Figure 4-19.--Simplified diagram of the Mk 19 Mod 3A compass element.

and follow-up alarm are located on the control panel.

When a power failure occurs, the power available lamp

will go out. When a follow-up error occurs, the

follow-up alarm lamp will light up and an audible alarm

will sound.

SPERRY MK 19 MOD 3

GYROCOMPASS

SYSTEMS

The Sperry Mk 19 Mod 3 gyrocompass systems

furnish roll and pitch angle information as well as

heading information. This roll and pitch angle

information is used to stabilize gunmounts, missile

launchers, and other equipment that must remain level

with respect to the earth's surface for proper operation.

The Mk 19 Mod 3 gyrocompasses are used as the master

compass on Navy combatant ships. Some ships will

have two Mk 19 compasses installed; one will be used

as the master compass and the other as the backup

compass. There have been five modifications to the

original Sperry Mk 19 Mod 3 gyrocompass system since

it was first introduced. These five modifications will be

discussed in the following paragraphs.

MK 19 MOD 3A GYROCOMPASS

SYSTEM

The Mk 19 Mod 3A gyrocompass is a navigational

Figure 4-19.--Simplified diagram of the Mk 19 Mod 3A

and fire control instrument with design features based

compass element.

on unusual requirements. The compass is designed to

operate in latitudes up to 80 with an accuracy of 0.1

in azimuth at sea. In addition, it accurately measures and

transmits angles of roll and pitch. These features

distinguish the Mk 19 Mod 3A from all other shipboard

gyrocompasses that preceded it.

An electric control system is used in the Mk 19 Mod

3A gyrocompass to make it seek and indicate true north

Design of the compass is based on the principle that

as well as the zenith. A gravity reference system is

two properly controlled horizontal gyros can, together,

employed for detecting gyro tilt, and torques are applied

furnish a stable reference for the measurement of ship's

electromagnetically to give the meridian gyro the

heading, roll, and pitch. Briefly, the basic unit consists

desired period and damping. Further, signals are

of two gyros placed with their spin axes as shown by

generated by the compass, which are used to stabilize

figure 4-19. The top gyro is a conventional gyrocompass

the entire sensitive element in roll and pitch, thereby

and is referred to as the north-seeking, or meridian, gyro.

Its spin axis is directed along a north-south line.

furnishing an indication of the zenith in terms of roll and

pitch data.

The lower gyro is a directional gyro with its spin

Both the meridian and slave gyros are enclosed in

axis slaved to the meridian gyro along an east-west line.

hermetically seated spheres and suspended in oil. The

It is referred to as the slave gyro and furnishes

indications of roll on north-sowb courses and pitch on

compass is compensated for northerly and easterly

east-west courses.

speed and acceleration, earth rate, constant torques, and

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