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Allison Transmission has been a key player in the Military and Heavy Duty Commercial truck markets for many years. These tough vocations require transmissions that are not only capable of heavy loads, rigorous duty cycles, and proven reliability, but also provide value for the end-user and maintain compatibility with leading edge technological improvements of engines and other parts of the vehicle system. The Allison HD4070 transmission is one of the latest transmission offerings from Allison Transmission to meet the “next generation” heavy-duty vehicle needs. This product increases value to the vehicle manufacturer and customer, and provides compatibility with the fast changing electronics capabilities of modern vehicle systems and engines. These improvements are offered in a durable design that has been the trademark of Allison transmissions in these markets.

The Allison MT643R is a fully automatic transmission with integral input retarder that has been designed and developed for the Latin American city bus market. This transmission provides a cost effective manner to integrate secondary braking into an automatic transmission to lower overall life cycle costs for the city bus. It provides the ease of operation of the fully automatic transmission while providing a system that will enhance vehicle braking and safety while saving on brake system repairs - all in one package. The MT643R has a 250 horsepower input retarder which has a two-stage capacity that, in conjunction with the gear multiplication through the drivetrain as the transmission downshifts, allows for tailoring of the retardation performance to very specific duty cycles. This paper will discuss the design, development, and specific product launch of the MT643R into the Latin American marketplace.

With the introduction of the AT545R, Allison Transmission completes its family of transmission integral retarders. These retarders, as an auxiliary braking system to vehicle service brakes, will now be available with all commercial on-highway and off-highway transmission models. The AT545R has a retarder located on the input side of the transmission that is designed for auxiliary braking for downhill speed control. This 160-hp retarder has a two-stage capacity that, in conjunction with selection of the appropriate gear ranges, can be used to tailor desired retardation performance to particular duty cycles. The design, development and performance of the AT545R are targeted for school busses and motorhomes, though many other users will find distinct vehicle control advantages with this low cost, compact retarder. The development from concept through production implementation will be discussed in this paper.

The 40-plus year history of the off-highway automatic transmission has been characterized by change. Ever-increasing demands in the marketplace have caused an evolution of design and features in transmissions to maintain competitive advantage. Allison Transmission's new models, CL(B)T-5963 and CL(B)T-6063, are being released to improve productivity and driveability. The incorporation of a programmable trim boost feature in the Allison Transmission Electronic Controls makes possible improved shift quality that will increase driver comfort. The addition of a two-speed reverse allows for a deep ratio reverse that helps provide ample pulling power to negotiate through severe conditions, and a shallow ratio to give increased speed in reverse that will help reduce cycle time.