Side topic:

I have read that the Wehrmacht's tanks, esp. the later ones that
were so large, suffered badly from final drive failures. So much
so that a road march of them for any distance would disable
say 33%. This helped me better understand Allied anti-railroad
tactics...forcing them onto the roads.

[They also lacked tank retrievers of enough strength to
salvage them....]

The failures were because of 2 basic reasons: they lacked
sufficient chromium to fully harden the gearing, and the second
was my question.....

This source (that I now can't find again...) said there was a
way to better design/machine the ring gears needed, but Germany
lacked the tooling/resources to use that approach, and instead
used less strong methods. I inferred the better way needed more
time or a better mill but beyond that, I don't know.

I'm curious about what that might have meant, and wonder if anyone
can speak to gear design issues...


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

On Fri, 2 Aug 2013 15:49:25 +0000 (UTC), David Lesher
wrote:

Side topic:

I have read that the Wehrmacht's tanks, esp. the later ones that
were so large, suffered badly from final drive failures. So much
so that a road march of them for any distance would disable
say 33%. This helped me better understand Allied anti-railroad
tactics...forcing them onto the roads.

[They also lacked tank retrievers of enough strength to
salvage them....]

The failures were because of 2 basic reasons: they lacked
sufficient chromium to fully harden the gearing, and the second
was my question.....

This source (that I now can't find again...) said there was a
way to better design/machine the ring gears needed, but Germany
lacked the tooling/resources to use that approach, and instead
used less strong methods. I inferred the better way needed more
time or a better mill but beyond that, I don't know.

I'm curious about what that might have meant, and wonder if anyone
can speak to gear design issues...

Only in fragments. If the issue was an internal-tooth ring gear, as
for a planetary gearset, that wasn't a milling issue. That was a
gear-shaper issue. They also can be broached, but I don't see that as
likely during the war, on big gears. Perhaps that's the tooling that
Germany lacked. It requires very big pieces of high-quality tool
steel, and chromium shortages would be an issue.

Germany had some very good gearmaking capability but that of the US
was better at that time. Gleason was the world leader in making big,
strong gears of several types.

BTW, the US had power-transmission issues on some tanks at the time,
too. Caterpillar made a big 24-cylinder porcupine diesel engine that
was supposed to be the end-all for our largest tanks. But it had so
much torque that it twisted off driveshafts like they were swizzle
sticks.

--
Ed Huntress

On Fri, 02 Aug 2013 12:05:18 -0400, Ed Huntress wrote:

On Fri, 2 Aug 2013 15:49:25 +0000 (UTC), David Lesher
wrote:

Side topic:

I have read that the Wehrmacht's tanks, esp. the later ones that were so
large, suffered badly from final drive failures. So much so that a road
march of them for any distance would disable say 33%. This helped me
better understand Allied anti-railroad tactics...forcing them onto the
roads.

[They also lacked tank retrievers of enough strength to salvage
them....]

The failures were because of 2 basic reasons: they lacked sufficient
chromium to fully harden the gearing, and the second was my
question.....

This source (that I now can't find again...) said there was a way to
better design/machine the ring gears needed, but Germany lacked the
tooling/resources to use that approach, and instead used less strong
methods. I inferred the better way needed more time or a better mill but
beyond that, I don't know.

I'm curious about what that might have meant, and wonder if anyone can
speak to gear design issues...

Only in fragments. If the issue was an internal-tooth ring gear, as for
a planetary gearset, that wasn't a milling issue. That was a gear-shaper
issue. They also can be broached, but I don't see that as likely during
the war, on big gears. Perhaps that's the tooling that Germany lacked.
It requires very big pieces of high-quality tool steel, and chromium
shortages would be an issue.

Germany had some very good gearmaking capability but that of the US was
better at that time. Gleason was the world leader in making big, strong
gears of several types.

BTW, the US had power-transmission issues on some tanks at the time,
too. Caterpillar made a big 24-cylinder porcupine diesel engine that was
supposed to be the end-all for our largest tanks. But it had so much
torque that it twisted off driveshafts like they were swizzle sticks.

Steven Ambrose has some interesting comments in "Citizen Soldier" about
the Sherman tank. The allied soldiers in Europe reportedly disliked it
because it was so wimpy compared to the big German tanks -- but
Eisenhower could get three Shermans for every one big US tank (I can't
remember what we had), and a Sherman used less gasoline. The thinking
was that as soon as the allies broke out in Normandy and started for
Berlin that the mobility of the Sherman tanks would outweigh the size
difference.

