NPFC - MIL-B-17931
BEARINGS, BALL, ANNULAR, FOR QUIET OPERATION
|Publication Date:||27 July 1987|
This specification covers annular ball bearings, with industry bore codes 00 through 22, and 32 for use in quiet operating (low vibration) machinery.
Ball bearings shall be identified by the standard part numbers designated in 1.2.1, as specified (see 6.2.1). Bearings shall be of the types and classes defined in 1.2.2 as listed for each standard part number.
Standard part numbers for ball bearings shall be as follows: Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 55Z3, Department of the Navy, Washington, DC 20362-5101 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.
The ball bearings specified herein (see 3.4) are of the following types and classes:
Type 111 - Single row, radial, nonloading groove, both rings same width, metric. Class 1 - Open. Class 2 - Single shield (suffix Z). Class 3 - Double shield (suffix ZZ). Class 7 - Single contact seal (suffix S). Class 8 - Double contact seal (suffix SS). Type 120 - Single row, radial, nonloading groove, both rings same width, sealed (cartridge type without grease plug), metric bore and outside diameter (od), inch width. Type 120 bearings have prefix S3. Class 1 - Noncontact or labyrinth seals. Class 2 - Synthetic contact seals. Type 131 - Single row, counterbore (primarily radial), contact angle 8 degrees 30 minutes - 10 degrees 15 minutes. Self-contained, both rings same width, metric. Class 1 - Single bearing (suffix R). Class 2 - Duplex pair (suffix RD), faces ground for universal mounting, that is, face-to-face (RDF), back-to-back (RDB), or tandem (RDT). Type 133 - Single row, angular contact (contact angle 25 degrees or less), self-contained, both rings same width, metric. Angular contact bearings have prefix 7. Class 2 - Duplex pair (suffix D), faces ground for universal mounting, that is, face-to-face (DF), back-to-back (DB), or tandem (DT). Type 134 - Single row, angular contact (contact angle greater than 25 degrees), self-contained, both rings same width, metric. Angular contact bearings have prefix 7. Class 1 - Single bearing. Class 2 - Duplex pair (suffix D), faces ground for universal mounting, that is, face-to-face (DF), back-to-back (DB), or tandem (DT). Bearings having suffix DF or DB are made for that mounting only.
The Navy code consists of a three-digit basic bearing number with prefix and/or suffix as specified in 1.2.2. The basic bearing number identifies the external boundary dimensions. The first digit of the basic bearing number identifies the bearing series (or weight) as follows:
1 Extra-light (for all types except 120) 2 Light (for all types except 120) 3 Medium (for all types except 120) 4 Heavy (for all types except 120) 5 Light (for type 120 bearings only) 6 Medium (for type 120 bearings only)
The second and third digits of the basic bearing number are the industry bore code. When multiplied by 5, these digits give the bearing bore diameter in millimeters for bore codes 04 and greater (this rule does not apply for bore codes 00 through 03).
The ball bearings covered by this specification are intended for use in low vibration machinery.