Jacobsen SLF 1880, Техническое руководство по ремонту

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8L-81
RAISE CIRCUIT SCHEMATIC AND
THEORY OF OPERATION
System Conditions:
• Engine running at fast idle
• Mower lift lever in the RAISE position
Oil Supply to the Lift Valve
Hydraulic oil is drawn from the hydraulic oil tank by
section 3 of the gear pump assembly. Operating pres-
sure oil from section 3 of the gear pump is routed to the
lift valve.
Raise Circuit
Operating pressure oil supplied by section 3 of the gear
pump enters the lift valve at port “P.” The oil flows
through the solenoid valve (raise position), opens the
check valves, and flows to the rod end of the front lift
cylinders. Oil also flows through the 0.040 in. (1.0 mm)
orifice while bypassing the three one-way 0.026 in.
(0.66 mm) orifices, and is routed to the rod end of the
rear lift cylinders. Oil flow to the rod side of the lift cylin-
ders raises the cutting units.
Oil is forced from the piston end of the lift cylinders and
is routed back to the lift valve and returned to the
hydraulic tank.
Circuit Relief
The lift circuit is protected by the 1750 psi (120 bar)
relief valve located in the lift valve. If the lift circuit pres-
sure reaches 1750 psi (120 bar), the pilot-operated
relief valve will open, allowing oil from the lift circuit to
bypass back to the hydraulic tank through port “T” of
the lift valve.
NOTICE
The cutting unit motors will automatically shut off as
the cutting units are raised.