This standard applies to involute splines and spline joints based on reference diameters for connecting hubs and shafts either with a removable connection, a sliding fit or a permanent fit. It lays down the following general characteristics for splines as in this standard: 

a) They have a standard pressure angle of 30°. 

b) The basic rack profile is the same for all pitches, therefore applying a uniform design rule to all profiles. 

c) They have a side fit profile (a diameter fit is permitted in some cases). 

d) Addendum modification is used in order to achieve specific reference diameters. 

e) The fit system includes tolerances for effective form deviations so that the effect of such deviations on backlash is taken into account. The specified range of fundamental deviations and tolerance classes takes due consideration of all requirements. 

Involute spine joints as in this standard are used for connecting hubs and shafts either with a removable connection, a sliding fit or a permanent fit. They have all the characteristics required for centring the parts and transmitting torques, as well as meeting all the requirements for economical manufacturing. 

The theoretical root diameters for hubs and shafts where the dedendum of the basic rack profile, hfP, is 0,55 ⋅ m. The dedendum depends on the manufacturing method used, and can therefore have various values (see DIN 5480-1, Table 3). The root diameters depend on the dedendum.