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21st December 2007The Mk IV Sherman Tank that was made available by the South African Defence Force School of Armour in Bloemfontein and which has been undergoing major reengineering work for the last 8-months is now mobile. The following report has come in from Jan Fouche who is in charge of the restoration team.
"We drove the Sherman for the first time a week ago. It has got a lot of power and goes well. We however had a problem on the gearbox not selecting reverse. The guys from PK Bus Services came yesterday and corrected the problem.
The biggest obstacle we have is that he cooling system does not work well enough. The radiators are big enough but the single cooling fan (which acts as an extractor fan) does not create enough air flow through the radiators and will have to be supplemented by adding two 24V electric fans onto each of the two radiators. These will be mounted into specially built cowlings in pairs with each pair mounted directly onto each radiator and with the existing fan then used to draw all hot air from the engine compartment.
The original oil coolers were in such a state they were not repairable and we had to buy new oil coolers and we also had to buy high pressure 50mm hydraulic hose to use as radiator hoses as we needed flexible hoses to enable the complete radiator pack to swivel to be able to reach the engine.
The oil coolers are mounted on top of the radiators compared to the original ones which were mounted inside the tank in the firewall which meant that special 4 metre high pressure hoses had to be made for the coolers.
The next problem was that the original oil pipes were all rusted away completely and all oil leaded out of the original gearbox and diff. The new gearbox also needed to be filled and both gearboxes and the coolers and pipes took a total of 128 litres of oil costing R3168 for the oil.
We are also going to need at least 200 litres of diesel to be able to test the tank completely. It seems at this stage that the fuel consumption will be in the region of 2.5 litres per km compared to the original engine's consumption of 9 litres per km."
The tank is now much closer to the Israeli converted Shermans that performed so spectacularly during the 6-day war in the Middle East many years back. Further reports to follow.
Andy Selfe says, "This book is highly to be recommended for anybody with an interest in this subject. It covers the history from the beginnings of Tank development and has one A-Z up to 1945 and another from that date to the present, from which the scans below are typical examples. www.lorenzbooks.com"
The Sherman Mk IV has now had its turret fitted and field trials have commenced.
To see this tank in action come to the Steam & Cosmos Festival 2008.
Nearly 50,000 Shermans were built during the Second World War, amounting to almost half of all American wartime tank production, and equal in numbers to the entire production of tanks in the UK and Germany combined! The tank appeared in many different configurations, from a basic gun carrier, via rocket launcher, engineer / recovery vehicles, armoured personnel carriers, mine clearers, self-propelled guns, howitzers, anti-aircraft guns to bridge-laying vehicles.
Originally it was fitted with the Continental R 975 radial engine, converted from use in aero applications. These compact engines were very powerful for their size (400 HP@ 2400 rpm and max torque @ 2200 rpm was 1250 nm.) but owing to the fact that some of the cylinders faced downwards, an accumulation of fuel built up in the lower cylinders while standing. This was normally cranked out, but in emergency situations the lower plugs were removed leading to a dangerous situation of unburned fuel in an enclosed space, waiting for a spark to ignite it!
Owing to demands from the wartime Aero Industry, the radial engine was in short supply and no less than four other engines were used, both petrol and diesel, including the Chrysler multi-bank 30 cylinder petrol engine.
Drivers of the original model with the crash box will tell you that it was not every driver who could manage the difficult double-declutching required to change gear smoothly. Replacement with an automatic, or at least a pre-select gearbox was the next sensible progression.
After the War, the Sherman was used by many armies across the globe, who made their own modifications according to local conditions and availability of power units and spares. Operating range, coupled with fuel efficiency would also have had an influence. The Israeli Defence Force was a prime example, fitting improved engines, armament and armour. This they called the M51 Sherman. It was based on the M4A3 Sherman hull which already had radiators into which they fitted the Cummins 460 hp diesel engine. They also fitted the wide track E8 HVSS suspension as an aid to combat mobility. No alterations or additions were made to the armour, either in the M50 or the M51 modification programme. They kept to the original gearbox to save space for ammunition.
This example has been modified locally, by fitting a large V8 Mercedes Benz / Atlantis Diesel Engine 442 twin-turbo diesel engine, rated at 400 hp @ 2100 rpm. Max torque is 1600 nm @ 1100-1500 rpm. Fitted directly to the engine is an Allison AC740 CR (close ratio) 4-speed automatic gearbox with the prop-shaft running into the original gearbox which now acts as a transfer box. This in effect gives the vehicle a total of 24 forward and 6 reverse gears.
Top speed is 45 kmh. Fuel consumption is now +/- 2.5 litres per km compared with 9 litres per km with the Continental engine!
Further modifications to this vehicle include the fitment of electronically operated turret turning motors (which were not standard on this specific type) and the fitment of modern optical equipment and sights.
The other major modification on the vehicle was the fitment of twin radiators with accompanying cooling fans. These radiators are fitted in such a way that the complete radiator pack swivels open in less than a minute for easy engine access.
Above information partly provided by:
The World Encyclopaedia of Tanks and Armoured Fighting Vehicles, written by George Forty and Jack Livesey and also by Jan Fouché from Lichtenburg, who carried out the conversion.