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TM 1-1730-231-13&P
c.
Motor and Pump Assembly. The motor (Figures 1-2 and 1-4) receives 24 volt direct current (vdc) supply from
either the aircraft, _F auxiliary power unit or batteries. The motor is a 1.5 horse power (hp), 1,800 revolutions per minute
(rpm), totally enclosed non ventilated motor and drives the hydraulic gear pump through the flexible coupling which
connects the motor output to pump input shafts. The pump rotation is clockwise and it pumps out minimum of 1.2 (gpm)
at 1,000 psi and 0.4 gpm at 3,000 psi. The motor/pump adapter attaches the pump to the motor. A case covers the
motor, start relay, circuit breaker, and electromagnetic interference filter to protect them from environment.
d.
Reservoir Assembly. The reservoir assembly consists of a reservoir tank which can store 5 gallons of hydraulic
fluid (MIL-H-5606 or MIL-H-83282) and supplies it for cart functions. A reservoir plate cover on top allows for reservoir
clean out and incorporates the breather/filler with removable cap and the bleed adapter stored in the filler cavity. Four
fluid level sight glasses are installed on the reservoir front side. The level at lowest level sight glass indicates the least
amount of fluid required to operate the pump. The level at next higher sight glass indicates the normal operating level.
The level at third higher sight glass indicates that the reservoir is full. The fluid level at uppermost sight glass indicates
that the reservoir is about to overflow if more fluid is taken in. A drain plug is installed at the bottom of the reservoir. A
suction strainer is installed inside the reservoir and a connection from the rear of the reservoir leads to the gear pump.
e.
Hydraulic Piping Assembly. The hydraulic piping assembly consists of tubes, tees, elbows, and connectors
connecting between reservoir, gear pump, filter, and the manifold (Figure 1-3). The filter is located in the outlet line from
the gear pump and is easily accessible by lifting up the control panel cover. A 1 micron disposable filter element within
the filter gives the pressurized fluid a final cleaning before outlet to the helicopter struts. A clogging indicator on the top
of the filter indicates high differential pressure between the filter inlet and outlet. Should the filter element become
clogged, a red marker will extend to show element requires replacement.
f.
Electrical Wiring/Components Assembly. A 30 feet (ft)(762 mm) 24 vdc shielded power cable with power
receptacle to mate with aircraft power plug is attached to the cart and stowed in the storage area. Another short cable
with power plug at one end and battery clips/ connections at the other end is also stowed in storage area.
Another 50 ft (1270 mm) cable with non ferrous metallic controller is stowed in the storage area. The controller has
four toggle switches and a POWER ON indicating light. One toggle switch is a maintained contact switch used for pump
ON/OFF operations. The other three toggle switches are momentary contact and are used for tall, left, and right
RAISE/LOWER operations to erect/kneel the helicopter struts. These toggle switches are fail-safe controls to prevent a
fully loaded helicopter from lowering (kneeling) without the proper switches being
1-4
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