scope:

This specification covers the general requirements for servomotors. It is not complete in itself, but should be used in conjunction with MIL-S-81963 which will form an inherent part of this specification.

The nomenclature consists of the item name, followed by a type designation which includes a modification letter and a military part number. All servomotors having the same design nomenclature should be physically, mechanically and electrically interchangeable for all military applications. The type designation is made up of a combination of digits and letters as explained in the following paragraphs. The type designation of 26-volt servomotors should be preceded by "26V". The complete nomenclature of a size 15, 400-hertz servomotor is illustrated in Table I. Nomenclature for new servomotor types will be assigned by the Naval Air Systems Command, Department of the Navy. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Systems Engineering and Standardization Department (Code 53), Naval Air Engineering Center, Lakehurst, NJ 08733-5100, by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.

The first two digits designate the maximum diameter in tenths of an inch. If the diameter is not exactly a whole number of tenths, the next higher tenth is used.

The succeeding group of two letters (SM) indicates the function is that of a servomotor.

*NOTE* When a servomotor is included in the same frame with a tachometer generator, the nomenclature for the servomotor will be followed by a second two-letter group (separated by a hyphen) indicating the function of the tachometer generator in accordance with the general specification, MIL-S-22820, Servomotor-Tachometer Generator (for example, SM-DG).

The succeeding digit(s) indicate the frequency of the power source in accordance with the following code:

Supply Frequency Code 60 6 400 4

An upper case letter "A" following the frequency digit indicates the original or basic design of a standard servomotor. The first modification that affects the external dimensions or electrical characteristics of the basic type should be indicated by the upper case letter "B". Succeeding design modifications will be indicated by "C", "D", etc., except the use of letters "I", "L", "O" and "Q" is prohibited.

The part identifying number (PIN) consists of the letter "M", the basic number of the specification sheet (not including the revision letter), an assigned dash number and an upper case suffix letter designating the latest modification letter in the type designation, as shown in Table II.

A servomotor classified as 15SM4C (see Table I) indicates the second modification to the original design of a 115-volt, 400-hertz servomotor whose body diameter is greater than 1.40 inches but not greater than 1.50 inches, and the part identifying number specifies that this servomotor has a splined shaft and terminal connections.

intended Use:

The intended use for servomotors covered by this specification must be in accordance with MIL-S-81963.