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 uid sup-
ply line for the pump is submerged in a 2.5 quart
capacity reservoir and is ltered by a 149 micron
screen.
The valve body directs hydraulic uid to operate
six hydraulic circuits, raise, lower, angle left, an-
gle right, vee and scoop. The raise, angle, vee
and scoop circuits receive uid under pressure,
and the lower circuit does not, however, pressure
is generated as uid returns to the reservoir.
RAISE MODE OF OPERATION
Operating the Raise switch energizes the 12
VDC motor, the S5 solenoid valve and de-en-
ergizes the S6 solenoid valve. Hydraulic uid
under pressure is then directed through the S5
solenoid valve and a one way check valve (CV1)
to the lift cylinder.
Releasing the Raise switch de-energizes the
12 VDC motor and the S5 solenoid valve. The
one way check valve (CV1) 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 S6 so-
lenoid valve, lowers the blade and establishes a
oat circuit. The oat circuit allows uid to enter
or exit the lift cylinder allowing the blade to fol-
low the contour of the ground.
ANGLE LEFT MODE OF OPERATION
Operating theAngle Left switch energizes the 12
VDC motor, the S2 solenoid valve and the S3
solenoid valve. Hydraulic uid under pressure is
then directed through the S2 solenoid valve to
the right wing cylinder. Hydraulic uid, not under
pressure, is directed from the left wing cylinder
through the S4 solenoid valve back to the reser-
voir as the cylinder retracts.
The right wing circuit is protected by a crossover
relief valve (RV2) set to relieve system pressure
at 2700 PSI. It is also protected by a retraction
relief (RV5) set at 3000 PSI.
ANGLE RIGHT MODE OF OPERATION
Operating the Angle Right switch energizes the
12 VDC motor, the S1 solenoid valve and the S4
solenoid valve. Hydraulic uid under pressure is
then directed through the S1 solenoid valve to
the left wing cylinder. Hydraulic uid, not under
pressure, is directed from the right wing cylinder
through the S2 solenoid valve back to the reser-
voir as the cylinder retracts.
The left wing circuit is protected by a crossover
relief valve (RV3) set to relieve system pressure
at 2700 PSI. Typically, pressure is relieved when
the left wing cylinder reaches its fully extended
position. It is also protected by a retraction relief
(RV4) set at 3000 PSI.
VEE MODE OF OPERATION
Operating the Vee switch energizes the 12 VDC
motor and the SI and S3 solenoids pumping uid
through hosesAand C to the rod end of the wing
cylinders. Fluid from the butt end of the cylinders
returns to the tank through hoses B and D and
valves S2 and S4
SCOOP MODE OF OPERATION
Operating the Scoop switch energizes the 12
VDC motor, the S2 solenoid valve and the S4
solenoid valve pumping uid through hoses B
and D to the butt end of the wing cylinders. Fluid
from the rod end of the cylinders returns to the
tank through hoses A and C and valves S1 and
S3
