Tank Restoration

[alejandro_]

15 hours ago, old_goat said:

When Wheatcroft announced the 4x Panther restoration recently, I asked him about the final drives. He told me that they are already restored, and he is confident about them. With careful driving, it should be all OK. 

In the video above the restorers talk about the final drives, they mention sharp corners and tweaks to improve design. It would be great if there was a video focusing on these. 

Regarding the issues:

The final drive served as the further reduction of the driving RPM.  It contained two spur gear sets.  The housing was sealed off by labyrinth packing at the point of the drive sprocket hub.  The drive sprocket was joined to the final drive by its drive sprocket shaft.  the toothed rims of the drive sprocket could be replaced without actually having to remove the sprockets themselves.  The final drive (gear teeth and bearing) was the weakest part of the Panther.  It was a risky proposition to use a spur gear system for transferring the drive power – especially considering that the available steel during the war did not have a particularly high stress tolerance (*).  A better solution would have been to use an epicyclic gear system; a prototype final reduction drive using planetary gear reduction had already been tested and had performed flawlessly.  However, as mentioned previously, a shortage of gear cutting machinery for the hollow gearing prevented this type of final drive from being mass produced.  In order to bridge the gap a final reduction gear system was installed in front of the main gear drive, but due to installation restrictions its mounting were far too weak and could not be strengthened.  Because of gear teeth being under too great a load and the weak mountings, the gears were pushed out of alignment – virtually guaranteeing mount and tooth breakage.

The general consensus of the industry was that inner-toothed gear wheels could not be produced due to a lack of proper machinery.  This meant that a final drive using planetary gear reduction and pre-selector spur gearing – found to be reliable in company testing – could not be installed in the production tanks.  All attempts to improve the final drive met with failure, despite the offers of a special bonus as an incentive. The housings, which initially had proven too weak and whose outer mounts had been bent out of alignment by the track’s pull, were eventually replaced by stronger ones.

page 60 “Panther and its Variants” by Walther Spielberg

https://tankandafvnews.com/2015/02/08/from-the-editor-panther-reliability/

(*) The steel originally planned was replaced by a tempered type 37 MnSi5, which was not suitable

Other interesting stuff mentioned in the video is the fact that some components were not easily interchangeable with other Panthers. I have come across this with some Soviet equipment. 

Regarding the use of a 3D scanner, how do you go about the tolerances? I guess that as production is basically in units you just make small adjustments if needed (machining)?

[Stuart Galbraith]

I recently repainted a Tamiya 1-16 model in the scheme of Tiger 114 of the 503 heavy tank battalion at Kursk. Its relatively well known, because of this photograph.

 Anyway, this led me down a rabbithole, because the Commander of these vehicle, Alfred Rubbel, wrote a memoir! He talks about the trouble here being the final drives, because they were, according to him at any rate, vulnerable to artillery fragments, which could penetrate the final drives and obviously immobilise the vehicle.

Its quite interesting to notice that both the later Tiger variants,  and the panther, have a C ring welded around the drive mount, presumably as an attempt to protect this vulnerable part. OTOH, probably not a lot they could do to stop it coming in from 90 degrees through the actual drive sprocket.

[old_goat]

5 hours ago, alejandro_ said:

Regarding the use of a 3D scanner, how do you go about the tolerances? I guess that as production is basically in units you just make small adjustments if needed (machining)?

If I remember correctly, the guys at Panzer Farm said that they tried to get as many factory drawings as possible. Together with 3d scans, they produce the actual part then. If no drawings available, they inspect the original part for wear, and adjust the 3d files accordingly.

Edited February 28, 2025 by old_goat

[old_goat]

5 hours ago, alejandro_ said:

(*) The steel originally planned was replaced by a tempered type 37 MnSi5, which was not suitable

Yep, one of the "twins" said that the gears used in restored Panthers are made from more advanced alloys, that would even outlive the tank itself. Perhaps thats why Wheatcroft is also very optimistic (Nick & Phil are also working with him in this project). I think its time to bust the myth that the final drives lasted "150 kilometers" only. But still, it still doestn mean that the design of these units werent a weak point of the tank. They definitely were, and even if they lasted significantly more than 150km, they still caused reliability issues, because for proper operation, the tank driver needed to be highly trained. And germans definitely had a shortage of good drivers. 

