Jump to content
Sturgeon's House

What the Hell is the Point of Interleaved Road Wheels?


Collimatrix
 Share

Recommended Posts

3 hours ago, Beer said:

Soviet evaluation of Pershing in summer 1945 gives some light to the previously discussed terrain speed of Panther and Pershing. The result didn't favour Panther... 

http://www.tankarchives.ca/2018/03/pershing-heavy-by-necessity.html

 

This is the measured average speed in comparison with other tanks on the same terrain track. Pershing was the fastest of them in this test mainly thanks to its torque converter. 

 

T26E3 - 18,9 km/h

T-44 - 17,5 km/h

M4A4 - 16,5 km/h

Panther - 15,8 km/h

IS-3 - 14,6 km/h

 

Fuel consumption on the same track however showed that the torque converter made it also very thirsty, basically same as Panther. 

IS-3 - 373 l/100 km

T-44 - 378 l/100 km

M4A4 - 503 l/100 km

T26E3 - 585 l/ 100 km

Panther - 595 l/100 km

 

 

What's extra damning is the M4A4 does better tan the Panther!    The Nazi could only dream of having a motor so complicated, yet reliable!

Link to comment
Share on other sites

Definitely unexpected results! Interesting assertion about the reduction gear preventing the Pershing's torque converter from slipping and that the Soviets found it performed well on slopes. In Marine Corps Tank Battles in Korea, Gilbert says, "The M26 was a powerful vehicle, but as the tank crews soon discovered, if it stopped on a steep gradient the transmission would slip, and it was difficult or impossible to get it moving again. Help was needed and Eugene Viveiros, who, with one of the Headquarters Platoon [Sherman] blade tanks, attached himself to the 3rd Platoon, was ready to supply it. He was called upon 'to pat them on the butt end with the blade of the 'dozer tank to shove 'em up and get 'em going again. Once they got traction, then they were all right,' Viveiros explained." Although at least some Army Pershings arrived in Korea in need of repairs or overhaul, these USMC tanks were in decent working order (despite a shipborne flooding mishap en route), so this wasn't a maintenance issue: in a discussion on the state of Korean Pershings over on TankNet Ken Estes said, "...the USMC [Pershings] were drawn from depots, with no miles...all the USMC WWII flame tanks and postwar M26s went from storage through the depot line before being shipped to the units."

 

Any idea what "average technical speed" means? Too bad the off-road test was cancelled; didn't General Fedorenko know that people would be arguing about these things on the Internet 80 years later??

Link to comment
Share on other sites

On 4/17/2021 at 10:59 AM, Lord_James said:


The transmission is also excellent! 

 

 

The whole powertrain, (transmission, differential and final drives) seems to have been overbuilt, or very well designed for its weight class. The powertrain changed very little through its life, and rarely seems problematic on tanks being restored. Most of the time, if it had fluid, remained sealed, and didn't take a round through it, they need little more than cosmetic attention when a Sherman is being restored. This includes the one installed in the M4A3E8 tank used as a bulldozer, to knock down a large section of Oakland California in the 60s. It needed pain job, and they changed the fluid, and replaced some rusty bolts, that's it. 

 

They also came apart in a easy, and were easy to work on. Everything used roller or ball bearings, probably all in sizes still available, and other than just the size, everything seems to have been easy to service. 

 

The only major mechanical change during the war, was going from single to double anchor brakes, and I think the newer brakes could be retrofitted to the older unit. Compared to the weak junk the Nazi's produced it was really an amazing achievement in engineering. 

Link to comment
Share on other sites

On 4/17/2021 at 7:31 PM, DogDodger said:

Definitely unexpected results! Interesting assertion about the reduction gear preventing the Pershing's torque converter from slipping and that the Soviets found it performed well on slopes. In Marine Corps Tank Battles in Korea, Gilbert says, "The M26 was a powerful vehicle, but as the tank crews soon discovered, if it stopped on a steep gradient the transmission would slip, and it was difficult or impossible to get it moving again. Help was needed and Eugene Viveiros, who, with one of the Headquarters Platoon [Sherman] blade tanks, attached himself to the 3rd Platoon, was ready to supply it. He was called upon 'to pat them on the butt end with the blade of the 'dozer tank to shove 'em up and get 'em going again. Once they got traction, then they were all right,' Viveiros explained." Although at least some Army Pershings arrived in Korea in need of repairs or overhaul, these USMC tanks were in decent working order (despite a shipborne flooding mishap en route), so this wasn't a maintenance issue: in a discussion on the state of Korean Pershings over on TankNet Ken Estes said, "...the USMC [Pershings] were drawn from depots, with no miles...all the USMC WWII flame tanks and postwar M26s went from storage through the depot line before being shipped to the units."

