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| Illustration 1 | g00513283 |
Pilot Manifold Valve (1) Passage (pilot oil) (2) Solenoid valve (boom float) (3) Pilot manifold (4) Passage (tank drain) (5) Line (boom control valve spool) | |
Boom float solenoid valve (2) controls pilot oil flow to the boom control spools. The boom float solenoid valve is normally nonenergized. A nonenergized boom float solenoid valve blocks pilot oil from flowing to boom control valve line (5).
When the boom float thumb switch is depressed and a small amount of BOOM DOWN to the right implement control lever is applied, an electrical signal is sent to the machine control module. The machine control module energizes the boom float solenoid valve (2) and pilot oil is supplied from passage (1) to line (5). Line (5) provides pilot oil to both ends of both boom control spools in the implement control valve in order to hold the valve stems in the center position.
At the same time, the machine control module activates the boom float dead engine relay which energizes the boom vent solenoids. When the boom vent solenoids are energized, the boom check valves open. Oil from the head end and the rod end of the boom cylinders is connected together with the return oil. The flow of the oil between the ends of the boom cylinders allows the bucket to follow the ground contours.
Note: The boom float thumb switch must be depressed and BOOM DOWN activated before the boom float function will operate.