M25 Tank Transporter "Dragon Wagon"
USA (1941). PCF G-160 (c1300 built)
The M25 Tank Transporter better known as the "Dragon Wagon", was one of the heaviest vehicles used by the United States in World War II. It was specialized transport 30 tonnes+ tanks or other heavy vehicles and just large bulky loads in general. It was a combination of the M26 Tractor 6x6 unarmored truck powered by a Hall-Scott 440 engine for towing heavy loads with a powered winch to loading/unloading and the 10 tons capacity M15 Trailer, a flatbed semi-trailer with ramps and eight roadwheels at the rear. A variant was used to recover disabled tanks and transport them to repair facilities or just move tanks from railway lines to forward positions. There were also semi-armoured or fully armoured variants. Thios go-to vehicle for the Sherman was developed in early 1940s by Knuckey and mass produced by Pacific Car and Foundry. It was used on the European theater, especially in Italy from 1944 and NW Europe, as well as in some threaters of the Pacific but also postwar in Korea, before being replaced by the M123 semi-tractor from 1955.
The most famous US tank Transporter
Given the specialty of tanks, roaming the battlefield often off-road, well served by its tracks, and the strain caused on its engine and massive consumption it was clear to all belligerents quite soon, that tanks needed to be preserved from further distances to the battlefield outside the envelope of their own range and speed. The usual way to transport a tank was by rail. Flatcars could accomodate up to 35 tonnes tanks, and in fact the M4 Sherman Family was designed with this in mind, define its weight and bulk. However when the railways were distrupted, which was the case in Italy and France, especially due to sabotages or allied air strikes in 1944, the allies needed another way to transport their tanks to the frontlines.
This way was by road, and on this, the British Army already had useful vehicles such as the
Scammel Pioneer TRCU-20. The US Army launched studies for these vehicles in early 1940 with specifications for a heavy-duty vehicle, and several truck manufacturers andswered the call. However only one was retained, the Diamond T M19. The M19 tank transporter became the prime allied TT at 6,554 vehicles, produced from 1941 to 1945. This 45t combination of the 12-ton 6×4 M20 Diamond T model 980 truck and companion 12-wheel M9 trailer was used both by the US, British but also Polish, and Free French armies among others.
Still in early 1942 the small wheels of the M19 seemed limited for good off-road capabilities. The full M19 had 24 of these total. So a new 40 ton semi-trailer tank transporter with better off-road performance needed larger wheels. On the other hand, the Fruehauf Trailer Company of Detroit, Michigan, built a 30 ton, 8 large-wheel Shelvoke and Drewry semi-trailers to be used by the Diamond T tractor unit. They were able to carry 40 tonnes vehicles, but the Diamond T was just unable to tow them, it just was not powerful enough. This led to a better tractor, at the time designed as a private venture by the Knuckey Truck Company. It was tested and standardized as the M26 tractor, and accepted for production later in 1942. However Knuckey's capacity was limited and just could not keep up with an order for 2000 vehicles.
Thus, production was given to the Pacific Car & Foundry Co. of Seattle in Washington. For this reason, the M26 was also nicknamed "the pacific". But in 1944 its new nicknamed became more popular, the "dragon wagon" because of its flame belching exhaust, from the 17-litre Hall Scott engine. Compared to the Diamond T, already considered a heavy truck, the M25 was properly "super-heavy". It could weight, when loaded and in the M26 (armoured) version, as much as 74 tonnes, so as much as the German heaviest tank. This by the way was an issue to cross many bridges. But this was the only transporter capable of handling absolutely any armoured vehicle in the inventory, including the late war M26 Pershing, or captured Tigers and Panthers. Production records diverged as some sources claims 2100 M26 tractors were delivered, others such as Baxter (see notes) confidently giving the figure of 1300.
Design of the M25 tank Transporter
Knuckle Tractor chassis
This vehicle is quite unique in the US inventory as being soon declined into an armoured variant, which was the only one in inventory. Thus the basic tractor truck with its rock solid ladder type chassis and 2+8 wheeltrain (forward directional axle, forward driving double axle, double roadhweel arrangement) was already an impressive tractor with much more power than the Diamond M19 and much larger wheels and tires for better off-road performances, which was the main objective here. The vehicle was capable of retreiving the largest US armoured vehicles on the most muddy, unheaven terrain, but also a heavy duty towing capacity, with a winch using the full power of the engine via a dedicated tranmission which was all about torque.
