Shifting Gears
This domain tests safe gear selection for manual and automatic transmissions, especially on grades. The exam looks for progressive shifting, engine-speed control, and avoiding coasting or clutch abuse.
Manual transmission rules
Start in a low gear and shift progressively. Match engine speed to road speed; do not lug the engine or over-rev it. Double-clutching is the standard technique for non-synchronized heavy transmissions. Keep the clutch fully engaged while driving-do not ride the clutch or rest your foot on the pedal. Never coast in neutral; you lose engine braking and acceleration control.
Grades and automatics
Before descending a grade, select a lower gear and let the engine brake help control speed. If rpm climbs toward the governed limit, downshift before the vehicle gains more speed. In an automatic, use the lower range or manual mode for grades; do not rely on the service brakes continuously, which can cause fade.
Worked example
A loaded tractor-trailer approaches a long 6 percent downgrade. At the top, select a gear that holds a safe speed without braking. If speed rises and rpm reaches the governed limit, downshift one gear while speed is still controllable. Use the brakes firmly for short periods to reduce speed, then release. Waiting until the vehicle is already too fast may make a downshift impossible or damage the transmission.
Traps that cost marks
Coasting in neutral to save fuel; holding the clutch halfway; skipping too many gears under a heavy load; and downshifting after the vehicle is already overspeed. On automatics, leaving the transmission in a high range on a steep grade is a common error.