It's hard to say who was right, but we did win using those little tanks.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Fri, 02 Aug 2013 12:09:24 -0500, Tim Wescott
wrote:

On Fri, 02 Aug 2013 12:05:18 -0400, Ed Huntress wrote:

On Fri, 2 Aug 2013 15:49:25 +0000 (UTC), David Lesher
wrote:

Side topic:

I have read that the Wehrmacht's tanks, esp. the later ones that were so
large, suffered badly from final drive failures. So much so that a road
march of them for any distance would disable say 33%. This helped me
better understand Allied anti-railroad tactics...forcing them onto the
roads.

[They also lacked tank retrievers of enough strength to salvage
them....]

The failures were because of 2 basic reasons: they lacked sufficient
chromium to fully harden the gearing, and the second was my
question.....

This source (that I now can't find again...) said there was a way to
better design/machine the ring gears needed, but Germany lacked the
tooling/resources to use that approach, and instead used less strong
methods. I inferred the better way needed more time or a better mill but
beyond that, I don't know.

I'm curious about what that might have meant, and wonder if anyone can
speak to gear design issues...

Only in fragments. If the issue was an internal-tooth ring gear, as for
a planetary gearset, that wasn't a milling issue. That was a gear-shaper
issue. They also can be broached, but I don't see that as likely during
the war, on big gears. Perhaps that's the tooling that Germany lacked.
It requires very big pieces of high-quality tool steel, and chromium
shortages would be an issue.

Germany had some very good gearmaking capability but that of the US was
better at that time. Gleason was the world leader in making big, strong
gears of several types.

BTW, the US had power-transmission issues on some tanks at the time,
too. Caterpillar made a big 24-cylinder porcupine diesel engine that was
supposed to be the end-all for our largest tanks. But it had so much
torque that it twisted off driveshafts like they were swizzle sticks.

Steven Ambrose has some interesting comments in "Citizen Soldier" about
the Sherman tank. The allied soldiers in Europe reportedly disliked it
because it was so wimpy compared to the big German tanks -- but
Eisenhower could get three Shermans for every one big US tank (I can't
remember what we had), and a Sherman used less gasoline. The thinking
was that as soon as the allies broke out in Normandy and started for
Berlin that the mobility of the Sherman tanks would outweigh the size
difference.

It's hard to say who was right, but we did win using those little tanks.

Yeah, I've always wondered how we shot up Tigers with Shermans. Did
the Shermans have the high-velocity 90mm guns, our answer to the
German 88s?

--
Ed Huntress

"Ed Huntress" wrote in message
news

Yeah, I've always wondered how we shot up Tigers with Shermans. Did
the Shermans have the high-velocity 90mm guns, our answer to the
German 88s?

--
Ed Huntress

The Panther and Tiger were susceptible to ambush from the side where
the armor was much thinner, though this upgunned British version could
penetrate their frontal armor if it managed to shoot first:
http://en.wikipedia.org/wiki/Sherman_Firefly

http://www.achtungpanzer.com/michael-wittmann.htm
"British Sherman VC "Firefly" armed with 17 pounder gun was capable of
penetrating Tiger's armor at range of 800m. "

General Hatcher claimed that our bridging equipment wasn't strong
enough for the heavy tank we had designed. The Germans retreated
across intact bridges and then demolished them. We chose instead to
use a gun too large for a turret in the open-topped Tank Destroyer,
which required infantry support and didn't suit Blitzkrieg assaults
but fit Eisenhower's slow, steady approach.
https://en.wikipedia.org/wiki/Tank_destroyer
"The weight saved from the lack of a turret could allow more armour to
be fitted, and the lower profile allowed this armour to be
concentrated in the hull."

"In part because of the effectiveness of US TD tactics, no German
campaign against the US ever achieved its objectives, nor did any TD
unit lose more vehicles than its German opponent."

The Bulge area was defended by a thin screen of infantry since we
considered it poor tank country.
jsw

On Fri, 2 Aug 2013 13:47:32 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
news

Yeah, I've always wondered how we shot up Tigers with Shermans. Did
the Shermans have the high-velocity 90mm guns, our answer to the
German 88s?

--
Ed Huntress

The Panther and Tiger were susceptible to ambush from the side where
the armor was much thinner, though this upgunned British version could
penetrate their frontal armor if it managed to shoot first:
http://en.wikipedia.org/wiki/Sherman_Firefly

http://www.achtungpanzer.com/michael-wittmann.htm
"British Sherman VC "Firefly" armed with 17 pounder gun was capable of
penetrating Tiger's armor at range of 800m. "

General Hatcher claimed that our bridging equipment wasn't strong
enough for the heavy tank we had designed. The Germans retreated
across intact bridges and then demolished them. We chose instead to
use a gun too large for a turret in the open-topped Tank Destroyer,
which required infantry support and didn't suit Blitzkrieg assaults
but fit Eisenhower's slow, steady approach.
https://en.wikipedia.org/wiki/Tank_destroyer
"The weight saved from the lack of a turret could allow more armour to
be fitted, and the lower profile allowed this armour to be
concentrated in the hull."