The basic TR-1 as designated by Pacific Car was a chain-driven 12-tons 6x6 tractor, powered by a massive Hall-Scott 440, 1,090 cu in (17.9 L) 6-cylinder gasoline engine, which developed 240 hp (180 kW) at 2000 rpm and 810 lbf.ft (1,098 N/m) at 1200 rpm. To compared the M19 tractor (M20 truck) had an Hercules DFXE engine rated for 201 hp (150 kW) with a torque of "only" 685 ft.lbf (929 N/m) at 1150 rpm. It was designed originally to fite British requirements, so for essentially smaller, lighter tanks. The M26's Hall-Scott 440 engine was connected to a 4 speed x 3 speed transmission, chain-driven for extra strenght. Fuel capacity was considerable due to the appetites of the beat, no less than 120 US gal (450 L) for a range of "only" 120 mi (193.1 km) and that's unladen. This was done at a senator's pace, top speed of 28 mph (45 km/h).
The M26 unladen was 48,000 lb (22,000 kg), 103,000 lb (47,000 kg) fully loaded, for a lenght of 25 feet 4 inches (7.72 m), 10 feet 10+3⁄4 inches (3.32 m) in width, 11 feet 5 inches (3.48 m) in height. The cabin was properly immense, with an equally impressive transmision tunnel dividing the interior in two. There were enough seats for seven, some forward, some back. They were equipped the same, however the only diverging point was the cabin, quite obviously different. The first was armoured, with slanted shapes, and two forward, six side windows closed by armoured shutters with sight slits.
The armour thickness was 3/4 inches or (19 mm) at the front, so to withstand even 20 mm rounds thanks to its slope, and for the sides and rear 1/4 inch or 6.4 mm, so proof against small arms fire and shrapnel. It was also armed, with a .50 cal M2 machine gun on a ring mount at the rear axis of the vehicle for a standing gunner for both anti-personal, light vehicles and anti-air defence. The second variant, for quieter theaters or just rear supply lines, was unarmoured, and called the M26A1. It was a simplified open cab vehicle with tarpaulin, rear access through steps, front windshields that could be folded down. The nose was peculiar, flat with central louvres, a short rounded top as the vehicle was in practice a "semi-COE". There was a single piece bumper with hooks and chains instead of a classic steel cable wing, going all the way behind the cab to a pair of ship-size powered winches. The M26A1 was ten tonnes lighter for improved performances.
The vehicle was an absolute behemoth of a truck, slow, ponderous, almost maneouvered with the same inertia as a ship. The crew of 6-7 inside had to endure the fedeaning noise, smoke and heat of the engine taking a large part with the transmission inside the cab. Due to its tall and unwieldy nature, visibility was poor and it needed all the eyes on board to avoid catastrophe, acting as assistants steersmen. With all shutters closed, visbility was even poorer and it was not rare for these massive vehicles to crumble walls, trees, or roll on any obstacle like a broken car without even noticing. Their width in particular was too much for the narrow roads of Europe, especially Normandy.
Fruehauf Trailer
The M15 trailer was the second part of the M26 combination. This trailer weighted 36,600 lb (16,600 kg) for 38 feet 5+1⁄16 inches (11.71 m) in lenght, 12 feet 6 inches (3,810 mm) wide, about 5 feet tall. It was supported forward by the rear wheeltrain of the M26 tractor and at the rear by two axles with single tires. These were of the same model as for the tractor, and the latter carried two spare tires at the rear of the cab. The trailer had no folding ramps, they were instead telecsopic, under the rear trailer chassis. When the pair of powered winches were used together, they had combined pull of 60 tons, thus being able to tow out and recover from the battlefield large vehicles such as the British Churchill tank. When used not for carrying tanks, the trailer could be jammed packed with crates to resupply an entire batallion if needed in one go.
M25 "dry run" transporting a captured Panther
The same could confidently carry a Higgins boat (LCVT landing craft).
