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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Controlling section size considerations for through hardened gearing. In any design it is critical to make allowances for unknown variables in materials, machining tolerances, loading.
Moore rotational beam tester, as shown in Figure 1. Bending strength is measured in terms of the bending tensile stress in a cantilever plate and is directly proportional to this same load. In gear design, however, service factors or overload factors have been used for this uncertainty.
These loads must be included with other externally applied forces in the overload factor, Ko. But in view of the limited data, it is presented as two straight lines with a knee at 1. This calculation can also be used for every other cylindrical gear configuration including planetary stages. For wide face gears, when methods for careful lead matching or lead corrections to compensate for deflection are employed, it may be desirable to use an analytical approach to determine the load distribution factor.
The use of the 0. When the gap in a double helical gear set is other than the gap required for tooth manufacture, for example in a nested design, each helix should be treated as a single helical set. The calculation of an accurate analytical load distribution across the face width of a spur or helical gear is a very complex and tedious process with many influencing factors. Designs which have high crowns to centralize tooth contact under deflected conditions may not use this method.
They are based on unity overload factor, 10 million stress cycles, unidirectional loading and 99 percent reliability. Experimental data from actual gear unit measurements are seldom repeatable within a plus or minus 10 percent band. The Association intends to continue working to update this Standard and to incorporate in future revisions the latest acceptable technology from domestic and international sources. However, it does have some significant differences, especially where S-N curves Woehler 2101-f04 are concerned.
The maximum controlling section size for a steel is based principally on hardenability, specified hardness, depth of desired hardness, quench rate and tempering temperature. These fundamental rating formulas are applicable for rating the pitting resistance and bending strength of internal and external spur and helical involute gear teeth operating on parallel axes.
If the failure rate is specified in terms of the PPM defective, the reliability factor can be estimated as:.
Variations in microstructure account for some variation in gear capacity. Substantial agreement means much more than a simple majority, but not necessarily unanimity. In this case the calculation must be performed using the graphical method. Lloyd’s register, classification for ships Calculation guideline for ships’ gears The root profiles are stepped or irregular.
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. Requests for interpretation of agmw standard should be addressed to the American Gear Manufacturers Association.
The fully reversing bending endurance limit of a material may be found from testing gears or may be found in publications for gears. The dynamic factor, Kv, does not apply to resonance. The grade cleanliness requirements apply only to those portions of the gear material where the teeth will be located, to a distance below the finished tip diameter of at least two times the tooth depth.
The surface condition factor can be taken as unity provided the appropriate surface condition is achieved. This is equivalent to a load reversal factor of 0. It includes tables for some common tooth forms and the analytical method for involute gears with generated root fillets.
Other sources of damping include the hysteresis of the gear shafts, and viscous damping at sliding interfaces and shaft couplings. This AGMA Standard and related publications are based on typical or average data, conditions, or applications.
Using large radii in the corners of the keyway or spline will help reduce the stress concentration and using a ductile not brittle material with good fracture toughness will also help.
The stress on a gear tooth on an idler or planet gear can also be considered to be fully reversing in the same way as the rotating shaft of Figure 1.
New Refinements to the Use of AGMA Load Reversal and Reliability Factors
Essentially in gears, this only occurs on idler gears or planet gears. This calculation is also performed using Method B.
The gear rating may be limited by either pitting resistance or bending strength for the selected grade and its core hardness requirement. The fatigue failure of any material can be characterized on an alternating versus mean stress diagram as depicted in Figure 4. The influencing parameters can be categorized into four groups, all of which are normal to the manufacturing 2101-v04 but still cause face misalignments of the mating gear teeth.
The only difference is that the stress may not be a sinusoidal-type pattern as much as a load-unload-reverse-load-unload situation e.
These items in particular, and others in general, are addressed in some standards.
Interference exists between tips of teeth and root fillets. For the fully reversing bending condition, the mean stress is 0. The dynamic factor, Kv, does not account for gear pair resonance, and operation in this regime is to be avoided. The alloy for the part is chosen Teeth from the quenching property of the equivalent round bar having a diameter equal to the 22101-d04 section size. It is now greater than 1.