gearbox.enums

Enumerations for the discrete choices that gear standards define as tables or categories.

Every enum accepts the legacy value (integer or string code used by earlier releases and by the standards’ tables), so Crowning(1) and MaterialType("St") keep working.

class MaterialType

Bases: str, Enum

Material groups of ISO 6336-5 (value = code used in the standard).

NORMALIZED_STEEL = 'St'

Structural / normalized steel.

THROUGH_HARDENED_STEEL = 'V'

Through-hardened (quenched and tempered) wrought steel.

NITRIDED_STEEL = 'NT'

Nitriding steel, gas nitrided.

THROUGH_HARDENED_NITRIDED_STEEL = 'NV(nitr)'

Through-hardening steel, nitrided.

NITROCARBURIZED_STEEL = 'NV(nitrocar)'

Through-hardening steel, nitrocarburized.

__new__(value)

class Crowning

Bases: IntEnum

Lengthwise crowning of the teeth (AGMA 2001 factor C_mc).

__new__(value)

class AssemblyCondition

Bases: IntEnum

Mesh alignment condition (AGMA 2001 factor C_e).

IMPROVED = 1

Alignment improved at assembly (shimming, lapping, …) or compatible with running-in (C_e = 0.8).

NOT_IMPROVED = 2

All other conditions (C_e = 1.0).

__new__(value)

class GearingType

Bases: IntEnum

Quality of the gear unit / casing (AGMA 2001 mesh alignment factor C_ma).

__new__(value)

class ShaftArrangement

Bases: IntEnum

Position of the pinion on its shaft: selects the constant K' (ISO 6336-1, figure 13).

The numeric values are those of earlier releases. s is the pinion offset from the mid-span and l the bearing span; the figure applies for s/l < 0.3.

BETWEEN_BEARINGS_TOWARDS_TORQUED_END = 1

K' = 0.48 with stiffening, 0.8 without.

Type:

Figure 13 a)

BETWEEN_BEARINGS_AWAY_FROM_TORQUED_END = 2

K' = -0.48 with stiffening, -0.8 without.

Type:

Figure 13 b)

OVERHUNG = 3

pinion outside the bearing span, K' = 1.33.

Type:

Figure 13 c)

TWO_GEAR_SHAFT_TORQUE_ON_SAME_SIDE = 4

two gears on the shaft, torque paths on the same side, K' = -0.36 with stiffening, -0.6 without.

Type:

Figure 13 d)

TWO_GEAR_SHAFT_TORQUE_ON_OPPOSITE_SIDES = 5

two gears on the shaft, torque paths on opposite sides, K' = -0.6 with stiffening, -1.0 without.

Type:

Figure 13 e)

__new__(value)

class LeadModification

Bases: IntEnum

Helix (lead) modification of the mesh: selects B1 and B2 (ISO 6336-1, table 12).

The numbering is that of the 2019 edition, which added case 3; the 0.1.x values 3, 4 and 5 are now 4, 5 and 6.

NONE = 1

B1 = 1.0, B2 = 1.0.

CENTRAL_CROWNING = 2

B1 = 1.0, B2 = 0.5.

Type:

Central crowning only, C_beta = 0.5 f_ma

CENTRAL_CROWNING_WITH_SHAFT_DEFLECTION = 3

B1 = 0.5, B2 = 0.5.

Type:

Central crowning only, C_beta = 0.5 (f_ma + f_sh)

__new__(value)

HELIX_CORRECTION = 4

B1 = 0.1, B2 = 1.0.

Type:

Helix correction only

HELIX_CORRECTION_AND_CENTRAL_CROWNING = 5

B1 = 0.1, B2 = 0.5.

END_RELIEF = 6

B1 = 0.7, B2 = 0.7.

class FlankModification

Bases: float, Enum

Profile and lead modification of helical gear sets: f_ZCa of ISO 6336-2, table 3.

The member value is f_ZCa; Z_B = Z_D = sqrt(f_ZCa) for eps_beta >= 1.

__new__(value)

OPTIMIZED_BY_3D_ANALYSIS = 1.0

Modifications designed with a 3D load distribution program; maximum stress near mid-height of the flank and an essentially uniform stress distribution.

SUITABLE_MODIFICATIONS = 1.07

Suitable flank modifications according to the manufacturer’s experience.

NONE = 1.2

Helical gear sets without flank modifications.

class DynamicFactorMethod

Bases: str, Enum

Method used to obtain the dynamic factor K_v of ISO 6336-1 (clause 6).

__new__(value)

METHOD_B = 'B'

Resonance analysis with the stiffness of the mesh (6.5).

METHOD_C = 'C'

Simplified formula by tolerance class (6.6); spur gears and helical gears alike.

class CutterType

Bases: str, Enum

Generating tool of a gear (selects the root fillet model of ISO 6336-3 clause 6.2).

__new__(value)

HOB = 'hob'

Hob or rack-type cutter (clause 6.2.3); also the default of the AGMA geometry factors.

SHAPER = 'shaper'

Pinion-type shaper cutter with Tool.cutter_teeth teeth (clause 6.2.4).

class Standard

Bases: str, Enum

Calculation standard used by the optimisation helpers.

__new__(value)