How we come to know what we know

The Sherman used existing suspension components, an existing lower hull design, exsisting engines, transmission and, many other parts that were common to the M3 medium and previous US tank designs.
The T/M 26 on the other hand used a new torsion bar suspension, an entirely new hull and turret, along with a good deal of other newly designed parts. As a result it would take longer for everything to be designed, tested and, then put into production. So, where the Sherman went from design to production in a year, the M 26 took nearly two to get to that point.

 

Your timeline does not tell the full story. They rarely do.

The plans for the Sherman had been completed when General Devers ordered the Pilot tank and arranged for production to start at the earliest possible moment. Thus, once the tank had someone with clout to cut the red tape and push it forward into production the process from drawing board to production took 5 or 6 months. (6 by your timeline.)

Duckbill

 

As previously mentioned, the Sherman went from the drawing board into production in 5 to 6 months with General Devers at the helm. There is no reason to think similar results for the T26 were possible had there been someone behind it like Devers.

Duckbill

 

It tells the full story quite well in this case.

No sorry. It took 6 months from the pilot to production. This is not drawing board to production.

Not my timeline. It can be found on pages 117-124 of Hunnicutt's book 'Sherman. A History Of The American Medium Tank'

 

You are wrong (Or more politely -- I disagree with you.) The pilot model was made from the existing blueprints. Thus, the tank went from the drawing board to production in 5-6 months.

Duckbill

 

This is only partially true the M4A1 (cast hull) did take 5 months for the initial example to be completed and another month to have tanks rolling off the assembly line. The Detroit Tank Arsenal, (where the Pershing was built) took more like ten months from completed plans to get the M4 a welded hull tank using a number of components from it's predecessor, into production. (Aberdeen sent plans to Chrysler for the new M4 tank in early Oct. 41, first handbuilt prototype completed 27Jun42, first production vehicle completed one month later. It took another five months to get up to peak production.
So let's look at the T-26/M26, remember it was a more revolutionary design, had few interchangeable components with it's predecessors and took different manufacturing techniques.
---24May1943 approval for production of ten T-26 prototypes, they were not delivered until Feb 44. The T26 had big problems with it's electric drive transmission. The tank was still in the blueprint stage in Sept 43 when the whole Devers/McNair controversy started, and it was over additional production not the original order for ten.
---20 May 1944 the Armored Board at Fort Knox reported that the T26 was not ready to enter production. Testing of the T26E1 with Torqmatic transmission also began this month, but additional problems arose from differential cooling problems, engine/flywheel seperation problems to the need to incorporate a muzzle brake on the main gun. (the T26E1 was the model eventually standardized for production).
So say you order it into production in May without working out the teething problems, it still doesn't arrive in Europe by shortly after D-Day.

 

When the Ordnance Dept. received permission to produce 10 T26 tanks for testing, they advised the War Department that they had the capacity to produce 500 more and requested permission to do so while making the changes made necessary from testing on the assembly line itself. (Tank production was done under the direct control of the Ordnance Dept. Tank and Automotive Division, so they would have known what they were about.) This was common practice for the production all sorts of munitions, and while not overly efficient, it was a fact of life during WWII.

If memory serves (and it may not) one of the other T-20 series tanks had the electric drive, not the T26.

The delay in getting the first prototypes is one of red tape and resistance by McNair, not technical difficulties. Everything could have and should have been sorted out during the summer of 1943.

I am not adverse to the possibility that the first T26 tanks might not have arrived in Normandy until sometime shortly after 6 June. However, a few hundred of these tanks would have been available for Cobra. They would have been put to good use in all the following campaigns. I think the idea was to equip a battalion of T26 tanks for each armored regiment/light division (or something similar).

Duckbill

 

True but it would have affected M4 production. Not a wise gamble for a radical new design of an unproven tank. Had they produced the additional 500 tanks, deliveries would have been after Feb 44 (when the first ten were delivered) and they would have had all the defects discovered during testing of the T-26.

The T-23, T-25 and T-26 all initially had the electric drive transmission. The T-25E1 and T-26E1 versions had the torque-converter fluid drive transmissions.

Actually, that's why in the initial post I provided the timeline for the M4 at the plant that eventually made the M26. Ten months from plans submitted to production deliveries. Look at the time required for the Pershing, 24May 1943 to Feb 1944, nine months. They were also still in the blueprint stage in Sept '43 so a prototype in the summer of '43 is just not realistic. I think much is being "read into" the McNair controversy, the T-25 which was more lightly armored and mounted a 76mm gun was not actively opposed, had a prototype ordered contemporaneously to the T-26 and was delivered around the same time. So why the delay with that tank?

