Not many vehicle manufacturers are going for a dual clutch option, but Volvo is one of them. The concept of a dual clutch is finally coming to heavy duty trucks in Australia, as an option for some Volvo truck buyers. Diesel News looks at the technology and its advantages.
There have been dual clutch vehicles in Australia before. They are an option in Volkswagen cars and available as the Duonic option on the Fuso Canter model. Volvo’s introduction of the concept is a first for the heavy end of the market.
The idea behind the new dual clutch gearbox is that while the transmission is driving one ratio, the next ratio is already engaged using the second clutch. When the gear change is made then the two clutches are swapped over from one to the other. According to Volvo there is no interruption to the power output in the driveline as the power swaps from one clutch to the other.
The two clutches are connected to two different input shafts, operating independently of each other. Since the gearbox has 12 gears, one shaft holds the six odd numbered gears, while the other holds the six even numbered gears. The gear changes using the two clutches can be used for all single step gear changes apart form the one between sixth and seventh gear, as this involves a range change from low to high range, or vice versa.
When the transmission control unit decides it is a good idea to skip ratios, either going up or down the box, the I-shift will change gears as it would normally without a second clutch.
“We have some information from some of our customers that there is a fuel consumption saving with the dual clutch,” says Ove Wikström, Volvo Global Heavy Duty Transmission and Rear Axle Manager. “If you go on a flat road, you don’t save any fuel, but if the road is up and down you can save three or four per cent, and we had one customer saving five per cent in fuel. You also have some time saving and smooth gear shifting is very good, both for the driver and the load.
“We ran a trial in Sweden to see how much time could be saved. We went from Gothenburg in the East of Sweden to the West Coast. This is a distance of 645km and we had an average speed of 70 km/h and it took 9.5 hours. The road was up and down, but not extreme, the normal landscape in Sweden, and the result was we saved them 15 minutes, which corresponds to a three per cent improvement.”
According to Volvo, the I-Shift Dual Clutch makes a big difference when transporting moving or liquid cargo, such as livestock and tanker operations. The smoother uninterrupted gear changes create less movement in the cargo itself. The power-shifting on offer also means there is less risk of getting stuck on slippery or uneven roads, for instance when hauling timber in the forest.
The dual clutch does introduce a number of new components into the gearbox and, as a result, the transmission is 120mm longer than its single clutch equivalent. The extra componentry also adds 100kg to the weight of the gearbox.
The dual clutch system Volvo have developed has been on the European market for some time and will be arriving in Australia sometime this year, rated up to 70 tonnes GCM. The I-Shift Dual Clutch will be available on the Volvo FH with Euro 5 D13 engines rated at 500hp and 540 hp. In Europe, the dual clutch is fitted in about five per cent of the 13 litre trucks sold.
“We are immensely proud to now offer this innovation to our customers in Australia ,” says Mitch Peden, Vice President Sales Volvo Trucks Australia. “Volvo Trucks invests heavily in talking to customers and getting to know exactly what they need. I-Shift Dual Clutch is a product that our customers asked for, we listened and we are delighted to give them exactly what they want. In situations that require a lot of gear changes, I-Shift Dual Clutch brings an entirely new dimension to truck driving.”