horizontal scanning drive shaft. Double universal joints and 5/8" 

 cold rolled steel rod made the linkage (fig. 8) to the yoke-mounted 

 worm and ring gear. Secondary drive shafts were moimted in split 

 bronze bushings and securely welded on the steel bushing housing. 

 These were fabricated of 1" key stock welded to the yoke arms of the 

 power suspension unit. 



The yoke arms were fabricated of circular bent steel tubing 

 2-1/2" O.D. with 3/l6" wall thickness (fig. 1). The camera housing 

 and ball fairing was supported at the lower ends of yoke arms by fabri- 

 cated steel split yoke bearing housings clamped to oilite bronze bush- 

 ings. The vertical drive ring gear was held in place on the turret 

 drive shaft with 3/8" Allen set screws (fig. iic). Limit smtch cams 

 (fig. Ua) and a reversing switch cam were welded on a close fitting 

 bronze ring that was secured with two 10 x 32 Allen set screws to the 

 hub of the bronze horizontal-drive worm gear. 



Drive Mechanisms 



The vertical- and horizontal-drive motors were 21; volt D.G., 

 2 amp. gear head drive, aircraft-flap actuating motors. General 

 Electric Model 5BA25DJ300 motors were selected for their low speed, 

 high torque, and small size. A worm gear speed of I4.O R.P.M. had a 

 ratio to the ring gear of i|0 to 1 which gave the 1 R.P.M. desired 

 scanning speed. Both worm and ring gears were purchased as stock items. 

 A shaft extension was installed to carry the worm gear and provided a 

 shaft for a side-thrust outboard bearing. The outboard bearing, a com- 

 bination end thrust and sipport bearing, was made of standard bronze 

 bearing material. It was installed on the end of an 8" piece of 1" x 

 1" X 3/16" angle iron which was welded to the base plate of the upper 

 pressure vessel (fig. Uc). Two other angle irons were similarly welded 

 to make a raised support for the horizontal drive motor (fig. Ua) . 

 These were drilled to fit and 5/l6" cap screws with nuts and lock wash- 

 ers were used to hold the motor in place. 



The vertical drive motor was mounted on a bracket fabricated 

 by welding and forming a section of 12 gauge galvanized sheet iron 

 (fig. Ub). A welded collar on the lower side provided attachment of 

 the bracket to the hollow horizontal scanning drive shaft. Positive 

 location of the vertical drive motor base was given by 10 x 32 Allen 

 head set screws set into drilled seats. 



A direct coupling secured with set screws connected the verti- 

 cal drive motor to the vertical scanning drive shaft. This coupling 

 mounted a small 8 tooth sprocket wheel providing a chain drive to a 

 larger 80 tooth camjned sprocket mounted on a small vertical shaft and 

 welded to the vertical drive shaft motor base (fig. Iia) . Limit switches 



8 



