TM 55-1905-223-24-14
(a) Terrestrial Bearings. To observe the bearing of a terrestrial object, the observer looks through the peep vane
(3) in the direction of the object and by means of finger lugs (9) provided on the circle, turns the circle until the object
appears on the vertical wire of the far vane (6). At the base of the far vane (6) is a mirror marked with a center line
agreeing with the vertical wire of the far vane (6). The mirror (7) reflects the compass card (of the bearing repeater or
magnetic compass) into the view of the observer to see the observed object and the compass card at the same time.
The compass bearing of the observed object can then be read by the vertical wire on the compass card.
(b) Celestial Azimuths. A dark glass reflector (7) is attached to the far vane (6), movable about a horizontal axis,
enabling the observer to adjust it so that the reflected image of a celestial body can be brought to the observer's eye, and
a compass azimuth can be read from the compass card as was described for a terrestrial object. At right angles to the
line of sight of the pair of vanes (3 and 6) is another set of observing devices for obtaining the compass azimuth of the
sun. Light is reflected by 45 degree reflecting prism encased in a metal housing (5) provided with a slit in which light is
received from a concave mirror (4) diametrically opposite, with the slit being in the focus of the concave mirror. Light is
reflected downward by the prism and appears on the graduations of the compass card as a bright narrow band or line. To
observe the compass bearings of the sun with this arrangement, the observer turns the-azimuth circle until the sun's rays
are reflected by the mirror across the card to the prism, where the bearing can be read on the compass card by means of
the narrow band of light.
c. Gyro Compass Equipment Data. Reference data for the Gyro Compass System is provided in Table 1-1.
Also see the equipment data given in the operator's manual, TM 55-1905-223-10.
Table 1-1. Equipment Data
Characteristic
Reference Data
Gyro Compass Power Input
24 Vdc from gyro control and power assembly
gyro Control and Power Assembly
24 Vdc from power converter or from power
Power Input
transfer unit (normal power failure)
Power Converter Power Input
120 Vac, single phase, 60 Hz, from ship's
power source
Switch Unit Power Input
70 Vdc from gyro control and power assembly
Relay Transmitter Power Input
120 Vac, single phase, 60 Hz, from ship's
power source
Power Transfer Unit Power Input
24 Vdc from ship's emergency 24 Vdc source
24 Vdc from power converter (sensing
voltage)
1-22
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