Technical Datasheet: Bosch Rexroth HM20-20/400

Product Type: High-Performance Hydraulic Pressure Transducer / Transmitter

Model Designation: HM20-20/400 (Also associated with the HM20-2X series)

Measuring Element: Thin-film metal strain gauge measuring cell

1. Product Characteristics & Application

• Sensor Type: Heavy-Duty Hydraulic Pressure Transmitter

• Pressure Measuring Range: 0…400 bar (High-pressure tracking capability)

• Media-Contacting Parts: Constructed from high-strength stainless steel for absolute compatibility with mineral-based hydraulic oils, fluids, and non-corrosive gases.

• Special Features: Built for harsh, heavy-duty hydraulic environments. It features outstanding operational reliability due to high burst pressure limits, extreme vibration/shock resistance, and high long-term stability. Widely used for precise system pressure monitoring in hydraulic power units (HPUs), plastic injection molding machinery, metal stamping presses, and mobile hydraulic systems.

2. Electrical Data

• Operating Supply Voltage ($V_s$): 18…36 V DC

• Analog Output Signal: 4…20 mA (Linear 2-wire current loop configuration)

• Load Impedance ($R_L$): $\le (V_s – 10\text{ V}) / 0.02\text{ A}\ \Omega$

• Approvals: CE Compliant, cULus Listed (IND. CONT. EQ. 11MA)

3. Performance & Protection Data

• Accuracy Class: High precision linearity profile ($\le 0.5\%$ of full scale typical)

• Response Time ($t_{90}$): $\le 2\text{ ms}$ (Engineered for immediate tracking of destructive high-pressure spikes and dynamic fluid cycles).

• Circuit Protections: Complete reverse polarity protection, short-circuit protection (SCP), and overvoltage protection.

4. Mechanical & Environmental Data

• Pressure Connection Port: Standard industrial threaded fluid connection (Typically $G1/4″$ or thread profiles matching heavy-duty manifold integrations).

• Housing Material: Heavy-duty, ruggedized stainless steel cylindrical body.

• Ambient & Medium Temperature Range: $-40\text{ °C to }85\text{ °C}$

• Ingress Protection Rating: IP67 when properly mated with an M12 connector line cable plug.

• Country of Origin: Made in Germany

5. Electrical Connection & Wiring Layout

The sensor features an integrated standard top-facing rugged male circular connector plug (M12 × 1, 4-pin layout).

Pinout & Core Circuit Mappings (2-Wire Setup):

• Pin 1: Brown wire reference $\rightarrow$ +$U_B$ / L+ (Power Supply Input, +18…36 V DC)

• Pin 2: White or Black wire reference $\rightarrow$ Analog Signal Output (4…20 mA / Loop return to ground)

• Pin 3: Not connected / Left open

• Pin 4: Not connected / Left open

Wiring Diagram:

       [ Pin 1 ] ───────────────────────── ( + 18...36 VDC )
          │
      ┌───┴─────────────┐
      │  Bosch Rexroth  │
      │  HM20-20/400    │───────── [ Pin 2 ] ──── [ 4...20 mA Signal Load ] ───┐
      └─────────────────┘                                                    │
                                                                             │
       Ground / Common Return Reference ─────────────────────────────────────┴─── ( - )
DATA SHEET