A German Mark II tank with an electric gyroscopic compass has made
its appearance in Libya. It is possible that all commander's tanks
may be equipped with this particular device.
The whole equipment is first-class in quality and workmanship. It is not
likely that breakdowns will occur to any great extent, and the equipment
should give long service without overhaul.
The main components of this instrument are the generator and the gyro, connected
to each other by a flexible multicore cable. Switches for operation
and lighting are fixed to the casing.
The motor generator is housed in a separate casing which may be placed
in a convenient location in the vehicle. A 12-volt motor drives a three-phase
alternator supply to the gyro. The whole arrangement is compact, and appears
fully suppressed and screened to avoid radio interference.
Fitted to the dashboard in front and to the left of the driver, the gyroscopic
instrument consists of a small box with a panel showing two cards rotating
in a horizontal plane. A switch and two control knobs, one for each dial, are
added features of this equipment (see accompanying sketch).
|German Electric Directional Gyroscope|
To march on a certain point, a celluloid disk, marked around the
circumference in clock-rays, is centered on the position of the
tank on the map with 12 pointing due north. A thread leading from
the center of the disk is joined to the point on the map which is
the objective, and thus shows, in terms of clock-rays, the bearing
of the objective from the tank. This is termed the "march number."
The indicator must be set before using. This is done by finding the
course of the tank, setting the gyro, and starting the gyro and
allowing it to gain speed. The course is set on the course-setting
dial and the tank steered until the dial markings on both dials coincide.
A special compass is provided to find the tank's course. It has a glass
marked with clock-ray divisions. The compass user must not stand nearer
than 15 yards from the tank when finding its heading. Setting of the
gyro is done by turning the gyro dial with the setting knob until it is the
same as the tank's course previously found with hand compass. After
setting, the gyro must be started and allowed 3 or 4 minutes to gain
speed; it then must be set free by pressing the release button.
The course-setting dial is to assist the driver in keeping to his course
without constantly remembering what the actual bearing is. Therefore, the
dial is set to the desired course (or march number) and the tank then
steered to make the top dial figures keep opposite the lower (gyro) dial.
Resetting of the indicator may be necessary, either periodically because
of deviation, or because exceptional tilt temporarily interferes with the
internal mechanism. When this occurs a red warning-light is shown.