Chevy Diesel News & 8-speed Trans. PLUS Ford/Chevy 10 speed Trans.

   / Chevy Diesel News & 8-speed Trans. PLUS Ford/Chevy 10 speed Trans.
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#31  
another reason for no 2 speed rearends is no 4wd unless you run 2 two speed rearends.

2 speed rear end + 2 speed rear end = 4 speed rear end :D
Doesn't 2 two speed rear ends equal one four speed rear end?
If you put one 2 speed differential in the front and one 2 speed differential in the rear, wouldn't they cancel each other out.
:confused3:
 
   / Chevy Diesel News & 8-speed Trans. PLUS Ford/Chevy 10 speed Trans. #32  
The Vario set a bench mark that others are still trying to follow. While JD still insists on using three clutch packs in theirs, Vario uses none, and is less failure prone because of it. Also having the CVT fluid separate from the hydraulics is another genius idea.
Fendt and Deere are both researching electric drives, as in trains. Lifespan of the hydraulic components on a CVT is still only around 10.000hrs, some die at 6000 some at 14.000.
Fendt may not be using clutch packs to change ranges on the go, but doing heavy tillage in high range is a known killer to Vario transmissions. I prefer automatic gear change like JD, Steyr and ZF have, even though JD builds the least reliable of all CVT's
 
   / Chevy Diesel News & 8-speed Trans. PLUS Ford/Chevy 10 speed Trans. #33  
If you put one 2 speed differential in the front and one 2 speed differential in the rear, wouldn't they cancel each other out.
:confused3:
thats exactly what he was saying :)
Using a 2 speed rear end in the back only, means that the front axle only makes the same speed as the rear end in either hi or low, if you shift the rear end whilst in 4wd it will eat tires like mad.

In Europe most trucks under 12 ton use a six speed, 12 ton with trailer has an 8 or 9 speed. The Volvo F89 of the 1970's had a 16 speed, but modern I-shift is only a 12 speed, because of the increase in horsepower per tonne ratio, as well as the much flatter torque curve of the last 15 years.

With a high power to weight ratio the acceleration is so fast that it takes more time to change gears than to actually accelerate to the next shift point: its just not efficient.
Only with a dual clutch design like VW is using, or Deere in tractors (Direct Drive) its useful to have more gears, because shifting occurs in milliseconds. With conventional automatic transmissions its no use either, because it has a torque converter to overcome gear differences, and using more clutch packs means more drag losses. The beauty of a dual clutch gearbox is that as the name says, it has only two clutch packs creating drag losses, and the speed difference between the two is never more than the ratio difference between one gear and the next, while auto transmissions make the 1st gear clutch slip as fast as the 6th will spin it.
 
 
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