Puppy clutch skids on the primary shaft to rotate with it. All the gear on the layshaft is fastened with it.  Once the left-hand Doggy clutch is brought to skid into the remaining with the gearshift lever, it messes with the clutch gear, and also the upper-velocity gear is attained. https://gearbox-auto13321.webbuzzfeed.com/34295802/an-unbiased-view-of-gearbox-auto