The Swimming Truck

The Alvis Stalwart

The Stalwart was a private venture by Alvis of Coventry that was adopted and entered service with the British Army in 1966 as a general transport truck in preference to the FV431, the load carrier variant of the FV430 series. It was one of the same line of vehicles that included the Alvis Saracen, Saladin and Salamander and they were all driven through all of their 6 huge 14 x 20 solid tyres with 4 wheel steering and had the ability to keep going even if one of its wheels was blown off.

The FV 620 Stalwart, informally known by servicemen as the ‘Stolly’, is a highly mobile amphibious military lorry built by Alvis that served with the British Army.

Weighing in at 9 tonnes with a length of 6.36m (20 ft 10 inches), width of 2.62m ( 8ft 9 inches) and height of 2.31m ( 7ft 6 inches), it had a crew of a driver and two passengers. 

Powered by a Rolls-Royce B81 Mk8B 8 Cylinder 6516cc petrol engine giving 220 BHP at 4000 rpm and 335 lbs/ft of torque at 2500 rpm, it had a range of up to 824 Km (515 Miles) at around 4.5 mpg and a top road speed  of  40 MPH and the ability to cross a 5 foot trench. In the water it was driven by vectored thrust water-jet propulsion units at about 6 knots.

Despite it’s modern appearance, the first Stalwart in fact saw light of day way back in 1959. It was not, however, until 1966 that the vehicle entered service with the British Army. It’s role was that of general amphibious transport truck, many units being fitted with a hydraulic crane and raised central canvas tilt support. The high mobility and amphibious capabilities were considered ideal for resupplying units in the field.

Unfortunately, rapid technical advancement in helicopter design rendered its usefulness in all-terrain load carrying prematurely obsolete.

The hull is the vehicle chassis, the engine is situated under the load deck in the rear of the hull and the gearboxes, differentials and transfer boxes forward of this. The load deck was open-topped with large drop down panels on either side. Waterproof seals ensured that these would not leak when in the water. The three man cab has the driver’s position in the centre and a seat for a passenger either side. The cab can only be entered through roof hatches.

 The Stalwart could carry 5 tonnes of stores, or tow 10 tonnes and today, fitted with modern diesel power-packs, Stalwarts are finding work in some unexpected places – such as the Florida everglades, splashing about with a cargo of tourists in the back.

The Stalwart’s main talking-point is its extraordinary transmission, which includes a bevel drive in the hub of each of its six wheels. There is no differential gearing between the three wheels on each side, nor from side to side. This means that if the Stalwart is driven on a hard surface (like a road) the transmission will ‘wind up’, eventually destroying the hub bevel drives. During military use the problem of transmission ‘wind up’ was solved by laying out railway sleepers in a grid on flat ground and driving over them if on long road moves, this allowed the transmission to ‘unwind’. On more than one occasion, servicemen drove Stalwarts into car parks and used the kerb stones separating parking bays for the same purpose…..quite unofficially. Another problem with the transmission was that the vehicle was designed to be driven ‘loaded’. Driving it ‘unloaded’ caused increased wear on the drivelines to the wheels as a result of the increased angle of mesh of the joints.

The drive system including the all-wheel drive, multiple gearboxes, and the water propulsion units was complex and needed a lot of maintenance. When the amphibious qualities become unnecessary, it was common for the water jets to be removed to reduce weight and maintenance.

Captain Tankboy uses an Alvis Stalwart FV622 as his Battle Truck in the crazy Destruction TV show, Tankboy TV.

A Stalwart FV623 Series 2 was featured in Children of Men.

An Alvis Stalwart FV622 was used in Tomb Raider 2 – The Cradle of Life.

 An Alvis Stalwart was also used in SeaQuest DSV.

 An Alvis Stalwart FV622 with a modified payload compartment was used in the TV series Firefly. It appears briefly in the opening of the 2-hour pilot episode of Firefly (known as “Serenity”) during the night battle scene.

A Mk2 Stalwart (registration NOP 225F) and two Saracens are featured in Altern8’s video for E-Vapor-8 on YouTube.

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