Personnel carriers M84, M59, T55
A LOWER COST ARMORED PERSONNEL CARRIERS
The M84 was manned by a crew of six consisting of the commander, driver, gunner, loader, and two ammunition handlers. It carried 88 rounds of 4.2 inch ammunition. The combat weight of the M84 was about 4500 pounds heavier than the M59.
As a result, the freeboard was reduced when the vehicle was afloat. To keep water out of the cooling air intake and exhaust grilles, folding snorkels were installed. These were to be erected around the grilles prior to entering the water. Other features of the M84 were the same as the late production M59 including the M13 cupola for the vehicle commander. Production of the M84 at FMC Corporation began in January 1957.
With a cost approximately 1/3 that of the M75, the M59 was popular with the U.S. Army. However, operations with the troops revealed some shortcomings. With its inexpensive commercial engines, it was somewhat underpowered. The low power was particularly obvious with the heavier M84. which had its maximum speed reduced to 27 miles per hour on land and 3.5 miles per hour in water.
The cruising range also was considered to be inadequate. FMC proposed modifications to correct these problems, but they were rejected by the army since interest had shifted to a new vehicle then under development. It would eventually appear as the armored personnel carriers M113.
It is interesting to note that a concept for a lightweight version of the M59 was proposed by the Ordnance Tank Automotive Command during the Questionmark III conference in June 1954. With an estimated combat weight of 34,260 pounds, it was to utilize the power train originally installed in the T59E1. These more powerful engines would have improved the performance and the cruising range was estimated to be 177 miles.
During the early 1950s, the Tractor Division of the Allis-Chalmers manufacturing Company produced two small personnel carriers. Designated as the infantry tracked utility vehicles T55 and T56, they differed only in length.
The T55 with an overall length of 148 inches was intended to carry six men including the driver. The T56, increased in length to 184 1/2 inches, was designed for ten men including the driver. Driven by a General Motors type 302, liquid-cooled, gasoline engine and an Allison XT-90 transmission, the T55 had a maximum road speed of about 30 miles per hour and a cruising range of approximately 150 miles.
The space inside these vehicles was extremely limited and they were not amphibious. Although they did not prove suitable as personnel carriers, the T55 provided the basis for the Ontos antitank vehicle armed with the 106mm recoilless rifle.
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