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Enhanced Allison 1000 Transmission Helps New Chevrolet Silverado Heavy-Duty Trucks Do More With Less Fuel

2010-02-10

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PONTIAC, Mich. – When customers put their new, 2011 Chevy Silverado 2500HD and 3500HD trucks to work, they’ll find greater capability and improved fuel efficiency. A new 6.6L Duramax diesel and Allison 1000 six-speed automatic transmission powertrain is integral in the trucks’ greater performance, with the Allison transmission ensuring engine power is transmitted smoothly and efficiently in trucks with higher GVWRs.

With a decade of durability behind it, the Allison 1000 is a proven and popular transmission among heavy-duty truck customers. The enhanced Allison 1000 for 2011 is strengthened to handle the higher torque capability of the new 6.6L Duramax engine (see separate release), while also designed to improve fuel economy and provide seamless operation of a new exhaust brake system.

“The changes and improvements to the Allison 1000 should allow it to continue to be the industry benchmark in heavy-duty transmissions,” said Tim Cooney, assistant chief engineer. “The Allison 1000 is a no-compromises transmission that has been highly integrated with the Duramax diesel to provide the unique performance characteristics of this heavy-duty powertrain.”

Key new features and popular carryover features include:

• Greater torque capacity – to handle industry-leading torque from the 6.6L Duramax diesel
• Greater fuel efficiency through reduced spin loss and improved lock-up operation
• Smart exhaust brake system
• Cruise grade braking
• PTO delivers class leading 250 lb.-ft. of torque
• Driver shift control with tap up/tap down range selection for greater driver control in certain driving conditions, such as towing on a steep grade
• Tow/haul mode improves towing performance and driver control on grades
• Cab warm-up mode, for more comfortable driving in cold climates
• Customer-friendly maintenance, with easy-access filter

A stronger transmission

To match the increased torque output of the new 6.6L Duramax diesel, engineers updated the Allison 1000 with structural improvements that include increased strength for the input and main housings, a new, higher-capacity torque converter and increased clutch and shaft torque capabilities. Additionally, a new 4WD output housing is matched with the upgraded transfer case for 2011. The changes enable the transmission to handle class-leading input torque and support the new heavy-duty trucks’ increased GVWR of up to 13,000 pounds (5,897 kg) and a maximum trailering rating of 20,000 pounds (9,072 kg).

“The bottom line is the Allison 1000 is a commercial-quality transmission that has been tested in the field by more than a million heavy-duty pickup customers, in addition to the hundreds of thousands of commercial customers that use its sister transmission provided by Allison Transmission, Inc.,” said Cooney. “The updated model builds on the commercial duty cycle and up-to-33,000-pound (14,968 kg) GCVW rating of the previous model, so it will handle the loads customers give it for years to come.”

More efficient performance

The Allison 1000 enables greater fuel economy and greater capability through engineered upgrades that allow it to channel torque to the axles more efficiently. Those upgrades include:

• New, low-drag clutch packs help minimize spin loss
• Optimized lube distribution throughout the transmission eliminates excess oil in spots to reduce spin loss
• Upgraded controls, including torque-based variable main pressure for more precise pressure in different conditions. This helps reduce overall pressure

• Hardware and controls improvements to reduce the transmission’s “spin loss,” which means more of the engine’s power is channeled to the wheels, allowing the vehicle to do more work with less energy:
• Increased converter lock-up – the transmission’s torque converter is “locked” at the same speed as the engine more often. When not locked, the converter “slips,” using more engine power and, consequently, more fuel

The Allison 1000’s six-speed configuration also contributes to greater fuel economy, with lower engine speed on the highway. Both the fifth and sixth gears are overdrives (turning slower than engine speed), with a sixth-gear ratio of 0.62:1 – a feature since 2005.

Exhaust brake system

New for the 2011 heavy-duty trucks is an optional, highly integrated exhaust brake system. It improves upon the Allison 1000’s industry-leading grade brake and cruise grade braking features that have been in place for several years.

The new, driver-selectable feature uses the compression power of the 6.6L Duramax engine to improve vehicle control and reduce brake pad wear. When the exhaust brake is engaged in cruise mode, exhaust cruise grade braking will help the cruise control system maintain the desired vehicle speed when travelling downhill, keeping the driver from having to apply the brakes and exit cruise control to maintain speed.

When the exhaust brake is engaged in non-cruise mode, the transmission and the exhaust brake deliver the correct amount of braking to assist in vehicle control, regardless of vehicle load. The system provides more engine braking with this feature for a heavier vehicle, for example.

Exhaust grade braking is one of the best examples of the Duramax engine and Allison transmission working as a seamless powertrain unit. It is a smart system that varies the amount of brakes needed for the vehicle, load and grade. The engagement of the system is smooth and quiet, while its performance enhances the driver’s feeling of control.

Power take off

The Allison 1000’s PTO feature offers a class-leading 250 lb.-ft. of torque for excellent performance in PTO applications, such as dump trucks, salt spreaders and snowplows. There are two locations (right- and left-hand sides of the transmission) for PTO accessories – such as hydraulic pumps – to be attached on the transmission.

Driver shift control

In addition to exhaust grade braking, the Allison 1000 offers driver shift control (DSC), which allows the driver to manually select and hold a desired gear to satisfy a variety of driving scenarios. The easy tap-up/tap-down shift control holds the desired gear, but also protects the engine by inhibiting downshifts when the engine speed is above allowable rpm limits.

Tow/haul mode

The driver-selectable tow/haul mode provides greater driver control and towing performance in certain conditions, such as steep grades. When engaged, shift schedules are optimized so that the system locks the torque converter earlier to minimize heat gain and to take greater advantage of engine braking when vehicle is traveling downhill.

A warm cab faster

A popular feature among customers in cold climates, the exclusive cab warm-up mode is retained in the enhanced Allison 1000. When engaged by the driver via the driver information center on the instrument panel, the engine speed is raised and the transmission increases the load on the engine, which allows the engine to produce heat quicker and warm up the truck’s interior faster.

“Customers in Alaska, Canada and other cold spots absolutely rely on this feature,” said Cooney. “It’s a feature you don’t find on other vehicles and we wouldn’t have updated the transmission without it.”

Easy maintenance

The Allison 1000 has an easily removable, spin-on filter with a long, 60,000-mile change interval. Another internal filter is rated for the life of the transmission. Some competitors’ transmissions offer longer filter change intervals, but require more intensive, time-consuming change procedures that include removing the oil pan.

Peace of mind

When it comes to durability and reliability, no other heavy-duty truck manufacturer has the level of experience as Chevrolet, which is why Chevy backs the Allison with a five-year/100,000-mile powertrain warranty. That’s 40,000 (64,000 km) miles longer than the Ford Super Duty powertrain warranty.