I think these figures are from a one off 1000 miles test conducted at Bovington during July/August 1942, at least that is what I recall from reading the Coombs book, and so are not quoted overhaul figures. They also aren't the figures that the War Office published themselves for this trial, which showed that, for example, both Covenanters reached 1200 miles before experiencing engine failures. I believe Coombs got his figures from a Nuffield Mechanizations report which is held in the British Motor Vehicle Heritage Trust, so this is something I need to track down sometime.critical mass wrote: ↑06 Jan 2019 15:23DonJ,
when judging mileages, one might interfere that the Comet, A30 and Cromwell are all very late ww2 AFV and benefitted from extensive post ww2 service (with all improvements that caused), intruduced considerably later than the PANTHER. The CENTURION is a post war serving AFV, entirely.
According to Coombs, British tank production and the War Economy 1934-1945 (London/New York 2013), p.90 (for what´s worth), these mileages were not obtainable midwar:
average mls before major drive train breakdown / replacement of engine under british environmental conditions:
CRUSADER 1942: 400mls
VALENTINE 1942: 950mls
CHURCHILL 1942: 500mls
MATHILDA II 1942: 800mls
COVENANTER 1942: 600mls
Perhaps Your data shows how much the average overhaul times improved late ww2/post ww2? At least the Cromwell sent to the US seems not to have been fit to 5000km, yet, if I understand the report correctly.
As for the actual overhaul mileages for these tanks, these would be 1500 miles for the Crusader and Covenanter, 1000 miles for the Matilda, and 2500 miles for the Valentine (Leyland engined variant). The Crusader overhaul life was reduced to 1200 miles for desert conditions, due to the constant dust. 500 miles was probably correct for the Churchill during this period, but this was raised to about 1000 to 1200 miles by the beginning of 1944. The GMC engined Valentines sent to the Middle East/North Africa weren't given an official overhaul figure, because they ran to the end of the campaign without having had a single overhaul - many of them had over 4000 miles on the clock.
Of course, overhaul figures do not tell the whole story, as the Crusader tended to be an unreliable tank when operating between overhauls, and the Matilda was extremely maintenance intensive. Overhauls themselves are not always comparable - for example a Matilda took six times more manhours to overhaul than an M3 Stuart.
The Cromwell wasn't really fit for 3000 miles until March/April 1944, when the "Full Specification" was finalised, although the main modification that improved its durability was introduced in late 1943 - this was the change in the final drive ratio from 3.71:1 to 4.5:1, which also reduced its speed from ~40 mph to ~32 mph. As I've stated upthread, I think the Panther was a very ambitious design, and so it doesn't surprise me that it had severe reliability/durability issues. I think it is generally under-appreciated just how much new ground was being broken with WW2 tank designs, and to expect a 45 ton tank capable of 30 mph to perform adequately with just a couple of years' development is unrealistic imho. It is notable that the British kept the maximum speed of the Centurion Mk.I down to 23 mph, and I think subsequent models were even slower. I suspect this was a compromise in order to enhance durability.