|Also called||Rover Meteor|
|Power output||600 bhp (447 kW)|
It was developed from the Rolls-Royce Merlin aero-engine by W. A. Robotham and his chassis design and development division at Belper, as they were not involved in aero-engine work. With the aid of engineers from Leyland, who were engaged in tank work, he considered RR's two V12s. The Kestrel, while having more power than the existing "Liberty" or Meadows engines, did not provide the desirable 20 bhp per ton required, so the Merlin III was used.
Despite his lack of experience in tank design or warfare, Robotham was made Chief Engineer of Tank Design and joined the Tank Board. He was involved in the Cruiser Mk VIII Challenger tank. The Tank Division at Belper was involved with the overall design of four versions of the Cromwell tank, using a standard set of components.
Design and development 
For tank use the Merlin had its supercharger, reduction gear, and other equipment removed from its camshaft, greatly simplifying its construction. It had cast, rather than forged, pistons, and was de-rated to around 600 bhp (447 kW), running on lower-octane pool petrol instead of high-octane aviation fuel. In addition, because weight saving was not so important for a tank engine, some of the Merlin's more expensive light-alloy components were replaced with cheaper, steel components in the Meteor X version. It was also envisaged that the Meteor would use some components rejected on quality grounds for the Merlin, i.e. Merlin scrap. In 1943 an acute shortage of blocks was met by dismantling surplus older marks of Merlins.
Unlike earlier British tank engines, such as the American Liberty L-12 of 340 bhp (250 kW) licence-built by Nuffield and used in the Crusader, the Meteor engine, of virtually the same 1,650 in³ (27 litre) displacement as the earlier Liberty engine, from its R-R Merlin origins was very lightly stressed and reliable, and doubled the power available. Previously British tanks had been regarded as underpowered and unreliable, and the Meteor is considered to be the engine that for the first time gave British tanks ample, reliable power. Initially it was used in the Cromwell tank, which was a further development of the cruiser line and would replace the Crusader tank.
But in 1941 Leyland, who had an order for 1,200 Meteor engines, were still advocating their own diesel tank engine, although it would deliver only 350 hp (260 kW), as they were concerned with the problems of sufficient cooling. Meadows produced some Meteors, but the small factory of 2,000 men was producing 40 different types of engine. So Meteor production was to be by Rover (Tyseley) and Morris (Coventry).
The first Merlin prepared for tank use was tried in a modified Crusader in September 1941 at Aldershot.
The Meteor was used in the following vehicles:
- A Mk II version of the Valiant tank, to use a two-thirds-size (V8) version of the engine called the "Meteorite" was suggested but not proceeded with.
When Leyland withdrew their support, Robotham took the problem to Ernest Hives. Hives took the problem to the Ministry of Supply, telling Lord Beaverbrook that he already had his hands full making Merlin aero engines, and Rolls-Royce would want £1 million to their credit and 'no interference' to make tank engines, Beaverbrook telegrammed back:
|OHMS Ministry of Supply to W. Hives Nightingale Road Rolls-Royce Derby
The British Government has given you an open credit of one million pounds. This is a certificate of character and reputation without precedent or equal. Beaverbrook
An order for 1,000 engines followed. The Meteor was initially produced by Rolls-Royce. Rolls-Royce were also aiding the development of production jet engines at Rover, but progress there was slow, and Rover were becoming disillusioned. Hives struck a deal in December 1942 with Spencer Wilks of Rover to trade W.2B/23 production at Barnoldswick for the Rolls-Royce tank engine factory in Nottingham and production of the Meteor, to become officially effective on 1 April 1943.
Rover took over the Meteor in January 1944, and in 1946 the British Government made Rover responsible for research and development of large military engines. In this role Rover continued the development and production of the Meteor Mk IVb and various derivatives, including the Meteorite V8 and the M120 V12.
Rover ceased this activity in 1964, having produced approximately 9,000 engines, and Rolls-Royce again became responsible for the manufacture of spare parts to support fielded engines. Future engines for British tanks were manufactured by the engine division Rolls-Royce Diesels of Shrewsbury, which was acquired by Perkins UK in the 1980s. Perkins was taken over by Caterpillar Inc of the USA in 1997.
See also 
- Rolls-Royce Meteorite, a V8 version
- Sidgreaves[clarification needed]
- "Rolls-Royce Enthusiasts' Club – Clan Foundry Belper". RREC. Retrieved 2010-12-01.
- Fletcher p34
||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (May 2009)|
- Peter Pugh (2000). "Volume 1 of The Rolls-Royce Story". The Magic of a Name: The Rolls-Royce Story, The first 40 Years. Cambridge: Icon Books. pp. 253–255. ISBN 1-84046-151-9.
- Evans, McWilliams, Whitworth and Birch (2004). The Rolls Royce Meteor. Rolls-Royce Heritage Trust. ISBN 1-872922-24-4.
- Ian Lloyd (1978). "chapter 7, The Meteor Tank-Engine Project". Rolls Royce: The Merlin at War. London: Macmillan. ISBN 0-333-24016-2.
- David Fletcher (1993). "3 The Next Generation". The Universal Tank. HMSO. ISBN 0-11-290534-X.