Transmissions and Shifting

Last Edited: July 23, 2017 // by TruckerScape, Inc.

Manual Transmissions

There are obvious differences between manually shifting a personal vehicle through its gears and doing so in a truck.  A truck has more forward gears, required to get to and maintain cruising speed under heavy loads, though some personal vehicles are now equipped with more than the familiar four and five speeds.  A common manual gear configuration in trucks is the ten speed that has a basic five forward speed gear pattern with a low and a high range.  The range is controlled by a lever or switch on the gear shift stick.  There are other gear patterns providing more speeds with an extra “overdrive” range—of these 13 and 18 speeds have been popular configurations.

Manual Shifting

Another difference is the extra effort to manually shift a truck.  Shifting most personal vehicles feels buttery smooth compared to shifting a truck.  A truck’s transmission has to stay in gear under considerable strain of the loads it is moving and a more solid mesh is required.  Shifting into each gear manually requires a more careful effort, whether double clutching or shifting without using the clutch pedal.  I find that heavier loads require more effort to shift.

To upshift with the shift stick and clutch pedal, the driver releases the accelerator pedal and depresses the clutch pedal to shift into neutral, releases the clutch pedal, then depresses the clutch pedal again to shift into a higher gear and resumes depressing the accelerator pedal.  To downshift the driver releases the accelerator pedal and depresses the clutch pedal to shift into neutral, releases the clutch pedal and depresses the accelerator to rev the engine, then depresses the clutch pedal again to shift into a lower gear and resumes depressing the accelerator pedal.  (To depress the clutch pedal a light pumping action is all that is needed, rather than stomping the pedal all the way to the floor.)

Most modern manual transmissions also allow upshifting and downshifting without using the clutch pedal and many drivers choose this method.  They shift when they feel the transmission accepting the gear change, when the engine reaches certain RPM (revolutions per minute) levels.

Automatic Transmissions and Shifting

Most of my experience has been with ten speed manual transmissions, but recently I have been driving automatics with 12 forward speeds.  The latter have been equipped with a lever on the steering column that allows a driver to set cruise control and defer to automatic “fuel saver” shifting  mode with moderate engine braking, to select more aggressive engine braking with accompanying non-fuel-saver auto shifting, or to switch to manual mode with selected engine braking.  I have found that these trucks perform well in most situations, with some minor loss of fine control in backing.

This brief note on shifting is included to make you aware of another aspect of truck driving that requires some extra measure of attention from a driver.  While many drivers still prefer a manual transmission for control in docking maneuvers and other situations, manufacturing innovations are making automatics increasingly more attractive in handling and economic performance.  Broader acceptance of automatics could facilitate this aspect of truck driving.

Takeaways

Shifting gears manually is another truck driving task requiring some attention.

Automatic transmissions are gaining industry favor for handling ease and economic performance.

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