Product Overview

The DREB6X-1X/175MG24-25Z4M is a Bosch Rexroth DREB6X pilot-operated proportional pressure reducing valve with an inductive position transducer.

Rexroth’s original technical document RE 29182/07.05 defines the DREB6X as a pilot-operated, 3-way proportional pressure reducing valve with an inductive position transducer. The main stage uses a spool valve, while the pilot stage uses a poppet valve.

The verified ordering code is:

DREB6X-1X/175MG24-25Z4M

with Rexroth material number:

0 811 402 051.

The valve provides continuous pressure reduction at the consumer port A according to the proportional solenoid command. The proportional solenoid is position-controlled against a spring, providing rapid response and low hysteresis.

For replacement applications, the complete hydraulic and electrical configuration must be matched. Our replacement solutions emphasize in-situ interchangeability and 100% simulated operating-condition testing.

Technical Specifications

DREB6X-1X/175MG24-25Z4M

• Manufacturer: Bosch Rexroth
• Series: DREB6X
• Full Model: DREB6X-1X/175MG24-25Z4M
• Material Number: 0 811 402 051
• Product Type: Pilot-operated proportional pressure reducing valve
• Nominal Size: NG6 / Size 6
• Component Series: 1X
• Main Stage: Spool valve
• Pilot Stage: Poppet valve
• Function: 3-way, P–A / A–T
• Position Feedback: Inductive position transducer
• Actuation: Position-controlled proportional solenoid
• Amplifier: External amplifier required
• Maximum Set Pressure: 175 bar at Qmin = 1 L/min
• Minimum Pressure at A: 0 bar relative or pressure at T
• Minimum Inlet Pressure at P: pP = pA + ≥5 bar
• Maximum Working Pressure at P: 315 bar
• Maximum Pressure at T: 250 bar, B sealed
• Maximum Flow: 40 L/min
• Internal Pilot Oil Flow: approximately 0.6 L/min
• Maximum Solenoid Current: 2.5 A
• Coil Resistance R20: 3 Ω
• Maximum Power Consumption: 30 VA
• Supply Voltage: 24 VDC nominal
• Solenoid Connector: DIN 43650 / ISO 4400, M16 × 1.5, 2P+PE
• Position Transducer Connector: Special plug
• Duty Cycle: 100%
• Protection: IP65
• Hysteresis: ≤1%
• Manufacturing Tolerance for pmax: ≤10%
• Response Time: On <50 ms; Off <20 ms at Q = 10 L/min
• Ambient Temperature: -20°C to +50°C
• Fluid Temperature: -20°C to +80°C
• Recommended Viscosity: 20–100 mm²/s
• Maximum Permitted Viscosity: 10–800 mm²/s
• Fluid Cleanliness: ISO 4406(c) Class 18/16/13
• Seal Material: NBR
• Weight: 2.4 kg
• Mounting: Subplate mounting
• Mounting Interface: ISO 4401-03-02-0-94
• Displacement: Not applicable
• Maximum Rotational Speed: Not applicable.

Ordering Code Breakdown

DREB6X

Pilot-operated proportional 3-way pressure reducing valve with inductive position transducer, NG6.

1X

Unit Series 1X, with Series 10–19 maintaining unchanged installation and connection dimensions.

175

Maximum set-pressure stage:

175 bar.

M

Without non-return valve.

G24

24 VDC supply for the trigger electronics.

25

Maximum solenoid current: 2.5 A.

Z4

DIN 43650-AM2 unit plug, with plug-in connector included in the original scope of supply.

Final M

NBR sealing, suitable for mineral oils HL/HLP according to DIN 51524.

Key Technical Advantages

1. Pilot-Operated Proportional Pressure Control

The DREB6X uses a two-stage pressure-reducing architecture consisting of a poppet pilot stage and spool main stage.

The pilot stage regulates the hydraulic pressure acting on the main spool, allowing continuous pressure reduction at port A.

2. Inductive Spool Position Feedback

An inductive position transducer monitors spool position.

The proportional solenoid is position-controlled against the spring characteristic, supporting rapid dynamic response and low hysteresis.

3. 175 Bar Pressure-Setting Range

The /175 code specifies a maximum set pressure of 175 bar at a minimum test flow of 1 L/min.

This must be distinguished from the 315 bar maximum P-port working pressure.

4. 40 L/min Main Flow Capacity

The official DREB6X data specify a maximum flow of 40 L/min, while the internal pilot oil flow is approximately 0.6 L/min.

This demonstrates the hydraulic amplification provided by the pilot-operated architecture.

5. Low Hysteresis and Fast Response

Official performance specifications include:

• Hysteresis: ≤1%
• ON response: <50 ms
• OFF response: <20 ms
• Test flow: 10 L/min.

6. Pressure Limitation During Electronic Faults

Rexroth states that the valve provides pressure limitation to a safe level even if the electronics malfunction and the solenoid current exceeds its specified maximum.

7. 315 Bar P-Port Capability

The P port can withstand up to 315 bar working pressure, while T is limited to 250 bar with B sealed.

8. External Amplifier Architecture

The DREB6X is designed for operation with an external trigger amplifier. Rexroth specifies a 24 V nominal electronics supply and 0–10 V setpoint control architecture for the external electronics.

Application Areas

Typical applications include:

• Industrial hydraulic power units
• Pressure-reduction circuits
• Hydraulic clamping systems
• Machine tools
• Industrial automation equipment
• Hydraulic test equipment
• Forming equipment
• Hydraulic cylinder pressure control
• Pressure unloading and reduction circuits
• Electro-hydraulic proportional pressure systems

The primary engineering function should be described as:

Proportional Pressure Reduction

rather than a conventional directional-control function.

Expert Maintenance Tips

1. Match the External Amplifier

The DREB6X requires an external amplifier.

The amplifier, command signal and valve must therefore be treated as one control system rather than selecting the hydraulic valve alone.

2. Verify the 24 VDC Electronics Supply

The G24 code specifies a 24 VDC supply to the trigger electronics, while code 25 specifies a maximum solenoid current of 2.5 A.

3. Maintain the Required P-to-A Pressure Differential

Rexroth specifies:

pP = pA + ≥5 bar

Insufficient inlet pressure differential may prevent correct pressure regulation.

4. Maintain Hydraulic Cleanliness

The specified cleanliness level is:

ISO 4406(c) Class 18/16/13.

Contamination can affect pilot-stage operation, spool movement, pressure stability and dynamic response.

5. Monitor T-Port Pressure

The maximum T-port pressure is 250 bar with B sealed.

Return-line restriction and excessive back pressure should therefore be avoided.

6. Verify the Non-Return-Valve Configuration

The M located after the 175 pressure-stage code means without non-return valve.

The replacement configuration must match the original hydraulic circuit requirements.

7. Inspect Both Electrical Connections

The DREB6X includes separate connections for the solenoid and inductive position transducer.

When troubleshooting unstable pressure control, check both the actuator circuit and the feedback circuit.

8. Perform Full Functional Testing After Replacement

The complete verification sequence should include:

24 VDC → external amplifier → command signal → proportional solenoid → pilot stage → main spool → A-port pressure

Then verify static pressure, dynamic response, leakage and fault-limiting behavior.

Our replacement program can include 100% simulated operating-condition testing to verify hydraulic performance and interchangeability before shipment.