BOOM, STICK, AND BUCKETCIRCUITS

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BOOM, STICK, AND BUCKETCIRCUITS

This presentation covers in more detail each implement circuit used for the 311D/312D/319D Series Hydraulic Excavators. The circuits to be covered include: - boom

- stick

- bucket

The idler pump provides oil to the boom 2 and stick 1 control valves. The drive pump provides flow to the bucket, boom 1, and stick 2 control valves.

The boom, stick, and bucket control valves are shifted by pilot oil from the joystick pilot valves when they are activated.

NOTE: The main control valve group and return system are covered in another presentation. The attachment/auxiliary circuits will be covered in the tool control section. The ISO schematics were created primarily from "312D Hydraulic Schematic" (KENR6556). Hydraulic schematics for the 311D and 314D may have variations from illustrations shown.

4 2

5 1 3

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The boom circuit uses two control valves to control the boom operation, boom 1 (1) and boom 2 (2). Both spools shift when fast boom movement is required. Both pumps provide flow to the boom for this condition. Boom 1 valve provides single pump flow, whenever the boom is shifted for slow movement.

The stick circuit also uses to two control valves to control the stick operation, stick 1 (3) and stick 2 (4). Both spools shift when fast stick movement is required.

The boom circuit and stick circuits also use regeneration valves and drift reduction valves. The regeneration valves (not shown)provide improved efficiency and require less engine horsepower for BOOMLOWERand STICK IN.

The drift reduction valves reduce cylinder drift when the boom or stick are in NEUTRAL.

Only one bucket control valve (5) is required to control the bucket. The bucket circuit is supplied with oil only from the drive pump.

2

1

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The two joysticks in the cab are used to control the movements of the boom, stick, swing and bucket circuits.

- right joystick (1) to control the bucket and boom (SAE excavator pattern)

- left joystick (2)to control the swing and stick (SAE excavator pattern)