Description
Technical Manual Change 1 (TM 9-1240-287-34) for M53 Sight Unit January 1969
Technical Manual Change 1 (TM 9-1240-287-34) for M53 Sight Unit – January 1969
Item Overview
This original U.S. Army Change 1 publication updates TM 9-1240-287-34, the direct-support and general-support maintenance manual for the M53 Sight Unit.
Change 1 was issued in January 1969. It applies to the original technical manual dated March 5, 1963.
This listing is for the Change 1 update only. It is not the complete March 1963 base manual and does not include the M53 Sight Unit, mortar, instrument light, carrying case, tools, or other equipment.
About the Original Manual
TM 9-1240-287-34 provided advanced maintenance instructions for the M53 Sight Unit. Its procedures were intended for trained support personnel rather than mortar crews.
The base manual covered subjects such as:
- Inspection and troubleshooting
- Disassembly and cleaning
- Optical and mechanical repair
- Assembly and adjustment
- Deflection and elevation calibration
- Level-vial inspection
- Final testing
- Preparation for storage or shipment
About the M53 Sight Unit
The M53 combined two major components into one fire-control instrument:
- M109 Elbow Telescope, part number 8588780
- M128 Telescope Mount, part number 8245970
The M109 is a fixed-focus optical instrument with 4x magnification and a 10-degree field of view. The M128 mount contains the scales, level vials, knobs, and locking controls used to set mortar elevation and deflection.
The complete M53 weighs approximately 5.25 lbs. Related instrument-light equipment allowed its reticle and scales to be viewed during night operations.
Historical Background
The M53 was developed during the Cold War as a standard sight for U.S. mortar systems. Documented applications include the 81-mm M29/M29A1 mortar and the 4.2-inch M30 mortar.
These weapons were also installed in armored mortar carriers. The M125 series carried the 81-mm mortar, while the M106 series carried the 4.2-inch M30.
Issued in January 1969, Change 1 dates from the height of the Vietnam War. Mortars provided mobile, high-angle fire support for infantry and armored units, making dependable sighting equipment essential.
This update documents the Army’s effort to keep M53 maintenance instructions current as the sight continued in service.
Identification
- Publication: Change 1
- Manual number: TM 9-1240-287-34
- Equipment: Sight Unit M53
- Change date: January 1969
- Original manual date: March 5, 1963
- Maintenance level: Direct support and general support
- M53 part number: 8245971
- M53 NSN: 1240-00-856-9452
- Telescope: M109 Elbow Telescope
- Mount: M128 Telescope Mount
- Documented applications: M29/M29A1 81-mm mortar and M30 4.2-inch mortar
Collector and Research Value
Change publications are often separated from their base manuals after installation. This example is useful for comparing editions, researching Vietnam-era mortar maintenance, or assembling a complete M53 technical-manual set.
Ideal For
- U.S. Army technical-manual collections
- M53 Sight Unit restoration research
- M29 and M29A1 81-mm mortar displays
- M30 4.2-inch mortar displays
- M106 and M125 mortar-carrier research
- Collectors assembling a complete manual set
Approx length 8", Approx width 10", Approx height .1", Approx weight .1lbs.
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