 

Any idea what "average technical speed" means? Too bad the off-road test was cancelled; didn't General Fedorenko know that people would be arguing about these things on the Internet 80 years later??

 

 

Maybe the hills of Korea were more extreme than what the Soviets used? It's an interesting question. Did the Marines lose any M26s to the well deck being flooded on the way to Korea?

Link to comment
Share on other sites

I doubt it is possible to compare slope driving tests between each other due to difference in soil composition, weather etc.

 

M26 was rated to climb 27° gradient which isn't much but here the test states it was able to climb 35°, surprisingly more when usually it was less than the rating. Probably the conditions in the particular test were good (soil offering good traction mainly). I think that the value is very difficult to use for any comparison except for the situation when one has the tanks at the same time on the same place, unfortunately the article doesn't give values measured for the other tanks in the test.

Link to comment
Share on other sites

8 hours ago, Beer said:

M26 was rated to climb 27° gradient which isn't much but here the test states it was able to climb 35°, surprisingly more when usually it was less than the rating. 

27 degrees or 27% (15 degrees) gradient?
If it’s a 27 degree gradient, that’s actually pretty good. 

 

Modern western AFV generally can do 60% (31 degrees), so 35 degrees (70%) is very, very good. 

Link to comment
Share on other sites

2 minutes ago, 2805662 said:

27 degrees or 27% (15 degrees) gradient?
If it’s a 27 degree gradient, that’s actually pretty good. 

 

Modern western AFV generally can do 60% (31 degrees), so 35 degrees (70%) is very, very good. 

 

27 degrees but most of the vehicles of that time were rated more. IMHO it has most to do with the vehicle mass and its ground pressure. The modern tanks are pretty bad in that regard. 

 

At least at that time I see a clear pattern of lighter vehgicles being better climbers. For example our pre-WW2 tanks were rated up to 45° (10,5 ton LT vz.35 and 16 ton ST vz.39). 

Link to comment
Share on other sites

On 4/17/2021 at 2:36 PM, Beer said:

Soviet evaluation of Pershing in summer 1945 gives some light to the previously discussed terrain speed of Panther and Pershing. The result didn't favour Panther... 

http://www.tankarchives.ca/2018/03/pershing-heavy-by-necessity.html

Curious isn't it. And we know from Swedish trials, technical stats, combat reports and opinions that panther's mobility was better than sherman's.

 

What is the tank to the left, on this photo?

t26e3heavyussr15-0ee0d8e04aa047aba2d5aaf

Shape looks like sherman's with pretty wide tracks and muzzle brake. why did Pasholok mention comparison with M4A4? Isn't that an early export 75mm version?

 

Panther has more powerful engine and much better steering mechanism than a pershing. I don't believe torque converter is such magical device to overcome both. These things don't add up. The article is only Pasholok's summary of the report.

 

The article states that there were no speed trials, which makes me believe it was an inclined terrain navigation course, as you suspected. Why else would a medium tank be slower than a heavy?

Link to comment
Share on other sites

25 minutes ago, delete013 said:

Curious isn't it. And we know from Swedish trials, technical stats, combat reports and opinions that panther's mobility was better than sherman's.

 

What is the tank to the left, on this photo?

t26e3heavyussr15-0ee0d8e04aa047aba2d5aaf

Shape looks like sherman's with pretty wide tracks and muzzle brake. why did Pasholok mention comparison with M4A4? Isn't that an early export 75mm version?

 

Panther has more powerful engine and much better steering mechanism than a pershing. I don't believe torque converter is such magical device to overcome both. These things don't add up. The article is only Pasholok's summary of the report.

 

The article states that there were no speed trials, which makes me believe it was an inclined terrain navigation course, as you suspected. Why else would a medium tank be slower than a heavy?

