SECTION III TECHNICAL PRINCIPLES OF OPERATION
1-12. GENERAL OPERATION.
General operation consists of positioning the Ground Handling Wheels Assemblies over the skids, attaching the cradle to
the helicopter with a nose pin or quick release pin, lifting the helicopter with the hand operated hydraulic pump, and
moving the helicopter.
1-12.1 Positioning. The Ground Handling Wheels Assemblies are positioned over the left and right landing skid lifting
lugs, which are located aft and forward of the helicopter center. The lug locations provide a "near balance" condition for
ground handling or moving the helicopter by hand. The cradles are aligned and attached to the skid lugs by nose pins
at the front and quick release pins at the rear.
1-12.2 Lifting. Two Ground Handling Wheels Assemblies are used to lift the helicopter off the ground. Each Ground
Handling Wheels Assembly has a hand operated hydraulic pump. Operating the hand pump provides hydraulic force
to hydraulic rams, which rotate the eccentric axles mounted in the cradle assembly. This action lifts the cradle
sufficiently to raise the helicopter landing skids off the ground.
1-12.3 Moving. Once lifted, the helicopter is supported by hydraulic pressure It can be moved by balancing, rolling, and
maneuvering into desired position manually.
Personnel injury may result when operating the hydraulic pump, If the metering valve Is not
mounted properly In the pump outlet. This valve controls the rate of descent, and any attempt
to use the control valve release knob to control descent of the helicopter, may prevent the
metering valve from activating properly.
1-13. HYDRAULIC HAND PUMP OPERATION.
The hydraulic hand pump will function in the horizontal, vertical, or any intermediate positions of the Ground
Handling Wheels Assembly. The hydraulic pump is operated as follows:
1-13.1 Metering Valve. The metering valve Is installed in the pump outlet, to restrict the flow of hydraulic fluid
when pressure is released. This ensures that the helicopter is lowered at a slow and safe rate, when the
pressure is released through the pressure control valve. The valve release knob must be rapidly turned, to
ensure proper operation of the metering valve.
1-13.2 Release Knob. The release knob is part of the pressure control valve in the pump body. The control
valve must be closed when pumping up pressure to lift the helicopter and must be opened, by the release knob,
to lower the helicopter. The control valve release knob must be rapidly turned to ensure proper operation of the
1-13.3 Pump Handle. The pump handle operates the pump piston to produce pressure and move a volume of
fluid to the hydraulic rams. The hydraulic rams extend and mechanically rotate the eccentric axles to lift the
helicopter. The control valve must be closed by the release knob before operating the pump handle.