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T40/M46


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The_Chieftain #1 Posted Feb 23 2016 - 22:04

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As it is well known, the M26 Pershing was not an unqualified success. By the end of WW2, deficiencies in the vehicles, many of which were already known even at the time of fielding, became reinforced. Thus, a general improvement program was started, the T40 which ultimately would become M46. It turned out that improving a tank isn’t always all that easy…

The program for T40 really kicked off in the first half of 1948, as a series of conferences between Army Field Forces and Ordnance Dept culminated in a number of changes, particularly to the power train, but also notably weapon and suspension, in what would become the M46. As an improvement of an extant design, tests of the ten T40s were relatively brief. In fact, M46 was standardised by the Ordnance Committee in July 1949, the month before the first T40 showed up at the Aberdeen Proving Grounds!

This did not, however, provide adequate time for field service testing. It’s one thing to run a vehicle around the test track for a couple hundred miles, it’s another to really run them through the grinder on the training grounds. As a result, the Army Field Forces Board #2 (i.e. Armored Board) received four of them to test out while the production run started.

Initial results were quite positive. The bore evacuator reduced flashback and fumes in the fighting compartment, at the cost of slightly increasing obscuration when combined with the new muzzle brake. (1.9 seconds for T40, 1.3 seconds for M26). However, the M3A1 gun was considered more accurate. Controls generally worked, although there was an issue with the power traverse mechanism which was a bit sluggish and rate of traverse control was unsatisfactory. The improved telescope aided accuracy, but the automatic cant corrector was a little unreliable, added ‘needless complication’, and was recommended to be removed. Overall, the Board reported that “The fightability of the Medium Tank, T40, is increased over that of Medium Tank, M26”

Trouble started to show up once a few hundred miles came on the clocks, though. “Test vehicles were operated primarily cross-country in order to detect deficiencies at the earliest possible time.” Total distances travelled before the tests were curtailed were as follows.

For that 3,805 miles, they required 3,543 man-hours of maintenance, or a whopping 1.07 miles per hour of work.

For a basis of comparison, hop on over to the Dracula tests of 1943

The Shermans ran nearly 14,000 miles, and required 420 hours of mechanic man-hours, or about 33 miles to the man-hour. Now, there’s a difference between mechanic man-hours, and maintenance man-hours, the US report is not specific as to what the 3,543 hours consists of. I suspect much of that is, however, mechanics. No matter how you cut it, though, at a mile to the hour, that’s not exactly ideal. You can do the maths yourself, but that works out, assuming the typical detachment of three or four mechanics to a tank company,  as two days of movement of 25 miles each, followed by a mandatory one full day of maintenance. Not acceptable. Some improvement was required.

In particular, the report suggested improvements in the oil cooling fans (oil seals, drive shafts, gear lock nuts, and fix the short circuits in the wiring), transmission (excessive wear of reverse and low gear bands and steering clutches, defective oil pressure sending units, leaky cooler hoses), engine (wear on crankshaft journals, connecting rod bearings, connecting rods, pistons and rings, carbs, starter motor, generator and leaks in oil and fuel lines) suspension (rear road wheel bearing, shock absorbers, front bumper spends, comp-idler wheels), and issues with the brake steering and accelerator linkages.

More generally, “steering control was inadequate during high-speed highway operation. Test vehicles were noted to have a tendency to oversteer at high speed to such an extent as to make them unsafe for convoy operation. A critical loss of steering control was evident when vehicle speed exceeded engine speed; eg when coasting on a highway and during down-hill operation.”

In all, it was concluded that “Medium Tank T40 in its present form is automotively unsatisfactory for military use due to its lack of mechanical reliability, inadequacy of steering control, and excessive maintenance requirements”

So, was it possible that the US Army had returned to the bad-old-days of ordering and constructing defective vehicles? And at this point, the Army didn’t even have the excuse of an ongoing war to push things along.

Of course, this excuse would shortly become a bit moot. The same month that the report was submitted, the Korean War kicked off. Fortunately, four production M46s showed up at Fort Knox, (M46s had first arrived at Aberdeen in November 1949)  so the T40 test was immediately terminated, and the focus turned to the M46, in the hopes that some of the issues had been identified at Aberdeen and the factory, and that the M46 wasn’t the disaster that the T40 was indicating it might be.

Armored Board’s hopes were soon to evaporate in the smoke of burning M46s. But that’s for next week.



wrwsadv #2 Posted Feb 27 2016 - 22:19

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To the forum thread, clock on Bob?
 

Tank3rDude #3 Posted Feb 27 2016 - 23:13

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Nice article, thanks Chieftain!

Joe717MarksmN #4 Posted Feb 28 2016 - 02:20

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I bought the m46r painted like a tiger. It could perform better. As for the superpershing would like that either If it had 1 shot kills

Brown_Ale #5 Posted Feb 28 2016 - 12:18

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thanks for the informative write up!

 

whoever thought tanks could be so interesting.



Maine_ARC_1 #6 Posted Feb 28 2016 - 21:52

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View Postkamikazekirb, on Feb 28 2016 - 04:18, said:

thanks for the informative write up!

 

whoever thought tanks could be so interesting.

 

i thought they were interesting.....

 

I don't know why however that wargaming keeps making tanks that were prototypes and not actually developing those that were on the field of battle. There are quite a few that are still unaddressed for the existing nations.



StormFlexes #7 Posted Feb 28 2016 - 23:24

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View PostLuke_Skywalker01, on Feb 28 2016 - 21:52, said:

 

i thought they were interesting.....

 

I don't know why however that wargaming keeps making tanks that were prototypes and not actually developing those that were on the field of battle. There are quite a few that are still unaddressed for the existing nations.

 

Such as? Just curious, not trying to be rude

Legiondude #8 Posted Feb 29 2016 - 00:35

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View PostStormFlexes, on Feb 28 2016 - 16:24, said:

 

Such as? Just curious, not trying to be rude

Betting $5 on Italian tanks, despite the many times it's been explained why they're ranked at such a low priority



SpectreHD #9 Posted Feb 29 2016 - 04:09

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M60A1.:(

qcarr #10 Posted Mar 01 2016 - 20:39

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View PostLuke_Skywalker01, on Feb 28 2016 - 15:52, said:

 

i thought they were interesting.....

 

I don't know why however that wargaming keeps making tanks that were prototypes and not actually developing those that were on the field of battle. There are quite a few that are still unaddressed for the existing nations.

 

If you're referring to the M46 as being one of these prototypes from Wargaming, stay tuned for next week's installment of The Chieftain's Hatch.  The T40 came out of the M26E2 and was the prototype for the M46 Patton.  The M46, as you will see, saw plenty of combat in the Korean War.

 

In-game, the M46 KR is pretty historically accurate while the tech tree M46 is really an M47 prototype mounting a 105 mm gun.



EtsyClickSpa #11 Posted Mar 02 2016 - 13:59

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great article!  There a few spell check errors, so have a person proof it first.  Clock = click and moot = mute.

The_Chieftain #12 Posted Mar 02 2016 - 17:08

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You have me on 'click', as wrw observed. 'Moot', however, is not an error. http://www.thefreedictionary.com/moot



Blackhorse_Six_ #13 Posted Mar 02 2016 - 17:27

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View PostSpectreHD, on Feb 28 2016 - 22:09, said:

M60A1.:(

 

All of them :izmena:

 

In the realm of the fantastic, Starship with the M68 or a short 120.

 

It's not as though WG hasn't made things-up before ... :sceptic:






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