TM-9-2350-311-10

TM 9-2350-311-10

3-7 FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS - CONTINUED

3-7.11 Field Verification of Scribe Lines On the M15 Elevation Quadrant

Emplace howitzer in firing position with spades emplaced.

Set the elevation counter (1) on the M15 elevation quadrant (2) to zero and then manually elevate or

depress the cannon tube until the elevation level (3) bubble is centered.

Carefully aline the scribed lines on the M15 elevation quadrant (para 3-7.8).

Slowly traverse the cannon tube manually as someone watches the elevation level (3) bubble and the

cross-level (4) bubble. If the elevation level goes off center, recenter it by elevating or depressing the

cannon tube. (As traversing continues, it may be necessary to repeat the raising and lowering of the

cannon tube to keep the elevation level bubble centered.)

At some point in the 6400 mil traverse, the cross-level (4) bubble will center. It is very important that the

bubble in the cross-level vial is centered exactly.

When elevation level (3) bubble and the cross-level (4) bubble are centered, the gun trunnions are level.

Repeat steps 3 through 8 of scribe verification using M145/M145A1 telescope mount check (para

3-7.10) and record the differences between the two readings.

Compare the M145/M145A1 telescope mount error from step 7 with the M145/M145A1 telescope mount

error recorded while the howitzer was still on the jacks (para 3-7.10). The difference between the two

M145/M145A1 telescope mount error readings must not be more than ~ 1 mil. If the difference is greater

than * 1 mil, go through the entire procedure again to ensure there were no mistakes made and no steps

overlooked. Then, if the difference between M145/M145A1 telescope mount error reading in the two

tests is still greater than + 1 mil, notify unit maintenance.

If the readings are within * 1 mil tolerance, the gun trunnions can be leveled and M145/M145A1 telescope

mount check can be performed in the field by use of the scribe lines on the M15 elevation quadrant.

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