GB611770A - Improvements in and relating to apparatus for indicating the position or course of a navigable vehicle - Google Patents

Abstract

611,770. Electric follow-up systems. YOUNG, F. B., CHAMPNEY, L., BURNSIDE, W., PLATT, J. M., SHORTEN, F. A., and LAURENCE, SCOTT, & ELECTROMOTORS, Ltd. May 7, 1946, No. 13827. [Class 40 (i)] [Also in Groups XX and XL (c)] In a course-recording apparatus in which a plan position picture of a navigable vehicle's surroundings obtained by radar or other echolocating apparatus is presented for view against a plotting surface, the speed of the driving motor is varied in accordance with impulses from the vehicle's log by an escapement speed control working through a variable friction gear. Resolver 10, Fig. 3, fed by compass repeater motor 16 and driven, in accordance with impulses from the ship's log through escapement 18 and gearing 19, by the motor 17, applies to the course-recording apparatus (see Group XX) the two rectangular components of the vehicle's speed. The variable friction gear, Fig. 8, comprises two conical rollers 71, 72 coupled by an idler disc 73. Roller 71 is driven by shaft 17a from the motor 17 and roller 72 drives the escapement disc 90, Fig. 12, by the shaft 74. The driving ratio may be adjusted by turning a screw 76 through gears 76a, 77a, which engage when the remote control shaft 77 is moved longitudinally, the screw having a carriage 75 mounted thereon in which the idler disc 73 is journalled. Means are provided for using impulses from a clock to give an estimated speed in the event of failure of the log. The plotting scale in use, i.e. miles covered by the ship for each inch of movement of the plotting surface, is shown on scale bar 78 moving with the carriage 75. Rotation of the knob 83 which changes the multiplying gearwheels of the drive also brings into use the scale appropriate to the main gearing. As shown in Fig. 12, the escapement disc 90 carried on a screw-thread 92 of the shaft 74 from the variable gears 71, 72, has two rings of circumferentially spaced studs 91 and rotation of the shaft tends to retract the disc 90 along the thread 92. This tendency is countered by rotation of the disc in the opposite direction by a coiled spring 93 to the extent permitted by periodical movement of an armature 94 out of the path of studs 91 under the influence of an electromagnet 95 receiving impulses from the log or a clock. An adjustable cap 96 on a boss on disc 90 bears against the longest blade 97 of a group of blades carrying electrical contacts c<SP>1</SP>, c<SP>2</SP>, c<SP>3</SP>, c'. Forward movement of disc 90 tends to open the contacts c<SP>1</SP>, c<SP>2</SP> and to close the others. As shown in Fig. 13, these contacts control the shunting and applied voltage of the driving motor.