DG34 HAWE Hydraulic Pressure Switch 400 bar

Product Overview

The DG34 is a piston-type pressure switch (pressure relay) from the HAWE Hydraulik DG series, featuring a precision spring-loaded piston design. It is widely used in hydraulic systems to convert fluid pressure changes into electrical signals for system monitoring, control, and safety protection.

The DG series pressure relay employs a spring-loaded piston design with an integrated high-quality electrical microswitch assembly. When system pressure reaches the set value, hydraulic pressure moves the piston upward, and the displacement is amplified through a lever mechanism to trigger the microswitch, closing or opening the electrical contacts. The DG34 features a robust cylindrical metal housing with a convenient, manually adjustable pressure setting knob on top, and a hexagon screw for precise adjustment. The bottom features a standard four-bolt flange mounting base for seamless integration into manifolds or hydraulic lines.

The DG34 is commonly used in applications requiring zero leakage performance, such as accumulator holding circuits. When the system pressure reaches the set value, the pressure relay sends an electrical signal to control solenoid valves, cut off pump motors, or unload the system, enabling sequential control or safety protection functions.

Our HAWE DG34 pressure relays strictly adhere to OEM technical standards, achieving 100% direct interchangeability with original components. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring performance parameters are fully consistent with genuine HAWE products.

⚠️ Brand and Model Attribution Note: The DG34 belongs to HAWE Hydraulik, part of the DG series pressure relays (Pressure Relay / Pressure Switch). The series also includes DG33, DG35, DG365, and other models. DG series pressure relays are also referred to as “electro-hydraulic pressure relays”.

⚠️ Model Note: DG34 is the base model. Derivative variants include DG34-1/4 and DG34-Y8, distinguished primarily by port specifications and connection types.

Technical Specifications

• Product Series: HAWE DG series piston-type pressure relay

• Model: DG34

• Brand: HAWE Hydraulik

• Product Type: Electro-Hydraulic Pressure Switch / Pressure Relay

• Design Type: Spring-loaded piston type

• Adjustment Method: Top-mounted manual rotary knob / Hexagon screw

• Adjustment Range: 100 – 350 bar/ 100 – 400 bar

• Maximum Operating Pressure: 400 bar

• Sealing Performance: Zero leakage

• Port Standard: DIN ISO 16873

• Threaded Ports: G1/2 or G1/4A

• Operating Fluid: Hydraulic fluid acc. to DIN 51524

• Viscosity Range: Min. approx. 4 cSt, Max. approx. 1500 mm²/s

• Optimal Operating Viscosity: Approx. 10 – 500 mm²/s

• Ambient Temperature: Approx. -40°C to +80°C

• Mounting Type: Four-bolt flange mounting base

• Housing Material: Heavy-duty cylindrical metal body

• Contact Type: Microswitch

• Reference Part Number: 3219077

Key Technical Advantages

1. Spring-Loaded Piston Design with Zero Leakage Sealing

The DG34 features a spring-loaded piston-type design. The precision fit between the piston and valve body achieves zero leakage sealing performance. This characteristic makes it particularly suitable for accumulator holding circuits and other applications requiring long-term pressure retention.

2. Wide Pressure Adjustment Range for Flexible System Integration

The DG34 offers a wide pressure adjustment range of 100 – 400 bar, covering medium to ultra-high pressure hydraulic systems. The top-mounted manual rotary knob and hexagon screw enable precise pressure threshold settingwith convenient operation.

3. Robust Mechanical Construction with Long Service Life

The DG34 features a heavy-duty cylindrical metal housing with compact, rugged construction. Full-steel bearing components and modular construction ensure high reliability and extended service life. The high-quality internal microswitch assembly guarantees reliable operation for millions of switching cycles.

4. Multiple Mounting and Port Options for Flexible Integration

The DG34 supports G1/2 or G1/4A threaded portsas well as a four-bolt flange mounting base. Whether for manifold or in-line installation, seamless integration is achieved. The compact design is particularly suitable for hydraulic equipment with limited installation space.

5. Wide Temperature Range and Excellent Media Compatibility

The DG34 supports a wide ambient temperature range of -40°C to +80°Cand is compatible with various mineral-based hydraulic oils meeting DIN 51524 standards. The viscosity range of 4 – 1500 mm²/saccommodates diverse global operating conditions.

6. 100% Direct Interchangeability and Simulated Condition Testing

All models strictly adhere to HAWE original mounting dimensions and interface standards, enabling direct drop-in replacement of original pressure relays without piping modification or system adjustment. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring consistent, stable performance at rated pressure and temperature.

Application Areas

• Accumulator Holding Circuits: Leveraging zero-leakage characteristics for long-term pressure holding, with automatic pressure replenishment when system pressure drops

• Hydraulic System Pressure Monitoring & Alarm: Real-time system pressure monitoring with overpressure and underpressure alarm signaling

• Pump Start/Stop and Unloading Control: Automatic pump motor cut-off or pump unloading when set pressure is reached

• Sequential Control & Automation: Electrical command signaling for subsequent operations (e.g., solenoid valve actuation)

• Machine Tools & Industrial Equipment: Pressure monitoring for CNC machines, hydraulic clamping systems, presses

• Safety Protection: System shutdown during overpressure conditions to prevent equipment damage or personnel injury

Expert Maintenance Tips

1. Verify Model and Range Compatibility Prior to Installation

The DG34 standard adjustment range is 100 – 400 bar. Confirm that system operating pressure falls within this range prior to installation. Variants such as DG34.2610 (40–160 bar) are also available—select the correct pressure range for your system requirements.

2. Correct Installation Torque and Sealing

The DG34 supports G1/2 or G1/4A threaded portsand a four-bolt flange mounting base. Use a torque wrench during installation to the torque value specified in HAWE technical manuals. Use OEM-specification O-rings or bonded sealing washers—PTFE tape must not be used (it may block internal passages). Ensure piping is clean prior to installation.

3. Pressure Setting and Commissioning

Set the switching pressure via the top-mounted manual rotary knob or hexagon screw. Rotate slowly while monitoring a pressure gauge to confirm the switching point. Never exceed the 400 bar maximum operating pressure. Lock the adjustment mechanism after setting to prevent set-point drift from vibration.

4. Electrical Connection Precautions

The DG34 integrates a microswitch assembly. Verify load current and voltage do not exceed contact ratings prior to wiring. Install appropriate overload protection devices in the contact circuit to extend contact service life.

5. System Cleanliness Management

The DG34 features precision piston construction and demands adequate oil cleanliness. Recommended system cleanliness: ISO 4406 Class 19/17/14 or higher. Install high-precision filters in the system return line and inspect filter elements regularly.

6. Periodic Functional Checks

Perform functional checks every 2,000 operating hours or annually: verify switching point accuracy, contact reliability, and external leakage. The DG series pressure relay utilizes direct hydraulic pressure on the piston with no dynamic seal leakage risk. If set-point drift or poor contact is observed, arrange for servicing or replacement.