Product Overview

The Bosch Rexroth SL10GA2-4X is a pilot operated check valve / isolator valve designed for reliable hydraulic locking of one actuator port and controlled release through hydraulic pilot pressure.

The SL/SV 4X family uses a housing, seat poppet, compression spring and control spool. The valve permits free flow from A to B, while reverse flow from B to A is blocked until sufficient pilot pressure is applied. The SL configuration uses external pilot-oil return.

The complete model SL10GA2-4X/M can be decoded as:

• SL: Pilot operated check valve with external pilot-oil return
• 10: Nominal size NG10
• G: Threaded connection
• A: With pre-opening
• 2: Cracking pressure version 2
• 4X: Component series 40–49

For NG10, Bosch Rexroth specifies cracking pressures of 1.5, 3, 6 and 10 bar. Therefore, version 2 corresponds to 3 bar. The maximum operating pressure is 315 bar.

The model SL10GA2-4X/M is cross-referenced to Bosch Rexroth Material Number R900450776 in current product documentation.

For industrial replacement applications, an engineered equivalent can be produced for in-place interchangeability, followed by 100% simulated working-condition testing covering pilot operation, load locking and valve response.

Technical Specifications

SL10GA2-4X / R900450776

• Manufacturer: Bosch Rexroth
• Material Number: R900450776
• Model: SL10GA2-4X/M
• Product Type: Pilot Operated Check Valve / Isolator Valve
• Series: SL/SV 4X
• Nominal Size: NG10
• Component Series: 4X
• Connection: Threaded Connection
• Connection Code: G
• Pre-opening: With pre-opening
• Cracking Pressure Version: 2
• Cracking Pressure: 3 bar
• Maximum Operating Pressure: 315 bar / 31.5 MPa
• Minimum Pilot Pressure: 5 bar
• Maximum Pilot Pressure: 315 bar
• Flow Direction: Free A → B; B → A by pilot opening
• Pilot Oil Return: External
• Control Method: Hydraulic pilot pressure
• Maximum Flow: Determined from Bosch Rexroth Δp–qV characteristic curves rather than a single universal value.
• Viscosity Range: 2.8–500 mm²/s
• Hydraulic Fluid Cleanliness: ISO 4406 Class 20/18/15
• Installation Position: Any
• Ambient Temperature, NBR: -30 to +80 °C
• Ambient Temperature, FKM: -20 to +80 °C
• Approx. Weight: 2.1 kg for the NG10 threaded configuration.
• Pilot Control: Through pilot port X
• Electrical Solenoid: Not applicable as a standalone SL10GA2-4X valve

Displacement and Maximum Speed

Displacement and maximum rotational speed are not applicable because SL10GA2-4X is a hydraulic valve rather than a pump or hydraulic motor.

Peak Pressure

The published Bosch Rexroth specification identifies 315 bar as maximum operating pressure. No separate standard peak-pressure value is assigned here without a verified model-specific transient rating.

Key Technical Advantages

1. Two-Stage Pre-Opening

The A version provides pre-opening.

When pilot pressure is applied through the X port, the control spool first actuates the pre-opening element before the main seat poppet is released. Bosch Rexroth describes this arrangement as providing controlled decompression and helping avoid switching shocks.

This is valuable for hydraulic systems with:

• Large actuator pressure volumes
• High load inertia
• Sensitive mechanical structures
• Frequent lock/unlock cycles

2. 315 Bar High-Pressure Capability

The SL/SV 4X family is specified for a maximum operating pressure of:

315 bar / 31.5 MPa

This makes the SL10 suitable for demanding industrial hydraulic circuits requiring secure actuator isolation and load holding.

3. Seat-Poppet and Control-Spool Architecture

The valve combines a spring-loaded seat poppet with a hydraulically controlled spool.

This arrangement provides:

• Reliable reverse-flow blocking
• Controlled pilot opening
• Compact hydraulic isolation
• Stable actuator load holding

The resulting architecture is well suited to cylinders, lifting systems and industrial clamping applications.

4. 3 Bar Cracking Pressure

For NG10, Bosch Rexroth offers four cracking-pressure settings:

• Version 1: 1.5 bar
• Version 2: 3 bar
• Version 3: 6 bar
• Version 4: 10 bar

Therefore, the “2” in SL10GA2-4X identifies the 3 bar configuration and must be retained when replacing the valve.

5. External Pilot-Oil Return

The SL type uses external pilot-oil return, allowing the pilot circuit to be separately integrated into the hydraulic system.

This configuration becomes particularly useful where pilot return pressure, unloading behavior or hydraulic sequencing must be controlled independently.

6. Modular Industrial Configuration

Bosch Rexroth provides the SL/SV family with different mounting arrangements, cracking pressures, pre-opening configurations and accessory options.

This modularity supports OEM hydraulic systems as well as replacement and retrofit projects where valve interface and control behavior must be matched precisely.

Application Areas

Typical applications for the SL10GA2-4X include:

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

It is particularly suitable where an actuator must remain hydraulically locked during standstill and be released smoothly through a pilot signal.

Expert Maintenance Tips

1. Verify the External Pilot Circuit

Because SL10 uses external pilot-oil return, check:

• X-port pilot pressure
• Y-port return path
• Return-line back pressure
• Pilot-line cleanliness

Incorrect pilot plumbing can prevent reliable unlocking even when the main valve body is mechanically correct.

2. Maintain the Pre-Opening Configuration

The difference between:

A = With Pre-opening

and

B = Without Pre-opening

is functionally significant.

Replacing an A-type valve with a B-type valve without evaluating the hydraulic dynamics can increase decompression shock, noise and mechanical loading.

3. Match the 3 Bar Cracking Pressure

Do not identify the valve only as SL10.

The complete configuration must be verified:

SL10GA2-4X

The “2” means 3 bar cracking pressure for NG10. Using a different cracking-pressure version can change the circuit’s opening behavior and pressure-loss characteristics.

4. Use the Correct Installation Torque

For the NG10 threaded configuration, Bosch Rexroth specifies an installation tightening torque of:

40 Nm

with a medium-strength thread locker.

5. Maintain Hydraulic Cleanliness

Bosch Rexroth specifies a maximum hydraulic-fluid contamination level of:

ISO 4406 Class 20/18/15

For pilot-operated valves, clean hydraulic fluid is essential for reliable spool movement, sealing and repeatable pilot response.