gearbox.transmission

A pair of meshing gears plus the operating conditions needed for strength calculations.

class Transmission

Bases: object

Gear pair (pinion drives wheel) with its operating conditions.

The pinion is always an external gear; the wheel can be external or internal (Gear.internal). For an internal wheel the signs follow ISO 6336-1: z_2, u, the centre distance and every diameter of the wheel are negative.

pinion

Driving gear (gear 1).

Type:

Gear

wheel

Driven gear (gear 2).

Type:

Gear

lubricant

Lubricant used in the mesh.

Type:

Lubricant

pinion_speed_rpm

Rotational speed of the pinion [rpm].

Type:

float

power_kw

Transmitted power [kW].

Type:

float

design_life_hours

Required design life [h].

Type:

float

application_factor

Application (overload) factor K_A.

Type:

float

min_safety_factor_pitting

Minimum required safety factor against pitting, S_Hmin.

Type:

float

min_safety_factor_bending

Minimum required safety factor against tooth breakage, S_Fmin.

Type:

float

gearing_type

Gear unit quality class, used by the AGMA mesh alignment factor.

Type:

GearingType

temperature_factor

AGMA temperature factor K_T (1.0 up to 250 degF / 120 degC).

Type:

float

reliability_factor

AGMA reliability factor K_R; see gearbox.standards.agma2101.RELIABILITY_FACTORS.

Type:

float

limited_pitting_allowed

Whether limited pitting is acceptable (ISO 6336-2 clause 4). It selects the life factor curve Z_NT of through-hardened and case-hardened steels.

Type:

bool

mesh_load_factor

Mesh load factor K_gamma of ISO 6336-1 (uneven load sharing between several load paths); 1.0 for a single mesh.

Type:

float

dynamic_factor_method

ISO 6336-1 method for K_v (B by default).

Type:

DynamicFactorMethod

measured_dynamic_factor

K_v obtained by Method A (measurement or a dynamic analysis); when given it replaces the calculated one.

Type:

float | None

agma_quality_number

Transmission accuracy level Q_v of AGMA 2001-D04 (5 to 11, higher is more accurate) for the dynamic factor. None estimates it from the ISO 1328 single pitch deviation of the gears.

Type:

int | None

flank_modification

Flank modifications of a helical pair (ISO 6336-2 table 3). Only used for helical gears with eps_beta >= 1 or a partial overlap; the default is the conservative case without modifications.

Type:

FlankModification

property module: float

Common normal module [mm].

property pressure_angle: float

Common normal pressure angle [deg].

property gear_ratio: float

>= 1 for an external pair, negative with an internal wheel.

Type:

u = z2 / z1

property wheel_speed_rpm: float

Rotational speed of the wheel [rpm].

property net_face_width: float

Face width of the narrower gear [mm] (F in AGMA 2001).

For double helical gears it is the width b_B of one helix.

property double_helical: bool

True if both gears are double helical.

property total_face_width: float

2 b_B for double helical gears.

Type:

Face width b of the load-carrying teeth [mm]

property profile_shift_sum: float

x1 + x2.

property working_pressure_angle: float

Transverse working pressure angle alpha_wt [deg].

property reference_center_distance: float

a, centre distance without profile shift [mm]; negative for an internal wheel.

property working_center_distance: float

a_w [mm]; negative for an internal wheel.

property transverse_contact_ratio: float

epsilon_alpha (ISO 6336-2 formula 32, without the active root diameter limit).

With the signed quantities of an internal wheel (negative d_b2 and a_w) the line of action is r_b1 (tan a_a1 - tan a_wt) + r_b2 (tan a_a2 - tan a_wt), as in formulae (32), (36) and (38).

property overlap_ratio: float

epsilon_beta (ISO 6336-2 formula 40, with b_B for double helical gears).

property total_contact_ratio: float

epsilon_gamma = epsilon_alpha + epsilon_beta.

property pitch_line_velocity: float

Tangential speed at the reference circle of the pinion [m/s].

property nominal_tangential_force: float

F_t at the reference circle [N].

property external_load_factor: float

K_A K_gamma, the factors applied to the nominal load before the internal ones.

property line_load: float

F_t K_A / b, the load per unit face width as used by ISO 6336-1 method B [N/mm].

b = 2 b_B for double helical gears.

__init__(*, pinion, wheel, lubricant, pinion_speed_rpm, power_kw, design_life_hours, application_factor=1.0, min_safety_factor_pitting=1.0, min_safety_factor_bending=1.0, gearing_type=GearingType.COMMERCIAL_ENCLOSED, flank_modification=FlankModification.NONE, agma_quality_number=None, temperature_factor=1.0, reliability_factor=1.0, limited_pitting_allowed=False, mesh_load_factor=1.0, dynamic_factor_method=DynamicFactorMethod.METHOD_B, measured_dynamic_factor=None)