Panther tank final drive planetary vs. spur gear

[Trilisser, M. A.]

Has any forumite conducted actual primary research on the issue of why the final drive of the Panther was of the inferior spur type instead of the much superior planetary type? Note: primary research is not the same as reading Jentz/Spielberger.

Some sources infer to a supposed shortage of internal teeth machining machines, but that stinks like rotten fish on 2 counts. 1st, planetary gears were even then a widely used mechanical construction and Germany was a leading country in mechanical engineering. 2nd, why wasn't the Farman-type used. There should be no engineering obstacles to its use in final drives.

[Alejandro_]

1st, planetary gears were even then a widely used mechanical construction and Germany was a leading country in mechanical engineering. 2nd, why wasn't the Farman-type used. There should be no engineering obstacles to its use in final drives.

Then perhaps you can explain why the epicyclical gear in the original MAN design was dropped and replaced with a double spur system?

[Trilisser, M. A.]

I cannot for it makes no sense.

[Denniss]

Perhaps not sufficient ball bearing production capacity available or fear that damage to ball bearing factories would have major effect on Panther production

[Alejandro_]

Perhaps not sufficient ball bearing production capacity available or fear that damage to ball bearing factories would have major effect on Panther production.

The answer is well known. From wikipedia:

The Panther's main weakness was its final drive unit. The problems stemmed from several factors. The original MAN proposal had called for the Panther to have an epicyclic gearing (planetary) system in the final drive, similar to that used in the Tiger I.[48] Germany suffered from a shortage of gear-cutting machine tools and, unlike the Tiger, the Panther was intended to be mass-produced. To achieve the goal of higher production rates, numerous simplifications were made to the design and its manufacture. This process was aggressively pushed forward, sometimes against the wishes of designers and army officers, by the Chief Director of Armament and War Production, Karl-Otto Saur (who worked under, and later succeeded, Reichminister Speer). Consequently, the final drive was changed to a double spur system.[49] Although much simpler to produce, the double spur gears had inherently higher internal impact and stress loads, making them prone to failure under the high torque requirements of the heavy Panther tank.

https://en.wikipedia.org/wiki/Panther_t ... ansmission

If this shortage of tooling was a myth or "stinks like rotten fish", how come the design was changed?

[Alanmccoubrey]

I don't know the answer to this very technical question but I do know that the answer to NOTHING is ever found in Wiki. Could you not find a real source ?

[Trilisser, M. A.]

The answer is not well-known since it is fishy. That claim of tooling shortage sounds implausible due to the fact that planetary gears were widely-used devices and that Germany was nevertheless a leading nation in mechanical engineering.

Spielberger's Panther book has an extract from a minutes from tank design conference. MAN's representative states that Heerestechnische Büro demanded spur gears. After this statement the minutes indicate that two colonels began to argue with each other.

By the way, Panzer III steering system employs planetary gears too.

[Richard Anderson]

Perhaps not sufficient ball bearing production capacity available or fear that damage to ball bearing factories would have major effect on Panther production.

The answer is well known. From wikipedia:

The Panther's main weakness was its final drive unit. The problems stemmed from several factors. The original MAN proposal had called for the Panther to have an epicyclic gearing (planetary) system in the final drive, similar to that used in the Tiger I.[48] Germany suffered from a shortage of gear-cutting machine tools and, unlike the Tiger, the Panther was intended to be mass-produced. To achieve the goal of higher production rates, numerous simplifications were made to the design and its manufacture. This process was aggressively pushed forward, sometimes against the wishes of designers and army officers, by the Chief Director of Armament and War Production, Karl-Otto Saur (who worked under, and later succeeded, Reichminister Speer). Consequently, the final drive was changed to a double spur system.[49] Although much simpler to produce, the double spur gears had inherently higher internal impact and stress loads, making them prone to failure under the high torque requirements of the heavy Panther tank.

https://en.wikipedia.org/wiki/Panther_t ... ansmission

If this shortage of tooling was a myth or "stinks like rotten fish", how come the design was changed?

It is a little odd that the supporting reference [48] is actually from Jentz's Tiger instead of from his Panther book. In fact, Jentz does not reference the supposed intervention by Sauer at all, which leads me to suppose he may have dismissed it as possibly apocryphal. In any case, the Henschel L 600 C steering gear and final drives were only ever considered for the VK 30.02. In Panther, Jentz does not make a big deal about the MAN-design final drive "problems" and I can find no evidence from the USSBS or other sources that there ever was a "shortage" of gear cutting machines at MAN.

[Alejandro_]

I have checked Spielberger's book on Panther and the issue of gear cutting machinery is explained in more detail. Note comment on Panther using machinery already used in Panzer III manufacturing. A few excerpts below:

A regenerative controlled steering unit (with two radii of turn in each gear) had been developed for the Tiger tank and had demonstrated its effectiveness without any major teething troubles. However, the manufacturing industry maintained that the machinery for gear production —primarily those necessary for the internal teeth gearing — were not available for large-scale production of the Panther tank and could not be obtained in sufficient quantities. As an interim measure a clutch-and-brake steering mechanism was considered acceptable. Development and testing of the controlled differential steering mechanism would have to be accelerated in light of the advantages it offered. The MAN design already provided for the possibility of its installation.

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With regards to production requirements in terms of hours needed, it turned out that the Daimler-Benz chassis required approximately the same amount of production time as the MAN version in its simplified form as currently submitted. This was explained by the fact that the firm of MAN had made constructive simplifications such as replacing the regenerative controlled differential discontinuous steering with a clutch-and-brake steering and the planetary type reduction gear in the final drive with a two stage spur wheel gear. Daimler-Benz, however, had switched from its simple support roller running gear with steel road wheels to an interleaved suspension in order to meet the speed requirements. It was generally felt that the machinery then being used in manufacturing the Panzer III would, with a limited expansion program, be adequate for the simplified design of MAN as well as for the Daimler-Benz Panther. Turning machines would have to be supplied to a few companies in order to produce the turret opening in the vehicle hull. A special type of hull drill press for manufacturing the hull of the MAN vehicle was designed by MAN; ten of these would be made available.

22

At this time, it was still not certain what steering type would be utilized, but it was assumed that a simple clutch-and-brake steering unit would be installed initially, since the companies making the vehicle's components did not have the proper gear cutting machines needed to produce a controlled differential steering unit (29 gear wheels per unit). There was an acute shortage of slotting machines necessary for the internal serration of the hollow gear. The housing was to be manufactured of cast steel with a strength of 60 kg/mm. Shrink holes which appeared might be welded over on the condition that the housing be annealed following the welding. In a conference with the Reichsminister fur Riistung and Kriegsproduktion (Armament and War Production) on the 19th of May 1942 it was agreed that the majority of machinery materials for the Panther would be acquired in France.

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Panther & its variants, by Walter J. Spielberger. Schiffer Publishing (2004).