Countershaft
ahd-5
noun.
An intermediate shaft between the powered and driven shafts in a belt drive.
The Century Dictionary and Cyclopedia
noun.
A shaft driven by a band or gearing running from another opposite and parallel shaft.
the GNU version of the Collaborative International Dictionary of English
noun.
An intermediate shaft; esp., one which receives motion from a line shaft in a factory and transmits it to a machine.
Wiktionary, Creative Commons Attribution/Share-Alike License
noun.
A
jackshaft
.
Word Usage
"Suzuki fine-tuned the R450 for 2009 by adjusting the ECU programming and cam profiles to make the engine perform even better at low - and mid-rpm range and also added a new countershaft for improved gear-shift feel."