gearbox.standards.agma2101._geometry#

Geometry factors I (pitting) and J (bending) of AGMA 908-B89 as used by AGMA 2001-D04.

class GeometryFactors[source]#

Geometry factors of a gear pair.

bending: tuple[float, float] | None#: (J_pinion, J_wheel); None for internal gears (AGMA 908-B89 gives no J).

__init__(pitting, bending)#

require_supported_gears(transmission, *, bending)[source]#

Reject the gear types AGMA 2001-D04 / 908-B89 are not implemented for.

Raises:: ValueError – For double helical gears (the 908-B89 factors are for single helical gears) and, when bending is set, for internal gears: AGMA 908-B89 gives no geometry factor J for them.

geometry_factors(transmission)[source]#

Compute the pitting and bending geometry factors, AGMA 908-B89 / AGMA 2001-D04.

Glossary of the local variables (AGMA 908-B89 notation):

n1, n2: numbers of teeth; nc: teeth of the generating cutter.
mn: normal module, later reused as the load sharing ratio m_N.
cr: operating centre distance over the module (eq. 3.7).
fi_n, fi, fi_r, fi_nr, fi_nl: normal, transverse, operating transverse, operating normal and load-application pressure angles; psi, psi_b, psi_r: reference, base and operating helix angles. All in radians.
f: face width over module; mp, mf: transverse and face contact ratios.
ro1, ro2: outside radii over module; r1, r2: pitch radii; rb1, rb2: base radii; mg: gear ratio; cr: centre distance over module.
c1..c6: lengths along the line of action; pb, pn: transverse and normal base pitch.
rho_1, rho_2: radii of curvature at the point of load; c_psi: helical overlap factor; lmin: minimum length of the contact lines.
rn, rnb, n: virtual spur gear pitch radius, base radius and teeth.
hf, sf, rho_f: tooth root height, thickness and fillet radius of the critical section; kf: stress correction factor; ch: helical factor.