Straight bevel gears are used to connect shafts whose axes intersect at some angle.
Spiral bevel gears fulfil the same purpose but have a better load carrying capacity.
Hypoid bevel gears are closely related spiral bevels but are used where the axes of the two shafts do not intersect.
A helical gear and a worm gear are pressed on the main driving hub. The helical gear meshes with the countershaft gear. The worm gear meshes with two worm gears which drive the camshafts.
The intake and exhaust cam shafts for each cylinder block are driven by worm gears, and are connected by shafts to the lower cam drive worm gear shafts.
The countershaft gear is integral with the countershaft. The countershaft, through bevel gears, drives the two accessory shafts, which in turn drive the fans. The magneto governor and drive gear are also driven off the end of the countershaft.
A set of hypoid bevel gears (with curved teeth) on the crankshaft turn a propeller shaft running vertically up the right side of the cylinder. Another pair of hypoid bevel gears connect the propeller shaft to the camshaft. The complete
assembly is oiled by the engine’s lubrication system.
The total length of the engine is basically determined by the bore, the bore pitch, and the cam gear train layout.
Gear train of the V6TDI engine
Comparison of gear train layout in V12TDI and V10TDI engines
Arrangement of the gear drive