WW2 US Unarmored Vehicles

Reno’s Endless Belt Tractor – Underwater ‘Tank’

United States of America (1919-1935)
Salvage Vehicle – 1 Built

There are not many tracked vehicles designed to work underwater, and whilst these might not fall into the usual category of what people consider ‘tanks’, they are worthy of consideration by anyone serious about tracked vehicle technology. The underwater realm offers challenges unique to vehicles whether they are armed and armored or not.

Jesse Wilford Reno 1861-1947. Source: National Inventors Hall of Fame.

This unusual vehicle was the brainchild of Captain Jesse Wilford Reno (4th August 1861-2nd June 1947), an American inventor from New York, whose most famous contribution to western culture was not a tracked machine, but the escalator, invented in 1899. As an anecdote, his father, Major General Jesse Lee Reno, a Union General in the American Civil War, had Reno, Nevada, named after him. In addition to this, in 1919, Mr. Reno saw an opportunity to put his inventive mind to use; he built an underwater machine designed for salvage operations.

In 1919, underwater operations were still extremely hazardous. The personal diving suit was a huge, clumsy and dangerous affair, and submarines were in their infancy, with numerous accidents still occurring. The depth to which many of these early underwater pioneers could venture was extremely limited and, therefore, salvage at even a nominal depth at the time was impossible. Reno was therefore correct in assessing an important commercial market for a machine able to operate at depth and salvage valuable cargoes from sunken vessels.

The Reno Underwater Tractor being lowered into the water, probably in 1923, showing the drills sticking out of the sides. The heavily riveted construction and narrow, rather crude tracks are readily apparent. Source: Gunning Wrecks,

The Design

The design was a simple one, basically being a sealed and heavily protected cylinder, capable of withstanding external water pressure, mounted on tracks for mobility. Large enough for up to two men, the cylinder measured some 6 feet (1.82 m) in diameter and 8 feet (2.44 m) in height according to the patent. During the recovery of the ‘Scally’, which sank in 1923, the Reno Underwater Tractor was described as being 7 feet (2.13 m) in diameter and 9 feet (2.74 m) tall, weighing some 18 tons (16.3 tonnes).

Air supply was provided by the ‘mother-ship’, which delivered air for the occupants of the vehicle but also compressed air which was to be piped into a large buoyancy sack attached to the sunken vessel or part of it. That buoyancy sack would then rise to the surface for recovery. This is still, to this day, effectively the same means by which things are raised from the sea. The mother ship also provided an electrical supply for the vehicle by means of the same umbilical cable down which air was pumped. This electrical power was used for lighting and also to power the equipment in the vehicle. Vision from inside the machine was limited to just a small glass porthole in each ‘side’ of the cylindrical chamber. Access was only possible via a single circular hatch on the roof of the machine.

Reno’s Underwater Tractor showing a significant problem of track sag.
Source: / tauchtechnik by Hermann Stelzner
Side view of the Underwater Tractor shows a significant change to that in the patent, namely a distinctive raised top run for the tracks. Source: Popular Science: September 1923

For raising a sunken vessel, the machine would simply be used to connect a series of buoyancy sacks along the exterior of the vessel which, once filled with air, would bring the whole ship either to the surface or just off the sea-floor so it could be towed to shallower waters for salvage. Additionally, clever knowledge and use of the tides could be used to raise the ship, move it to shallow water and then resink at high tide, whereby it would be exposed by the receding waters.

Two images from US Patent US1523660 dated 1919 showing the drilling system (left) and compressed air hose (right)

Air Bags and the Cannon

The ‘airbags’ were, in fact, large steel boxes into which the air was pumped, but the question was how to attach these buoyancy devices to the hull of the ship. Each one would be exerting a lifting force of 300 tons, so the connection had to be extremely strong. The solution Reno settled upon was that of hooks which would be fastened into the side of the sunken vessel’s hull.

The question, therefore, was how to make holes in the side of sunken vessels. In his original 1919 Patent, he determined that it should be made by means of a drill rotating within a water-tight coupling. This drilling system though, was after he had already submitted a patent application for the concept of using a gun to make the holes.

