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DogDodger

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DogDodger last won the day on April 17

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  1. For the record, the design to which I was referring as poor was the final drives, not the Panther per se. Going over all of its inherent pluses and minuses would take a longer post.
  2. As we discussed previously, the design itself was poor because it was known that the available materials were not up to the task. Spielberger says that a higher-strength steel was intended for the gears, but after this was "unexpectedly" replaced no alterations in the design were made (and depending on when this replacement occurred, alterations may have been impossible). The report was from Hauptmann Noak, commander of s.H.Pz.Jg.Abt.654, and was written on 24 July 1944, before the final drive improvements, to be fair.
  3. Ha, thanks! That's awesome, I didn't even realize until you said something. Unbalanced loads are hard on tracks: e.g., the weight imposed by the Tiger Ausf.B's overlapping Staffellaufwerk was biased to the inboard portion of the tracks, resulting in track pins bent to the point that they couldn't be pulled out of the link.
  4. 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??
  5. If it doesn't count as spam, there are some pictures of the spaced-out suspension on a hybrid M4 here.
  6. Ha, thanks. Flattery will get you...well pretty far, I suppose. Indeed. The state of German automotive technology was unprepared for mass-production of a 45,000 kg tank. As we've been over, and as Spielberger notes, "Since it was envisaged to produce the Panther in large numbers, production costs of various subassemblies would have to be kept to a minimum...If it had been possible to foresee what difficulties the final reduction gearing was to cause, it would have been a much better solution to have selected a more expensive final drive which provided a greater degree of reliability. In the end, the final drive proved too weak to handle braking with the Klaue disk break [sic] when steering through tight curves. The use of epicyclic gearing for the final drive hinged upon the bottleneck being encountered in the supply of gear cutting machines for producing the hollow gearing. When passing judgement on the double-spur final reduction gear it should be noted that the high-quality steel originally planned for the spur gears in the final drive was not available for mass production and was unexpectedly replaced by VMS 135 (today 37 MnSi5) tempered steel (not as suitable for this purpose)... "The final drive (gear teeth and bearings) 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 mountings were far too weak and could not be strengthened. Because of gear teeth breaking 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 in 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 production tanks. All attempts to improve the final drive met with failure, despite the offers of a special bonus as an incentive..." To quantify this a bit, Ristuccia and Tooze in "Machine tools and mass production in the armaments boom: Germany and the United States, 1929-44" note that Germany did make strides in increasing the number of gear-cutting machines in service, going from at least 10,407 in 1939 to 28,621 in January 1945. Even with these increases, compared to the US there were only 0.74 gear-cutting machines per German metalworking employee in 1945.
  7. Could be, haven't read about that. Interesting, thanks; what is this from? Ogorkiewicz differentiates between double-differentials and the Panther's steering system, and has a pretty high opinion of it: ... Seeing M48s in person, the gun seemed a bit unimpressive compared to the size of the vehicle to me as well. The original cupola was pretty slick, but couldn't be reloaded from under armor, of course, so the bad M1 cupola was a go. Because he's the assistant driver; the radio was in the turret bustle. Perhaps a better question would be: why was the assistant driver not provided with duplicated controls in all US designs? The TC's cupola has a rotating periscope in the hatch door, as well. As we mentioned earlier, trials at Aberdeen indicated that the T26E1 was better cross-country than the HVSS Sherman. We're lamenting the M26's near-vertical turret armor while comparing it to the Centurion? The M26's performance in Korea can be considered an outlier as far as reliability goes. MacDonald et al in "The Employment of Armor in Korea," vol.I, noted, "The M26 tanks were a later World War II development and were in a generally poor physical condition." And when discussing the cannibalization required due to spare part scarcity: "This situation was aggravated because many of the tanks brought to Korea had seen extensive service elsewhere or had deteriorated while in storage. One battalion with M26 tanks departed the US with all but 10 to 12 tanks in unsatisfactory operating condition. These tanks, in operation since 1946 in troop training, were in serious need of complete overhaul." Scarce indeed. In Korea, the physical width of the tank precluded some routes, and the steep hills were taxing, but what issues were prevalent off-road? The Pershing wasn't really a heavy tank, as noted earlier. It was named a heavy for morale purposes for a couple years, but actual heavy tanks were in development. The T26E5 was tested starting in July 1945 and performed well besides having to take it easy over rough ground to avoid suspension damage. World War II was over, though, so a prototype was all that was going to be produced. Panther's steering design was clever, but in practice the final drive design and material hindered this advantage since using the steering brakes caused the final drives to shear, no?
  8. The 90 mm gun T54 was in response to the PITA of loading the separate projectile/propellant case of the 90 mm gun T15E2 found in the T26E4 Pershing. The 90 mm gun T15E2 was in response to the PITA of loading the unitary ammunition for the 90 mm gun T15E1, which was fitted to the first T26E1 pilot and sent over to Europe during World War II, and whose adventures can be read in Hunnicutt's Pershing and Irwin's Another River, Another Town. The T54 gun went back to a unitary round, but the propellant case was shorter and wider, which eased handling in the confines of the tank but kept the chamber volume and ballistics equal to the gun T15E2. Two M26 pilots were armed with the T54 and designated M26E1; forty-one 90 mm rounds were stowed, with five in the loader's ready rack and the rest in the hull floor bins. Tests were conducted from 1947-1949, and the T54 was deemed the best extant US tank gun. Then nothing else happened with it... MV with AP-T was 3,200 ft/s (4.9" RHA penetration at 1,500 yards and 30 degrees); HVAP 3,750 ft/s (7.7" RHA at 1,500 yards and 30 degrees).
