Tip circle diameter (specification)

The tip diameter d_a can either be directly specified, or determined according to the following criteria:

Overcut by tool

The tip diameter is cut by the tooth base of the tool.

According to DIN3960

According to DIN3960, the addendum coefficient h_aP* is defined as 1.

The addendum alteration is calculated from the addendum modifications of both rolling partners, the center distance, and the zero center distance. For external gears, the tip diameter becomes smaller. For internal gears, the tip diameter of the ring gear becomes smaller, the tip diameter of the pinion becomes larger.

$d_{\mathit{a}}\mathit{ }\mathit{=}\mathit{ }d\mathit{ }\mathit{+}\mathit{ }\mathit{2}\mathit{(}x\mathit{ }\mathit{\times }\mathit{ }{m}_{\mathit{n}}\mathit{ }\mathit{+}\mathit{ }{h}_{\mathit{a}\mathit{P}}\mathit{ }\mathit{+}\mathit{ }k\mathit{)}$

According to DIN867

According to DIN867, the addendum coefficient h_aP* is defined as 1.

The addendum alteration factor is 0. Otherwise, the calculation is performed as in DIN3960.

Specification of the addendum coefficient h_aP* of the reference gear tooth profile

The program performs internal checks to verify whether the tip circle is compatible with any specified tools or gear pairings. If this is not the case, the geometrically executable tip circle that meets the determining limit criteria is used.

Note on using the tip circle diameter d_a / usable tip diameter d_Na in the load carrying capacity calculation according to DIN 3990:1987 / ISO 6336:1996 / ISO 6336:2006

Some equations use the tip circle diameter d_a, others use the effective tip diameter. From a purely mechanical perspective, the effective tip diameter d_Na should be used exclusively. However, consistency with standards is essential. Therefore, the corresponding equations are used for load carrying capacity calculations according to DIN 3990:1987 / ISO 6336:1996 / ISO 6336:2006.