Chauvel

Introduction

The shortage of tanks in Australia following the Halifax-Butler Coup meant that domestic production was the obvious move, the problem being the Australians had neither a design to work from, nor any basis for building anything heavier than the Bren-carrier. Fortunately the Directorate of Armoured Vehicle Production (DAVP) that was set up in 1939 to oversee the carrier program, had been daydreaming about local tank production ever since, so the situation at the end of 1940 didn’t find it completely lacking in ideas. The two vehicles we had in numbers, the Carrier LP and the Vickers Mk VI were both products of Sir John Carden’s drawing board, so a fusion of the two seemed (and was) a reasonably safe course that was within the abilities of local industry. The result was the Tank Light (Aust) Chauvel Mk.I.

Description

The Ford built hull was copied from the Mk VI but built along the lines of the LP Carrier. A simple welded box of 3/8” face hardened steel on the sides, ¼” for the bottom, rear and top deck, a 3/4” bow plate and 5/8” on the almost horizontal (65deg) glacis/engine cover. The engine was offset to the left in the front hull driving forward through a transmission in the bow, the driver sat to the right of the engine and the fighting compartment filled the back half of the vehicle ending with a pair of rear access doors. The doors were to permit easy loading of ammunition and so the space between the turret basket and the back of the hull could be used as a storage compartment.

Ford were also responsible for the running gear. The suspension on either side was by a pair of 2 wheeled Horstmann units borrowed from the Carrier LP with up-rated springs. There was no rear idler wheel but an adjustable return roller was fitted to the rear suspension unit on each side to tension the Carrier LP tracks.

The transmission unit was the greatest technical challenge and in my view the make-or-break point for AFV development in Australia. General Motors Holden (GMH) of Fisherman’s Bend Melbourne was given the task of adapting the Vickers-Wilson epicyclic (5 forward, 1 reverse) transmission for local manufacture and it must have been a bugger of a job too. The end result was based on the theory of the Vickers but so changed to make the best use of GM - Chevrolet components as to be a whole new design.

In operation the biggest change from the original was the use of a spur gear transfer case between the primary clutch and the gearbox to provide reverse (I think who ever was running the GMH drawing office wasn’t too confident in their grasp of Sun and Planet type gears). This added a little weight and bulk to the unit but meant that if it wasn’t for a blanking plate on the gear shift the Chauvel would have had as many gears backwards as it did forwards. In the field this plate was usually modified with a hacksaw and cold chisel to give 3 reverse gears, any more and the Chauvel started to shed tracks. GMH were also responsible for assembly of the whole tank, so as not to disturb Ford’s carrier production more than necessary. It wasn’t all smooth sailing however, the transmission was the last component to reach production and it took 4 revisions over the next two years to get it right. Once the bugs had been ironed out, this unit proved its self to be both reliable and versatile, seeing service in several other vehicles over the years.

The engine was a Canadian Ford V8 of 90hp, GMH had wanted to use an 80hp American GM diesel, but it was felt that both power and pounds were lacking.

The manual turret had a full basket, and looked very similar to that on the A15-Crusader being developed by Nuffield in Britain before the capitulation. There has been a lot of speculation about how much the local designers knew about this tank, I’ve never seen any solid evidence of a linkage, but where ever the inspiration came from the resemblance is uncanny. For the Chauvel this meant a lozenge shaped turret with well-sloped sides and a sliding hatch that covered the rear half of the turret. The only elements lacking from Crusader was that tanks sharp reverse slope on the bottom of the turret and crested roof, the Chauvel turret had a flat bottom and roof with the sides at a less acute angle to compensate. The prototype turrets were riveted and built by the Victorian Railway Commission (VR) workshops at Newport, across the river from GMH at Fisherman’s Bend. The production turrets were from the same source but all welded, VR delivered the turrets and turret rings to GMH for assembly and fitting out by the old car ferry across the Yarra.

