Volvo launches I-Shift electronic automatic transmission
SAVANNAH, Ga. -- Volvo Trucks North America has announced that its acclaimed 12-speed automated manual transmission, I-Shift, will soon be available in North America. Orders are being taken now for Q2 delivery in all Volvo truck models, including the Volvo VN and Volvo VT highway tractors, and the Volvo VHD vocational truck.
With more than 80,000 units already in service overseas, this mature, third generation two-pedal, non-synchronized, heavy duty transmission crosses the pond with a well-established service record. I-Shift has been extensively redesigned to meet North American expectations, but it retains the high level of electronic and component integration needed to deliver the exceptional performance and fuel economy that have made the transmission so popular in other markets.
Volvo optimized the I-Shift for use with the new D11, D13, and D16 engines by programming each of the engine's fuel maps and performance curves into the transmission. This highly integrated approach allows the transmission and the engine to calculate optimum output with appropriate gear selection to achieve the best possible combination of fuel ecomony and performance.
I-Shift is also eqipped with a unique road grade sensor, allowing it to read hills and calculate torque demand so can predict when up- or down-shifts may be necessary. This combination of built-in intelligence and data collection from numerous sensors helps the transmision determine the appropriate starting gear, when it can successfuly skip-shift, and even when to apply engine braking when coasting through a down grade.
Among the interesting features of I-Shift is a operation mode called "Eco-Roll", where the transmission disengages the high-low splitter allowing the truck to coast down grades that do not require brake or power -- with the engine at idle. Volvo says Eco-Roll reduces parasitic drag of about 30 hp making more efficient use of vehicle momentum.
Eco-Roll re-engages the engine as soon as one of the following happens:
The speed reaches the engine brake set speed for the cruise control; The driver touches the brake; The driver touches the engine brake control stalk; The driver touches the accelerator; or the vehicle speed increases past a pre-set limit.
"We believe customers will immediately recognize the advantages I-Shift offers for productivity, lower cost of operation, safety, and driver recruitment and retention," said Scott Kress, senior vice president, sales & marketing.
"The truck, the engine, and the transmission have all been engineered and designed to work as one integrated, exceptionally efficient machine," he said. "Customers can always get the perfect ratio at the right time for optimal engine and vehicle performance, which means a higher degree of productivity, fuel economy and reliability."
I-Shift is as close to a one-size-fits-all transmission as we've seen in North America, and Volvo offers three models of I-Shift with torque ratings engineered to meet or exceed the ratings of the engine they're mated to. Buyers really don't have any mechanical spec'ing options with I-Shift -- there's really no need for them. All transmission models are engineered to mate to a specific engine, and customer choice comes in the form of electronic and programming options.
The 12-speed I-Shift is a single counter-shaft, three-speed gearbox with high and low ranges and a two-speed splitter for each gear. The two reverse gears can be shifted on the fly, giving drivers more flexibility while backing.
There's no clutch pedal, but there is an electronically activated air-over-hydraulic single-plate clutch. The X-Y shifter mechanism is electrically operated. I-Shift is available in three ratings to meet customer demand and engine output parameters:
I-Shift model AT2512C AT02512C AT03112C
Engine D11/D13 D11/D13 D16
Overall ratio 14.94:1 15.04:1 15.04:1
Top ratio Direct 1:1 O/D 0.78:1 O/D 0.78:1
Weight lb(kg) 597 (275) 597 (275) 610 (281)
The I-Shift driver interface consists of a seat-mounted shifter console for gear selection (reverse, neutral, drive -- auto, drive -- manual) with a toggle switch for manual gear selection, and an economy/performance mode selector switch. There's also a stalk mounted control for programming any of I-Shift's special features such as Eco-Roll, Brake Cruise control, and the engine brake output control.
-- For a more detailed explanation of the benefits of I-Shift's user friendly technology, see the next installment of Lockwood's Product Watch, and read about Jim Park's test drive of the I-Shift in the November issue of Today's Trucking magazine.