description
Specification for High Speed Helical Gear Units
ANSI/AGMA 6011-J14
ANSI/AGMA 6011-J14

SCOPE
This high speed helical gear units standard is provided as a basis for improved communication regarding:

  • establishment of uniform criteria for rating;
  • guidance for design considerations; and,
  • identification of the unique features of high speed gear units.

APPLICATION
Operational characteristics such as lubrication, maintenance, vibration limits and testing are discussed. This standard is applicable to enclosed high speed, external toothed, single and double helical gear units of the parallel axis type. Units in this classification are:

  • single stage units with pitch line velocities equal to or greater than 35 meters per second or rotational speeds greater than 4500 rpm;
  • multi-stage units with at least one stage having a pitch line velocity equal to or greater than 35 meters per second and other stages having pitch line velocities equal to or greater than 8 meters per second.

When specific experience exists, this standard may be applied to gear units that operate below the limits specified above.

Marine propulsion, aerospace and vehicle gearing are not covered by this standard.

FOREWORD
[The foreword, footnotes and annexes, if any, in this document are provided for informational purposes only and are not to be construed as a part of ANSI/AGMA 6011-J14, Specification for High Speed Helical Gear Units.]

The first high speed gear unit standard, AGMA 421.01, was adopted as a tentative standard in October, 1943. It contained formulas for computing the durability horsepower rating of gearing, allowable shaft stresses, and included a short table of application factors. AGMA 421.01 was revised and adopted as a full status standard in September, 1947 and issued as AGMA 421.02.

The High Speed Gear Committee began work on the revision of AGMA 421.02 in 1951, which included: classification of applications not previously listed; changing the application factors from “K” values to equivalent Service Factors; revision of the rating formula to allow for the use of heat treated gearing; and develop a uniform selection method for high speed gear units. This Uniform Selection Method Data Sheet became AGMA 421.03A.

AGMA 421.03 was approved as a revision by the AGMA membership in October, 1954.

The standard was reprinted as AGMA 421.04 in June, 1957. It included the correction of typographical errors and the addition of a paragraph on pinion proportions and bearing span, which had been approved by the committee for addition to the standard at the October, 1955 meeting.

In October, 1959 the Committee undertook revisions to cover developments in the design, manufacture, and operation of high speed units with specific references to high hardness materials and sound level limits. The revisions were incorporated in AGMA 421.05 which was approved by the AGMA membership as of October 22, 1963.

The significant changes of 421.06 from 421.05 were: minimum pitch line speed was increased to 5000 feet per minute (25 meters per second); strength and durability ratings were changed; and some service factors were added. AGMA 421.06 was approved by the High Speed Gear Committee as of June 27, 1968, and by the AGMA membership as of November 26, 1968.

ANSI/AGMA 6011-G92 was a revision of 421.06 approved by the AGMA membership in October, 1991. The most significant changes were the adaptation of ratings per ANSI/AGMA 2001-B88 and the addition of normal design limits for babbitted bearings. ANSI/AGMA 6011-G92 used “application factor” and not “service factor”.

ANSI/AGMA 6011-H98 was a further refinement of ANSI/AGMA 6011-G92. One of the most significant changes was the conversion to an all metric standard. The rating methods were changed to be per ANSI/AGMA 2101-D04 which is the metric version of ANSI/AGMA 2001-D04. To provide uniform rating practices, clearly defined rating factors were included in the standard (ANSI/AGMA 6011-H98). While some equations slightly changed to conform to metric practices, no substantial changes were made to the rating practice for durability and strength rating. In addition, minimum pitch line velocity was raised from 25 m/s to 35 m/s and minimum rotational speed increased to 4000 rpm.

AGMA had reverted to the term “service factor” in their standards, which was reflected in ANSI/AGMA 6011-H98. The service factor approach is more descriptive of enclosed gear drive applications and can be defined as the combined effects of overload, reliability, desired life, and other application related factors. The service factor is applied only to the gear tooth rating, rather than to the ratings of all components. Components are designed based on the rated power and the guidelines given in this standard.

In continued recognition of the effects of scuffing in the rating of the gear sets, additional information on scuffing resistance was added to annex B of ANSI/AGMA 6011-H98.

