Re: Some more \"Never Beens\" for the USA
Cribbd from "Patton"
The Army Equipment Development Guide of December 1950 recommended the development of a 105mm tank gun. The future need for such a weapon was considered during the design of the T48 (aka M48) and its 85 inch turret ring provided ample room for a larger cannon. OTCM 33842 officially initiated a development project to improve the armament on 6 July 1951 designating two new vehicles. These were the 105mm gun tank T54 when fitted with a conventional turret and the 105mm gun tank T54E1 when an oscillating turret was installed. Both vehicles used the T48 chassis.
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At United Shoe Machinery, work on the T54E1 turret paralleled that on the T54 at Rheem. The oscillating turret consisted of a cast turret body mounted on the trunnions of the ring casting which was bolted to the bearing race assembly of the M48 tank. The turret casting varied in thickness from 5 inches at 60 degrees from the vertical in front to 2 inches at 30 degrees in the rear. The sides were equivalent to 2� inches at 30 degrees. The turret basket was attached to the trunnion ring casting. Seats for the tank commander and the gunner were installed on the right side and moved with the turret in both azimuth and elevation. The loader's seat on the left moved only in azimuth. The 105mm gun T140E2 was installed in the T157 mount with a .30 caliber coaxial machine gun to the left of the cannon. An interim design cupola for the tank commander was located on the right side of the turret roof. It essentially consisted of the standard World War II type vision cupola modified just above the six vision blocks to include a rotating section. The rotating part incorporated a hatch with a periscope and a mount for a .50 caliber machine gun. A large section of the left turret roof was hinged along the left side and could be opened for easy access during maintenance or ammunition loading. A small flat hatch for the loader was installed in the hinged section for normal use. The primary fire control system included the tank commander's T50 range finder, the T34 ballistic computer, and the gunner's M20(T35) periscopic sight. A T170 or T170E1 telescopic sight was provided for the gunner as a backup system.
A major reason for the oscillating turret was to simplify the design of the automatic loader. Since the cannon moved only in recoil relative to the turret, the position of the loader could be fixed. In the T54E1 turret, the automatic loader consisted of a nine round rotary magazine and a main drive assembly which operated the loading tray and ramming mechanism. The tray lifted the selected round from the top of the magazine until it was aligned with the cannon bore. The rammer then propelled the round into the gun at a velocity of 15 feet/ second. After firing, the case was ejected along a continuous path provided by the ejection chutes and bustle groove to the port in the back of the turret. This port was opened automatically by the gun recoil. Any one of three types of ammunition could be selected and the maximum design firing rate was 35 rounds/minute. In addition to the nine rounds in the magazine, six were stowed in the turret bustle, two in the basket, and 17 in the hull for a total of 34. Later specifications increased the hull stowage to 19 raising the total number of 105mm rounds to 36.
Work on both the T54 and T54E1 began in earnest during 1952, but progress was slow because of design problems and difficulty in obtaining much of the required government furnished equipment. The latter problem reflected the demands of higher priority projects. Because of the delays, the program was overtaken by later developments of more powerful guns and lighter more mobile tank chassis such as the T95 series.
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