SM4-20(5)19-300/30-10-S143

The SM4-20(5)19-300/30-10-S143 servo valve is manufactured by Vickers as part of the Servo Valves series. It meters hydraulic oil to actuators for closed-loop position and force control. Each coil presents a resistance of 300 ohms at 21 °C, allowing the electronics to develop magnetic force with low power dissipation, while the rated coil current of 30 mA establishes the nominal drive signal range for the amplifier. Electrical connection is made through an MS-3106-14S-2S four-pin plug, which supports quick replacement and maintains environmental sealing around the windings. The flow stage is tuned for 19 l/min (5.0 US gpm) at a differential pressure of 70 bar, matching medium-size cylinders and motors in machine tools or test rigs. These characteristics define the electrical and hydraulic interface so the valve responds predictably under proportional command.

Mechanical mounting details permit accurate alignment with the manifold block. The valve seats on a port circle of 22.2 mm (0.875 in), and the mating surface must be held to a 32 µin finish to avoid leakage across pressure zones. Flatness deviation cannot exceed 0.025 mm (0.001 in), ensuring the spool body is not distorted when the screws are tightened. Sealing is handled by AS568-013 O-rings; each ring has an inside diameter of 10.82 mm (0.426 in) and a cross-section of 1.78 mm (0.070 in), providing the squeeze necessary to contain 70 bar system pressure. These dimensional controls ensure repeatable installation torque, stable hydraulic paths, and long service life without extraneous maintenance.