MIL-DTL-48557 Mount, Telescope And Quadrant - M171A1This specification covers the Mount, Telescope and Quadrant: M171A1 which supports the Telescope, Panoramic: M137A2 and Quadrant, Fire Control: M17A1 for use on the M777 and M198 series of howitzers. The mount provides adjustments in pitch and compensates for angles of cant when laying the guns for indirect fire.

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MIL-DTL-48557B

3.9 Knob torque. The running torque required to operate the knobs shall conform to

the values in Table IV at the corresponding temperatures.

TABLE IV. Knob torque.

Knob

Torque at +60 �F to +90 �F

Torque at +145 � 5 �F

and -50 � 5 �F

Cross level

4 to 12 inch pounds

27 inch pounds maximum

Pitch level

4 to 12 inch pounds

27 inch pounds maximum

3.10 Interchangeability.

3.10.1 Interchangeability of mounting surface of M171A1 mount. The mounting

surfaces of the M171A1 mount shall be able to be mounted on the corresponding mounting

surfaces of the howitzer.

3.10.2 Interchangeability of mounting surface for M17A1 quadrant. The mounting

surface on the M171A1 mount for the M17A1 quadrant shall be able to accept a M17A1

quadrant with its mounting surfaces at maximum material condition.

3.10.3 Interchangeability of mounting surface for M137A2 telescope. The

mounting surface on the M171A1 mount for the M137A2 telescope shall be able to accept

a M137A2 telescope with its mounting surfaces at maximum material condition.

3.11 Workmanship. Workmanship of the M171A1 mount shall be in accordance

with the requirements of MIL-F-13926.