VARIABLE BACK PRESSURE VALVE OF CONTROL VALVE
FUNCTION OF VARIABLE BACK PRESSURE VALVE OF CONTROL VALVE
• This valve applies back pressure to the drain circuit to prevent cavitation which is caused by negative pres-
sure of each actuator (motor, cylinder, etc.)
• Lower the back pressure of the drain circuit except for travel operations in order to reduce output loss.
OPERATION OF VARIABLE BACK PRESSURE VALVE OF CONTROL VALVE
When the engine is stopped
1.
No pressurized oil is supplied from the main pump to self-
pressure reducing valve (1).
2.
No hydraulic pressure is supplied from variable back pres-
sure solenoid valve (3) to spring chamber (C), and valve
(6) is pressed to the right by the reaction force of spring
(5).
3.
Drain circuit (A) of the control valve is interconnected with
port (T) through orifice (b) of valve (6).
When engine is in operation (swing or travel operation)
1.
Pressurized oil (PR) output from self-pressure reducing
valve (1) flows to variable back pressure solenoid valve
(3).
2.
Since drive signal (IS3) to variable back pressure solenoid
valve (3) is “OFF”, pressurized oil (PR) flows to spring
chamber (C) of variable back pressure valve.
3.
Pressurized oil (PR) flowing to spring chamber (C) acts on
the left end surface (area of diameter "d") of valve (6) and
pushes valve (6) to the right together with the reaction
force of spring (5).
4.
Pressure (PA) in drain circuit (A) of the control valve acts
on the right end surface (area of diameter "d1") of valve (6)
and pushes valve (6) to the left.
5.
Valve (6) keeps balance so that the back pressure be-
comes (PA) in the following equation. PA = (Area of diame-
ter "d" x Pressure (PR) + Reaction force of spring (5) ) /
Area of diameter "d1"
6.
The oil flow from drain circuit (A) of the control valve to
port (T) is adjusted to the set pressure of variable back
pressure valve (4).
A E P 2 1 6 1 3
A E P 2 1 6 1 4
COMPONENT PARTS OF HYDRAULIC SYSTEM
10 STRUCTURE AND FUNCTION
10-186
PC500LC-10R
Summary of Contents for PC500LC-10R
Page 1: ...HYDRAULIC EXCAVATOR SEN06722 00 PC500LC 10R SERIAL NUMBERS 100001 and up...
Page 2: ......
Page 3: ...00 INDEX AND FOREWORD PC500LC 10R 00 1...
Page 76: ......
Page 77: ...01 SPECIFICATIONS PC500LC 10R 01 1...
Page 94: ......
Page 95: ...10 STRUCTURE AND FUNCTION PC500LC 10R 10 1...
Page 177: ...When balanced 10 STRUCTURE AND FUNCTION CLSS PC500LC 10R 10 83...
Page 178: ...When lever is returned to fine control state CLSS 10 STRUCTURE AND FUNCTION 10 84 PC500LC 10R...
Page 179: ...When lever is pulled at a stroke 10 STRUCTURE AND FUNCTION CLSS PC500LC 10R 10 85...
Page 180: ...When lever is in stroke end CLSS 10 STRUCTURE AND FUNCTION 10 86 PC500LC 10R...
Page 377: ...20 STANDARD VALUE TABLE PC500LC 10R 20 1...
Page 407: ...30 TESTING AND ADJUSTING PC500LC 10R 30 1...
Page 583: ...30 TESTING AND ADJUSTING METHOD FOR STARTING UP KOMTRAX TERMINAL PC500LC 10R 30 177...
Page 604: ......
Page 605: ...60 MAINTENANCE STANDARD PC500LC 10R 60 1...
Page 636: ...MAINTENANCE STANDARD OF MAIN PUMP 60 MAINTENANCE STANDARD 60 32 PC500LC 10R...
Page 638: ...MAINTENANCE STANDARD OF SWING MOTOR 60 MAINTENANCE STANDARD 60 34 PC500LC 10R...
Page 641: ...60 MAINTENANCE STANDARD MAINTENANCE STANDARD OF TRAVEL MOTOR PC500LC 10R 60 37...
Page 644: ...MAINTENANCE STANDARD OF CONTROL VALVE 60 MAINTENANCE STANDARD 60 40 PC500LC 10R...
Page 646: ...MAINTENANCE STANDARD OF CONTROL VALVE 60 MAINTENANCE STANDARD 60 42 PC500LC 10R...
Page 648: ...MAINTENANCE STANDARD OF CONTROL VALVE 60 MAINTENANCE STANDARD 60 44 PC500LC 10R...
Page 650: ...MAINTENANCE STANDARD OF CONTROL VALVE 60 MAINTENANCE STANDARD 60 46 PC500LC 10R...
Page 652: ...MAINTENANCE STANDARD OF CONTROL VALVE 60 MAINTENANCE STANDARD 60 48 PC500LC 10R...
Page 658: ...MAINTENANCE STANDARD OF TRAVEL PPC VALVE 60 MAINTENANCE STANDARD 60 54 PC500LC 10R...
Page 668: ...MAINTENANCE STANDARD OF WORK EQUIPMENT LINKAGE 60 MAINTENANCE STANDARD 60 64 PC500LC 10R...
Page 679: ...90 CIRCUIT DIAGRAMS PC500LC 10R 90 1...
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Page 704: ...Symbol Content Buzzer Antenna SYMBOLS USED IN ELECTRICAL CIRCUIT DIAGRAM 90 26 PC500LC 10R...
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