300.9D VPS Mini Hydraulic Excavator Machine Systems Blade Hydraulic System Caterpillar


Blade Hydraulic System
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1.1. BLADE DOWN
2.1. BLADE UP


Illustration 1g06013814
Partial hydraulic schematic (BLADE DOWN)
(1) Blade cylinder
(2) Changeover valve
(3) Main control valve
(4) Blade control valve
(5) Relief valves
(6) Hydraulic pump
(7) Hydraulic tank
(14) HPU changeover valve


Illustration 2g02468720
Operator controls
(2) Changeover valve

Changeover control valve (2) must be in the correct position for the blade to function.

BLADE DOWN



Illustration 3g02468520
Blade control valve (BLADE DOWN)
(8) Cylinder port B
(9) Cylinder port A
(10) Return passage
(11) Spool
(12) Center bypass passage
(13) Parallel feeder passage

Spool (11) has a mechanical linkage which actuates the valve. When the linkage is pushed, spool (11) shifts downward. The pump oil then flows to cylinder port A (9). The oil flows through lines to the head end of the blade cylinder to extend the cylinder rod. Return oil in cylinder port B (8) flows through the spool to return passage (10). The oil then returns to the tank.

BLADE UP



Illustration 4g02468694
Blade control valve (BLADE UP)
(8) Cylinder port B
(9) Cylinder port A
(10) Return passage
(11) Spool
(12) Center bypass passage
(13) Parallel feeder passage

Spool (11) has a mechanical linkage which actuates the valve. When the linkage is pulled, spool (11) shifts upward. The pump oil then flows to cylinder port B (8). The oil flows through lines to the rod end of the blade cylinder to retract the cylinder rod. Return oil in cylinder port A (9) flows through the spool to return passage (10). The oil then returns to the tank.

Refer to the Systems Operation, "Main Control Valve" for more information on the main control valve and the blade control valve.

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