Alvis Stalwart & Bedford Files - Development of the Punt hull

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The Development Of The Punt Hull

The following sets out where the ideas for the 1946 General Staff Specifications probably came from - and how the Punt Chassis designed by Fighting Vehicle Design Establishment (FVDE) was used on the Alvis FV600 range, which ending up underneath the FV620 Alvis Stalwart.

It's a work in progress. So please do come back in the future for another look.

Part of the vast expense of the Second World War, and the shortage of vehicles - was down to the cost of broken vehicles that had to be abandoned.

Not only were different manufacturers using different components (filter housings, lift pumps, etc), but manufacturers were also using different components on different batches of their own vehicles, and across their range of different vehicles. This included of manufacturers using their own or different screw threads to other manufacturers. This resulted in being unable to source parts for broken down vehicles and even bolts from other broken vehicles due to differences in design.

Interesting to note that

UNC and UNF are symbols of Unified National threads, of the Unified Screw Thread Series.

The Unified Thread Series was agreed by Canada, Great Britain and United States in 1949 to obtain changeability. Recently, modifications have been made to the original 1949 specifications for ease of use.

The United Thread Series is classified into Coarse threads, Fine threads and Extra fine threads, much like Metric screw threads are.

UNC: Is the symbol for Unified Coarse pitch threads.
UNF: Is the symbol for Unified fine pitch threads.
UNEF: Is the symbol for United extra fine pitch threads.
UNS: is the symbol for Unified special threads.

Also - https://www.fastenerdata.co.uk/threads
It was not until 1947 with the re-founding of the International Standards Organisation (ISO) that further development took place eventually leading to the promotion of the ISO standard metric thread in 1960.

As a side note - Nicholas Straussler, and armoured cars

Alvis were involved with providing engines for armoured cars with Straussler of Hungary, mostly for the RAF - and even trialled their own scout car before the Second World War.

Further, the name Dingo was used by Alvis for their trial armoured scout car.

Nicholas Straussler's first armoured car, the AC1, was produced as a chassis by Manfred Weiss of Budapest, trading as Weiss Manfred RT.

The tubular chassis was of a rear-engine layout with four-wheel drive and four-wheel steering. No make is given for the engine although we are told that it was a four-cylinder unit rated at 100bhp with overhead valves.

It drove forward into a six-speed each way gearbox and had a tubular backbone chassis with swing arms to each wheel and transverse leaf springs. The interesting thing is that the company stopped building commercial vehicles in 1929 and did not start again until 1935. Yet the AC1 chassis appeared in 1932/1933.

Anyone who knows the mechanics of the Daimler Dingo will have bells ringing at the familiar details given above. This vehicle AC1 was tested in Britain in 1933.

The AC2 was made in Hungary in 1935, and driven by road to the UK where it was given improvements - including a turret and an Alvis engine. It was given to the RAF, who liked it.

AC2 of 1935 en route from Port Said to Baghdad, escorted by a Rolls-Royce armoured car of the Royal Air Force

Text by David Fletcher

See https://www.keymilitary.com/article/strausslers-and-alvis

Amongst Straussler’s interesting joint ventures was that with the Alvis company following the incorporation of Alvis-Straussler Ltd on 13 July 1936. This combination of Alvis engineering and Straussler ingenuity produced the AC3, which used a chassis imported from Manfred Weiss powered by a 120bhp Alvis 4.3-litre engine. With a fuel capacity of 45 gallons (205 l), the AC3 had a theoretical, but impressive, range in the region of 375 miles (600km).

The RAF ordered 12 AC3s in 1937 which were duly shipped out to the Middle East for use as civil defence vehicles and given the designation of ‘Car, Armoured, Alvis-Straussler, Type A’. Most, if not all, were based in Aden.

The AC3, known to the RAF as ‘armoured car, Alvis-Straussler Type A’, had a rear steering position with second steering wheel and duplicate controls. It ran on 10.50 x 20 tyres and had a transfer box added to the gearbox which gave a low ratio when required and incorporated forward/reverse gear and disconnected steering to the front axle for driving in reverse.

An Alvis-Straussler AC3, one of 12 for the Royal Air Force seen here during a trial run in Britain before going to the Middle East

Two other vehicle designs appeared shortly before the war. Although technically of Straussler parentage this was not acknowledged with either design but they are included out of interest.

One was the Alvis ‘Dingo’ Scout Car, a two-man machine powered by a four cylinder engine. It was entered for a War Office competition and came second to a BSA design and was never heard of again.

Text by Sheldon Michael Rogers

See https://someinterestingfacts.net/straussler-armored-car-ac1-ac2-and-ac3/

The Alvis Dingo, which lost to the BSA Scout car

This image, from the Imperial War Museum, shows the rear of the Alvis Dingo scout car

In 1938, the British War Office issued a specification for a scouting vehicle. Three British motor manufacturers, Alvis, BSA Cycles and Morris, were invited to supply prototypes.

Alvis had been in partnership with Nicholas Straussler and provided armoured cars to the Royal Air Force, Morris had participated in trials and production of armoured cars and BSA Cycles – whose parent Birmingham Small Arms (BSA) was involved in armaments – had a small front wheel drive vehicle in production.

Testing began in August 1938. All were of similar size and layout – rear engine and all four-wheel-drive. The Morris design was eliminated first – suffering from poor speed even after modification by its builders. The Alvis prototype – known as "Dingo" – could manage 50 mph (80 km/h) over a cross-country course but had a high centre of gravity.

