MIL-DTL-48554 Telescope, Panoramic - M137A2, M137A3, And M137A4This specification covers Telescope, Panoramic ?√ M137A2, M137A3, and M137A4 which are types of panoramic telescopes which provide four-power magnification and a ten-degree field of view. They are equipped with numerical counters which indicate azimuth settings and corrections.

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MIL-DTL-48554B

3.12 Open sight. With the telescope positioned as in 3.4, the line of sight of the

open sight shall be within 10 mils of the line of sight through the telescope optics in both

azimuth and elevation.

3.13 Torque. The running torque required to operate the following knobs shall be

within the values specified at the temperatures specified in Table II. The torque values for

the azimuth knob shall be met with the five mil click lead actuator set to "Indirect."

TABLE II. Knob torque values.

KNOB

At +60 �F to +90 �F

At -50 �F and +145 �F

Azimuth

3 to 8 in. lbs.

15 in. lbs. max.

Correction Counter

10 to 20 in. ozs.

40 in. ozs. max.

Boresight Adjustment

7 to 80 in. ozs.

10 in. lbs. max.

Elevation

5 to 40 in. ozs.

80 in. ozs. max.

Clutch Release (lever)

7 to 80 in. ozs.

10 in. lbs. max.

3.14 Direct force, elbow assembly. At a standard ambient temperature of +60 �F to

+90 �F, a direct force of 1 to 10 pounds, applied horizontally and in the direction of

movement adjacent to the eyepiece, shall be required to rotate the elbow assembly in each

direction through the full extent of travel with the elbow detent lock pin released. The

force required at the extreme operating temperatures of 3.3.2 shall not be greater than 15

pounds.

3.15 Operability. The azimuth counter cover and latch, head cover and latch,

azimuth knob folding handle, elbow detent lock pin, and the five mil click lead actuator

shall be operable at standard ambient temperature and the extreme operating temperatures

specified in paragraph 3.3.2.

3.16 Counter numerals. With the units digit of each counter in coincidence with its

respective index line, the remaining numbers shall be in horizontal alignment within one-

sixteenth of an inch and more than half of each number must be visible through the shield.

3.17 Illumination.

3.17.1 Reticle. With the battery in place, the reticle markings shall be clearly

distinguishable when observed in ambient light conditions, ranging from dusk to darkness.

3.17.2 Counters. The numerals on the azimuth, deflection or bearing and correction

counters, when illuminated using the telescope's power and lighting system, shall be

clearly distinguishable when observed in ambient light conditions ranging from dusk into

darkness with and without the use of a 50% neutral density filter.