Bosch Rexroth R901078002

4/4 directional design In principle, the function of these valves corresponds to the function of the 4/3-way version. With de-energized solenoid, the control spool is, however, held in a fail-safe position by a compression spring. The 4/4 directional control valves are designed as direct operated devices in plate design. Operation is effected by means of control solenoid. The solenoid is controlled via integrated control electronics. Set-up: The valve basically consists of:

• Housing (1) with connection surface

• Control spool (2) in sleeve (3) with compression springs (4)

• Solenoid (5) and cover (6)

• Position transducer (7)

• Integrated control electronics (8)

• Zero point adjustment accessible via Pg9 (9)

Functional description:

• With de-energized solenoid (5), fail-safe position of the control spool (2) by compression spring (4)

• Direct operation of the control spool (2) by energization of a control solenoid (5)

e.g. control of the solenoid

• Displacement of the control spool (2) proportionally to the electric input signal

• Connection from P to A and B to T via orifice-type cross-sections with continuous or inflected linear flow characteristics

• Switching off the solenoid (5)

• The compression spring (4) brings the control spool (2) back into the fail-safe position

The 4/3 and 4/4 directional control valves are designed as direct operated devices in plate design. Operation is effected by means of control solenoids. The solenoids are controlled via integrated control electronics. Set-up: The valve basically consists of:

• Housing (1) with connection surface

• Control spool (2) in sleeve (3) with compression springs (4 and 5)

• Solenoids (6 and 7)

• Position transducer (8)

• Integrated control electronics (9)

• Zero point adjustment (10) accessible via Pg9

Functional description: 4/3 directional design

• With de-energized solenoids (6 and 7), mechanical central position of the control spool (2) by compression springs (4 and 5)

• Direct operation of the control spool (2) by energization of a control solenoid

e.g. control solenoid "b" (7)

• Displacement of the control spool (2) to the left, proportionally to the electric input signal

• Connection from P to A and B to T via orifice-type cross-sections with continuous or inflected linear flow characteristics

• Switching off the solenoid (7)

• The compression spring (4) brings the control spool (2) back into the central position

In the de-energized condition, the control spool (2) is held in a mechanical central position by the control springs. This position does not correspond to the hydraulic central position! When the electric valve control loop is closed and with command value presetting 0 (0 V with A1 and/or 12 mA with F1), the control spool (2) is positioned in the hydraulic central position.