Images from Canadian Patent CA225695 showing the means of puncturing the side of the wrecked ships hull and attaching the large vertical floatation units by means of hooks into those holes

The hole would be made by firing a horizontally mounted gun using compressed air. The calibre of this air cannon was given as 4” (101.6 mm) of an unspecified “well-known type” firing a pointed solid steel slug through the outer hull of the sunken vessel to make a hole for the attachment of buoyancy bags/boxes. The barrel of this gun was supported by the walls of the crew chamber through which it was projecting and was fitted with crude ‘stuffing boxes’ acting as the recoil buffers. As drawn, this arrangement was hazardous and likely to violate the watertight nature of any seal around that gun. In his submission, Reno mentions that he considers a gun using the ‘Davis’ principle to balance the recoil of the gun. The shell was only to be fired with enough force to rupture the side of the hull without causing damage to the interior of the ship, although quite how this was to be calculated is unclear. With up to 50 holes needed per side or a hole every ten feet (~3 m) by Reno’s calculations, a large number of projectiles would have to be carried in order to perform this means of hole-making. The fact that a month after this ‘gun’ idea had been submitted he had switched to a drilling system demonstrates that even he understood the impracticality of this underwater cannon concept. When Reno’s machine was used in 1923, it was using not one but two 4” (101.6 mm) diameter drills.

The original Patent (US1523659 of 1919) featuring the compressed air gun for shooting holes in the sides of the sunken ships.

The Tractor

The vehicle itself was described as an ‘endless track tractor’ or ‘mobile tractor’ consisting of a large watertight cylinder mounted on a low pair of tracks. No suspension was provided in the track run on either side which was made from two large wheels, one at each end, separated by 5 smaller wheels. All were attached to a rigid horizontal frame. Drive for the tracks was delivered to the rear-most wheel via a drive chain running from a small motor estimated to be just 20 hp or so mounted inside the steel chamber. Each track was driven independently with the clutch controls worked from a small handwheel. This level of control over the drive to each track was complex but allowed for fine manoeuvering. The operator, who would also have to drive the machine, could maneuver by means of clutches that could engage and disengage with the tracks. Engaging the right track, the machine would move to the left and vice-versa.

On the outside of the chamber was a pressurized hose that could be manipulated by the operator to blast away sand, dirt, and debris from his locale, allowing him to work clearly on the side of the vessel. The chamber itself was divided into two portions. The lower part was attached to the tracked chassis and contained the motor and driveshaft. The upper part of the chamber contained the operator and controls and could rotate, allowing the machine to use its drills against the sides of the ships it was salvaging.

Artist’s impression of the Reno salvage method and underwater tractor at work. Source: The Leader 2014
The raising of the ‘Scally’ as depicted in Popular Science Magazine, September 1923.


The tractor unit could not float or ’swim’ and was simply lowered to the sea bed by chains from a hoist where it had limited movement, but it had proven itself to be a viable system. Reno’s underwater salvage firm employed his salvage methods successfully in the 1920s and 30s. It was used in the Baltic for the Estonian government reclaiming parts from the 15,000 ton Russian battleship ‘Slava’ from a depth of 40 feet (~12 m), and closer to home with the recovery of the 500-ton Coast Guard cutter ‘Scally’ which sank off Long Island Sound in 65 feet (~19.8 m) of water. Reno’s suggestion of using this method to raise the Lusitania was not, however, ever taken seriously.


Reno never described his underwater vehicle as a tank. He did have other military ideas but not for this vehicle, although it has appeared subsequently online as some form of underwater tank akin to a Tauchpanzer. The machine was tracked, and potentially armed with a cannon, but it was not a military vehicle. Despite this, the design is an interesting one and important in regards to the development of tracked vehicles as it is likely the first underwater tracked vehicle ever built. It was certainly not to be the last, with both Great Britain and Germany looking at tanks which could drive on the sea-bed in WW2. What became of Reno’s underwater vehicle is not clear, likely it was simply scrapped though, as diving technology caught up through the 20s and 30s. Jesse Reno was inducted into the National Inventors Hall of Fame in 2007 for his work on the escalator and died in 1947, leaving behind a legacy of inventions well known, like his escalator, and obscure, like his underwater tractor.

Illustration of Reno’s Endless Belt Tractor or ‘Underwater Tank’ produced by Andrei Kirushkin, funded by our Patreon campaign.


