DBDH6G1X/315 Bosch Rexroth Relief Valve 315 Bar

Product Overview

The Bosch Rexroth DBDH and DBDS series are direct-operated hydraulic pressure relief valves designed to limit system pressure to a defined setting.

Unlike pilot-operated relief valves, the DBD architecture acts directly through the hydraulic pressure, spring and poppet/ball mechanism. When the pressure at port P reaches the preset value, the valve opens toward port T and relieves hydraulic flow, protecting pumps, actuators and other system components from excessive pressure. Bosch Rexroth identifies the DBD as a direct-operated pressure relief valve family covering nominal sizes from NG6 to NG30.

The DBD family uses different internal configurations according to the pressure rating. Poppet-seat construction is used for pressure ratings up to 400 bar, while ball-seat construction is used for the 630 bar configuration available for selected NG10 versions.

The model group supplied in the original title includes:

• DBDS6G1X/315
• DBDH6G1X/315
• DBDH8G1X/315
• DBDH10G1X/315

These are not interchangeable solely because they share the DBD family name. Nominal size, threaded connection, adjustment mechanism and pressure rating must all be verified before replacement.

For replacement applications, our engineering approach focuses on form-fit-function compatibility, including mounting dimensions, port configuration, pressure class, adjustment mechanism and hydraulic-fluid compatibility. Replacement units can also undergo 100% simulated working-condition testing before shipment.

Technical Specifications

DBDH6G1X/315

• Model: DBDH6G1X/315
• Manufacturer: Bosch Rexroth
• Valve Type: Direct-operated pressure relief valve
• Nominal Size: NG6
• Component Series: 1X
• Pressure Setting: Up to 315 bar
• Maximum Inlet Operating Pressure: 400 bar
• Maximum Outlet Pressure: 315 bar
• Maximum Flow: 50 L/min for the documented NG6 configuration
• Flow Path: P → T
• Actuation: Mechanical
• Adjustment: H-type handwheel/rotary adjustment configuration
• Connection: G1/4 according to ISO 228-1
• Ports: 2
• Seal: NBR
• Viscosity Range: 10–800 mm²/s
• Recommended Cleanliness: ISO 4406 Class 20/18/15
• Ambient Temperature: -30 to +80°C with NBR seals
• Hydraulic Fluid Temperature: -30 to +80°C with NBR seals
• Reference Weight: approx. 1.65 kg for the documented configuration
• Material Number: R900424197 for DBDH6G1X/315; related /12 configuration R900458278.

DBDS6G1X/315

• Model: DBDS6G1X/315
• Manufacturer: Bosch Rexroth
• Valve Type: Direct-operated pressure relief valve
• Nominal Size: NG6
• Component Series: 1X
• Pressure Setting: 315 bar
• Maximum Inlet Operating Pressure: 400 bar for the NG6 family
• Maximum Flow: 50 L/min
• Flow Path: P → T
• Actuation: Mechanical
• Adjustment: S-type hexagon/grub screw with protective cap
• Connection: G1/4 according to ISO 228-1
• Seal: NBR
• Weight: approx. 1.56 kg
• Material Number: R900423720.

DBDH8G1X/315

• Model: DBDH8G1X/315
• Manufacturer: Bosch Rexroth
• Valve Type: Direct-operated pressure relief valve
• Nominal Size: NG8
• Component Series: 1X
• Pressure Setting: 315 bar
• Maximum Operating Pressure: 630 bar for the documented NG8 family
• Connection: G3/8 according to ISO 228-1
• Flow Path: P → T
• Actuation: Mechanical
• Seal: NBR in the referenced configuration
• Reference Weight: approx. 3.66 kg
• Material Number: R900428386
• Maximum Flow: Must be determined from the applicable Rexroth characteristic curve for the selected pressure setting and valve configuration.

DBDH10G1X/315

• Model: DBDH10G1X/315
• Manufacturer: Bosch Rexroth
• Valve Type: Direct-operated pressure relief valve
• Nominal Size: NG10
• Component Series: 1X
• Pressure Setting: 315 bar
• Maximum Operating Pressure: 400 bar
• Connection: G1/2 according to ISO 228-1
• Flow Path: P → T
• Actuation: Mechanical
• Seal: NBR in standard configurations
• Available DBD pressure classes: 25, 50, 100, 200, 315 and 400 bar, with selected NG10 configurations also available at 630 bar
• Material Number: R900424189
• Maximum Flow: To be selected from the applicable Rexroth characteristic curve rather than from an unverified generic figure.

