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An M274A2 Mule With A Kick!

Posted in Features on March 14, 2017
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The United States military has long been obsessed with lightweight, easily transported vehicles. In World War II, it was all about getting them into gliders or transport planes. Then it was parachute capability. When the helicopter went mainstream, the goal was to make them luggable by chopper.

The development of an air-portable extra-light 4x4 started not long after the legendary jeep went into production. On its own, the notable small car maker, Crosley, came up with the “Pup” 4x4 in 1942, and the military liked it enough to make specs for a revised vehicle and sent them out to a number of manufacturers. The 1943 result was prototypes from Chevrolet, Crosley, Kaiser, and Willys. They all weighed between 900 and 1,600 pounds. The Chevrolet was probably the most advanced, followed by the Kaiser, but the Willys Air Cooled (or WAC) survived the tests longer and provided a basis for more development and tests.

The M274A2 was the third evolution from the original Willys design and Tom Price’s was delivered in January of 1966, about midway into production of that model. Tom has owned this mule for 20 years. In fact, he had the M40 106 Recoilless rifle and mounting kit before he had the Mule. This was originally a USMC Mule but had not been converted to the M40. Using the template in the NOS mounting kit, he installed it exactly as intended. The M40 has been thoroughly demilled and will not fire, nor chamber a round. The four-wheel steering, which could be disabled, allowed for maneuvering in tight areas.

In late 1944, Willys debuted the Jungle Burden Carrier (JBC), which incorporated some of the better features of the Chevrolet combined with the platform of the WAC. It had a cast “H-frame” that incorporated a rear transaxle and driveshaft with front and rear portal-style axles. This structural member provided the majority of the structural elements for the JBC with a platform on top. The driver sat in one corner, feet extended out onto a tubular platform. The JBC, patent file 1944, was the clear ancestor of the later M274 Mule. Barney Roos, the chief engineer at Willys, and the guy primarily responsible for the Willys version of the WWII jeep, has his name on the 1944 JBC patent.

The end of WWII also brought an end to the lightweight projects, but when they were revived in the early ’50s, Willys dusted off the JBC design, gave it some fresh technology, and by 1956, their XM274 design had been accepted for production. It was a remarkable vehicle, capable of carrying 110 percent of its curb weight. There was seating for only one, but all of the 96x46.6-inch platform was optionally available for cargo with the operator driving the vehicle as he walked behind or beside it. The “Mule” had a top speed of up to 25 mph and a range of up to 150 miles.

The Mule was rear engine with a rear transaxle with steerable hubs. The front axle was similar but without the transaxle attachment. The rated payload was 1,000 pounds—more than the mule actually weighed. The 7.50-10 tires were the only suspension, so it didn’t have a plush ride. The last A5 Mules had an optional 12.00-10 high-floatation tire kit that included tires and fenders.

There were six variations of M274. The first two models, the M274 and M274A1, were built by the commercial products division of Willys Motors to the tune of 4,357 units and had a Continental-Willys AO-53 four cylinder air-cooled engine (53ci, 17 hp/30 lb-ft of torque) that was patterned after the legendary VW pancake engine. The AO-53 was backed up by a three-speed manual and a two-speed transfer case. It didn’t have a suspension system, the fat tires at 12 psi serving that purpose. It was four-wheel steer, but the rear steer could be disengaged. The axles were portal-style with a 4.11:1 overall ratio, with 2.2:1 of that from the reduction in the portal.

The M274A2 debuted in 1965 and was built by Bowen-McLaughlin-York into 1967. The major difference in the A2 was a change to the two-cylinder A0-42 engine. It was a Continental/Hercules 42ci engine that made 14 hp. The AO-53 was problematic, with overheating problems in hot weather. The A2 was the most numerous variant, with 3,609 units built. The M274A3 was an M274 with a rebuild that included replacing the A0-53 with an AO-42. The M274A4 was a similar rebuild of the M274A1. In both cases, the units received upgrades to the latest and greatest parts. The final variant was the M274A5 built starting in 1965 and finishing off in 1970. These were a major upgrade that eliminated the magnesium alloy platform, replacing it with an aluminum piece. Of the 3,240 A5 models built, 875 were built with two-wheel steering. A total of 11,240 Mules were built of all types

The Mule’s seating arrangement would not inspire any long trips and it’s doubtful many soldiers and Marines drove them to their maximum 150-mile range in one sitting. A firefight might be preferable. This one has the upgraded seat with about 10 times more padding than the standard seat. The foot basket was removable and stowable on the Mule. The steering column could then be released to pivot forward and the Mule could be used with the operator on foot. To the left of the seating arrangement, at the front of the platform, is the pull start for the engine.

Besides schlepping cargo, the Mule could even mount weapons systems. The most powerful system commonly seen was the M40 106mm recoilless rifle, and it was extensively used in Vietnam and later. When the TOW (Tube-launched, Optically-tracked, Wire-guided) missile went into service in 1970, a mount was designed for the Mule and so equipped, it’s most common purpose in later years was with Airborne units, or the Marines, as a missile carrier. Reportedly there were mounting systems for the 7.62mm M60 machine gun and .50 cal M2.

Mules saw extensive use in Vietnam, and most of the approximately 5,000 units lost in service died there or were left to the South Vietnamese Army when the United States left. The Mule’s role in military doctrine gradually faded starting in the mid-’70s and, by the early ’80s, had been largely withdrawn from service. The early models hit the surplus market in the late ’60s, with the last ones sold off in the late ’80s.

This Mule belongs to Tom Price, whose experience as a Marine in the ’60s led him to collect everything that caught his fancy, from Mules to LVT Alligators (Landing Vehicle Tracked), as long as it was once Marine Corps issue. Stay tuned to see more from his extensive collection.

The two-cylinder military-standard engine displaced 42 cubic inches and made 14 hp. Originally, they were a pull-start with a magneto ignition. Later, an electric starting kit was developed, as well as electronic ignition, and many of the older Mules were retrofitted. Max power was at 3,000 rpm, with redline at 3,600. Other members of this engine family were used in generators and other stationary applications.
The M40 recoilless rifle was developed from similar weapons designed in WWII. It packed a lot of wallop into a small package that weighed just under 500 pounds. With an effective range of 1,480 yards (maximum over 20,000 yards), it could fire anti-tank, high-explosive or anti-personnel rounds. NATO countries also used it and some developed their own special ammunition. It had rudimentary sights, but the device on top of the barrel is a .50 cal. spotting rifle. It didn’t use a standard .50 MG round but one whose ballistics matched the main gun. You sighted the weapon, fired a spotting round, which had a bit of white phosphorus to mark its fall, adjusted the aim as needed, then fired for effect. The M40 was called “recoilless” because all the gases were released by the shell (which were perforated) and directed out the rear, thus cancelling the muzzle blast and recoil almost completely. You did not want to be standing behind this when it fired!
The installation kit for the M79 mount came with racks for six ready rounds. You can see the business end of the M581 anti-personnel round that had 21 pounds of flechettes in plastic—basically tiny arrows—with an effective range of about 300 yards. The original M344A1 anti-tank round (HEAT: High-Explosive Anti-Tank) could penetrate 400 mm of armor plate. Later HEAT rounds could punch through up to 700 mm. The HEP-T rounds (High Explosive Plastic-Tracer) were the general purpose rounds for lightly armored vehicles, buildings, or personnel. There were also inert dummy rounds for practice.
The M40 could be removed from the Mule and fired from the tripod that was part of the mounting kit.

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