C6, TM 9-2350-230-12
B. M13A1C ELEVATION QUADRANT.
A. GUNNER'S M1A1 QUADRANT
ZEROING M13AIC QUADRANT
DETERMINING M1A1 QUADRANT CORRECTION
1. MOVE VEHICLE TO APPROXIMATELY LEVEL GROUND.
6. COMBINE M1A1 CORRECTION WITH QUADRANT SEAT
2. SET M1A1 QUADRANT TO ZERO ELEVATION.
CORRECTION (STAMPED ON QUADRANT SEAT). SET TOTAL
3. PLACE M1A1 QUADRANT ON QUADRANT SEAT AND ELEVATE
CORRECTION ON M1A1 QUADRANT AND ELEVATE OR
OR DEPRESS GUN LAUNCHER TO CENTER BUBBLE IN
DEPRESS GUN LAUNCHER TO CENTER BUBBLE. GUN
QUADRANT LEVEL VIAL.
LAUNCHER IS NOW LEVEL.
4. TURN QUADRANT END FOR END, AND CHECK TO SEE IF
7. ADJUST M13AIC QUADRANT WITH MICROMETER KNOB UNTIL
BUBBLE IS CENTERED.
BUBBLE IS CENTERED IN LEVEL VIAL.
A. IF BUBBLE IS CENTERED, QUADRANT CORRECTION
8. IF MICROMETER SCALE DOES NOT READ ZERO, LOOSEN 3
IS ZERO.
SCREWS, PULL OUT ON KNOB AND ROTATE UNTIL ZERO
B. IF BUBBLE CAN BE CENTERED WITH MICROMETER
READING IS OBTAINED. TIGHTEN SCREWS.
KNOB, DIVIDE MICROMETER READING BY 2.
9. IF ELEVATION SCALE DOES NOT READ ZERO LOOSEN TWO
THIS IS A PLUS CORRECTION.
SCREWS SECURING SCALE TO HOUSING AND ALIGN ZERO
C. IF BUBBLE CANNOT BE CENTERED WITH
ON SCALE WITH INDEX. TIGHTEN SCREWS.
MICROMETER KNOB, DROP INDEX PLUNGER 1 CLICK (10
MILS), THEN CENTER BUBBLE WITH MICROMETER KNOB.
SUBTRACT MICROMETER READING FROM 10AND DIVIDE
BY 2. THIS IS A MINUS CORRECTION.
5. SET CORRECTION IN QUADRANT, DEPRESS OR ELEVATE
GUN LAUNCHER TO CENTER BUBBLE, AND AGAIN TURN
QUADRANT END FOR END. BUBBLE WILL BE CENTERED IF
CORRECTION HAS BEEN ACCURATELY DETERMINED. IF NOT,
REPEAT STEPS 2 THROUGH 5.
WE 12066
Figure 2-28. Adjusting M13A1C elevation quadrant
2-45
