-pressure rating is stated in the manufacturer documentation used here

Key Technical Advantages

1. Reliable Actuator Load Locking

The Z2S is designed to provide leakage-free blocking of one or two actuator ports, supporting stable actuator positioning during machine standstill.

2. Pre-Opening for Damped Decompression

Pre-opening provides controlled decompression before full valve opening, reducing switching shock, noise and potential component wear.

3. Control-Spool and Seat-Valve Architecture

The combination of a control spool with the check element provides both reliable shutoff and hydraulically controlled release.

4. Multiple Cracking Pressures

NG10 Z2S configurations are available with 1.5, 3, 6 and 10 bar cracking-pressure settings, allowing better matching to circuit pressure-drop requirements.

5. ISO Standard Sandwich Mounting

The NG10 configuration uses the ISO 4401-05-04-0-05 mounting interface, while NG6 uses ISO 4401-03-02-0-05. This supports standardized valve-stack and hydraulic-manifold integration.

Application Areas

Typical applications include:

• Hydraulic Cylinder Load Holding
• Vertical Lifting Equipment
• Hydraulic Presses
• Injection Molding Machines
• Machine Tools
• Material Handling Equipment
• Hydraulic Clamping Systems
• Construction Machinery
• Hydraulic Power Units
• Position-Holding Circuits
• Industrial Automation
• High-Pressure Hydraulic Manifolds

The Z2S is particularly suitable where an actuator must remain hydraulically locked during standstill and be released through a controlled pilot operation.

Expert Maintenance Tips

1. Verify the Complete Type Code

Do not order solely by Z2S6 or Z2S10.

Confirm:

Blocking Configuration + Cracking Pressure + Component Series + Special Version

For example, Z2S10-2-3X/, Z2S10A1-3X/ and Z2S10B1-3X/ are different hydraulic configurations.

2. Verify Pre-Opening

For high-pressure actuators with significant stored fluid volume, confirm whether the original valve uses pre-opening. Rexroth documents the effect of non-pre-opening versions on switching shock and noise.

3. Inspect the Sandwich Interface

Before installation, inspect the valve contact surface, O-rings, mounting screws and manifold cleanliness. Rexroth specifies surface-quality requirements for the valve contact interface.

4. Calculate Mounting-Screw Length

For sandwich-mounted Z2S valves, mounting-screw length and tightening torque depend on the components installed above and below the valve. Do not reuse a fixed screw length across different stack configurations.

5. Check the Control Spool and Seat

If actuator drift, reverse leakage or incomplete unlocking occurs, inspect the control spool, poppet/ball, seat and contamination condition.

6. Maintain Hydraulic Cleanliness

Effective filtration reduces the risk of control-spool sticking, seat contamination and abnormal leakage. Bosch Rexroth explicitly recommends effective filtration to prevent faults and extend component service life.