TM-9-1290-262-24&P Technical Manual for M2A2 Aiming Circle Download
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ARMY TM 9-1290-262-24&P MARINE CORPS TM 00476C-24&P AIR FORCE TO 49A7-3-72/74 CIRCULAR ERROR TEST 1 2 3 4 5 6 7 8 9 NOTE Circular error can be present in aim- ing circle even though worm and worm gear mechanisms operate smoothly and do not have excessive backlash. Error is due to poorly spaced worm gear teeth. Set azimuth ring (1) of test fixture to zero. Rotate azimuth knob (2) to set aiming circle azimuth index and micrometer scale to zero. Using orienting knob (3) quick release, direct aiming circle elbow telescope line-of- sight into collimator. Using orienting knob (3), adjust aiming circle to superimpose elbow telescope vertical reticle line on collimator vertical reticle line. Using elevation knob (4), superimpose aiming circle horizontal reticle line on colli- mator horizontal reticle line. Offset test fixture azimuth ring (1) 800 mils counterclockwise. Rotate azimuth knob (2) to set aiming circle to 800 mils. Look through elbow telescope eyepiece. Error between aiming circle verticle reticle line and collimator vertical reticle line should not exceed 0.7 mils. If tolerance is exceeded, refer to azimuth worm backlash test and adjustment, page 3-39. Repeat steps 7 and 8 at 800-mil intervals until the complete circle is made. 4-33