 

It appears from my quick check of the sources that the electric drive was pretty much on the back burner by mid-summer 1943, and the Ordnance Dept. was generally happy with the automatic transmission.

MG Barnes had received the support of LTG Devers to produce 1,000 T23s, but after he left for London in May 1943 there was no one who could push the tank through AGF. (I think the turret that could accept the 90mm gun was already designed.) Had the production line been started heavy tanks would have been available by mid-1944. McNair took over full control of the Armored Force shortly after Devers left, and pretty much put a halt on the production of heavy tanks.

The fact that the Ordnance Dept. said it had the capacity to make these tanks suggests they were confident they could still meet the requirements for the M4 medium.

Duckbill

 

They tried the 'move to production before the pilot was fully tested' route with the T-23 and ended up with 300 tanks unfit for combat.
250 T-23 were available in 1944 but were turned down as 'too complicated'

 

One issue with the M 26 was the transmission. The General Motors torquematic transmission was a new design and suffered from the usual teething problems associated with such complex pieces of machinery. Below is a diagramatic sketch of how it worked:

 

Wasn't a few hundred 76mm armed Shermans available for D-day, but declined by Eisenhower/Bradley in favor of conventional Shermans?

 

Looks like the Houston I-10/Loop 610 interchange to me. Probably works about as well.

P.S. Lookie I finally figured out the 'Quote" function. One of these days when nobody is looking I am going to start running with scissors!

 

Interesting points, which provide us with some equally interesting conclusions.

Firstly, the Ordnance Dept. Tank and Automotive Division had the capacity to begin production of heavy tanks with 90mm guns by mid-summer 1943. Thus diminishing the argument that production of heavy tanks would have compromised production of the M4 medium tank.

Secondly, the Ordnance Dept. understood the electric drive system for heavy tanks was too heavy, and despite having shifted its attention to the automotive transmission in May 1943, was required by the Army Ground Forces to produce tanks that proved unusable in combat.

Thirdly, without a champion with sufficient clout to carry the heavy tank program forward despite McNair’s objections, the Ordnance Dept. experienced difficulties in gaining acceptance for its automatic transmission equipped heavy tank even after most of its developmental problems had been sorted out.

The end result is that after Devers left the Armored Force there was no one with the clout to bring new tanks from the drawing boards to the field forces. As a result, the development and production of heavy tanks was allowed to languish in the mire of various committees, boards, and McNair’s stubbornness. Had Devers been replaced as Chief of the Armored Force by someone of equal stature and the same level of access to the Sec. of War and the Army Chief of Staff, heavy tanks would have been available for use in the ETO by mid-summer 1944.

Duckbill

 

Thanks for the schematic. It is my understanding the teething problems of the tranmission were sorted out rather quickly. After all, automatic transmissions had been around for a little while, and were pretty well understood by the automotive industry.

Having rebuilt a few automatic transmissions over the years, I can see from the schematic that it was not overly complicated, just new to many people, a fact that made it more of a "selling" problem to gain its acceptance than one of performance.

Duckbill

 

Well I guess thats one mystery solved. I had wondered what could cause a dishonorable discharge and how to avoid the same. I guess I now know. I hope the thread can stay alive, because I have seen alot of great info.

 

I would note on that transmission that it took GM until 1949 to straighten out all of the issues with it. At that point the Allison division was the lead developer and it became the CD 850. That transmission became standard for US tanks up through the M 60 series and is still in service today.

 

Was a post removed? In spite of the barbs being tossed around the converstion was quite good I thought (informative and provacative anyway).

 

If I implied I had any special insight that was not my intent. I am still just another FNG around here ( I hope to keep my nose clean and get promoted to pouge someday!). Whatever was the cause of the Dishonorable is between the Mods and our former comrade in arms, and is probably best left there. Still clear and reasonable advice and warnings was posted for everyone's benefit, and it is up to us to heed the word of god, er I mean chief, when he graces us with them.

 

Back to conversation....
As posted earlier:

Good point, its should also be notable that the MK IV was automotively mature (compared to Panther and Tiger), did not have the mechanical issues associated with the "heavies" of the period and also had 80mm of frontal armor and the KwK 40 L/43 75mm which was far superior to the Sherman's weapon(s) for AT purposes.
The MK IV's versatility is just as diverse as the Sherman's, with TD models, SP Guns and Anti-Aircraft variations. It would seem every argument to be made for the Sherman could be made for the MK IV...no?
As far as ease of production or production numbers are concerned, shouldn't we compare US factories with German Factories before making a judgement on that?