AGMA 427.01 was withdrawn. The information found in AGMA 427.01 was included in annex D of ANSI/AGMA 6011-H98.

ANSI/AGMA 6011-I03 was a further refinement to ANSI/AGMA 6011-H98. Symbols were changed where possible to conform with ANSI/AGMA 2101-D04 and ISO standards. The minimum rotational speed was increased to 4500 rpm. Helix angle limits were changed, and a minimum axial contact ratio was added. The L/D limits were changed, and use of modified helices is encouraged based on the use of predicted rotor deflection and distortion. Bearing load design limits also changed. For gear tooth accuracy, reference was made to ANSI/AGMA 2015-1-A01 rather than to ANSI/AGMA 2000-A88. The Zn and Yn life factors now have a maximum rather than a minimum limit when the number of load cycles exceeds 1010. A table of dynamic factor as a function of accuracy grade was added. References to AGMA oil grades were removed; now only ISO viscosity grades are listed. To facilitate communications between purchaser and vendor, an annex with data sheets was added.

Realistic evaluation of the various rating factors of ANSI/AGMA 6011-I03 required specific knowledge and judgment which come from years of accumulated experience in designing, manufacturing and operating high speed gear units. This input has been provided by the AGMA High Speed Gear Committee.

The first draft of ANSI/AGMA 6011-I03 was made in May, 2001. It was approved by the AGMA membership in October, 2003. It was approved as an American National Standard on February 12, 2004.

ANSI/AGMA 6011-J14 is a further refinement of ANSI/AGMA 6011-I03. For flank tolerance classification, previously referred to as accuracy grade or quality number, the referenced quality standard has been changed to ANSI/AGMA ISO 1328-1-B14.

This revision expanded the definition section and provides detailed attention to improving quality and reliability of high speed gearing. The most notable changes are:

  • normative referral to material requirements in accordance with AGMA 923-B05 replacing ANSI/AGMA 2101-D04;
  • tightened controls on allowable and recommended filtration of lubricants;
  • clarified test requirements and test options;
  • eliminated the rotor dynamics annex and transferred it for adoption to the Sound and Vibration Committee;
  • expanded the annex on systems considerations for high speed gears;
  • introduced new material in gear efficiency annex eliminating a specific method for determining mesh and windage losses;
  • added an annex on metallurgical consideration for high speed gearing;
  • added an annex on lubrication considerations;
  • added an annex on procedures for assembly and functional testing of gearboxes.

The first draft of AGMA 6011-J14 was made in May, 2011. It was approved by the AGMA membership in July 28, 2014. It was approved as an American National Standard on August 8, 2014.

Suggestions for improvement of this standard will be welcome. They may be submitted to tech@agma.org.

NORMATIVE REFERENCES
The following standards contain provisions that, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.

  • AGMA 915-1, Inspection Practices -- Part 1: Cylindrical Gears -- Tangential Measurements
  • AGMA 923-B05, Metallurgical Specifications for Steel Gearing
  • AGMA 925-A03, Effect of Lubrication on Gear Surface Distress
  • ANSI/AGMA 1010, Appearance of Gear Teeth - Terminology of Wear and Failure
  • ANSI/AGMA ISO 1328-1-B14, Cylindrical Gears - ISO System of Flank Tolerance Classification - Part 1: Definitions and Allowable Values of Deviations Relevant to Flanks of Gear Teeth
  • ANSI/AGMA 2101-D04, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth
  • ANSI/AGMA 6000-B96, Specification for Measurement of Linear Vibration on Gear Units
  • ANSI/AGMA 6001-D97, Design and Selection of Components for Enclosed Gear Drives
  • ANSI/AGMA 6025-D98, Sound for Enclosed Helical, Herringbone, and Spiral Bevel Gear Drives
  • ANSI/AGMA 9005-E02, Industrial Gear Lubrication
  • ISO 4406:1999, Hydraulic fluid power -- Fluids -- Method for coding the level of contamination by solid particles
  • ISO 14179-1:2001, Gears -- Thermal capacity -- Part 1: Rating gear drives with thermal equilibrium at 95°C sump temperature
  • ISO 14635-1, Gears – FZG test procedures – Part 1: FZG test method A/8,3/90 for relative scuffing load carrying capacity of oils
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