"In part because of the effectiveness of US TD tactics, no German
campaign against the US ever achieved its objectives, nor did any TD
unit lose more vehicles than its German opponent."

The Bulge area was defended by a thin screen of infantry since we
considered it poor tank country.
jsw

Very interesting. Thanks.

--
Ed Huntress

"Jim Wilkins" writes:

https://en.wikipedia.org/wiki/Tank_destroyer

"The weight saved from the lack of a turret could allow more
armour to be fitted, and the lower profile allowed this armour
to be concentrated in the hull."

The tank destroyer story I liked {and feared} was when Patton
was trying to relieve Bastogne; he sent several M18 Hellcats at
top speed to attack the German rear and create confusion.

A Hellcat, powered by a 9 cyc. 450HP radial aircraft engine,
could do 60 MPH full out and these did just that. Imagine
those 40,000 lbs going 60 mph up a narrow road....

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

On 2013-08-02, Ed Huntress wrote:
On Fri, 2 Aug 2013 15:49:25 +0000 (UTC), David Lesher
wrote:

Side topic:

I have read that the Wehrmacht's tanks, esp. the later ones that
were so large, suffered badly from final drive failures. So much
so that a road march of them for any distance would disable
say 33%. This helped me better understand Allied anti-railroad
tactics...forcing them onto the roads.

[They also lacked tank retrievers of enough strength to
salvage them....]

The failures were because of 2 basic reasons: they lacked
sufficient chromium to fully harden the gearing, and the second
was my question.....

This source (that I now can't find again...) said there was a
way to better design/machine the ring gears needed, but Germany
lacked the tooling/resources to use that approach, and instead
used less strong methods. I inferred the better way needed more
time or a better mill but beyond that, I don't know.

I'm curious about what that might have meant, and wonder if anyone
can speak to gear design issues...

Only in fragments. If the issue was an internal-tooth ring gear, as
for a planetary gearset, that wasn't a milling issue. That was a
gear-shaper issue. They also can be broached, but I don't see that as
likely during the war, on big gears. Perhaps that's the tooling that
Germany lacked. It requires very big pieces of high-quality tool
steel, and chromium shortages would be an issue.

Germany had some very good gearmaking capability but that of the US
was better at that time. Gleason was the world leader in making big,
strong gears of several types.

BTW, the US had power-transmission issues on some tanks at the time,
too. Caterpillar made a big 24-cylinder porcupine diesel engine that
was supposed to be the end-all for our largest tanks. But it had so
much torque that it twisted off driveshafts like they were swizzle
sticks.


Everything is a problem with tanks, because they are so heavy, and yet
required to go very fast, off road, and turn on a dime.

The large tanks of Hitler were more of a liability, than an asset,
they could only be transported with great difficulty, could not go
over most bridges, and as you mentioned, could not easily be
retrieved. They were more of a Hitler's play toy than a way to win the
war.

i

"David Lesher" wrote in message
...
Side topic:

I have read that the Wehrmacht's tanks, esp. the later ones that
were so large, suffered badly from final drive failures. So much
so that a road march of them for any distance would disable
say 33%. This helped me better understand Allied anti-railroad
tactics...forcing them onto the roads.

[They also lacked tank retrievers of enough strength to
salvage them....]

The failures were because of 2 basic reasons: they lacked
sufficient chromium to fully harden the gearing, and the second
was my question.....

This source (that I now can't find again...) said there was a
way to better design/machine the ring gears needed, but Germany
lacked the tooling/resources to use that approach, and instead
used less strong methods. I inferred the better way needed more
time or a better mill but beyond that, I don't know.

I'm curious about what that might have meant, and wonder if anyone
can speak to gear design issues...

I haven't been able to find adequate details of the problem from a
military historian / machinist. Supposedly the bombing had purposely
targeted the makers of gear hobbers and shapers, along with ball
bearings. The stainless tanks and plumbing for the hydrogen peroxide
subs consumed most of their chromium and nickel.

This may help but I can't check it with dial-up:
http://www.youtube.com/watch?v=k9NCPthmTsU

The Wiki is as good as anything else I've found:
http://en.wikipedia.org/wiki/Panther_tank

jsw