The Chrysler A57 Multibank is a 30-cylinder engine that was created in 1941 as America entered

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. It consists of five banks of inline-6 cylinder engines.

History

left, Chrysler multibank It was born out of the necessity for a rear-mounted tank engine to be developed and produced in the shortest time possible for use in the M3A4 Lee medium tank and its successor M4A4 Sherman medium tank. Each had lengthened hulls to accommodate the A57. In order to use existing tooling, five Chrysler flathead engines (bore , stroke ) were arranged around a central shaft, producing a unique 30-cylinder engine in a relatively compact but heavy package. A total of 109 Lees and 7,499 Shermans were fitted with the A57. The M4A4 was largely supplied to the British, the US preferring the M4A3 with the more conventional Ford GAA V8 engine, and restricting their M4A4s to overseas use.

Design

The combined assembly consisted of five of these straight-six engines mounted in a pseudo-radial fashion upon a central cast-iron crankcase. The arrangement employed a common radiator, water pump, oil pan & dual oil pumps, with each of the five component crankshafts fitted with a geared flywheel that meshed with a central sun gear driving a main shaft running through the central crankcase.Berndt, p.190. Each of the six-cylinder sub-blocks had an iron head and featured a Carter TD-1

carburetor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Ventu ...

and a 6.2:1

compression ratio The compression ratio is the ratio between the maximum and minimum volume during the compression stage of the power cycle in a piston or Wankel engine. A fundamental specification for such engines, it can be measured in two different ways. Th ...

, with tuned pipes that fed into a common exhaust; output was at 2400 rpm. This large engine assembly necessitated a longer hull (same as the M4A6),Berndt, p.192. becoming the M4A4; most of these were supplied to Allied countries under

Lend-Lease Lend-Lease, formally the Lend-Lease Act and introduced as An Act to Promote the Defense of the United States (),3,000 Hurricanes and >4,000 other aircraft) * 28 naval vessels: ** 1 Battleship. (HMS Royal Sovereign (05), HMS Royal Sovereign) * ...

. In the February 1944 issue of the magazine ''

Popular Science Popular science (also called pop-science or popsci) is an interpretation of science intended for a general audience. While science journalism focuses on recent scientific developments, popular science is more broad ranging. It may be written ...

'', an advertisement by Chrysler claimed the A57 could still move the tank it was fitted in even if 12 out of its 30 cylinders were knocked out.

Preservation

The engine was preserved at the Walter P. Chrysler Museum in America and at the

Imperial War Museum Duxford Imperial War Museum Duxford, also known as IWM Duxford or simply Duxford, is a branch of the Imperial War Museum near Duxford in Cambridgeshire, England. Duxford, Britain's largest aviation museum, houses exhibits, including nearly 200 aircraf ...

in the United Kingdom. The Tank Museum in Dorset, England has a complete A57. That museum also acquired a second engine without radiator in 2019, from the UK Defence Academy at Shrivenham. Both are currently in storage in the museum's Conservation Centre.

References

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External links

The Chrysler A57 Multi-Bank Engine - An amazing engine
by Julian Edgar of AutoSpeed. A57 multibank Radial engines M4 Sherman tanks