Page 17 - Gear Technology Solutions

1.3 Core Diameter at the Pinion Heel

The Special Methods Dimension sheet prints in part 1 the core diameter of the
pinion at the heel (see Figure 1). The core diameter becomes interesting in
case of a low number of pinion teeth. If the tooth count of the pinion is below 4,
then a particular attention has to be paid to the core diameter because the
bending stress at core diameter exceeds the bending stress at the root of the
teeth. GEMS can also generate a fatigue stress calculation which helps to
quantify the critical core bending [2].

Figure 1: Special Methods Dimension-Sheet
part 1, pinion heel core diameter

1.4 Strength Factors

In the past strength factors for SHR, Coniflex and Coniface gearsets have not
been available. In order to allow strength estimations also for those types of
gears, the latest Coleman calculation has been added to the UNICAL
Dimension-Sheet program. Figure 2 shows the J, Q and I-factors. The Q-
factor is the most frequently used factor in the Dimension-Sheet. In order to
obtain the pinion root bending stress in PSI, the Q-factor of the pinion is

2