R900507740 SV20PB4-4X Rexroth Pilot Check Valve 315 Bar

Product Overview

The Bosch Rexroth SV20PB4-4X / R900507740 is a hydraulically pilot-operated check valve designed for reliable actuator load locking and controlled release in high-pressure hydraulic systems.

The SV series uses a seat-poppet design with a compression spring and control spool. In the normal flow direction, hydraulic fluid can pass from A to B. In the reverse direction, the valve remains hydraulically closed until pilot pressure is applied through the control circuit.

The SV20PB4-4X configuration is identified as:

• SV: internal pilot oil return
• 20: nominal size NG20
• P: subplate mounting
• B: without pre-opening
• 4: 10 bar cracking-pressure configuration for NG20
• 4X: component series 40–49

Bosch Rexroth documentation specifies a 315 bar maximum operating pressure for the SV/SL 4X series. The NG20 subplate version has an approximate weight of 4.7 kg.

This makes the valve suitable for hydraulic systems where actuator position must remain stable during extended standstill periods.

Technical Specifications

• Manufacturer: Bosch Rexroth
• Valve Series: SV
• Valve Type: Hydraulically pilot-operated check valve / isolator valve
• Model: SV20PB4-4X/
• Material Number: R900507740
• Nominal Size: NG20
• Component Series: 4X
• Mounting: Subplate mounting
• Pilot Oil Return: Internal
• Pre-opening: No
• Cracking Pressure: 10 bar
• Maximum Operating Pressure: 315 bar
• Minimum Pilot Pressure: 5 bar
• Maximum Pilot Pressure: 315 bar
• Maximum Flow: Determined from the Bosch Rexroth characteristic curves; the overall 4X family is specified up to 550 L/min depending on nominal size/configuration.
• Flow Direction: Free A → B; B → A via hydraulic pilot opening
• Hydraulic Fluid Viscosity: 2.8–500 mm²/s
• Fluid Cleanliness: ISO 4406 Class 20/18/15 maximum
• Approx. Weight: 4.7 kg for NG20 subplate-mounted version
• Installation Position: Any
• Ambient Temperature with NBR: -30 to +80 °C
• Ambient Temperature with FKM: -20 to +80 °C

Bosch Rexroth also offers related SV20GA1-4X configurations with threaded connection and pre-opening. R900587550 is associated with SV20GA1-4X, while R900508425 corresponds to the SV20GA1-4X//12 configuration.

Key Technical Advantages

Reliable Actuator Load Locking

The SV20 isolates one actuator port and maintains hydraulic blocking during standstill, making it suitable for applications requiring stable cylinder or motor positioning.

Seat Valve Architecture

The seat-poppet construction is engineered for reliable reverse-flow blocking. The valve combines the seat poppet, spring-loaded closing mechanism and pilot-controlled spool into a compact hydraulic isolation solution.

Hydraulic Pilot Control

The valve can be released through pilot pressure rather than requiring direct mechanical actuation of the main hydraulic path. For NG20, Bosch Rexroth specifies a minimum pilot pressure of 5 bar and a maximum pilot pressure of 315 bar.

Configurable Opening Characteristics

Bosch Rexroth provides both with-pre-opening (A) and without-pre-opening (B) designs. The pre-opening version enables a controlled two-stage release and helps reduce pressure shocks during actuator unloading.

Multiple Cracking-Pressure Options

NG20 versions are available with several cracking-pressure configurations:

• 2.5 bar
• 5 bar
• 7.5 bar
• 10 bar

The SV20PB4-4X specifically corresponds to the 10 bar configuration.

Standardized Mounting

The NG20 subplate version follows the Bosch Rexroth mounting interface associated with ISO 5781-08-10-0-00, supporting integration into standardized hydraulic manifold and power-unit architectures.

Application Areas

The SV20PB4-4X can be applied in:

• Construction Machinery
• Hydraulic Presses
• Injection Molding Machines
• Material Handling Systems
• Lifting Equipment
• Machine Tools
• Industrial Hydraulic Power Units
• Steel and Metallurgical Equipment
• Mobile Hydraulic Systems
• Hydraulic Cylinder Load-Holding Circuits
• Vertical-Axis Hydraulic Systems
• Clamping and Positioning Systems

It is particularly valuable in circuits where accidental actuator movement during shutdown must be minimized.

Expert Maintenance Tips

Maintain Pilot-Circuit Cleanliness

The X-port pilot circuit directly controls valve opening. Contamination can interfere with control-spool movement and compromise reliable operation.

Bosch Rexroth specifies a maximum hydraulic-fluid cleanliness level of ISO 4406 Class 20/18/15 for the component.

Verify the Complete Type Code

Do not replace an SV20 valve based only on nominal size.

Before replacement, verify:

• Material Number
• Complete Type Code
• Cracking Pressure
• Pre-opening Configuration
• Mounting Type
• Pilot-Oil Arrangement
• Port Thread
• Seal Material

This is especially important when replacing SV20PB4-4X with SV20GA1-4X, because these configurations have different mounting and opening characteristics.

Verify Installation Torque

For threaded NG20 versions, Bosch Rexroth documentation specifies an installation tightening torque of approximately 70 Nm and recommends a medium-strength thread locker.

Do Not Ignore Cracking Pressure

Replacing a 10 bar version with a lower cracking-pressure version can change reverse-flow behavior, pilot-pressure requirements and actuator load-holding characteristics. The complete cracking-pressure code should therefore be treated as a critical spare-parts identification parameter.