 

That tank at the back looks indeed like a Sherman M4A2(76)W. It could be a mistake in the report but the fuel consumption doesn't add up, it is way too high for a diesel tank, albeit 3 tons heavier than M4A4. 

 

As for the torque converter. When driving very slow and uphill it makes a great difference - that's one of the reasons why it exists in first place. In very slow speeds the torque converter works like a torque multiplier. That's not possible with the mechanical clutch and transmission. The reason is simple - when a clutch is engaged the engine RPM and the vehicle speed is bound together, i.e. at very low speed the engine RPM is also very low, unlike with the torque converter which allows the engine to run in high power RPM even in ridiculously low vehicle speed for the cost of low efficiency, i.e. high fuel consumption. Another important advantage is that it increases traction because it delivers the torque very smoothly. 

 

I have never suspected that it was a navigation course. Not at all. 

Link to comment
Share on other sites

8 hours ago, Beer said:

...torque converter. When driving very slow and uphill it makes a great difference

 

...I have never suspected that it was a navigation course. Not at all. 

My wrong judgement then. If overcoming steep obstacles at slow speeds was the primary factor in speed average and no "max. speed test" was performed, then I don't know what else could be concluded? It would also explain why fairly heavier pershing was faster than T-44.

Link to comment
Share on other sites

45 minutes ago, Sturgeon said:

 

As if you know what kind of device a torque converter is at all!

@Beer is an engineer, no? He should know. I rely on his statement.

I didn't know what torque converter was until yesterday! But I went to check. Clever device. Too bad Americans attached that awful controlled differential to it. Pershing turned like Ever Given.

Link to comment
Share on other sites

Man, millions and millions of automatic gearboxes in past eighty years all around the Globe have been equipped with torque converter. If you never heard about the most common coupling solution in automatic gearboxes, it means without any doubt that you have zero clue about transmissions and since differentials are rather difficult topic to grasp I think you shall not argue about them. Even what you just wrote is simply stupid. 

Link to comment
Share on other sites

21 minutes ago, Beer said:

Man, millions and millions of automatic gearboxes in past eighty years all around the Globe have been equipped with torque converter. If you never heard about the most common coupling solution in automatic gearboxes, it means without any doubt that you have zero clue about transmissions and since differentials are rather difficult topic to grasp black magic I think you shall not argue about them. Even what you just wrote is simply stupid. 

Fixed.

Link to comment
Share on other sites

1 hour ago, delete013 said:

@Beer is an engineer, no? He should know. I rely on his statement.

 

Your delight in your own ignorance is truly astounding. If you could think, you might cogitate on whether it's productive for anyone else to engage in serious conversation with someone so flagrantly uninterested in actually knowing anything.

Link to comment
Share on other sites

1 hour ago, delete013 said:

I didn't know what torque converter was until yesterday! But I went to check. Clever device. Too bad Americans attached that awful controlled differential to it. Pershing turned like Ever Given.

 

"I don't know what a torque converter is, but I won't let that stop me from laying down baseless judgments on the rest of the transmission!"

 

BEHOLD! A PERSHING DOING DONUTS!

 

https://youtu.be/si4J0XjClsE

Link to comment
Share on other sites

30 minutes ago, Beer said:

Man, millions and millions of automatic gearboxes in past eighty years all around the Globe have been equipped with torque converter. If you never heard about the most common coupling solution in automatic gearboxes, it means without any doubt that you have zero clue about transmissions and since differentials are rather difficult topic to grasp I think you shall not argue about them.

I know it is, but I had no idea how it works or what it is good for on a tank. I don't think it was that common on tanks. Renk has it in modern transmissions, but only as a specialised device for climbing.

I can't claim I know about differentials, but at least I know what effect they have on tank steering. I haven't heard anything on differentials from you during the Pershing mobility discussion. Maybe you can comment on that.

 

30 minutes ago, Beer said:

Even what you just wrote is simply stupid. 

What is stupid?

Link to comment
Share on other sites

On 4/19/2021 at 3:41 PM, 2805662 said:

27 degrees or 27% (15 degrees) gradient?
If it’s a 27 degree gradient, that’s actually pretty good. 

 

Modern western AFV generally can do 60% (31 degrees), so 35 degrees (70%) is very, very good. 

M26 was rated for 60% (31 degrees) as well.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...