Michigan Commercial Driver's License (CDL) Practice Exam

Which of the following provides extra gears on some trucks?

1. Overdrive transmissions

2. Auxiliary transmissions

3. Standard manual transmission

4. Continuously variable transmission

The correct answer is: Auxiliary transmissions

Auxiliary transmissions provide extra gears on some trucks, allowing for enhanced gear ratios and better control of power and speed. This can be particularly useful for large commercial vehicles that require more versatility when hauling heavy loads or traveling on varied terrains. Auxiliary transmissions often come in the form of a second transmission unit that works in conjunction with the main transmission. This setup facilitates more efficient gearing and can improve fuel efficiency, reduce engine strain, and enhance overall performance in various driving conditions. While overdrive transmissions also enable more efficient travel at highway speeds by allowing the engine to operate at lower RPMs, their primary purpose is to reduce engine wear over long distances rather than to provide additional gear ratios for varied driving circumstances. Standard manual transmissions have a fixed number of gears and do not allow for the same level of adaptability as auxiliary transmissions. Continuously variable transmissions (CVTs) offer a different mechanism for gear management, using a system that seamlessly alters gear ratios rather than offering distinct extra gears.