998212-A is referenced by 4 patents.
998,212. Sighting devices. WAR DEPARTMENT, SECRETARY OF STATE. April 29, 1964 [Jan. 29, 1963; Aug. 19, 1963], Nos. 3569/63 and 32636/63. Heading F3C. [Also in Division G2] A sighting device for guns and surveying or or other optical instruments includes a portion 2 incorporating a sighting instrument, e.g. a telescope and rotatable by a worm wheel 19 integral therewith and a worm 23 carried by a shaft 20 which is pivoted by a ball- and-socket joint 25, 26, 27 to swing about an axis parallel to that of the worm wheel to disengage the worm from the worm wheel. The worm 23 is urged into engagement with the worm wheel by a spring-pressed wedge member in the form of a plunger 30 which receives the end of the shaft 20 in a guideway 31, the plunger 30, when depressed, acting to disengage the worm from the worm wheel to permit the sighting instrument to be rotated by hand.; The sighting instrument is normally rotated by a knob 24. In another embodiment the plunger moves in a bore parallel with the shaft 20 the end of which is received in a guideway of the plunger inclined to the axis of the shaft 20. The sighting instrument, which is mounted in the portion 2 by a universal joint, can be moved in azimuth and elevation by two pairs of sliding cams 40 each pair being connected by a lever 41, adjusted by a screw 43 and urged into gripping engagement with the housing 4 of the sighting instrument by a spring 48.