The worm gearbox takes advantage of a big diameter warm wheel. A worm or screw meshes with tooth around the outer circumference in the gearbox. Do not forget that in the neutral position, just the clutch shaft gear is engaged to your countershaft gear. Other gears are totally free, https://gearbox16920.onesmablog.com/the-smart-trick-of-gearbox-that-no-one-is-discussing-74400619