Parallel shaft transmission

A parallel shaft transmission comprising:

• an input shaft, a first countershaft and an output shaft, which are disposed in parallel with one another;
• a second countershaft, which is provided externally, coaxially and rotatably with respect to said first countershaft;
• an input-shaft first gear, which is provided on said input shaft;
• an input-shaft second gear, which is provided on said input shaft;
• an input-shaft third gear, which is provided rotatably on said input shaft;
• first clutching means, which connects or disconnects said input-shaft third gear to or from said input shaft;
• a first countershaft gear, which is provided on said first countershaft to mesh with said input-shaft second gear;
• second clutching means, which connects or disconnects said first countershaft to or from said second countershaft;
• a second countershaft first gear, which is provided rotatably on said second countershaft to mesh with said input-shaft first gear;
• third clutching means, which connects or disconnects said second countershaft first gear to or from said second countershaft;
• a second countershaft second gear, which is provided rotatably on said second countershaft to mesh with said input-shaft third gear;
• fourth clutching means, which connects or disconnects said second countershaft second gear to or from said second countershaft;
• and
• an output-shaft first gear, which is provided on said output shaft to mesh with said input-shaft third gear.