G-160 (M26 tractor) specifications |
| Dimensions (L-w-h) | 25 ft 4 in x 10 ft 10+3/4 in x 11 ft 5 in (7.72 x 3.32 x 3.48m ) |
| Curb weight | 48,000 lb (22,000 kg) unladen |
| Crew | 7 |
| Propulsion | Hall-Scott 440 gas. 240 hp (180 kW) |
| Transmission | 4x3 Gearbox |
| Top speed | 28 mph (45 km/h) |
| Max range | 120 US gal (450 L): 120 mi (193.1 km) |
| Protection | Front 3/4 in (19 mm), sides, rear 1/4 in (6.4 mm) |
| Armament | .50 cal M2 Browning HMG |
Production and variants
The M26 tractor truck was manufactured at Pacific Car & Foundry (PACCAR). The company was founded by William Pigott Sr. at Seattle as car manufacturer in 1905. It started producting railway and logging equipment, much in demand in the area. It was especially renowned for oxen-drawn logging trucks for the dense and hilly forsts of the northwest. Later the company specialized in more demanding brake systems, refrigerated boxcars for shipment of perishable items and an universal trailer. Integrating a fundry it also manufactured structural steel reworked by hand which went into many building of Seattle. The company was barely touched by the great depression and its income grew.
During World War II, Pacific Car and Foundry was sollicited for specialized steel that was used in airplanes, airports, bridges, naval ships and all related to the US infrastructure. It sub-contracted for Boeing for aluminum that went into B-17 bombers. But from late 1942 it also started to directly built M4A1 Sherman tanks and also managed to cast all parts and export some. The company was knowon for heavy duty vehicles, not only the M25 tank transporter but also the massive T28 super-heavy tank, heaviest of all WW3 US armoured vehicles. Everett-Pacific Shipbuilding & Dry Dock created in 1942 started to crank up ships as well for the USN. The company was a powerhouse and major employer on the Pacific north west.
The Number produced in two variants, for the M26 tractor we are interested into, was 753 M26, armoured, and 629 M26A1, unarmoured (soft skin).
M26 Tractor
The M26 is the original, common production version comprising the following:
-Steel armored cab with fixed roof.
-Slanted shapes wit angles forward and on the sides to deflect projectiles
-Front cabin with armoured shutters forward, and three windows either side, plus small door aft.
-Employed without semitrailer as a wrecker where the armour made more sense to retrieve tanks on the battlefield.
M26A1 Tractor
The M26A1 is a later version without armored cab, designed to save steel when tank trabsport was made in a quieter conditions far enough for the frontline. Caracteristics are:
-No steel roof but tarpaulin roof.
-Lighter hull with a proper radiator nose, fuller sides.
-Better Mobility from the same powerplant (at the expense of crew protection).
-M26A2: Postwar variant with improved electrical system.
M15 Semi-Trailer
Dependency used by the M26 or M26A1 tractors:
-Eight large wheels at the rear on two axles.
-Chassis extending between the inner and outer wheels, on each side.
-Two foldable ramps to help towing in the vehicle thanks to the massive winch.
-30 tons nominal capacity, but capable of carrying tanks up to 70 tonnes.
The trailer was further declined into three main versions by builder:
-M15 trailer: 36.3 t maximum load, by Pacific Car & Foundry.
-M15A1 trailer: 40.8 t maxi load, also by Pacific.
-M15A2 trailer: 45.4 t max load, made by Fruehauf.
The "Dragon Wagon" in action
Quite a feat: The Germans needed three of their heaviest half-track for towing the Tiger I, whereas a single Dragon Wagon could carry the 70 tons Jagdtiger, the heaviest tank of WW2
Better known than it's army designation of G160, the vehicle started to arrive in frontline units in 1942. As time passed by, more and more were available, but they could never replace the M19. They saw action in north africa for some, and mostly from January 1944 in Italy and from June 1944 in France and NW Europe.
They provided a very important link to the coast, especially after D-Day, due to broken infrastructures notably trains. It was full capable of retreiving the Sherman and thus became indispensible for the allied war effort. Some were used aslo on the pacific front, on the equally vital burma road. As the front became quieter in Europe, the M26A1 started to arrive on many units. In 1945 itw as replaced by the improved M26A2. Service went on with the same tanks, even the new M46 and M47 Patton for the Koren war until 1955. From there, they were completely replaced by the new Mack M123/125 10-ton 6x6 tractor. However many saw action for many more years in UK, Yugoslavia and Japan with the JSGDF.