320C Excavator Hydraulic System – Solenoid Valve (Fine Swing)

Illustration 1 g00479383

Side of swing motor

(1) Block

(2) Swing motor

(3) Anti-reaction valve

(4) Anti-reaction valve

(35) Fine swing solenoid valve

Illustration 2 g00479488

Fine swing solenoid valve

(1) Block

(8) Passage

(9) Passage

(10) Passage

(31) Passage

(35) Solenoid

(36) Fine swing valve

(37) Passage

(38) Passage

(39) Spool

(40) Spring

(41) Orifice

(42) Orifice

Illustration 3 g00682690

The fine swing control switch is on the right side instrument panel.

The fine swing control is installed in order to ensure an exact movement of the swing with minimal shock load. This is done by equalizing the oil pressure in passage (8) and (10) .

When fine swing solenoid (35) is de-energized, spool (39) is in the NEUTRAL position. Spool (39) is located in valve (36). The NEUTRAL position creates a closed connection between passages (37) and (38). In this position, the swing circuit operates in the normal manner.

When the fine swing control switch is ON, solenoid (35) is energized. Spool (39) shifts downward against the force of spring (40). With the spool in this position, passage (8) is open to passage (10) through passages (37) and (38). Orifices (41) and (42) control the flow rate. Orifices (41) and (42) are located in block (1) .

Because the right and the left swing circuits are now connected to each other, some of the outlet oil is allowed to flow to the inlet side. The operation of the swing circuit is more precise with this connection.

Note: When the fine swing control switch is ON, the swing brake is OFF.