In addition to the already well known advantages of continuous variable gearboxes, here the variably controllable pressing force is added. Either an optimum in efficiency or a torque maximum of, until now, not reached by the CVT-gearbox, of up to, at present, 400 nm is possible, particularly when starting off. This also makes this gearbox usable for somewhat heavier vehicles (perhaps also for lighter tractors). In addition, an even greater ratio-spreading becomes possible.

As with all CVT gearboxes two pairs of cone pulleys are positively and without force, connected to each other. In this case they are embraced by a chain whose cross-bars are bevelled in such a way, that they have maximum surface contact precisely in the wedge gap of each pair of cone pulleys. Of the two pairs one is movable (figure 2). Not only the gear ratio is altered by an electro-hydraulic controller, but also the pressing force is adapted to the torque measured in the gearbox. In this case, sensors help for the RPM of the output shaft and the drive shaft and perhaps also a torque sensor. The pressing force is never much higher than is required to transfer the torque. This decidedly improves the efficiency in certain operational areas.

This positive-force chain-drive is combined with a simple or combined set of planet gears to make driving in reverse possible. In addition a wet clutch is necessary. Another clutch makes starting off possible. Because with CVT gearboxes the same speed is possible, forwards or backwards, the bevel wheel sets are in this case, not shifted.

The control would be hardly possible without a CAN-bus (Controller Area Network Bus) for connection with the engine control module. This module transmits, e.g., load and engine speed data. Alternatively, it can also reduce the torque when starting off or in the event of the gearbox overheating. The control devices of engine and gearbox together succeed even in simulating the crawling, well known with the graded fully automatic gearbox, and in doing so, simplify, e.g., controlled driving in reverse or starting off on a gradient. Unfortunately, to presumably make it easier for drivers to make the changeover, a staggering of the gear ratios is also simulated.The possibilities of this gearbox design are by far, not yet exhausted. E.g., a controlled slip which could also take over the duties of the dual mass flywheel would be conceivable. Also the complete separation, in certain fuel saving situations, of the engine from the driving wheels is, in contrast to the fully automatic system with a torque converter, possible. 09/08

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