TM 5-3805-261-23-1
THEORY OF OPERATION - CONTINUED
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BLADE SYSTEM - CONTINUED
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e.
Blade Float Hydraulic System (CCE and Type I Machines).
(1)
The purpose of this circuit is to allow blade lift cylinder rods along with the blade to move freely up and
down over uneven surfaces when moving snow, gravel, and other loose materials.
(2)
The system consists of a manual switch at the EMS panel, one blade float pilot valve assembly, one blade
float check valve for each cylinder, and a limit switch at each of the blade lift lever linkages.
(3)
When moved to the ON position, the switch at the EMS panel opens a normally closed solenoid valve and
closes a normally open solenoid valve in the blade float pilot valve assembly. The opened valve sends
pump pressure oil to actuate the blade float check valves. The closed valve prevents pressure oil from
returning to the tank from the blade float check valves.
(4)
Pistons within the blade float check valves then move check balls off their seats, which allows free move-
ment of oil between the head and rod ends of the lift cylinders. This allows the blade to move freely up and
down over uneven surfaces.
(5)
The limit switches on the blade lift lever linkage allow raising and lowering of the blade lever even when
the blade float system is on. If the lift lever is moved, the limit switch turns off the current to the solenoids
in the blade float pilot valve. This turns off the blade float system until the lever is returned to its NEU-
TRAL position.
(6)
When the switch at the EMS panel is moved to the OFF position, the blade float pilot valve assembly
returns to normal, which now prevents free circulation of oil between upper and lower ends of the cylin-
ders. It also allows any pressure remaining in the check valve to return to the tank.
f.
Blade Sideshift Cylinder. Cylinder is attached to blade mounting bracket and to blade assembly. Control lever is
located in control lever group mounting at side of steering console. Cylinder provides sideways movement of
blade. Hydraulic oil for sideshift cylinder operation is routed through the hydraulic swivel.
g.
Blade Circle Drive Motor. Motor is mounted on drawbar assembly so that hydraulically driven gear on motor
drives the circle gear. The circle gear rotates the blade horizontally. The motor is controlled by a lever in the cab.
BLADE CIRCLE
DRIVE MOTOR
397-071
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