TITLE
Introduction
POWER UNIT OPERATION
GENERAL
The hydraulic power unit consists of a 12 VDC
motor, a hydraulic pump rated at 1.9 GPM @
1600 PSI, and a valve body containing six nor-
mally closed electric solenoid valves and three
adjustable pressure relief valves. The fluid sup
-
ply line for the pump is submerged in a 2.5 quart
capacity reservoir and is filtered by a 149 micron
screen.
The valve body directs hydraulic fluid to oper
-
ate six hydraulic circuits, raise, lower, angle left,
angle right, vee and scoop. The raise, angle and
scoop circuits receive fluid under pressure, and
the lower and vee circuits do not, however, pres-
sure is generated as fluid returns to the reser
-
voir.
RAISE MODE OF OPERATION
Operating the Raise switch energizes the 12
VDC motor, the S3 solenoid valve and de-en-
ergizes the S4 solenoid valve. Hydraulic fluid
under pressure is then directed through the S3
solenoid valve and a one way check valve (CV2)
to the lift cylinder.
Releasing the Raise switch de-energizes the
12 VDC motor and the S3 solenoid valve. The
one way check valve (CV2) maintains hydraulic
pressure in the lift cylinder.
The raise circuit is protected by a pressure relief
valve (SYSRV) set to relieve system pressure at
2250 PSI. Typically, pressure is relieved when
the lift cylinder reaches the full up position.
LOWER MODE OF OPERATION
Operating the Lower switch energizes the S4 so
-
lenoid valve, lowers the blade and establishes a
float circuit. The float circuit allows fluid to enter
or exit the lift cylinder allowing the blade to fol-
low the contour of the ground.
ANGLE LEFT MODE OF OPERATION
Operating the Angle Left switch energizes the 12
VDC motor, the S5 solenoid valve and the S2
solenoid valve. Hydraulic fluid under pressure is
then directed through the S5 solenoid valve and
a one way check valve (CV3) to the right wing
cylinder. Hydraulic fluid, not under pressure, is
directed from the left wing cylinder through the
S2 solenoid valve back to the reservoir as the
cylinder retracts.
Releasing the Angle Left switch de-energizes
the 12 VDC motor, the S5 solenoid valve and
the S2 solenoid valve. The one way check valve
(CV3) maintains hydraulic pressure in the right
wing cylinder.
The right wing circuit is protected by a pressure
relief valve (RV2) set to relieve system pressure
at 2700 PSI. Typically, pressure is relieved when
the right wing cylinder reaches its fully extended
position.
ANGLE RIGHT MODE OF OPERATION
Operating the Angle Right switch energizes the
12 VDC motor, the S1 solenoid valve and the S6
solenoid valve. Hydraulic fluid under pressure is
then directed through the S1 solenoid valve and
a one way check valve (CV1) to the left wing
cylinder. Hydraulic fluid, not under pressure, is
directed from the right wing cylinder through the
S6 solenoid valve back to the reservoir as the
cylinder retracts.
Releasing the Angle Right switch de-energizes
the 12 VDC motor, the S1 solenoid valve and
the S6 solenoid valve. The one way check valve
(CV1) maintains hydraulic pressure in the left
wing cylinder.
The left wing circuit is protected by a pressure
relief valve (RV1) set to relieve system pressure
at 2700 PSI. Typically, pressure is relieved when
the left wing cylinder reaches its fully extended
position.