W345B Series II Material Handler Hydraulic System Control Valve (Stick Lowering) Caterpillar


Control Valve (Stick Lowering)
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W345B Series II Material Handler Hydraulic System [RENR5574]
HYDRAULIC SYSTEM
VALVE GP-LOAD CONTROL
W345B Series II Material Handler Hydraulic System Control Valve (Stick Lowering)
W345B Series II Material Handler Hydraulic System Control Valve (Boom Lowering)
1.1. Construction
2.1. STICK OUT Operation
3.1. STICK IN Operation
4.1. Stick Hold
5.1. Relief Operation of the Cylinder Head End



Illustration 1g00815234

Location of stick lowering control valve

(1) Stick lowering control valve

(2) Pump oil line

(3) Stick cylinder

(4) Return oil line

The stick lowering control valve is located on the head end of the stick cylinder.

The stick lowering control valve prevents the stick from falling if a hydraulic supply line fails or if a supply tube to the stick cylinder fails.

Note: The stick lowering control valve is supplied only when there is a boom lowering control valve.

Construction




Illustration 2g00813416

Simplified hydraulic schematic (stick lowering control valve)

(1) Pilot control valve

(2) Pilot line

(3) Stick I control valve

(4) Pump oil

(5) Inlet port (A) for pump oil

(6) Check valve

(7) Relief valve

(8) Spool

(9) Stick lowering control valve

(10) Check valve

(11) Outlet port (C) for pump oil

(12) Stick cylinder

(13) Pump oil

(14) Line to tank

(15) Pilot line

(16) Drain line

STICK OUT Operation




Illustration 3g00813175

Stick lowering control valve (STICK OUT position)

(5) Inlet port (A)

(6) Check valve

(11) Outlet port (C)

When the operator moves the joystick to the STICK OUT position, pilot control valve (1) is activated. This allows pilot oil to flow through line (2) to the top of stick I control valve (3). The pilot oil shifts the spool in stick I control valve (2) downward. This allows pump oil to pass through stick I control valve (3) and flow to inlet port (5) in stick lowering control valve (9). The oil flows through check valve (6), and the oil exits the stick lowering control valve through outlet port (11). The pump oil enters the head end of stick cylinder (12). The rod extends, and the stick moves outward.

STICK IN Operation




Illustration 4g00812693

Stick lowering control valve (STICK IN position)

(8) Spool

(10) Check valve

(11) Outlet port (C)

(14) Line to tank

(15) Pilot line

When the operator moves the joystick to the STICK IN position, pilot oil flows from the pilot control valve through line (15) to the pilot port of the stick lowering control valve. The pilot oil shifts spool (8) to the right. This action opens check valve (10). Oil flows out of the stick cylinder rod end and into the stick lowering control valve through outlet port (11). Oil moves through the stick lowering control valve and back to the hydraulic tank. The rod retracts, and the stick moves inward.

Stick Hold




Illustration 5g00821123

Stick lowering control valve (NEUTRAL position)

(5) Inlet port

(6) Check valve

(7) Relief valve

(10) Check valve

(11) Outlet port

When the operator moves the joystick to the NEUTRAL position, the stick cylinder is held in the raised position. Check valves (6) and (10) and the check valve in relief valve (7) prevent pump oil from flowing through the stick lowering control valve.

Relief Operation of the Cylinder Head End




Illustration 6g00821126

Stick lowering control valve

(7) Relief valve

(11) Outlet port

(14) Line to tank

When the stick is pushed inward by an outside force, the oil pressure at port (11) increases. The oil pressure is sensed at relief valve (7). When the oil pressure overcomes the relief valve setting, the relief valve opens. This allows oil to flow through the stick lowering control valve through line (14) to the hydraulic tank. This lowers the hydraulic oil pressure until the hydraulic oil pressure is lower than the relief valve setting.

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