The BSA prototype was completed in September and handed over for testing. By December, it had covered 10,000 mi (16,000 km) on - and off - road, with few mechanical problems. Policy from the War Office changed to a requirement for an armoured roof. The BSA vehicle needed a more powerful engine and strengthened suspension. It was chosen over the Alvis and the first order (172 vehicles) for the "Car, Scout, Mark I" was placed in May 1939. The actual production was passed to Daimler, which was a vehicle manufacturer within the BSA group of companies.

The potential of the design was recognised, and it served as the basis for the development of a larger armoured car – a "light tank (Wheeled)", which would later become the Daimler Armoured Car.

The first pilot vehicle was built by the end of 1939, later to be named 'Daimler Scout Car' but already known by the name of the Alvis design - the Dingo.

See https://en.wikipedia.org/wiki/Daimler_Dingo

The Daimler Armoured car on the left, with the Daimler (Dingo) Scout car on the right.

Both models having the H drive replicated later in the Daimler Ferret and Crossley/Alvis Saladin.

The driveline layout of the Daimler armoured car. The rear mounted engine, coupled via a pre-selector gearbox to a transfer box. The driveshafts take the drive to the front and rear wheels, and bevel boxes take the drive through right angles to the wheels. This layout would become the basis of the FV600 series

This video of the Daimler Armoured Car shows how the H drive train works

The Daimler Armoured Car

Back to the Punt hull

In 1946, the General Staff issued a Specification for new armoured cars, using components common with other vehicles. Also that a range of vehicles should be created using common chassis. It was decided that the Rolls Royce B Series engine would power the various sized vehicles from all vehicle manufacturers to ensure commonality across the field. Hence the early military Land Rovers having Rolls Royce engines.

Having taken note of the successful Daimler Dingo drivetrain (See Straussler below), the Fighting Vehicle Design Establishment (FVDE) came up with a Punt chassis, with an H drive line from a central differential giving a permeant 4 wheel drive Medium Mobility Wheeled vehicle and 6 wheel drive High Mobility Wheeled vehicle.

According to Mike Dunn (Son of Willie Dunn - see Mike's article on the Stalwart development page), FVDE in association with Alvis' Willie Dunn, started designing the 6x6 Punt hull in 1947. Willie Dunn was the chief Engineer of Alvis, and designed the Saladin, Saracen, Salamander and Stalwart. Mike Dunn became Chief Engineer and designed the Stalwart Mk 2.

In 1952 FVDE merged with the Fighting Vehicle Proving Establishment (FVPE) and became Fighting Vehicle Development and Research Establishment (FVRDE)

A Punt hull, produced by Alvis to explain how the Alvis Punt hull worked. This was located at the Army School of Mechanical Transport, at Leconfield - near Hull. Current location or fate is unknown.

Two versions to this story, and still researching it, but;

1) In 1947 Alvis were given the 6 wheel Punt hull design by FVDE, and asked to produce an armoured car to a set specification. Alvis then asked Crossley Motor Company to produce prototypes, which Crossley thought would turn the company around and save it. Alvis was then asked to rush the Saracen through, due to the Malayan conflict. The Saracen coming into service in 1952.

2) Crossley Motor Company at Stockport had previously made various trucks and armoured cars for the British Military. They were given the 6 wheel Punt hull design by FVDE in 1947, and asked to produce an armoured car to a set specification. 6 Saladin prototypes were produced. Alvis where then asked to produce the Saracen as a matter of urgency due to the Malayan crisis. Once sufficient Saracens had been provided, Alvis was given the contract for the Saladin, rather than Crossley.

Crossley Motors Limited agreed to be taken over by AEC in 1948.

Photo of the Trails of the Alvis Saladin. This version without a locking central differential.

According to David Fletcher of The Tank Museum, all the Saladin with civilian registrations were built by Crossley Motors Company.

Photo of the Trials of the Alvis Saladin. This version with a locking central differential.

GX is a London registration. Apparently, RGX was a London registration only used by Government - and included FVRDE.

https://www.lrsoc.com/forum/index.php?topic=22097.0

It should be remembered that each model of the FV600 had it's own chassis designed and manufactured. The common part being the wheel stations, suspension and transmission. The chassis were not interchangeable between vehicles.

These images below show how the Saladin and Saracen have wide bodies, but narrows for the driver's compartment on the Saladin, and for the engine on the Saracen.

Saladin hull

Saracen hull

With the Saracen and Saladin under it's belt - Alvis then looked at what else this Punt chassis could be used for. The first designed was an Airfield Crash fire tender, becoming known as the Salamander.

The Salamander's Punt hull chassis shares the same common components of the Alvis six-wheel-drive FV 601 Saladin armoured car and FV 603 Saracen armoured personnel carrier. The chassis itself is specific to the Salamander.

This is the bare chassis of the Alvis Salamander

Then Alvis wondered if they could also make an off road truck, that would carry 5 tonnes.

The first cargo carrying Stalwart Project Vehicle (PV1) was known as Camion, which means truck in Spanish. It was known in the factory as The Beast. PV1 was purely to prove as cheaply as possible that the theory of the Punt hull carrying 5 tons off road was a realistic idea. It was nothing more than a Salamander, with a cheap drop side body.

The Camion Stalwart. PV1

The story of the Alvis Stalwart development continues on the next page.

Below are links to videos and records of the development of the Saladin and Saracen, because of how that resulted in the Stalwart.

A lot of the above is recorded in The Times. Simply search The Time's archive for Alvis Board meetings. https://www.thetimes.co.uk/archive/

The Development Of The Punt Hull

As a side note - Nicholas Straussler, and armoured cars

Back to the Punt hull

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