Description
U.S. Army Technical Manual Change 1 for TM 9-1240-312-35, M149 Telescope Mount, March 1968
This official U.S. Army publication is Change 1 for TM 9-1240-312-35, the field-and-depot maintenance manual for the M149 Telescope Mount. Issued in March 1968, it updated the original technical manual dated April 25, 1966.
This listing is for the Change 1 update only. It is not the complete TM 9-1240-312-35 maintenance manual. It does not include an M149 mount, telescope, missile tracker, sighting equipment, weapon, or vehicle.
Purpose of Change 1
Army technical-manual changes supplied official corrections, revised instructions, and replacement material for an existing publication. Change 1 was intended to be kept with the original April 1966 manual so maintenance personnel had the latest approved information.
The update applies to the higher-level maintenance publication for the M149 Telescope Mount. The original manual supported trained personnel performing inspection, troubleshooting, disassembly, cleaning, repair, assembly, adjustment, optical alignment, testing, and final inspection.
About the M149 Telescope Mount
The M149 was a sealed optical, electrical, and mechanical assembly used with the M551 Sheridan’s fire-control system. It held the gunner’s articulated telescope and the infrared missile tracker in alignment with the vehicle’s 152mm gun-launcher.
An internal checksight allowed the missile tracker to be aligned with the telescope. The mount included ERROR and ALIGN controls, azimuth and elevation adjustments, a telescope-locking mechanism, electrical circuits, optical components, and a checksight lamp. Its sealed optical section was filled with dry nitrogen to help prevent moisture and internal fogging.
The mount was identified by Federal Stock Number 1240-762-9334. Under the later National Stock Number system, this became 1240-00-762-9334. The standardized M149 was also identified by military part number 10527950.
Fire-Control Application
The M149 mount supported the M119 Articulated Telescope and later the improved M127. These telescopes provided the gunner’s direct-fire view for conventional 152mm ammunition and also worked with the guidance system for the MGM-51 Shillelagh antitank missile.
The mount was installed coaxially with the gun-launcher, allowing the sighting equipment to follow the weapon through elevation and depression. Accurate alignment between the telescope, tracker, mount, and gun-launcher was essential for conventional and guided-missile fire.
Historical Background
The original TM 9-1240-312-35 was issued on April 25, 1966, while the mount and the XM551 vehicle program were moving from development into production. The mount was first documented as the experimental XM149 and later standardized as the M149.
Change 1 was released in March 1968, after the M551 Sheridan entered Army service in 1967. It represents an early update made as the Army began fielding and maintaining the new vehicle and its complex missile-guidance equipment. Sheridans entered combat in Vietnam in 1969.
The Army later published TM 9-1240-312-34 for the standardized M149 Telescope Mount in May 1973. This Change 1 publication helps document the earlier maintenance history of the mount during the Sheridan’s development and initial service period.
Publication Details
- Publication type: Technical Manual Change 1
- Applicable manual: TM 9-1240-312-35
- Change date: March 1968
- Original manual date: April 25, 1966
- Subject: M149 Telescope Mount
- Earlier experimental designation: XM149
- Federal Stock Number: 1240-762-9334
- Standardized M149 part number: 10527950
- Original manual type: Field-and-depot maintenance
- Documented parent system: M551 Sheridan
- Weapon system: 152mm gun-launcher and MGM-51 Shillelagh missile
- Item included: Change 1 update only
Collector and Research Value
This Change 1 update is a specialized addition to a U.S. Army technical-publication, military-optics, or armored-vehicle collection. It is useful for completing an original TM 9-1240-312-35 manual set and for studying the early maintenance history of the M149 mount and M551 Sheridan fire-control system.
Ideal For
- TM 9-1240-312-35 manual sets
- M149 Telescope Mount research
- M551 Sheridan restoration references
- Vietnam War armored-vehicle displays
- MGM-51 Shillelagh fire-control research
- Cold War military-optics collections
- Museum and archival collections
Approx length 8", Approx width 10", Approx height .15", Approx weight .2lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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