Description
Technical Manual Change 1 (TM 9-1240-309-34) for XM44, XM44E1, XM44E2, XM44E3, and XM44E4 Tank Periscopes January 1975 NSN 1240-00-788-5463
U.S. Army Technical Manual Change 1, TM 9-1240-309-34, for XM44-Series Tank Periscopes, January 1975, NSN 1240-00-788-5463
Item Overview
This U.S. Army publication is Change 1 for Technical Manual TM 9-1240-309-34, covering the XM44, XM44E1, XM44E2, XM44E3, and XM44E4 Tank Periscopes. Issued in January 1975, it updates the original manual dated March 14, 1973.
This listing is for the Change 1 publication only. It is not the complete original manual unless specifically stated. The periscope, vehicle, weapons, mounts, and other fire-control equipment are not included.
Change 1 Update
Change publications allowed the Army to revise technical information without replacing an entire manual. Change 1 was intended for use with the original March 1973 edition of TM 9-1240-309-34.
Depending on its original format, this update may contain replacement pages, added pages, corrected procedures, or instructions for changing the base manual. It records the maintenance information considered current in January 1975.
About the XM44-Series Tank Periscopes
The XM44 series served as the gunner’s primary night fire-control periscope on the M551 Sheridan Armored Reconnaissance/Airborne Assault Vehicle. These units combined a unity-power daylight viewing system with a passive low-light system offering approximately 9-power magnification.
The passive system used available light rather than an active infrared beam. Its large optical system directed light to an image-intensifier tube, while a projected ballistic reticle helped the gunner aim the weapon.
The periscope consisted mainly of a head assembly and body assembly. Complete periscopes could be installed as units, but major assemblies from the original XM44 and later XM44E-series designs were not always interchangeable.
M551 Sheridan Application
The XM44-series periscope was part of the fire-control system for the M551 Sheridan. The Sheridan was a lightweight armored vehicle designed for reconnaissance, airborne operations, and mobile fire support.
Its main weapon was the 152mm M81 gun/launcher, which could fire conventional ammunition and the MGM-51 Shillelagh guided missile. The XM44 periscope gave the gunner a day-viewing channel and passive night capability for aiming conventional ammunition. Separate tracking equipment supported the guided-missile system.
Historical Background
The M551 entered U.S. Army service in the late 1960s and saw combat during the Vietnam War. Its light weight made it easier to transport by aircraft than a main battle tank, but its advanced weapon and fire-control systems required specialized maintenance.
The XM44 and its E1 through E4 variations reflect the Army’s continued work to improve low-light viewing and nighttime fire control. The “XM” prefix shows that the equipment retained an experimental designation even while versions of the periscope were used with fielded Sheridan vehicles.
The original manual was issued in March 1973, after the Sheridan had gained several years of operational experience. Change 1 followed in January 1975 and preserved later corrections and updated maintenance information for this specialized optical system.
Publication Details
- Publication: Change 1
- Manual number: TM 9-1240-309-34
- Change date: January 1975
- Original manual date: March 14, 1973
- Subjects: XM44, XM44E1, XM44E2, XM44E3, and XM44E4 Tank Periscopes
- Manual level: Direct support and general support maintenance
- Optical functions: Unity-power daylight viewing and 9-power passive low-light viewing
- Equipment role: Gunner’s night fire-control periscope
- Parent vehicle: M551 Sheridan
- Associated weapon: 152mm M81 Gun/Launcher
- Item included: Change 1 publication only
Collector and Research Value
This publication is a specialized addition to a U.S. Army technical-manual, armored-vehicle, night-vision, or military-optics collection. It is useful for studying Sheridan fire-control equipment and the development of early passive night-sighting systems.
Ideal For
- U.S. Army technical-manual collections
- M551 Sheridan research and displays
- XM44-series periscope restoration references
- Vietnam War armored-vehicle exhibits
- Early night-vision technology collections
- Military optics and fire-control research
- Museum and archival reference libraries
Approx length 8", Approx width 10", Approx height .2", Approx weight .2lbs.
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