Hydraulic Schematic; General Notes - Doosan DX140R Shop Manual

HYDRAULIC SCHEMATIC

The hydraulic schematic(s) is available in the "Hydraulic and
Electrical Schematic Shop Manual." This manual is a collection
of diagrams and schematics for a number of models.

General Notes

When referring to the schematic, refer to the following items:
• As shown in the schematic, the main pump assembly
is driven by the engine. Mechanical energy is
converted to hydraulic power, generating the required
hydraulic flow which drives the system. Two main
pumps (a right side pump and a left side pump) make
up the main pump assembly.
• Hydraulic output from the right side pump is
transmitted to the right side of the control valve.
Output from the left side pump is transmitted to the
valve spools on the left side of the control valve.
Hydraulic output from the pilot pump is used to
control the pump and to operate pilot and solenoid
valves.
• The right half of the hydraulic control valve, supplied
by the right pump in the pump assembly, operates
valve spools for left travel, bucket, boom up and arm
functions. The amount of oil flow to the actuators at
the output end of each of those circuits is regulated
through the movement of each individual valve spool.
• The left half of the hydraulic control valve, fed by the
left pump in the pump assembly, has control spools
for right travel, swing, boom and arm function.
• Two-stage operation is a feature of boom and arm
function. All of these circuits can be operated using
the output of only one half of the hydraulic pump
assembly (one pump or the other), or – since both
halves of the control valve have a spool and available
circuit for these functions – the output of both pumps
can be combined, allowing higher speed operation.
Boom up, arm crowd and dumping functions can
operate in any one of the two available power modes
– the standard or general duty mode, the high speed/
rapid cycling mode.
• Whenever the right travel or left travel control spools
are shifted, output from the main pump assembly
flows through the center joint to one or both of the
axial piston motors driving the side frame crawler
tracks. A pilot valve connected to the swash plate of
each travel motor changes motor capacity (and
output) in direct proportion to the position of the travel
switch selected by the operator.
Hydraulic System Troubleshooting, Testing and Adjustment
SP001942
Page 7