  9. You might be able to get close with extra normally-spaced road wheels, but then you risk getting into TOG- or T-35-sized length, which would itself affect maneuverability. Not suggesting that the Schachtellaufwerk is worth the effort (the caveats at the end of the post hint toward my opinion), but when comparing the Pershing and Panther, just wanted to point out that nominal ground pressure tells far from the whole story. Perhaps Schachtellaufwerk might be thought of as almost a sort of technology demonstrator: outstanding softer-terrain performance though not necessarily cut out for the ease of use desirable for a war machine. Not the lifting capacity per se as I understand it, but as N-L-M said, more of an issue of the products which were presented. Armored Force commander MG Devers said in December 1942, "Due to its tremendous weight and limited tactical use, there is no requirement in the Armored Force for the heavy tank. The increase in the power of the armament of the heavy tank does not compensate for the heavier armor." Hunnicutt opines that the Armored Force would rather have shipped two medium tanks than a single heavy tank. But of course, the heavy tank that Devers was talking about was the M6, so it's no wonder...
  10. You have high standards for ground clearance. The Pershing was designated as a heavy for a short while, but was begat by a medium design; actual heavy designs were ongoing but didn't see service before the war ended. Hunnicutt and Yeide agree that the "heavy" nomenclature was mostly for morale purposes. I'm not sure it was quite as bad off-road as you make it seem, but I do find the T25 a tantalizing what-if. Panther used a geared steering system and not a triple-differential, no? The nominal ground pressures were indeed similar (and even favored the Pershing, depending on the source), but the Panther's mean maximal pressure and other off-road performance characteristics would benefit from its maintenance-unfriendly road wheel setup. Wong has some interesting simulations in Terramechanics and Off-road Vehicle Engineering between a baseline M113-type vehicle with 5 road wheel stations, the same vehicle with 6 road wheel stations, and the same vehicle with 8 overlapping road wheel stations. The simulations are run on snow and clayey soil, and the machine with more road wheels shows better performance in everything from wheel sinkage to drawbar pull to tractive effort to trim angle, etc. Panther weighed 6.9-8.6% more than the M26, but its tracks were 2-3" wider and it had 2 more road wheel stations per track in the same ground contact length and essentially the same track pitch (5.9" for the Kgs 64/660/150 vs. 6" for the M26's tracks). Double torsion bars were probably needlessly complex, the interleaved wheels required inordinate effort and time for maintenance, and the final drive was never adequately strengthened, but credit where due: the thing should perform quite well off-road.
  11. Of course, I took it as a figurative statement. What I was hoping to illustrate, though, was that despite being ~17,000 lb heavier than an HVSS M4A3 and having essentially the same engine, the T26E1 was a large improvement in cross-country mobility with just a single torsion bar supporting each road wheel pair. The Panther's system doubtlessly provided a good and stable ride, but should the improvement over a single-bar system have justified its implementation? Germany was never going to out-produce its enemies, so a strategy of "qualitative" enhancement was logical, but it still seems that discretion is the better part of valor in some areas, especially when your tanks are expected to fire from the short halt. Could you please expand on what you mean by Pershing was not a finished vehicle as a medium? Thanks. Although tank maintenance was a struggle for all US tank types in Korea, especially in the first year of the conflict, the M26 still showed itself to be the least reliable in that theater. To be fair, many of the M26s shipped to Korea were in poor condition and some overdue for overhauls, so the M26's performance there may be an outlier... One was designed, but it seems it was not possible to actually manufacture it in the numbers needed to install on the new medium tank. Spielberger notes an epicyclic final drive had been tested successfully, but "a shortage of gear cutting machinery for the hollow gearing prevented this type this type of final drive from being mass produced." So spur gears with weakish steel were used by necessity.
  12. Thanks The Pershing was labeled a heavy tank from 29 June 1944 to May 1946, mostly for morale purposes. It was begat from a program to replace the M4 medium tank, and there were actual heavy tanks being concurrently developed. The M26, though more heavily armored than its T25 sibling, still weighed over 34,000 lb less than the heavy tank M6. In September 1944, i.e., two months before the 90 mm gun, 92,000 lb T26E3 emerged from the T26E1, the Ordnance Committee recommended the development of the 105 mm gun, 141,000 lb T29 and the 155 mm gun, 142,000 lb T30. These were the US heavy tanks. Production of 1,200 T29s was requested on 1 March 1945, but of course the war ended before this could occur. Also, the passage of the post being replied to was referencing the suspension systems specifically, as I understood it? The M26's relatively low power:weight became an issue in the mountains of Korea, but cross-country its single-torsion bar suspension (and automatic transmission?) could be quite an improvement over even much lighter tanks: A race was held at Aberdeen Proving Grounds' Churchill cross country area involving T26E1, T25E1, HVSS M4A3, and VVSS M4A3. The T25E1, being torsion bar-sprung and having a pretty sprightly weight, came in first with a 23-minute time. The heavier T26E1 was second at 26 minutes. The M4A3s, with the same engines but ~13,150-17,750 lb less weight than the T26E1, crossed the line in 28 minutes 25 seconds for the HVSS machine and 30 minutes 40 seconds for the VVSS machine. So perhaps "immobile" is a bit unfair, and perhaps the double torsion bars were in fact a bit of luxury.
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