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StuG III Thread (and also other German vehicles I guess)


EnsignExpendable
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I'm not so sure.  Here are a Panther and a Sherman sitting on a level, hard surface next to each other:

pTsaWof.jpg

The Panther's cupola appears to be the highest object, but the M4's roof may be a bit higher.  However, the tracks on the Panther appear to be quite loose, and may have lost some tension over time, and in action the tank might have been taller.

If the numbers in books are to be believed, the big cats are both a little taller than the Sherman.

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5 hours ago, SH_MM said:

Panther is not the only tank taller than (or as tall as) a Tiger though ;)

283a31f37111cf2a1a72b174e2ad96ce.jpg

UrnF44f.jpg

 

Well, the Sherman and just about all German tank designs shared the same flaw, having the transmission, differential and final drives up front while the motor was in the back, making the tank taller so a drive shaft can be run under the turret basket.  The US fixed this in the Shermans follow on, the T20 series that lead to the M26/46. The was a lesson Nazi Germany didn't learn, or decided wasn't good, since the VK3002 was rear motor, rear drive, but of course, the Nazis chose to produce the tank that became the panther, instead of something actually good.  The nice thing with the Sherman was the tranny/dif/final drives were easy to service and replace, this was not the case in German tanks. 

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1 minute ago, Collimatrix said:

Some day I would love to learn why the designers in Germany and the USA were convinced that they needed the drive sprocket to be in the front.  I still haven't found a good explanation for this, especially considering that British and Soviet designers never suffered any such delusion.

Strong reliance on the automotive industries in the case of the US, I bet. Lemme look in Hunnicutt, he may talk about it.

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1 hour ago, Collimatrix said:

Some day I would love to learn why the designers in Germany and the USA were convinced that they needed the drive sprocket to be in the front.  I still haven't found a good explanation for this, especially considering that British and Soviet designers never suffered any such delusion.

My understanding was that it was a combination of having the gearbox close to the driver (simple linkage requiring less grunt to change gears) and the simple fact that all their previous designs used the same system.

 

Ultimately, we could blame Vickers for making the concept popular back in the '30s.

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The US was no stranger to rear-sprocket tanks with the M1917, Mk.VIII, Cunningham machines, medium tank M1, and various Christie-inspired prototypes all having the sprocket at the rear. The break seems to be in 1933-4 when the light tank T2 (M2) and the associated combat car T5 (M1) were constructed with the rear engine-front transmission layout, as Jeeps noted by Rock Island Arsenal to Ordnance Committee requirements. 1936 saw the start of development of the medium tank T5 (M2), which was basically a larger light tank M2, and the automotive layout was similar. Interestingly, the front-drive layout was not totally abandoned once the T20 series was initiated: the T20 program was started in spring 1942 and the first of those tanks to be completed was a T23 in January 1943, while development of the front-drive light tank T24 (M24) didn't start until March 1943, with the first prototype being completed in October 1943.

Having the transmission closer to the driver supposedly eased the effort needed to work the controls (although Estes quotes a marine veteran tanker saying the steering in the M26 "was done the same as the M4's, pull the levers with 'brute' strength, good way to build the arms and upper body"), and the front sprocket alleviated some worry about track shedding due to mud since the track had more time to clean itself before engaging the sprocket. I haven't seen anything concrete that these factors influenced US designers at the time, though...

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Well, Hunnicutt says that with the jump to the 76 mm gun in the T70 from the 75 mm gun in the T67, "The heavier gun installation required that the weight be redistributed in the T70. Thus the transmission and final drives were shifted to the front of the vehicle." :) So maybe this factor played a decently large part as well?

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12 hours ago, Collimatrix said:

Some day I would love to learn why the designers in Germany and the USA were convinced that they needed the drive sprocket to be in the front.  I still haven't found a good explanation for this, especially considering that British and Soviet designers never suffered any such delusion.

Wehraboos like to claim that this gives better torque or something like that. Soviet documentation either specifies that the transmission should be in the rear or lets the designer choose. I've only seen a choice available on light tanks, though. The idea that there should be a removable transmission hatch in the front armour was rather unwelcome. The Chaffee gets burned for it during trials.

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12 hours ago, DogDodger said:

Well, Hunnicutt says that with the jump to the 76 mm gun in the T70 from the 75 mm gun in the T67, "The heavier gun installation required that the weight be redistributed in the T70. Thus the transmission and final drives were shifted to the front of the vehicle." :) So maybe this factor played a decently large part as well?

Maybe.  Normally the weight of the transmission isn't a big deal, but those TDs had such thin armor that maybe it did make a difference to overall weight distribution.

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What I don't get is why it took the americans until the M7 before they realised that the drive shaft didn't have to exit the firewall a foot above the floor. The sherman with a transfer case to move the drive shaft lower, bringing the turret basket down and by extension the whole tank roof, would be a much superior option

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17 hours ago, DogDodger said:

The US was no stranger to rear-sprocket tanks with the M1917, Mk.VIII, Cunningham machines, medium tank M1, and various Christie-inspired prototypes all having the sprocket at the rear. The break seems to be in 1933-4 when the light tank T2 (M2) and the associated combat car T5 (M1) were constructed with the rear engine-front transmission layout, as Jeeps noted by Rock Island Arsenal to Ordnance Committee requirements. 1936 saw the start of development of the medium tank T5 (M2), which was basically a larger light tank M2, and the automotive layout was similar. Interestingly, the front-drive layout was not totally abandoned once the T20 series was initiated: the T20 program was started in spring 1942 and the first of those tanks to be completed was a T23 in January 1943, while development of the front-drive light tank T24 (M24) didn't start until March 1943, with the first prototype being completed in October 1943.

Having the transmission closer to the driver supposedly eased the effort needed to work the controls (although Estes quotes a marine veteran tanker saying the steering in the M26 "was done the same as the M4's, pull the levers with 'brute' strength, good way to build the arms and upper body"), and the front sprocket alleviated some worry about track shedding due to mud since the track had more time to clean itself before engaging the sprocket. I haven't seen anything concrete that these factors influenced US designers at the time, though...

The Sherman and T-34 have the same amount of effort required to operate them in Soviet trials, so the effort thing isn't true.

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Neither the Sherman nor the T-34 has hydraulically boosted controls, right?  And the steering is just the driver activating a clutch or brake (planetary drive clutch in the T-34, Cletrac steering brake in the Sherman).  So I would think that turns would require about the same muscular effort.

IIRC the first guys to drive the IS-7 were blown away by how easy the thing was to drive, since it was the first tank they'd gotten their hands on that had hydraulic boost for the controls.

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I wonder if part of the reason the Germans liked the Transmission in the front had to do with their pre-war requirement that the gun not stick out beyond the front of the hull.  With the transmission in the front, the turret sits in the middle of the vehicle, unlike the British or Soviet designs where the turret is in the front half of the hull and the transmission is in the rear.  I have no evidence to back this up, it's just a thought.

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