Traction rollers, point contact (Hertz)

Increase in maximum subsurface stress and matching decrease in allowable normal load for Hertzian POINT-contact rollers (crowned/ball-like contact) under a given traction coefficient Ftan/F.

✓ validated against legacyoriginal: /calculators/t4_1.htm

Traction rollers, point contact (Hertz) — original diagram from /calculators/t4_1.htm

Traction coefficient, Ftan/F

Increase factor, maximum stress under traction, τmax/τmax(μ=0)1

Decrease factor, maximum normal load under traction, F/F(μ=0)1

The mu in [0.6, 0.7) table entry interpolates down towards 0.621 instead of up towards the 1.06 the next bin starts from — a discontinuity/typo present in the original source, preserved exactly (see module header). mu > 1 ("out" in the legacy source) yields NaN for both outputs, matching the original string-arithmetic NaN propagation.

Method & references

Hertzian point-contact rollers with combined rolling and traction (tangential) load — max subsurface shear stress factor interpolated from a lookup table.

The computation is a literal port of the original client-side JavaScript from /calculators/t4_1.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.

Traction rollers, point contact (Hertz) — Engineering ABC