TM 55-4920-394-13&P
1-10. Test Stand. The test stand as illustrated in Figure 1-1, incorporates the controls to operate the hydraulic
system, designated as System. No. 1, Operator's controls and instruments are located at the rear of the test
stand. These controls and instruments are functionally grouped and color coded on the control panel as
follows:
Hydraulic Panel No. 1-red (center)
System Control Panel-yellow (right side)
External test connections are located on top of the test stand to the rear of the control panel. Hoses are
supplied with the test stand for connection to the aircraft. Hose retainer hooks are provided on the front of the
test stand to store the hoses.
1-11. Test Stand Operating Components. The test stand operating components, including the control panel
are enclosed in a steel, weather resistant cabinet, mounted on a four wheel trailer, capable to being towed by a
vehicle at speeds up to 20 miles per hour. Hand-operated, mechanical-type parking brakes which act upon the
rear wheels, hold the test stand in a fixed position while in operation or when parked on a grade. The unit may
be fork lifted by inserting fork lift under the unit frame at marked channels. The major components and
systems of the test stand are as follows: trailer and running gear, housings, electric motors, main hydraulic
pump, oil cooler, fill pump and bleed system, hydraulic reservoir, hydraulic filters, instruments and controls and
the electrical system.
1-12. Detail Description.
1-13. Trailer And Running Gear Assembly (3, Fig. 1-2). The trailer frame is of welded steel construction.
The trailer rolls easily on four steel wheels equipped with 6.00 x 9.00 inch, 6 ply tires. Individual leaf springs for
each wheel give the stand good cushioning against road shocks and rough terrain, protecting the components
of the test stand. A hinged towbar (7, fig. 1-3) permits ease of positioning of the test stand and towing. The
front wheel steering is the conventional type with steering knuckles, tie rods, and king pins. A hand lever (6,
fig. 1-3) sets the rear wheel brakes, holding the test stand in a fixed position during test operation or in parking
on a grade. Two tie-down rings are provided on both the front and rear of the trailer frame to permit tie-down of
the test stand for storage or shipment.
1-14. Housing. Hinged doors on the sides of the cabinet permit access to all internal components. A hinged
instrument panel cover-protects the controls when the test stand is not in use. A screened air inlet panel is also
provided for the oil cooler (3, fig. 1-4). The tool box is located above the hydraulic fluid reservoir. Sound
deadening polyurethane foam is adhesively bonded to the inside of the housing in order to reduce noise levels.
The entire housing may be removed by releasing all the suitcase latches and lifting up using four eyebolts in
the top corners.
1-15. Electric Motor. Power for each test stand system is supplied by a 60 HP, 440 Volt, 3 Phase, 60 Cycle,
3550 RPM electric motor (1, fig. 1-3) directly coupled to the main pump (4, fig. 1-2).
1-5
