High speed tractor
HIGH SPEED TRACTORS (continuation)
Tests by the Field Artillery Board indicated that it was feasible to install a spaced out suspension and tracks with extended end connectors on the M4. This increased the track width from inches to 20V8 inches with the extended end connectors on only one side of the tracks. If they were installed on both sides, the track width increased to 23n/i6 inches.
On 28 November 1944, OCM 26329 recommended the standardization of the vehicle with the spaced out suspension as the 18 ton high speed tractor M4A1. The M4 was then reclassified as Limited Standard. This action was approved on 11 January 1945. A total of259 M4Als were built during the period June through August 1945.
The M4 and the M4A1 continued to serve into the postwar period. When the vehicles were modified to carry projectiles and fuzes in the crew compartment, the designations were changed to M4C and M4A1C. The number of personnel carried in these vehicles was reduced from eleven to eight. When the new M8 series cargo tractor was in short supply in 1954, Bowen-McLaughlin received a contract to refurbish and modernize some of the M4 series tractors. These vehicles were designated as the 18 ton high speed tractor M4A2.
The unarmored cargo carrier T13 was a high speed tractor developed by the International Harvester Company as a companion vehicle to the 3 inch gun motor carriage M5. Development was approved by Ordnance Committee action in March 1942. The T13 used the Continental R6572 gasoline engine and a modified M3 light tank suspension.
Manned by a crew of four, it had a combat weight of about 25,000 pounds. The maximum road speed was 35 miles per hour and the cruising range was approximately 150 miles. It was designed to carry 113 rounds of 3 inch ammunition. When the 3 inch gun motor carriage M5 project was canceled, the T13 program was terminated in the Spring of 1943.
The experience gained on the T13 project was applied to the development of the 13 ton high speed tractor M5. This was a prime mover for artillery pieces weighing up to 16,000 pounds. These included the 105mm howitzer carriage M2, the 4.5 inch gun carriage Ml, and the 155mm howitzer carriage Ml.
The M5 had a loaded weight of28,300 pounds and was driven by the same Continental R6572 gasoline engine as the T13. This was a six cylinder, in-line, power plant developing 235 net horsepower at 2,900 rpm. Like the T13, the M5 used the tracks and a modified suspension from the light tank M3. The maximum road speed was 35 miles per hour and the 100 gallon fuel capacity provided a cruising range of approximately 125 miles.
A folding top with side curtains was installed and the vehicle had space for nine men including the driver. A front mounted winch had a capacity of 17,000 pounds. The only armament was a .50 caliber machine gun on an M49C ring mount. The M5 was manufactured by the International Harvester Company. A total of 5,290 vehicles were produced during a run from May 1943 through May 1945.
When fitted with a new steel cab carrying eleven men, the vehicle was designated as the 13 ton high speed tractor M5A1. The overall length was increased from 1911/8 inches to 196 3/8 inches. Production of the M5A1 totaled 589 during the period May through August 1945.
Like the 18 ton high speed tractor M4, the M5 continued to serve well into the postwar period and it was subject to additional modifications. The most important of these was the installation of a new horizontal volute spring suspension replacing the earlier vertical volute spring suspension. The new suspension was fitted with 21 inch wide, center guide, tracks replacing the 11 5/8 inch wide, outside guide, tracks on the earlier vehicle. After modification, the M5 and M5A1 were designated as the 13 ton high speed tractors M5A2 and M5A3 respectively.
In February 1942, Ordnance Committee action initiated the development of the heavy tractors T22 and T23. The T22 was designed with a fifth wheel on the rear deck for semi-trailing transport wagons of the 240mm howitzer Ml and the 8 inch gun Ml. The heavy tractor T23 was identical to the T22 except that the fifth wheel on the rear deck was replaced by a large cargo box for ammunition and equipment.
The T23 was intended to be the prime mover for the 4.7 inch antiaircraft gun Tl. The decision by the Field Artillery Board to carry the 240mm howitzer and the 8 inch gun on full-trailed transport wagons eliminated the need for a fifth wheel on the prime mover. The T22 was dropped and the T23 was standardized in June 1943 and designated as the 38 ton high speed tractor M6.
It could tow artillery loads of 30,000 to 60,000 pounds and carried eleven men in two rows of seats as well as ammunition and equipment. Two Waukesha 145GZ gasoline engines supplied the power through torque converters and a constant mesh transmission. The vehicle rode on a horizontal volute spring suspension with three, two wheel, bogies per side and a large trailing idler. The double pin, center guide, tracks were 21 9/16 inches wide.
Towing the tube of the 240mm howitzer Ml, the M6 could reach 20 miles per hour on a level road. A 250 gallon fuel U.S. Tank provided a cruising range of about 110 miles. The vehicle also was equipped with a 60,000 pound capacity winch. An M49C ring mount for a .50 caliber machine gun was on the roof.
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