forward direction. The second overdrive is with ring 2 braked which will cause sun 2 to spin faster than in the first overdrive gear. There is one reverse gear. Ring 1 and ring 3 are braked with the input only connected to sun 1. Sun 1 will drive ring 2 in the forward direction and with carrier 2 braked, sun 2 and sun 3 will spin in reverse. With Ring 3 braked, the output will be spun in the reverse direction by sun 3. Allison 1000 Initially the Allison 1000 was a 5 speed transmission, rated to handle up to of torque. This rating has increased as the transmission was updated several times, to stand at by 2011 in GM truck applications. A new "Generation 4" 1000 was introduced in 2005 that added a 6th gear at the very top of the ratio ladder, making it a double-overdrive. For the 2006 model year, manual gear selection was introduced. This feature gives the driver greater control over the transmission, enhancing operation when engine braking or less frequent shifting is desired. Gear ratios: Applications: Chevrolet Silverado Chevrolet Kodiak/GMC Topkick GMC Sierra Hummer H1 Chevrolet B-Series Allison 2000 The Allison 2000 is rated to handle up to of torque. Gear ratios: Applications: B-7 bus C-Series truck Cheetah MMPV F-Series truck (Ford F-650) International XT Series Allison 3070/4070 Applications: Western Star Trucks Kenworth Trucks Peterbilt Trucks Freightliner Trucks International Trucks Allison 3700SP Applications: Family of Medium Tactical Vehicles (FMTV) BAE Caiman MRAP See also Allison Transmission References External links 1000