Following on from the popularity of Honda’s DCT automatic gearbox, KTM appears set to tread a similar path as Big Red with patent documents suggesting that the Austrian brand is developing a semi-automatic gearbox of its own.
Since introducing the current Africa Twin, Honda has found that around half its customers opt for the semi-automatic DCT version rather than the conventional manual model so it’s surprising that rivals in the hotly-contested adventure bike market haven’t adopted similar technology. But now it looks like KTM is developing a simple automated manual box for its 1301cc ‘1290’ models that offers a much cheaper route to the semi-auto goal.
While Honda’s DCT is an engineering marvel with seamless shifts thanks to a pair of computer-controlled clutches and the ability to select two ratios at once, modern quickshifters and auto-blippers are opening the door to a much cheaper type of semi-auto box. That’s the route KTM is taking, as its patent shows a largely conventional six-speed transmission with just a few key alterations to make it a semi-auto.
The patent that reveals the system is actually related to one very specific element, a transmission lock to use when the bike is parked. It’s a simple L-shaped pawl that’s moved by the shift drum and, when ‘park’ is selected, drops a claw into the teeth of one gear, locking the box solid. It’s needed because KTM intends to use a scooter-style centrifugal clutch, which engages as revs rise and disengages at idling speeds to allow the bike to come to a halt without stalling and pull away without needing any manual control of the clutch. Because the centrifugal clutch defaults into an open position when the bike isn’t running, unlike a conventional clutch, leaving the bike in gear doesn’t stop it from being able to roll. That poses a problem, particularly when parking on a slope, that the transmission lock shown in the patent solves.
However, it’s the rest of the transmission described in the same patent that’s really interesting. As well as the centrifugal clutch, which allows twist-and-go operation, there’s an electric actuator that moves the shift drum, replacing the normal foot-operated lever. Combined with a modern quickshifter and auto-blipper, connected to the bike’s ignition and ride-by-wire throttle system, the actuator can either shift gears at the touch of a button or be used in a fully-automatic mode, following a programmed shifting map.
The idea of combining a manual transmission with a centrifugal clutch was already in use by MV Agusta, even before KTM took a 25% share in the company. MV uses a Rekluse centrifugal clutch system combined with a conventional transmission and quickshifter on some 800cc three-cylinder models, but still has a completely conventional, foot-operated gearchange. On MVs with the Rekluse system, a small, secondary parking brake lever on the bars solves the problem of parking on inclines. Similarly, manual transmissions have been automated in the past – notably on the Yamaha FJR1300 – but that used a computer-controlled clutch rather than a centrifugal design.
The KTM design promises to be cheaper to make than systems like Honda’s DCT or even the Yamaha FJR1300 semi-auto, since the quickshifter, auto-blipper and centrifugal clutch tech are already available. All that’s added is the actuator to actually shift the gears, along with the shift buttons, the transmission lock for parking, and the computer to control it all.
By controlling the transmission lock from the shift drum, the lock can’t physically be engaged when the bike is in gear, and because the system is servo-operated and computer controlled, it can be prevented from ever selecting the ‘park’ position on the shift drum when the bike is in motion.
Although KTM’s patent doesn’t mention specific models that could be fitted with the system, the drawings are detailed enough to include part numbers on several components. These show that the gearbox is built from the transmission used on the 1290 Super Duke R, the 1290 Super Adventure and the Brabus 1300 R. KTM is known to be developing a touring ‘GT’ version of the Super Duke R at the moment, which could be a suitable candidate for the semi-auto, and Honda’s experience with the Africa Twin shows that there’s strong demand for automated transmissions on adventure bikes as well, making the 1290 Super Adventure another possible home for the new KTM gearbox.
Ben Purvis
