Patent GB-124845-A (GB)
Title: Improvements in or relating to Repeaters for Gyro-compasses.
Inventor: BROWN SIDNEY GEORGE
IPC: G01C19/40
Filed: 1917-05-05
Abstract: 124,845. Brown, S. G. May 5, 1917. Gyroscopic compasses.-A repeating system for gyro-compasses consists of an air blast generated in the gyro-casing of the master compass, a twocoil relay, a reversing-switch controlled by the relay, a direct-current motor the direction of which is controlled by the reversing-switch, and step-by-step rotary field motors the energization of which is controlled by a commutator driven by the direct-current motor. The coils of the relay are placed in electric circuits containing hot wires the resistances of which are varied by the air blast; and the relay is biassed by a spring or by making the ampere turns of the coils unequal. The bias is overcome by causing the air blast, in its normal position, to produce unequal cooling effects on the hot wires in the circuits of the coils. In a modification, the air blast controls a switch controlling the two-coil relay. A switch is provided by means of which the stepby-step motors of the master compass and of the repeaters and the direct-current motor are zeroized. The armatures of the step-by-step motors are braked by pressing them against the casing by means of springs, which are overcome to release the armatures when the field magnets are energized. The coils a<x>, Fig. 2, of the relay A, Fig. 1, are placed in circuit with hot wires F, Figs. 2 and 3. The contact-arms a<2>, Fig. 1, are biased by a spring a<6> in order that one of them may engage its contact a<3> when either of the F is cocled by an air blast issuing from a nozzle 0, Fig. 3, or when the normal cooling effect on both wires is disturbed. This biasing action prevents the system from becoming inoperative when the air blast is moved completely from its operative position relative to the wires F. A relay A controls the operating-windings a<5>, Fig. 1, of a reversing-switch B which controls the direction of rotation of a direct current motor c<1>. The motor c<1> drives a master repeater C, and a ccmmutator c<3> controlling the supply of current to step-by-step rotary field motors e. To set the motors c<1>, e in their zero positions, a three-position switch D is provided, and the contact rings c, J, J<1> are provided with insulating-segments c<4>, j adapted to engage brushes c<5>, j<1>. When the switch arm d of switch D is in position 1, the system is set for normal working. When the arm d is in position 2, the motors e are rotated until the segments y come under the brushes j<1>. When the arm d is in position 3, the motor c<1> is rotated until its circuit is broken by the brush c<5> engaging the insulating contact segment c<4>. The air blast is supplied from the casing N, Fig. 3, through a hollow pivot pin n to the nozzle 0 mounted on the orientating frame M adapted to rotate about a vertical axis o. The hot wires F are mounted between two pairs of insulated arms f, f<1>, the lower of which are pivoted and operated upon by springs f<3> to tension the wires F. The arms f, f<1> are mounted on an arm f<2> depending from the ring J, which carries three. slip-rings K through which current is supplied to the wires F, and is rotatably mounted upon rollers j<2> the outer ends of which engage a groove in a relatively fixed ring l. The lower edge j' of the ring J is provided with teeth engaged by a pinion e<1> driven through worm gearing by the motor e of the master compass. The ring l and the motor e are mounted on the gimbal ring or pendulous frame L mounted on a pivot pin l<1> The brush j<1>, Fig. 1, is mounted on the frame L and engages the outer edge of the flange j<4> of 'the ring J, this flange acting as a fourth slip-ring. The compass card m is mounted on the frame M. When the orientating frame M rotates about the axis x. the air blast from the nozzle O is moved therewith to cool the wires F differentially, thereby causing the motors c, e to rotate synchronously, the motor e of the master repeater E, Fig. 1, operating the ring J until the relay A is de-energized, and the. other motor e operating this repeater. The notched-disc armature e<4>, Fig. 4, is normally pressed against the casing by a spring e<6> and when the magnet coils e<7> are energized the armature e<4> is lifted from the casing and then rotated. Upon de-energization of the coils e<7>, the armature is forced against the casing and braked. The hot-wire system cooled by the air blast, as shown in Figs. 2 and 3, may be replaced by a switch shown in Fig. 6, in which the air blast operates a pivoted contact-arm f<5> moving between contacts F<1> to control the relay A.