[says Dean. “Allison automatic transmissions are also becoming popular with heavy haul customers, both for ease of operation and the initial torque multiplication provided by the torque converter.
Volvo Trucks recommends its Volvo I-Shift AMT for heavy-haul trucks. “Powertrain integration and smoother shifting algorithms will reduce driveline shock,” says Felder. “The 13- or 14-speed Volvo I-Shift with crawler gears is a solution for GCW loads up to 220,000 lbs. The deep reduction of the crawler gears provides excellent startability, which reduces the need for a higher axle ratio. This allows a faster rear axle ratio to be paired with the I-Shift with crawler gears, bringing greater fuel efficiency to vocational and heavy-haul when at highway speeds by lowering cruise rpms. Volvo’s heavy-haul software package optimizes shifting for high GCW applications, allowing shifting to occur at higher revs, and enabling drivers to control downshifts.”
Ten-speed manual transmissions, on the other hand, have a 40% step between those gears, and that rpm drop is going to be 500 when you are shifting between them,” says Wrinkle. “So when you have a big, heavy load and you need to keep that momentum up, that rpm drop is hurting you in performance and efficiency.”
