CAUTION NOTICE: AGMA technical publications are subject to constant improvement, ANSI/AGMA D04, Fundamental Rating Factors and Calculation. Credit line should read: “Extracted from ANSI/AGMA. Standard D04 or -D04 Fundamental Rating Factors and Calculation Methods for Involute Spur. Citations should read: See ANSI/AGMA D04, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear.
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Many of these factors have been empirically developed from accumulated experience. Effects of modified tooth proportions and load sharing avma considered.
Type B indicates only hardening of flanks extending to the form diameter.
Centrifugal and thermal distortion should be determined similarly and also combined to give the final total distortion or gap between the mating gear flanks. It is a function of the backup ratio, mB, or the ratio of the rim thickness below the tooth root, tR, as compared to the tooth whole depth. This standard is intended for use by the experienced gear designer, capable of selecting reasonable values for the factors.
The formulas evaluate gear tooth capacity as influenced by the major factors which affect gear tooth pitting and gear tooth fracture at the fillet radius.
New Refinements to the Use of AGMA Load Reversal and Reliability Factors
Therefore, Equation 24 can be rewritten to only have a positive value result as:. A major problem occurs in the calculation of the deflections.
Wear in high speed applications could be catastrophic where the magnitude of dynamic loading that can occur from nonconjugate gear tooth action is excessive. Allowable stress numbers in this standard are based on cycles, 99 percent reliability and unidirectional loading. The ratings of both pinion and gear teeth must be calculated to evaluate agmaa in geometry factors, number of load cycles, and gama properties.
It is affected primarily by the correctness of pinion and gear leads. It also reflects a change to clause 10, dealing with the relationship between service factor and stress cycle factor. The standard states that for fully reversing loading conditions on a gear, where the critical point on the fillet sees both a full tensile and nearly equivalent full compressive load in the agmaa rotation cycle, the allowable bending stress number is adjusted to only 70 percent of its value.
It should not be used with other gear calculation methods, unless there is sufficient knowledge and experience to make a satisfactory conversion between methods. This iterative agja of solution is well suited to computer analysis.
A normalized reliability level means that both endurance limits must be at the same statistical reliability level from Table 2. Figure 16 shows suggested values for allowable yield strength for through hardened steel.
Mixing factors from different standards can result in an 2101-d40 design. However, as load is applied, cantilever bending deflection of the wgma tooth as well as Hertzian deflection occurs and this localized contact is spread across some percentage of the active face width.
As the extent of these factors become known with more certainty, the value of the factor of safety can be more accurately determined.
Furthermore, the method of measuring the case as well as the allowable tolerance in case depth may be a 1201-d04 of agreement between the customer and the manufacturer. The stress cycle factor adjusts the allowable stress numbers for design lives other than cycles.
The adjustment of the ultimate tensile strength, S utfrom the material property reliability level to some selected normalized reliability level is:. The stress cycle factor accounts for the S–N characteristics of the gear material as well as for the gradual increased tooth stress which may occur from tooth wear, resulting in increased dynamic effects and from shifting load distributions which may occur during the design life of the gearing.
Calculated gear afma are intended to be conservative, but the scatter in actual results may exceed 20 percent. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. Sometimes the gearing is reground after initial pattern checks to correct for the assembly variations.
It depends primarily on: However, it does have some significant differences, especially where S-N curves Woehler lines are concerned. These items in particular, and others in general, are addressed in some standards. In the final form of Equation 17, the normalized reliability level is factored out of the equation.
Reliability levels are used to ensure that the material property data values match each other. Methods and limits for determining acceptable wear at low speeds should be based on the field or test experience of the manufacturer. Initial 2101-r04 occurs in localized, overstressed areas.
The AGMA service factor as traditionally used in gear applications depends on experience acquired in each specific application. Also, there are many possible sources of other overloads that should be considered, such as system vibrations, acceleration torques, overspeeds, variations in system operation, split–path load sharing among multiple prime movers, and changes agmx process applied load conditions.