The sandwich plate design elements L808103C… are 3 way proportional pressure compensated direct solenoid operated valves. They control the inlet (P) flow and allow through (out of P1) only the flow required by the downstream operators; the excess oil, pressurized at working pressure, is diverted from the inlet P line to Tank. The combination of the proportional regulator with the unloading compensator guarantees stable and constant flow, independently from the working pressure. The proportional control is achieved by a wet pin proportional screwed-in tube, with removable coil which is energized by an external electronic feed regulator; the electronic regulator performs an “open loop” control of the current supplied to the coil.
These elements basically consist of a stackable housing (1) with a control spool (2), a solenoid (3), and one return spring (4); additionally there is a compensator (6), with a preset spring (7), a spring retainer plug (8) and a drain orifice (9). A coil (5) is held to the solenoid tube by the ring nut (10).
With the solenoid de-energized, the spool stays in the closed position; the pressure overcomes the compensator spring (7) and the inlet (P) oil is unloaded to Tank at the Δp value shown by the characteristic curve. Pressure at (P1) is drained to Tank through the orifice and drops to zero.
By energizing the solenoid (3) through the electronic feed regulator, the control spool (2) is displaced from its rest position proportionally to the current; the corresponding opening allows a pressure compensated flow to proceed to P1, while the excess flow is diverted to Tank.
With the solenoid (3) de-energized, the return spring (4) pushes the spool (2) to its rest position “0” fully closed. No flow goes to P1 and any residual pressure at P1 is drained through the orifice. The compensator (6) is pushed fully open all the oil is unloaded to Tank.
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