Exactly what to fit in the turrets was yet another hurdle for DAVP. The 2pr Q.F. AT gun was the obvious choice and the Government Ordnance Factory at Maribyrnong was tooling up to produce it, however what to use as a co-axial MG? Eventually, they settled on VMG Mk III

In service

The general consensus is that the was reliable (once the gearbox was sorted out) easy to drive and very responsive. On the other hand it wasn’t very fast when compared with other vehicles in the same class (even the Mk VI). Top speed was limited by the gear ratios to about 30mph, but the low gears gave it very good acceleration and cross country performance while keeping the engine relatively unstressed.

Inside they were dimensioned with the large sized soldier in mind, that-is if he was careful about where he put his bits and pieces, but were a bit cramped for height in the turret. The ride was good enough for the crews to practice firing on the move and access was easy both for the crew and the fitters.

The Chavuel’s main faults were either fundamental or in the detail design. The worst was of course the two-man turret. When fitted with the radio as designed (some spent as long as a year before fitted with them), the commander just had too much to do loading, commanding and communicating to do any one job very well. This was recognized from the outset, but the Carrier LP chassis just couldn’t take the weight of a three-man turret and still have any meaningful armour if reliability wasn’t to suffer. The DAVP soon came to the conclusion that while for a tank intended for reconnaissance the two-man turret was acceptable, it would never do for a ‘proper’ tank.

The detail design flaws on the other hand were for the most part typical beginners mistakes. Crew vision when buttoned down was poor, ground pressure was high and the tracks were fragile. With the drivers and turret hatches open the vehicle was still stuffy and for the driver especially very hot. Even after an extraction fan was fitted, you couldn’t fire more than three or four rounds buttoned up with out the crew starting to choke on the fumes. The rear access doors in the hull, which were a much appreciated practical feature and repeated in later designs. Leaked like a sieve on the Chauvel, while theoretically capable of wading to a maximum of three feet, at this depth the semi-recumbent driver would have been up to armpits in water and the turret crew wet to the knees.

Of these the only really intractable problem was with the tracks. The original carrier chassis used a form of flexible track steering, that is the tracks flex sideways for gentle turns (as this was part of the original le Mole proposal in 1912, so I suppose Australia has only its self to blame). To get the required flexibility, the track’s had a very short pitch (length of each link) which had the benefit of helping achieve higher speeds. Unfortunately it also bought two rather unwelcome side effects. The first was that for a given length of track there were more links, which meant more connecting pins and with a small sized track with small pins, this resulted in more breakage’s. And breaking a track is bad news even when people are not shooting at you. The other problem is short link tracks have inherently higher ground pressure than long link tracks. The only way around this is to use more road wheels to spread the weight across more track blocks, but the Chauvel had only 4 wheels per side. As one author put it “by default the Chauvel was a Grand Prix racing tank doing the job of a Fordson (farm tractor).”

Operational History

The Chauvel’s service career was fairly brief, they spent the war mostly as training tanks and they were well on their way out by 1945. Sixty of them were refurbished by Sunshine Harvester in late 44 and used to mechanize the PNG Mounted Rifles (Militia) as they were the heaviest armor the bridges up there could cope with and were still on strength in 1955. The rest being laid up and disposed of in 47-48.

Against the Japanese light tanks of the early 40’s, most authors believe that the ‘Shovel’ would have been a formidable opponent. Tactically the vehicle was low, agile (if not a speed demon) and the 2-pr was more than equal to defeating armor it was likely to meet. According to the modern AP formulae, the Chauvel’s well-sloped plates had a good chance of keeping out Japanese medium velocity AP despite their meager thickness and having an R/T in every vehicle would have given Australian units a great advantage. The only two areas the Chauvel suffers in comparison to the contemporary Japanese tanks are habitability in the tropics and the lack of a decent HE shell.

Of the 146 built in two years over 100 still survive in one form or another. The majority sit coated in various shades of green paint and bird droppings in parks or in front of RSL’s across the country. At least two are in private hands are runners and one is now a working exhibit at the Australian Army Museum. It might not have been a great tank, but it has a fond place in Australian society as a symbol of its development, progress and independence.

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