TeamsterGrrrl Posted June 30, 2015 Share Posted June 30, 2015 I'm looking for some arguments to use in the debates I get into with defenders of the Volvo, Daimler, etc. automated single countershaft transmissions. My strategy is to argue the longer life of the multi-countershaft transmissions such as the Maxitorque and Eaton's. I had a Daimler engineer reply that the multi countershaft transmissions were built to get a shorter overall length for the short wheelbase trucks common when we had overall length limits prior to the 1982 STAA. He claimed that because length requirements were now relaxed, they could use wider bearings in their single countershaft transmission and get the same life expectancy as a multi countershaft transmission. I don't have any truck transmissions around here to measure, but found online that Scania's single countershaft transmissions had bearings in the range of 40 and 46 millimeters (almost 2 inches) wide by 70 mm. inside diameter. That struck me as bigger than the Eaton double countershaft bearings I've seen, never seen a Maxitorque apart so I don't know their bearing dimensions. Haven't been able to find any bearing dimensions for Volvo or Daimler's automated manual transmissions, both seem to have that data sewed up pretty tight.So anybody who has seen the bearings on these transmissions or better yet has specs on them, how do they compare? Quote Link to comment Share on other sites More sharing options...
james j neiweem Posted July 1, 2015 Share Posted July 1, 2015 There is no reason why a single shaft transmission can't be made as stong as a double or triple countershaft. Metallurgy being the same shaft cross section is the key. Quote Link to comment Share on other sites More sharing options...
Freightrain Posted July 1, 2015 Share Posted July 1, 2015 Transmitting power across a wider surface area(more cluster gears) is the reason for double/triple countershafts. If you can make the box longer and use wider gears(surface area), then the same basic function is accomplished.I don't think it is the shaft size persay that is the weak link. Just the capabilities of the gears to transmit the power and survive without breaking. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment Share on other sites More sharing options...
TeamsterGrrrl Posted July 1, 2015 Author Share Posted July 1, 2015 That's my theory- no reason they couldn't design a single countershaft transmission as durable as a multi countershaft transmission, but it would end up bulkier and heavier. Volvo claims a weight of only 723 pounds for their automated manual which includes the clutch, Eaton claims 850 pounds with clutch for a fleet model 10 speed with a lower torque rating. IIRC, the Maxitorque's 9 to 18 speed transmissions weight around 650 to 800 pounds without the clutch, and Scania's manuals run around 800 pounds... They ought to last longer than Volvo's lightweight? Quote Link to comment Share on other sites More sharing options...
Popular Post Challenger Posted July 1, 2015 Popular Post Share Posted July 1, 2015 How about this,Maxitorques and Eatons can be repaired/replaced by the customer in their own shops. Ishifts and Mdrives can be replaced at the customer's shop but have to be towed to the dealer for programming and calibration, this includes clutch replacement. But as long as you get the extended warranty on the Ishift/Mdrive, or you are a bigger fleet with programming capabilities, this will never be a problem. 3 Quote Link to comment Share on other sites More sharing options...
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