Oct 1, 2006 12:00 PM
VOLVO Trucks North America introduced the innovative I-Shift, an automated transmission for Model Year 2008 Volvo trucks that will be marketed in the United States and Canada. I-Shift can be ordered now for delivery in the second quarter of 2007. The announcement was made September 20 at a news conference in Savannah, Georgia.
I-Shift was designed specifically for Volvo's new family of heavy-duty diesel engines (D11, D13 and D16) that will comply with the 2007 Environmental Protection Agency emission regulations. I-Shift incorporates a host of fuel-saving and productivity-enhancing features into a reliable, durable, and lightweight design.
Volvo will offer three I-Shift models, with the ability to handle all power and torque inputs from its new engine family, including the top 600-horsepower/2,050 lb-ft rating.
Volvo introduced the I-Shift in Europe in 2002 and has sold approximately 80,000 of the automated transmissions to date. It is Volvo's third generation of automated manual transmission.
I-Shift is a 12-speed, single countershaft transmission built up with a splitter, a main section with three forward and one reverse gear, plus a range gear. It is an automated mechanical transmission and does not use synchronizers in its main section. It is a “two-pedal” transmission that does not require a clutch pedal. Transmission controls are located on a compact control console and lever attached to the driver's seat.
I-Shift's road grade sensor not only helps the transmission determine which gear to start off in, but also when it can skip shift, for further smooth operation and fuel economy. The road grade sensor is exclusive to Volvo. I-Shift can also determine how the gradient is changing, which helps it predict whether a gear change will be necessary.
I-Shift is also fully integrated into the Volvo Engine Brake system, and can automatically downshift the engine to maintain set cruise speeds on downhills.
I-Shift has other fuel economy improvement features built-in. One is Eco-Roll, an energy management feature that improves fuel economy in the top gear when operating in rolling hills. This is particularly useful since most linehaul trucks spend 90% of their time in top gear.
Eco-Roll is a Volvo-exclusive feature that automatically disengages the engine when the vehicle is in top gear on a long, slight downgrade that requires no engine torque input. 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, if the vehicle speed increases past a pre-set limit.
Another fuel-saving option is direct drive. When an I-Shift with direct drive shifts to 12th gear, the transmission output shaft is tied directly to the input shaft. This results in less power loss due to friction between mating gears. Transmissions with direct drive can save as much as 1.5% in fuel versus overdrive transmissions.
Volvo's enhanced engine brake, I-VEB, is standard with I-Shift. I-Shift also is available with a kick-down switch on the accelerator pedal, a feature designed to enhance driving performance.
There are two major operating modes offered with I-Shift: Fuel Economy (E) and Performance (P). In “E” mode, the transmission will select shift points and engine parameters to maximize fuel economy. In “P” mode, gradeability is maximized.
Volvo also offers a third mode, for congested traffic when creeping along is the only option. The idle governor driving mode complements the cruise control when driving slowly and without cycling the clutch. The idle governor will adjust the torque to maintain idle speed and thereby constant vehicle speed, although the engine load may vary.
Each I-Shift comes with the following warranty:
Five years/750,000 miles parts and labor for engines with 1750 lb-ft of torque or less
Three years/500,000 miles for engines above 1750 lb-ft of torque.
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