[Tim the Tank Nut]

they lasted til you hit something that stressed the unit which could have been 5 miles or 40.

[alejandro_]

On 2/28/2025 at 4:34 PM, old_goat said:

Yep, one of the "twins" said that the gears used in restored Panthers are made from more advanced alloys, that would even outlive the tank itself. Perhaps thats why Wheatcroft is also very optimistic (Nick & Phil are also working with him in this project). I think its time to bust the myth that the final drives lasted "150 kilometers" only. But still, it still doestn mean that the design of these units werent a weak point of the tank.

Final drives issues were documented, and there is also information on the solution, which Germany could not apply due to lack of machinery and appropriate materials. In 1944 a Jagdpanther with epicyclic gearing was tested, and after 600 km there was no evidence of wear.

Regarding crews, that could be discussed in another topic, as my impression is that throughout the war there were plenty of veteran crews. You can find reports of all crews in a Jagdtiger unit having experience in the Eastern Front. Situation would be different in newly created panzer brigades, but issues with final drives/transmission cannot be blame on driver training. 

Meeting in Berlin 23rd January 1945.

Present : Speer, Guderian, Porsche, Maybach. (+ others)

"From the front there continues to be serious complaints regarding final drive breakdowns in all vehicle types. Approximately 200 breakdowns have been reported with the 38(t). Prior to the 1945 eastern offensive there have been 500 defective final drives in the Panzer IV. From the Panther 370 and from the Tiger roughly 100. General Thomale explained that in such circumstances an orderly utilization of tanks is simply impossible. The troops lose confidence and, in some situations, abandon whole vehicles just because of this problem. He requests an increase in efforts to the final drive, since only this way can the problem be laid to rest. With the previously intense criticism of the engine and the final drives continually playing such a roll, it is welcome news to learn that the gearbox generally enjoys good reputation."

Page 259 Spielberger, Panther and Its Variants

[sunday]

On 2/28/2025 at 11:43 AM, alejandro_ said:

In order to bridge the gap a final reduction gear system was installed in front of the main gear drive, but due to installation restrictions its mounting were far too weak and could not be strengthened.  Because of gear teeth being under too great a load and the weak mountings, the gears were pushed out of alignment – virtually guaranteeing mount and tooth breakage.

The bolded parts seem to be the main problem.

Are there any drawings of the final drive cases and mountings around?

[old_goat]

4 hours ago, alejandro_ said:

Final drives issues were documented, and there is also information on the solution, which Germany could not apply due to lack of machinery and appropriate materials.

Nobody doubted that the final drives of the Panter were bad. The only question is, how bad exactly? There are several reports about the final drives, and unfortunately, almost all contradict each other. This ranges from the french report (most pessimistic) that they lasted only 150 kilometers, to a german wartime report (most optimistic) about a Panther with ~1900km in the clock, still with original drive components. 

Even more bizarre are the reports about the Bergepanther. And without doubt, It was the variant where the final drives were tortured the most cruelly. Yet the main conplaint is about the engine failures... Not a single word about the final drives!

Also there is even a report (Panzer Tracts 16-1) about a Bergepanther, with 4200km in the clock, (including 1000km with towing other tanks) original engine, transmission, clutch and final drives. Honestly, just like the french 150km claim, I dont believe it.

4 hours ago, alejandro_ said:

issues with final drives/transmission cannot be blame on driver training. 

I think it is. In the same report with the ~1900km Panther, it was especially emphasized the importance of the driver training. In fact, you can even break a much more modern tank if you dont know what you are doing. The first time I drove a VT-55A, I was immediately told NOT to rev the engine when going downhill, and to be very careful when steering up/downhill.

Edited March 4, 2025 by old_goat

[Stuart Galbraith]

This was pretty good.

 

[old_goat]

Just how many AFVs are in the Wheatcroft collection??? In one of the latest news, they reported that they are restoring at least 2 Panzer IIs, and at least 10(!!!) Sd.Kfz.251s... Crazy... 

