I. Core Parameters and Specifications

OEM Part Number: 309-5769 (3095769, CA3095769); Replacement Models: 167-3466, 309-5795

Official Name: Pressure Switch Assembly / Hydraulic Pressure Switch

Type: Mechanical Pressure Switch (Normally Open / Normally Closed); Non-continuous analog output—triggers switch action only at the set pressure point.

Core Applications:

Monitoring hydraulic pilot pressure (Boom / Stick / Bucket pilot circuits)

Monitoring main pump system pressure to trigger pressure protection functions

Used in hydraulic safety interlocks to prevent component damage caused by overpressure

Electrical: 2-pin waterproof connector; Operating Voltage: 6–36V DC (Compatible with 12V/24V systems)

Mechanical: Alloy housing; Protection Rating: IP67; Operating Temperature: -40°C to 125°C; Thread: M12×1.5 or SAE standard interface

Key Pressure Values (Core):

Closing Pressure (ON): 2646 ± 196 kPa (≈ 26.5 bar)

Reset Pressure (OFF): 2156 ± 196 kPa (≈ 21.6 bar)

Accuracy: ±7% (Typical tolerance for pressure switches)

Compatible Engine: C6.4 (Standard equipment for the 320D Series)

II. Compatible Equipment (Mainstream Excavators)

Small / Medium-sized Excavators (Most Common Applications)

311C / 312C / 314C / 315C Series

312D / 313D / 315D / 318D / 319D Series

320C / 320D / 320D2 / 323D / 324D / 326D Series

329D / 330D / 336D / 345D / 349D Series

III. Failure Symptoms and Diagnosis

Typical Symptoms

Abnormal hydraulic operation (Boom / Stick lacks power or responds sluggishly) Pilot pressure alarm triggered; ECM reports a hydraulic pressure switch fault.

Safety interlock failure; equipment enters torque-limiting mode or is unable to operate normally.

Internal switch contacts are burnt or stuck, resulting in no signal output or a permanently closed circuit.

Quick Diagnostics

Continuity Test: The switch should be Normally Open (OPEN) when unpressurized; it should close (CLOSED) when pressurized to **≥ 26.5 bar**; and it should open (OPEN) when pressure drops to **≤ 21.6 bar**.

Circuit Inspection: Measure the voltage at the connector plug and verify proper grounding; check for short circuits or open circuits.

Pressure Verification: Using a pressure gauge, verify that the switch accurately switches state at the 26.5 bar and 21.6 bar thresholds.