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The Development of the M422

By Lloyd White, Oregon City, Oregon

The M422 Mighty Mite, introduced in 1959, was the result of a pilot model test made at the end of the WW II. The vehicle was conceived in response to the need for a truck light enough to be flown to forward positions by helicopter and manhandled if necessary. The initial design of the M422 was made by Ben F. Gregory, an automotive engineer. Gregory's first pilot model did well enough in tests in 1946 to lead to the formation of a company to develop the vehicle, and the Mid-American Research Corporation Incorporated (MARCO) in Wheatland, Pennsylvania to accomplish the task.

The Mighty Mite prototype in 1950 had curb weight, including fuel, of only 1500 pounds, and could pull a payload of two men plus a cargo of 500 pounds. Successful demonstrations to the U.S. Marine Corps led to the awarding of a contract for ten vehicles. As previously mentioned the Marine Corps required a light tactical vehicle for its projected ‘Vertical Envelopment’ strategy - vertical envelopment requires combat forces to be moved at high speed into forward positions. The Mighty Mite seemed to be just what the U.S. Marine Corps, indeed, the entire military had been looking for.

It had a number of unique features; center-point steering, individual wheel suspension with front leading arms and rear trailing arms, inboard brakes mounted on the differential case, and lightweight aluminum construction.

When MARCO studied the history of the Jeep, one name which kept cropping up in their research was Harold Crist, and the company decided that it needed him for the project. Crist was not to be found easily. The company's efforts to locate him bore no fruit until after the publication on July 27th, 1952 by the ‘Erie Times’, of a Jeep story in which Crist was said to be living locally.

The Vice President of MARCO Clarence L. Summers, read the ‘Erie Times’ story and at once took steps to contact Crist. Once found, Crist had the project described to him and, on 1 January 1953, he joined MARCO as the Mighty Mite's project manager. Crist brought with him three of the men who had worked on the original Bantam; Mr. Hempfling, Mr. Turner, and Frank McMillan.


Let's look at a brief description and introduction of the M422 Mighty Mite, 1/4 ton, 4x4, lightweight tactical truck.

The Mighty Mite was designed and developed by American Motors Corporation for the use by the United States Marine Corps as a tactical vehicle for support of their ‘Vertical Envelopment’ operations. It was planned to be airlifted by helicopter to forward positions.

A basic design requirement was to develop a compact, lightweight, rugged vehicle. Other 1/4 ton military vehicles either in design or in the supply system were not deemed acceptable for these operations.

These goals were accomplished without compromising the ability to perform other required functions of a 1/4 ton, 4x4, tactical vehicle. The curb weight of the vehicle, including fuel, was 1750 pounds, and had an overall length of 107 inches, an overall width of 60 inches and a reducible height of 45 inches. The shipping cube was 171 cubic feet. The M422 satisfactorily performed all required military tests in respect to mobility, carrying capacity and durability.

It was to be basically a personnel-cargo vehicle that included towing the M416B1 model 1/4 ton cargo trailer. It could carry four personnel or two personnel plus 500 pounds, and in cross country operations was capable of pulling a trailer loaded with 1000 pounds. The Mighty Mite could be adapted for mounting the 106 mm recoilless rifle. Two litters could also be installed and it sometimes was used for command radio installation. All components were completely waterproofed and, with little prior preparation, could ford completely submerged.

The Mighty Mite was powered by a newly designed aluminum V-4 air-cooled engine with an output of 55 horsepower at 3600 rpm. The power plant was extensively tested not only in the field but had been qualified as well by the army test facility at Aberdeen Proving Grounds and the navy test facility at Annapolis, Maryland for performance and durability. Tests and evaluation of the Mighty Mite proceeded at Quantico, Virginia.

The Marine Corps wished to bring the vehicle into production without delay but an item in military regulations prevented this happening. The test vehicles had Porsche 4-cylinder engines. Military regulations, while allowing the use of imported motors for test vehicles, for obvious reasons did not extend this permission to production models. The unfortunate and slightly embarrassing fact was that there had been no satisfactory American production engine available. MARCO made contacts within the vehicle and engine industry to see if any company or group had a project going to produce an engine with the characteristics required for the Mighty Mite. They were lucky.

At American Motors Corporation an engine existed in prototype stage, a V-4 air cooled aluminum engine capable of producing about 50 HP This engine seemed to be approaching the answer to the power problem, and it satisfied the Marine Corps' requirement. MARCO and American Motors found it convenient to reach an agreement which involved the transfer of the Mighty Mite's manufacture to American Motors, which proceeded with the development of the vehicle.
One of the first modifications was the enlargement of the engine from 95 to 104 cubic inches (about 1700cc) for extra horsepower, after which it gave 54 HP at 3600 rpm. The Marine Corps proposed modifications including changing the tubular frame construction to the conventional type frame construction. This change would lessen the frame's weight and reduce the corrosive effects of the exhaust gases and also "the vehicle was increased to an overall length of 107 inches on a 65 inch wheel base. This increase in length, plus other changes, increased the curb weight to 1700 pounds which was still considered to be within the limits of the requirements of the Marine Corps."

Development of the vehicle continued from November 1954 to November 1957. Negotiations with the military led, on 30 April 1958, to a contract which called for the production of fifty vehicles. The first requirement, however, was seven prototype vehicles for testing by the US Army and the US Marine Corps. Conditional, upon satisfactory performance in the tests, a further 243 would be purchased.

Tests on the first seven were completed in December 1959. Deficiencies were corrected and production of the remaining 243 vehicles began. Early in the process of filling the order a contract for 1000 more M422s were issued. In the middle of the 1000 vehicle order a change proposed that the M422s length should be increased. Again the weight issue emerged, as any increase in length inevitably involved also an increase in weight. The vehicle’s length went up six inches but by careful reworking the weight increase was held to thirty pounds and was now designated the M422A1. Two contracts, which between them brought production up to 3922 vehicles, followed the length modification. The final unit of the order was produced in December 1962.

The Mighty Mite (standard models, M422 and M422A1) looks like an abbreviated Jeep. Both models had two non adjustable bucket seats, a downfolding and demountable windshield, a hinged tailgate and independent suspension with longitudinal leaf springs to reduce the roll-over danger. Lifting hooks or clevises are mounted on the front and rear bumpers.

Illustration shows the M422 with Deepwater Fording Kit installed, as the vehicle was being tested by the Armor Engineer Board around 1960.

Article courtesy of ‘Army Motors’ magazine, issue 91, Spring 2000.