Also there was a report about the Tiger I restoration project, 3 gun barrels are complete, and theoretically can fire live projectiles.

[Stuart Galbraith]

1 hour ago, old_goat said:

Just how many AFVs are in the Wheatcroft collection??? In one of the latest news, they reported that they are restoring at least 2 Panzer IIs, and at least 10(!!!) Sd.Kfz.251s... Crazy... 

Also there was a report about the Tiger I restoration project, 3 gun barrels are complete, and theoretically can fire live projectiles.

Send it to Ukraine. Asov can train up ready for when the T34s and JS2s appear.

[old_goat]

Look at the background! Also the second picture!

 

[Stuart Galbraith]

Henschel never built them as well.

[old_goat]

Panzer I gearbox in good condition, Wheatcroft Collection... How on earth do they find things such as this???!

[Tim the Tank Nut]

that is in astonishingly good shape.  I'm glad somebody kept it but it begs the question, why?

[Stuart Galbraith]

A lot of surviving German armour got reroled into different things. For example, ive seen a picture of a panther converted into a mobile crane. Conceivably someone had a Panzer 1 as a tractor or something, and wanted a spare gearbox?

Interestingly saw a twitter feed the other day, with polish farmers still using Tiger 1 tracks as counterweights on their tractors. What a come down for the thousand year reich.

 

[Stuart Galbraith]

This is stretching the point a bit. These guys spend a lot of time digging on the Eastern Front, and find some truly remarkable things in amazing condition. Here they find what appear to be the remnants of a German halftrack truck. Perhaps enough to have a stab at recreating one.

 

[Stuart Galbraith]

 

[shep854]

Aus Armour does it again!

 

[rmgill]

On 2/28/2025 at 11:34 AM, old_goat said:

Yep, one of the "twins" said that the gears used in restored Panthers are made from more advanced alloys, that would even outlive the tank itself. Perhaps thats why Wheatcroft is also very optimistic (Nick & Phil are also working with him in this project). I think its time to bust the myth that the final drives lasted "150 kilometers" only. But still, it still doestn mean that the design of these units werent a weak point of the tank. They definitely were, and even if they lasted significantly more than 150km, they still caused reliability issues, because for proper operation, the tank driver needed to be highly trained. And germans definitely had a shortage of good drivers. 

Could the weakness have been a crapshoot of good and bad forgings used to make the gear sets. Some being good, some being bad? I assume forgings, if they were cast then inclusions or not in the blanks that were machined with the gears? 

Also, the possibility of a handful of swarf tossed into some and not others by slave labor could also be a random factor. Even a well made gear set is going to eat it self sooner or later if there's debris in the systemt that will add extra pressure to gears and damage gears due to overloaded clearances by the introduction of added metal fragments. 

[Stuart Galbraith]

Just found a video the other day of someone tearing apart a Liberty engine if its of any interest. im not sure im going to follow it because he is going to cut it down to a V8 so he can fit it in an old car, but the mechanics of dismantling it are interesting.

[old_goat]

48 minutes ago, rmgill said:

Also, the possibility of a handful of swarf tossed into some and not others by slave labor could also be a random factor. Even a well made gear set is going to eat it self sooner or later if there's debris in the systemt that will add extra pressure to gears and damage gears due to overloaded clearances by the introduction of added metal fragments. 

That is not a possibility, it is a certainity. Sabotage was common. And not just the Panther was affected. Other, generally reliable vehicles, like the Panzer IV became victims more and more frequently as the war progressed. 

Generally, german tanks were well designed, their engineers werent stupid. But slave labor and material shortages had serious consequences.

[Stuart Galbraith]

'And I am become Chieftain ARRV, destroyer of worlds...'

 

Edited May 29, 2025 by Stuart Galbraith

[rmgill]

Destroyer of worlds would be an AEV like an FV180 CEV. Aka killdozer. 

Edited May 29, 2025 by rmgill

[DB]

Mr Hewes has been tasked to bring one of Armourgeddon's butchered Greek M60s back to life.

It's been heavily gas axed, but there is a surprising amount of it still working.

Avert your eyes if you're still emotionally attached to the M60.