Bosch Rexroth 4WS2EM6‑22/20B11XLET315K17EV‑100 (R901508364) Two‑Stage 4‑Way Directional Servo Valve

Product Description

4WS2EM6‑22/20B11XLET315K17EV‑104, part number R901508364, is a two‑stage, subplate‑mounted Rexroth 4‑way hydraulic servo valve with mechanical spool feedback. It adopts a dry torque motor and nozzle‑flapper first‑stage hydraulic amplifier design, rated at 315 bar maximum working pressure and 20 L/min nominal flow. This ATEX / IECEx certified explosion‑proof version requires an external servo amplifier for drive commands. Precision‑machined control sleeve and spool provide high repeatability and fast dynamic response for closed‑loop hydraulic control systems.

Product Functions

• Convert analog electric command signals into precise hydraulic flow and direction output
• Mechanical spool feedback realizes high‑accuracy closed‑loop position, speed, force and pressure control
• Nozzle‑flapper pilot stage provides high sensitivity and rapid dynamic response
• ATEX‑compliant construction for installation in hazardous explosive gas and dust zones
• Control bidirectional movement of hydraulic cylinders and rotary hydraulic actuators
• Maintain stable flow output and suppress zero drift during long‑term continuous operation

Application Scenarios

• Steel mill rolling mill hydraulic gap and tension closed‑loop control systems
• Plastic injection molding machines, high‑precision die‑casting and forming equipment
• Test benches for aerospace, automotive and hydraulic component fatigue testing
• Oil & gas, petrochemical and hazardous‑area explosion‑proof hydraulic actuator packages
• Large machine tools, presses and dynamic vibration simulation hydraulic systems

Common Problems

• Slow response and poor positioning repeatability: Contaminated hydraulic oil, blocked first‑stage nozzle or flapper fouling.
• Zero drift and actuator hunting oscillation: Torque motor aging, feedback spring fatigue or oil temperature fluctuation.
• No hydraulic output despite normal electric command: Pilot filter clogging, insufficient pilot pressure or internal spool sticking caused by dirt particles.
• Intermittent unstable movement: Degraded oil cleanliness, worn spool‑sleeve clearance or loose electrical connector terminals.
• Reduced flow capacity: Abrasion of spool and sleeve, internal leakage increase or contaminated pilot filter element.