Bryan Berg drives a semi with a 13-speed transmission, and he’s been double-clutching and shifting gears in his rig for 30 years. He’s not about to start driving a truck that shifts automatically.

A transmission truly lives up to its name: it transmits the motor’s power and torque from engine to driveline and beyond. A manual transmission does so with sets of gears that the vehicle’s driver can ...

Bryan Berg drives a semi with a 13-speed transmission, and he's been double-clutching and shifting gears in his rig for 30 years. He's not about to start driving a truck that shifts automatically.

The new transmissions are now better integrated in the trucks and the computers have gotten more precise, evaluating engine torque, engine speed, vehicle speed and vehicle angle before shifting gears.

The nine- and 10-speed transmissions so popular with fleets are examples of this basic range-type box. To get even more ratios, a “splitter box” can be added behind the range box. This is done with ...