Description
U.S. Army Technical Manual TM 9-1240-322-35 for Infinity Sight 8635466, August 1964 with Change 1
Item Overview
This U.S. Army technical manual covers field-and-depot maintenance for Infinity Sight 8635466, also identified as the M45C Infinity Sight. Originally issued as TM 9-1240-322-35 in August 1964, this copy has Change 1, dated March 1, 1967, integrated into the manual. It was prepared for trained personnel responsible for inspecting, troubleshooting, repairing, adjusting, and testing this armored-vehicle fire-control component. This listing is for the technical manual only. It does not include an infinity sight, periscope, weapon, vehicle, or other optical equipment.
Identification and Features
The “35” suffix identifies this as a field-and-depot maintenance publication. It covers work beyond normal operator and organizational maintenance. The manual provides technical guidance for servicing the sight’s optical, mechanical, electrical, and sealed components.
- Manual number: TM 9-1240-322-35
- Original publication date: August 1964
- Integrated update: Change 1
- Change 1 date: March 1, 1967
- Subject: Infinity Sight 8635466
- Later model identification: M45C Infinity Sight
- Official item name: Sight, Infinity
- Part number: 8635466
- FSN: 1240-056-4854
- Later NSN: 1240-00-056-4854
- Federal Supply Class: 1240, Optical Sighting and Ranging Equipment
- Manual type: Field-and-depot maintenance
- Primary vehicle application: M728 Combat Engineer Vehicle
- Associated gunner’s periscope: M32C
- Later replacement publication: TM 9-1240-322-34&P, July 1980
- Issuing authority: Headquarters, Department of the Army
- Country of origin: United States
- Item included: Technical manual and Change 1 only
Manual Coverage
The manual supported maintenance tasks such as inspection, troubleshooting, disassembly, cleaning, repair, reassembly, optical alignment, boresight adjustment, electrical testing, and final inspection. The sight included a lamp assembly, observation window, variable and fixed resistors, a toggle switch, and elevation and azimuth boresight controls. The sealed optical unit could also require purging and charging with dry nitrogen to help control internal moisture and protect image clarity.
How the Infinity Sight Worked
The 8635466 Infinity Sight projected an illuminated reticle into the viewing field of a gunner’s periscope. On the M728, it was installed behind the unity window of the M32C periscope and projected a 20-mil illuminated circle onto the window. The gunner could adjust the reticle in elevation and azimuth and control its light intensity. This provided a clear aiming reference for the vehicle’s coaxial machine gun without requiring a separate external sight picture.
Weapon and Vehicle Application
The M32C periscope was the M728 gunner’s secondary direct sight for the 165mm M135 demolition gun and the primary direct sight for the coaxial 7.62mm machine gun. Infinity Sight 8635466 supplied the illuminated aiming circle used for machine-gun engagements. The M728’s separate M105F telescope served as the primary direct sight for the 165mm gun. This means the infinity sight was part of the vehicle’s complete fire-control system, but it was not the main sight for aiming the demolition gun.
Historical Background
TM 9-1240-322-35 was issued while the U.S. Army was completing development of the M728 Combat Engineer Vehicle. Based on the M60-series tank, the M728 entered service during the mid-1960s and combined armored protection with a dozer blade, winch, crane boom, and short-barreled 165mm M135 demolition gun. It was designed to clear obstacles, break through fortifications, move debris, and support troops during combat-engineering operations. M728 vehicles served during the Vietnam War and later took part in Gulf War operations. The 1967 Change 1 and later replacement manuals show that the 8635466 sight remained part of the Army maintenance system for many years.
Condition
Please check the pictures for the general condition of the item. This listing is for one TM 9-1240-322-35 technical manual with Change 1 integrated; the infinity sight, M32C periscope, weapons, vehicle, and other equipment are not included.
Ideal For
This manual is well suited for collections and research projects covering Cold War fire-control equipment, armored engineering vehicles, and U.S. Army optical maintenance.
- U.S. Army technical-manual collections
- Infinity Sight 8635466 research
- M45C sight restoration references
- M728 Combat Engineer Vehicle displays
- M32C periscope and fire-control research
- 165mm M135 weapon-system collections
- Vietnam War and Gulf War vehicle exhibits
- Military museums and archival collections
Approx length 8", Approx width 10", Approx height .2", Approx weight .25lbs.
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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