2011.05.05 Grinding Down My Ego

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Yesterday I spent a whole day out at the Daimler Trucks North America test track in Madras Oregon driving an array of different trucks. Which, primarily, was an opportunity to practice driving the 10 to 18-speed non-synchromesh transmissions.

For those of you not pursing your lips and sucking in a hissing breath of respectful appreciation, I'm guessing there are two major subsets:

  • those of you who drive class-8 trucks and are snickering at me, and
  • those who don't know what I'm talking about.

Back in the early 50's, Porsche introduced a synchronizing system that kept the internal gearing of the transmissions constantly turning at a speed either coupled to the input (engine) or the output (wheels). This allows modern manual transmissions to shift between gears as long as the relative speeds are even somewhat close. Shifting up with one of these babies is as follows:

  1. Simultaneously - lift throttle and disengage clutch.
  2. Move gear shift lever up to next incremental gear. The short duration of this is usually just about right to let the engine slow down to matching speed.
  3. Simultaneously - engage clutch and roll on throttle, feathering each as necessary.

Bada-bing, bada-boom.

Here's how you up-shift a non-synchronized transmission (with double-clutching):

  1. Simultaneously - lift throttle and disengage clutch, careful not to depress the clutch pedal too far thus actuating the internal transmission brake.
  2. Move shift lever to neutral.
  3. Engage clutch.
  4. Apply throttle the exact right amount to keep the transmission internal gears moving such that they are the same speed as the output shaft.
  5. Disengage clutch, again being careful with the internal transmission brake.
  6. Simultaneously - engage clutch, roll on throttle, and move shift lever to next gear. If the engine speed matches the transmission speed and both of those match the output shaft speed, the gear will engage!

The middle bit with the throttle blip is hard, but I can usually manage it. What messes me up is my reflexive clutch action. Years of driving passenger cars has me over-actuating the clutch pedal and hitting that damn internal transmission brake. Very frustrating.

And, frankly, the upshifting is sooo much easier than the down shifting. Because the downshifting makes that throttle-matching bit pretty damn challenging all on its own. Oh, the grinding I committed in those poor trucks. After working at it pretty hard, I was able to accomplish a downshift - but I had to be driving in a manner specifically accommodating to the downshift. Any case where I actually had to slow down, I lost track of gears pretty much immediately, and finding a new one again was purely a matter of luck. And even more horrific gear grinding with each attempt.

I generally consider myself pretty adept at manipulating machinery. Especially cars. Stole the term from Ulrich: machine empathy. It is extremely humbling to have such great difficulty with what I attach so much ego to.