Practice for Enclosed Cylindrical Wormgear Speed Reducers and Gearmotors
ANSI/AGMA 6034-C21
ANSI/AGMA 6034-C21


This standard covers the wear rating and strength rating of wormgearing. This standard applies to the rating and design of enclosed cylindrical wormgear speed reducers and gearmotors having either solid or hollow output shafts and single or multiple reductions that may include other types of gearing used in conjunction with cylindrical wormgearing. The rating and design considerations contained in this standard are valid for rotational speeds of the worm not greater than 3600 rpm and sliding velocities at the mesh of not more than 6000 ft/min.

This standard applies only to cylindrical worm gear meshes where the worm is made of surface hardened steel and the worm wheels are made of bronze provided that all limits of application as outlined in 1.2 are adhered to.

The knowledge and judgment required to evaluate the various rating factors come from years of accumulated experience in designing, manufacturing, and operating gear units. Empirical factors given in this standard are suited to the particular use shown. This standard is intended for use by the experienced gear designer, capable of selecting reasonable values for the factors. It is not intended for use by the engineering public at large.

No limitation is placed on the method of producing the worms and gears, but the tooth form of the gear must be conjugate to the thread form of the worm. See ANSI/AGMA 6022, Design Manual for Cylindrical Worm Gearing.


This standard gives a method for rating and design of specific enclosed cylindrical wormgear reducers and gear motors at speeds not greater than 3600 rpm or mesh sliding velocities not more than 6000 ft/min. It contains power, torque and efficiency equations with guidance on component design, thermal capacity, service factor selection, lubrication, and self-locking features of wormgears. Annexes are supplied on service factors, user recommendations.


The purpose of this document is to provide rating and general design specifications for enclosed speed reducers incorporating cylindrical wormgearing in single or multiple reductions. It covers types of speed reducer designs most commonly made by a number of manufacturers.

The formulas presented in this standard contain terms whose individual values can vary significantly depending on application, system effects, accuracy, and manufacturing method. Proper evaluation of these terms is essential for realistic rating. The knowledge and judgment required to properly evaluate the various rating factors come primarily from years of accumulated experience in designing, testing, manufacturing, and operating similar gear units. The detailed treatment of the general rating formulas for specific product applications is best accomplished by those experienced in the field.

ANSI/AGMA 6034-A87 was a revision of AGMA 440.04 (1971), and in addition contained information for cylindrical wormgear hollow output shaft speed reducers and for cylindrical wormgear gearmotors previously contained in AGMA 442.01 (1965) and AGMA 461.01 (1966). These two standards have been withdrawn.

AGMA 6034-A87 power rating formulas were unchanged from those provided in the now withdrawn AGMA 440.04 (1971).

Service factors which appeared in AGMA 440.04 and AGMA 461.01 were revised and placed in the annex rather than the body of AGMA 6034-A87. These factors for modification of basic power ratings have been determined through experience and are intended as a guide. Suggested service factors for various applications were shown in Appendix A of ANSI/AGMA 6034-A87 as an additional aid.

A draft of ANSI/AGMA 6034-A87 was made in October 1982, and that version was approved by the AGMA membership in October 1987. In March 1988, it was approved as an American National Standard.

ANSI/AGMA 6034-B92, a revision of ANSI/AGMA 6034-A87, updated lubricant recommendations, removed bronze specifications by referring to ANSI/AGMA 2004-B89, Gear Materials and Heat Treatment Manual, plus other minor editorial changes.

ANSI/AGMA 6034-B92 was approved as a revision by the AGMA membership in October 1991.

ANSI/AGMA 6034-C21 is a revision of ANSI/AGMA 6034-B92. It updates the rating and lubrication sections of the standard. The tabulated values for rating factors have been eliminated and replaced by equations from the previous Annex C which was eliminated. Rating equations have had a lubricant factor and strength capacity equations added. Terminology in the lubrication section has been updated.

The first draft of ANSI/AGMA 6034-C21 was created in September 2015. It was approved by the membership in September 2020 and as an American National Standard on April 9, 2021.


The following documents contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions were valid. All publications are subject to revision, and the users of this standard are encouraged to investigate the possibility of applying the most recent editions of the publications listed.

ANSI/AGMA 6022, Design Manual for Cylindrical Worm Gearing

ANSI/AGMA 2004, Gear Materials and Heat Treatment Manual

ANSI/AGMA 1012, Gear Nomenclature, Definitions of Terms with Symbols

ANSI/AGMA 6001, Design and Selection of Components for Enclosed Gear Drives

ANSI/AGMA 6013, Standard for Industrial Enclosed Gear Drives

ANSI/AGMA 9005, Industrial Gear Lubrication

Pages: 43

ISBN: 978-1-64353-092-5

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