Key Technical Advantages

Direct-Operated Pressure Limitation

The DBD architecture applies hydraulic pressure directly to the pressure-balancing mechanism. This eliminates a separate pilot stage and provides a straightforward mechanical pressure-limiting function.

Poppet and Ball Seat Configurations

Bosch Rexroth uses different seat designs according to the pressure class. Poppet-seat construction covers pressure ratings from 25 to 400 bar, while ball-seat construction is used for selected 630 bar NG10 configurations.

Multiple Pressure Adjustment Options

The DBD family can be configured with different adjustment elements, including hexagon adjustment with protective cap, rotary knob, handwheel and lockable rotary knob. This supports different requirements for initial commissioning, field adjustment and tamper resistance.

Standardized Threaded Connections

The G configuration uses ISO 228-1 pipe threads. NG6, NG8 and NG10 correspond to G1/4, G3/8 and G1/2 respectively, which simplifies model identification and replacement engineering.

Broad Pressure-Class Coverage

The DBD platform supports multiple pressure settings, including 25, 50, 100, 200, 315 and 400 bar, with selected NG10 designs extending to 630 bar. This gives hydraulic designers a common valve platform across different pressure levels.

Controlled Hydraulic Cleanliness

Bosch Rexroth specifies ISO 4406 Class 20/18/15 as the maximum permissible contamination level for the standard DBD hydraulic data and emphasizes filtration as a means of reducing faults and increasing component life.

Application Areas

Typical applications include:

• Hydraulic power units
• Hydraulic presses
• Injection molding machines
• Die-casting machinery
• Machine tools
• Metal-forming equipment
• Steel-processing machinery
• Industrial automation systems
• Hydraulic test benches
• Clamping and fixture circuits
• Accumulator protection circuits
• High-pressure industrial hydraulic systems

The primary function in these applications is reliable limitation of system pressure to protect pumps, actuators, piping and downstream hydraulic components.

Expert Maintenance Tips

Verify Pressure Setting Versus Maximum Operating Pressure

A 315 bar pressure class does not mean that 315 bar and the valve’s maximum operating pressure are the same specification. For example, the documented DBDH6G1X/315 configuration has a 315 bar pressure setting class while its inlet maximum operating pressure is 400 bar.

Control Back Pressure at Port T

Back pressure at port T is particularly important. Bosch Rexroth specifies that counter pressure at the outlet adds directly to the valve response pressure. Excessive tank-line pressure can therefore cause the actual system pressure to exceed the nominal adjustment value.

Adjust Pressure Under Representative Flow Conditions

The DBD characteristic curves show that pressure response changes with flow. Therefore, pressure adjustment should be verified under the actual hydraulic operating condition rather than relying exclusively on a static, near-zero-flow setting.

Confirm Nominal Size and Connection

Always verify the complete connection configuration:

• NG6 → G1/4
• NG8 → G3/8
• NG10 → G1/2

This prevents incorrect replacements caused by selecting a similar-looking valve with a different hydraulic interface.

Confirm the Adjustment Configuration

DBDS and DBDH should not be treated as identical configurations. The adjustment element differs, and this can affect machine integration and operator access. Verify the complete ordering code before replacing an installed valve.

Inspect the Poppet, Seat and Damping Components

Pressure drift, incomplete unloading or unstable pressure response may indicate contamination, wear at the valve seat, damaged spring components or restricted movement of the damping piston. Clean hydraulic oil and correct filtration are important for maintaining reliable operation.

Test Replacement Units Under Actual Simulated Conditions

For replacement valves, quality validation should reproduce the customer’s hydraulic conditions as closely as possible. Recommended checks include pressure-setting accuracy, pressure override behavior, tank-line back pressure, repeated pressure cycling, external leakage and long-duration pressure holding.

This supports a professional 100% simulated working-condition testing program while maintaining a clear distinction between the replacement product and the original Bosch Rexroth product.