Dimensions (L-W-H) 2.5 x 2.74 x 2.5 meters
Total weight 18 tons (16.3 tonnes).
Crew 1 – 2
Propulsion 20 hp
Speed (road) Maneuvering only
Max. depth 400 feet (~122m)
Armament drill or 4” (101.6mm) gun
Armor Pressure hull


US Patent US1523659 ‘Apparatus for Raising Sunken Ships’. Filed 25th November 1919. Patented 20th January 1925.
US Patent US1523660 ‘Apparatus for Raising Sunken Ships’. Filed 27th December 1919. Patented 20th January 1925
US Patent US136142 ‘Raising Sunken Vessels’. Filed 23rd February 1920. Patented 4th January 1921.
US Patent US1364143 ‘Raising Sunken Vessels’. Filed 2nd April 1920. Patented 4th January 1921.
US Patent US1416754 ‘Device for Raising Sunken Vessels’. Filed 17th March 1921. Patented 23rd May 1922.
US Patent US1400316 ‘Art of Raising Submerged Vessels’. Filed 13th June 1921. Patented 13th December 1921.
US Patent US 1495529 ‘Raising Sunken Ships’. Filed 2nd August 1923. Patented 27th May 1924.
Canadian Patent CA225695 ; Raising Wrecked Vessels’. 7th November 1922
Modern Mechanix January 1935 ‘Under-Sea Tractor-Sphere Roams Ocean Floor’
Modern Mechanix April 1932 ‘Submarine Safety: An Insolvable Problem?
Popular Science Monthly, September 1923
National Inventors Hall of Fame
‘Gunning Wrecks’
Grohman, A. (2014). Salvage of the Scally. The Leader.

WW2 US Unarmored Vehicles

Cargo Carrier M29 Weasel

United States of America (1942)
Cargo Carrier – 15,892 Built

In 1942, the American Studebaker company based in South Bend, Indiana, famed for their luxury automobiles, answered a call for an armored vehicle capable of traversing deep Norwegian snow drifts for special forces operations. The vehicle became the M29 Weasel and went on to be a popular universal vehicle outside of its original intended use, akin to the British Universal Carrier. The M29 could traverse the hardest of terrains where wheeled vehicles could not go and saw service through the Second World War, the Korean War, the Vietnam War and saw use in the civilian sector.

An M29 named ‘Snookie’, date and location unknown. Photo:


The idea for the Weasel came from the British Inventor Geoffrey Pyke, a man famed for his unorthodox methods. His most famous invention was Pykrete, a material that would’ve been used for the Habbakuk iceberg aircraft carrier. Pyke had long planned for Commando assaults on German power plants and industrial areas in Norway and also planned actions to interrupt the Nazi atomic weapons program in Operation Plough. Operation Plough is very much the origin of the Weasel. Pyke called for a small, lightweight and fast vehicle, able to transport small teams of men across deep snow to take them deep into enemy territory.

The T15 Prototype in testing. Photo:


The proposed design was designated T15, with the finalized design receiving T24. It was soon accepted and became the M29, a simple vehicle consisting of little more than a box on tracks. The Studebaker company would go on to build almost 16,000 M29s. Key elements of its design required that it be air-transportable, able to withstand the impact of a parachute drop, and able to carry enough supplies for a small commando team. It was powered by a 70 hp Studebaker Model 6-170 Champion 6-cylinder engine which propelled the vehicle to 36 mph (58 km/h), a speed it could sustain over most terrain types.
Suspension for the M29 consisted of rear mounted drive wheels (and transmission) with idlers in the front that were lower, giving the running gear the appearance of leaning forward. It featured four, two-wheeled bogies on each side, with two track return rollers. It had wide tracks from 15″ (380 mm) to 20″ (510 mm). This gave the Weasel a very low ground pressure of just 1.9 psi (Pounds Per Square Inch)a benefit in crossing soft ground. The tracks consisted of long metal plates connected by inner rubber bands, with a total of four bands per track, two on the outer edge and two in the center with a center guide horn. The bogie wheels ran on the center bands and. the outer face of the tracks featured two rubber blocks per link for grip on road surfaces.

A Weasel freeing a Willys Jeep from thick mud.
The M29 was operated by one driver and could carry three passengers. The driver was positioned in the front left with the engine compartment to his right and a row of three seats in the rear for the passengers. Though officially an unarmed vehicle, Browning M1919 .30 cal or .50 cal M2HB Machine Guns were often mounted for some form of offensive/defensive capability.


M29C Water Weasel

The M29C was the main variant of the Weasel. The M29 was already partly amphibious, able to traverse shallow and calm waters such as rivers and streams, but could not operate in rough, sea like waters. The M29C amended this issue, with the addition of buoyancy aids in the rear of the hull as well as two rudders. Removable pontoons were also added to the front and rear and changes were made to the treads of the track links to allow it to propel itself in water, although it was very slow. This still didn’t make the M29 capable of seaborne amphibious landings, but allowed to be more stable in deeper or slightly rougher inland waters.

