Head shortening

Head abbreviation is a term from gearing and transmission theory . Gears with a shortened tip have a reduced tooth tip height. The relatively seldom performed tip shortening is used for heavily loaded gears if certain problems are to be expected in the operation of a gearbox. Under heavy loads, the engaged tooth is deformed (“it is pushed away”). When the next, still unloaded tooth comes into engagement, the corner of the tooth tip hits the flank of the mating gear tooth. This leads to a significantly louder noise and increased wear. These problems can be avoided by shortening the head. During production, the outside diameter of the gear is reduced in accordance with the desired head shortening, which is very easy to accomplish. The amount of head shortening in millimeters is calculated from the head shortening factor k multiplied by the module, i.e. k · m .

Alternative to head shortening

In order to avoid the mentioned engagement problem, a head flank relief is often used. Here, the tooth is made somewhat thinner in the area of ​​the tooth tip so that the corner of the tooth tip no longer hits the flank of the mating gear too early. With this alternative, you lose nothing of the load-bearing tooth height and it can be easily manufactured on modern tooth flank grinding machines.