Stub gear

The fundamental characteristic of a stub gear is a reduced tooth depth = about 3/4 of the normal tooth depth, see figure below.

By this smaller tooth depth the tooth possesses a broader basis and also the moment of flexure resulting from the applied force on the tooth becomes smaller; hence a greater resistance to breakage.

Along with a slight reduction of the dimensions these are the only advantages of the stub gear. On the other hand, the length of the contact line is being severely reduced so the gripping produces more sound, the distribution of the force across the teeth and across the contact areas is less beneficial with natural faster occurring wear of the tooth flanks.

The use of a stub gear is strongly declined and is limited to gears intended for the transmission of a large torque, but that are not constantly in operation. All the more because the production of such gears also requires special tools.

For the metric module stub and the Anglo-Saxon system one rarely exceeds module 6 and DP4 (module 6.35).

The basic features are indicated by different figures for the pitch and tooth depth; a first digit (m) refers to the step followed by a diagonal and again a second digit (m’) that indicates the depth of the teeth. Hence stub module 6/4 means that one has a gear whose pitch is equal to p x 6 and whose depth 4 is one of a regular module.

For the Anglo-Saxon system applies the same spelling: DP8/10, for example, indicates a gear with a step of DP8 x p x p, and DP10 or 3,175 for the tooth depth.

The pressure angle of stub gears is always 20° and the dedendum ± 1.25 x the module.

The following are the formulas for the calculation of the dimensions of a stub gear and the tables with the standardized values.