The M29C Water Weasel during testing.

M29/M29C Type A, B and C

These variants were all virtually unchanged from the standard M29/M29C, the only difference being that these were armed versions. The Type A featured a center-mounted 75mm M20 recoilless rifle. The Type B featured a rear-mounted 75mm Recoilless Rifle. The Type C featured a center-mounted 37mm Gun M3, the same gun used in the M3/M5 Stuart Light Tanks.

A Water Weasel armed with a 75mm Recoiless Rifle. Photo: TankPorn of Reddit

M29 Weasel
The standard M29 Weasel
M29C Weasel
The amphibious M29C Water Weasel. Both illustrations are by Tank Encyclopedia’s own David Bocquelet.

WW2 Service

The Norwegian mission that the M29 was designed for never took place. This did not mean that time had been wasted on the vehicle, as it soon found use in multiple roles, in multiple theaters, and by multiple countries.

An American Weasel in Normandy, 1944. Photo:WW2 in Color
The United States used the vehicle extensively during World War Two. It was used in Italy, the Western Front, and even in the Pacific. It saw action during the Normandy landings, St. Lo, and the Battle of the Bulge. It proved its usefulness at the engagements on the Ruhr and Rhine, where it was able to cross the thick, sticky river mud. In the Pacific, it was used by the United States Marine Corps (USMC) at Iwo Jima and Okinawa, where it proved capable of crossing loose sand, and the harsh tropical island terrain where the Marine Corps’ jeeps wouldn’t dare venture.
The use of the M29 Weasel as a universal vehicle soon became clear to the Americans. They used it regularly as a light troop carrier and cargo hauler, and also as a mobile command center, ambulance, and to lay telegraph wires. One of its major attributes was its ability to cross minefields, as its low-ground pressure was often not enough to trigger the anti-tank mines. The ground pressure was still more than enough to trigger anti personnel mines which could easily split a rubber track.

An M29C in an ambulance role on the Rhine

Service in the Commonwealth

The British and Canadian armies also used the Weasel in World War Two. Supplementing a number of LVT Buffalos, M29C Water Weasels of the 79th Armored Division were used by Commando troops in the Walcheren Operation. The 79th also used a number of the standard M29s to clear mines and other defensive devices.The Canadians made use of the Weasel’s semi-amphibious nature in their engagements in the flooded estuaries of Antwerp in 1944, and would go on to serve them through the Netherlands and into Germany.

After WW2

The Weasel remained in service after the Second World War. In 1946, there was a plan for the US Army to use the Weasel to rescue the victims of the C-53 Skytrooper crash on the Gauli Glacier but the Swiss Air Force managed to rescue the victims first. With the US Army, they would go on to serve in the Korean War. Despite plans to replace the Weasel with the M76 Otter, it carried on in service.

French M29C in Vietnam
In 1947, the French Army used the M29 in the First Vietnam war, where the 1er Régiment Étrangers de Cavalerie were equipped with the M29C variant. They armed them with multiple types of weapons, from the Chatellerault M1924/29 and Browning M1919 machine guns to 57mm recoilless rifles. The M29 would remain in service with French mountain troops and Gendarmerie as late as 1970.

Civilian Use

With a large surplus supply, the United States sold off large quantities of the M29 to various countries, including Sweden, France and Norway. Many Weasels served in scientific Arctic expeditions, but their most famous use in civilian hands was at the 1960 Olympic Winter Games at Squaw Valley, California, USA.
The Automotive Company, Consolidated, sought to update the Weasel in 1960. They designed the ‘Sno T’rrain,” which was two Weasel chassis coupled together with fully enclosed canopies.
Today, there is a large community of Weasel collectors and restorers. As such, there are many running examples in private collections world wide.

An article by Mark Nash

Cargo Carrier M29 Weasel

Dimensions (L-W-H) 10′ 6” in x 5′ x 4′ 3”
(3.20 x 1.5 x 1.80 m)
Total weight 1.8 tons
Crew 1 driver, 3 passengers
Propulsion Studebaker Model 6-170 Champion 6-cylinder, 70hp
Speed (road) 36 mph (58 km/h)
For information about abbreviations check the Lexical Index

Links, Resources & Further Reading

The M29 on Military Factory