Enlighten Me. I hear many people call it a CVT, the CVTs i know are the Fendt CVTs. and I highly doubt the prius is anything like those CVTs.
Does this help? Graham's Toyota Prius Click on "Understanding the Prius" The CVT on the Prius is a planetary gear type, not the cone & belt that's more commonly found
So its actually somewhat similar to the Fendt design. the Patented Fendt design uses a planetary setup that uses both hydraulic and mechanical components to provide infinite steps from 60' per hour to 35mph in increments of 1 hundredth of a km. Glad to see its at least a good CVT design.
The link TP provided is an excellent source. This link also has information about improvement made in HSD (THS2) from the original THS. http://www.toyota.co.jp/en/tech/environment/ths2/SpecialReports_12.pdf
It seems the CVT Fendt uses hydraulic instead of electric. HSD eCVT can go from 0 to 112 MPH in one-speed.
The Fendt Uses their design for a number of reasons. The main reason is the load that tractors are put under. With an engine making 1,400lb-ft or torque and sometimes over 100,000lbs behind it, it is put under different scenarios than the Prius. Plus on a tractor hydraulics are already there. Nevertheless the Prius setup sounds good
Then this begs the question. Can that be transplanted into, say a semi trailer? You know how they have to shift through 16 gears (or what have you) because of the small power band of the diesel engine that they use. Can they not use a CVT such as the Fendt to keep the diesel engine in its power band?
It looks the Fendt CVT is hydraulic series-parallel hybrid comparing to Prius' electric series-parallel hybrid. Fendt 900 Series Tractors Ken@Japan
medium duty trucks wil be getting one soon. Allison has one made, but I do not know if it is in production yet. Semis have between 9 and 18 gears typically and they are only shifted if needed. For example an 18spd is essentially a 5 spd but with a high low range and an overdrive in most gears. However when the splitter is flipped into high range you cannot use Low, well you can but it is the same ratio as 4th. Here is the gear shifter pattern R 1 2 L 3 4 If you were to shift all 18 gears you would go LO direct LO over 1 direct 1 under 2 direct 2 over 3 direct 3 over 4 direct 4 over flip to high range 1 direct 1 over 2 direct 2 over 3 direct 3 over 4 direct 4 over. useless info but somebody might be wondering. 9 times out of ten you never split the lower half of the gears. You just dont need to really unless you are hauling an oversized load or cruising around in a field. Personally I dont mind shifting all of those gears, it gives you something to do when you're sitting in a truck all day. But back on topic, a CVT would probably work in a truck well, you just have to get past the politics of it and convince truckers to use it. A Lot are stubborn especially after the Autoshift, which has been a success but only lasts half as long as a true manual.
Interesting. Fendt is doing hydraulically what the Prius and other HSD-type hybrids do electrically. Take the battery out of the equation in the Prius, and you have essentially the same thing -- engine power splits at the planetary, an electric motor/generator collects the part that doesn't go to the wheels, and feeds that over to another electric motor that helps push the drivetrain. That's what happens during steady-state highway travel when very little charge goes in or out of the battery. . _H*
Well I remember counting once while beside a truck and he shifted 8 times before he got to even 20 or 30km/h!! so where would be he in terms of gear? Autoshift.. some sort of automatic transmission?
It really depends on driver preference and the load. In city driving most dont really push the truck. Actually most drivers rarely rap the motor out in the lower gears, theres really no point. So there is a chance he couldve shifted that much, its up to him really. Another note about the shifting in big trucks is that its not too big of a hassle. For all of the direct gears you just float shift. To shift into an over drive in any of the gears you just simply slide the overdrive button forward, let off the throttle, then reapply the throttle after a short pause. This breaks the torque allowing it to engage the overdrive. Its fairly effortless. Here is what an 18spd knob looks like. The 18spds have a grey OD splitter, 13spd a red, 8LL and 9LL a blue and the super ten speeds have a grey OD splitter but no high/low range splitter. As for the autoshift it is nearly the same transmission but it is run off of air shifter solenoids. Some of them require you to start the truck out with the clutch and it will do the rest, others start themselves.
