TM-9-2350-311-10

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; OPERATOR’S MANUAL

NOVEMBER 1994

TM-9-2350-311-10 - Page 237 of 775

TM 9--2350--311--10

Change 6

2--139

2--11 OPERATION OF FIRE CONTROL EQUIPMENT UNDER NORMAL CONDITIONS

— CONTINUED

2--11.1

M117/M117A2 Panoramic Telescope and M145/M145A1 Telescope Mount — Continued

d. Quick Alinement of M117/M117A2 Panoramic Telescope Using the M140/M140A1 Alinement Device

WARNING

The M140 alinement device is radioactively illuminated. Check for loss of luminescence,

breakage, damage, or defects. If present, follow the procedures on pages b and c.

NOTE

•

To assure the M140/M140A1 alinement device is in collimation and can be used for quick

alinement procedure, the fire control instruments must first be boresighted using either

distant aiming point method or test target method (para 2--12.2). Paragraph 2--12.2 also

provides procedures for checking the M140/M140A1 alinement device while boresighting

on the test target.

•

M140/M140A1 alinement device is used to aline M117/M117A2 panoramic telescope with

cannon tube.

•

Parallax occurs when panoramic telescope ballistic cover is not perpendicular to line of

sight of M117/M117A2 panoramic telescope. To eliminate this refraction problem, keep

panoramic telescope ballistic cover perpendicular to line of sight of M140/M140A1

alinement device and M117/M117A2 panoramic telescope during boresighting.

1

Gunner removes M140/M140A1 alinement device (28) from stowage and hands it to driver.