Roebling Alligator LVT

Developed and, in part, financed by its inventor, Donald Roebling, the Alligator amphibian tractor is the predecessor of every Landing Vehicle, Tracked (LVT) in the world. The story of the Roebling amphibian tractor starts with the devastating hurricanes which struck southern Florida in 1926, 1928, and 1932. Donald Roebling's father, financier John A. Roebling, had witnessed the loss of life brought about by these storms in the swampy areas of the Okeechobee region. Spurred by a challenge from his father to use his engineering talents to design and develop a vehicle "that would bridge the gap between where a boat is grounded and a car is flooded out." Donald Roebling, the grandson of the designer and builder of the Brooklyn Bridge, started work on his Alligator amphibian tractor in early 1933.

Roebling and his staff completed their first model Alligator in early 1935. It used aluminum, a comparatively new and unproven material, in the construction of the hull to reduce weight and increase buoyancy. It was propelled on land and water by paddle-tread tracks and was then powered by a Chrysler 92-horsepower industrial engine. This first model was then modified and upgraded so extensively that it is generally referred to as the second model Alligator. This second Alligator had improved tracks with built-in roller bearings which rode in specially designed steel channels which eliminated the need for idler and bogie wheels to support the tracks, as were used on most tractor and tank designs.

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Roebling Alligator Landing Vehicle, Tracked (LVT)

In 1937, U.S. Navy Rear Admiral Edward C. Kalbfus, Commander, Battleships, U.S. Pacific Fleet, showed Major General Louis McCarty Little, Commanding General, Fleet Marine Force, an article on Roebling's amphibian tractor in the October 4th issue of Life magazine. In turn, General Little forwarded the article to the Commandant of the Marine Corps. In March 1938, Major John Kaluf of the Equipment Board at Quantico was dispatched to Clearwater, Florida, with orders to investigate the military potential of the Roebling Alligator. Major Kaluf returned a favorable report in May 1938 the Commandant of the Marine Corps requested that a "pilot model" be purchased for "further tests under service conditions." This request was down by the Navy's Bureau of Construction due to limited funding.

In the fall of that year, the new President of Corps Equipment Board, Brigadier General Emile P. Moses, and Kaluf's replacement as Secretary, Major Ernest E. Linsert, made a visit to Clearwater which would become a turning point in the development of the amphibian tractor. It was during this visit that General Moses persuaded Roebling to design a new Alligator which would incorporate a number of improvements. The fact that the Marine Corps did not have any available funds at this time forced Roebling to come up with most of the $18,000 required to fabricate this vehicle from his own pocket. Construction on this new Alligator was completed in May 1940.

With the political and military situation in Europe and Asia worsening, military appropriations from Congress improved and the Navy's Bureau of Ships was able to fund a $20,000 contract with Roebling for the construction of a new test vehicle. It was almost identical to "Alligator 3," but was powered by a 120-horsepower Lincoln-Zepher engine. This Alligator was completed in October 1940, and was tested at Quantico, Virginia, and later in the Carribean. While the testing of this fourth Alligator revealed some deficiencies, the general design was deemed a success. The tractor was redesigned using a welded steel hull and incorporating many of the recommendations of the test team. A contract was then let by the Navy for one hundred Landing Vehicle, Tracked (1) (LVT(1) or AMTRAC). The first of these production LVTs would roll off the Food Machinery Corporation's (FMC) assembly line in July 1941.

Source: Text above from Opening Moves: Marines Gear Up For War. The later prototype Alligators are called the Roebling Crocodile by some sources.

Find additional photos and hi-res versions of the Roebling Alligator LVTa at the Olive-Drab Military Mashup.

Roebling Alligator Landing Vehicle, Tracked (LVT) Photo Gallery

National Archives 1936 photo of a Roebling Alligator undergoing testing in Florida
National Archives 1936 photo of a Roebling Alligator undergoing testing in Florida.

National Archives 1936 photo of a Roebling Alligator undergoing testing in Florida
National Archives 1936 photo of a Roebling Alligator undergoing testing in Florida.

National Archives 1937 photo of a Roebling Alligator undergoing testing in Florida
National Archives 1937 photo of a Roebling Alligator undergoing testing in Florida.