TM-9-2350-311-10 M109 Operator's Manual for M109A2, M109A3, M109A4 and M109A5 Download
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TM 9-2350-311-10 3-7 FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS — CONTINUED 3-7.3 Leveling Gun Trunnions — Continued b. Scribed Lines Method 1 2 3 4 NOTE This procedure applies only to weapons with M15 elevation quadrants that have been previously scribed (para 3-7.8). Position the weapon on as firm and level ground as is possible or hardstand if one is available. Turn on M15 elevation quadrant (12) lights with toggle switch (13) and carefully aline scribe lines (16) and (17). Set zero mils on M15 elevation quadrant (12) and level the elevation bubble (15) by elevating or depressing the cannon tube (6). Manually and slowly traverse the cannon tube (6) (either direction) while someone watches the cross-level bubble (18). Stop traversing when the cross-level bubble centers. Manually elevate or depress the cannon tube until the elevation bubble (15) centers. Recheck the cross level bubble. If cross-level bubble remained exactly centered, the gun trunnions are level. If not, traverse until the cross-level bubble is centered. The gun trunnions are now level. 3-92