Wipaire WIPLINE 13000, Руководство по обслуживанию

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SERVICE MANUAL & ICA
WIPLINE 13000 FLOATS
Page 22 Revision H P/N 1002548
2.1 DESCRIPTION AND OPERATION
Retraction and extension of the main and nose landing gear is effected by a hydraulic actuation system shown
schematically in figure 2.1.
The gear system is hydraulically actuated and driven by two hydraulic pumps located on the fuselage bulkhead
60.00.
A pressure of between 525 and 1250 psi is maintained in the supply line. When the pressure falls below 525
psi, the pressure switch activates the pump solenoid, providing power to the pump. When the pressure reaches
1150-1250 psi, the pressure switch deactivates the solenoid and the pump motor stops. Figure 2.2 shows the
electrical schematic of the system. A check valve on the output side of the pump retains pressure in the system
while the pump is off. The pump has an internal relief valve, which directs oil back to the pump reservoir when the
line pressure exceeds 1450 psi. The system also has an internal relief valve to protect against thermal expansion
when line pressure exceeds 2000 psi.
A cockpit mounted control valve accomplishes the selection of gear up or gear down. Each float gear has
individual indicator lights on the control valve allowing the pilot to confirm that each gear has fully retracted or
extended.
An emergency hand pump is provided, in case of total electric pump failure, or loss of fluid. The reservoir has
additional hydraulic fluid, available only to the hand pump.
The main gear is mechanically locked in both up and down positions. Locking and unlocking is effected utilizing a
small amount of lost motion of the actuator rod. Retraction takes place when pressure is exerted on the actuator
piston driving the collar along the slide tube. The lock is tripped when the follower slides up the contoured track in
the actuator as shown in figure 2.4. A reverse process affects extension. Gear position light proximity switches are
closed when the appropriate hook (containing the magnetic material) nests over the locking bar.
Shock absorption for the main landing gear is provided by a hydraulically dampened air spring. Figure 2.5 shows
the main components. The oil and air share a common chamber. When the oleo is collapsed, the oil is forced
through the main orifice, compressing the air in the upper cylinder. Extension reverses this process. The extended
oleo is initially set at the factory to 250 psi no load. In-field adjustment of air pressure and oil volume is described
in section 2.2.
The nose gear has an over-center down lock. Retraction occurs when pressure is applied to the forward face
of the actuator piston and the carriage is drawn along the tracks in the nose box as shown in figure 2.9. Gear
position light proximity switches are closed when the piston containing the magnetic material has reached either
end of its travel.
The nose gear consists of composite fiberglass beams that are attached at the bottom to castering blocks. Inside
the block is a castering pin that is set into the machined fork assembly. The castering pin allows the nose wheel
to pivot in a complete circle. The geometry is such that no shimmy dampers are necessary. A spring loaded ball
rides in a groove machined in the castering pin. This groove is a round pocket on the back face with the result that
the cam provides retention of the pin the block and self-centering of the wheel. A thrust bearing is on top of the
castering pin, along with a lower bearing.