MIL-PRF-94 Resistors, Variable, Composition General Specification ForThis specification covers the variable resistors having a composition resistance element shaped in an arc, and a contact bearing uniformly thereon, so that a change in resistance is produced between the terminal of the contact and the terminal of either end of the resistance element when the operating shaft is turned. These resistors are capable of full load operation \(where maximum resistance is engaged\) at a maximum ambient temperature of 70 degrees C and are capable for continuous operation when properly derated, at a maximum temperature of 120 degrees C \(see 6.9\).

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MIL-PRF-94G

(Copies of this document are available from https://www.ncsli.org/ or from the National Conference of Standards

Laboratories (NCSL) International, 1800 30th Street, Suite 305, Boulder, CO 80301-1026.)

2.4 Order of precedence. In event of a conflict between the text of this document and the references cited herein,

the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and

regulations unless a specific exemption has been obtained.

3. REQUIREMENTS.

3.1 Associated specifications. The individual part requirements shall be as specified herein and in accordance

with the applicable associated specifications. In the event of a conflict between requirements of this specification and

the associated specifications, the latter shall govern (see 6.2).

3.2 Qualification. Resistors furnished under this specification shall be products which are qualified for listing on

the applicable qualified product list (QPL) before contract award (see 4.4 and 6.3).

3.3 Materials. Materials shall be used which will enable the resistors to meet the performance requirements of this

specification. Acceptance or approval of any constituent material shall not be construed as a guaranty of the

acceptance of the finished product.

3.4 Interface and physical dimensions. The resistors shall meet the interface and physical dimensions specified

3.4.1 Operating shaft. All operating shafts shall be of metal construction.

3.4.1.1 Size. The diameter and length of the operating shaft shall be as specified (see 3.1).

3.4.1.2 Style of operating shaft.

3.4.1.2.1 Slotted operating shaft. In no case shall the slots of slotted shafts be deep enough to interfere with shaft

retainers or bearing surfaces. The slot shall be so positioned that the longitudinal centerline of the slot is within �10

degrees of the longitudinal centerline of the contact area (see 3.1).

3.4.1.2.2 Flatted operating shaft. When flattened operating shaft are specified, the flattened portion shall be as

specified in 3.1 and shall be as shown on figure 1. For shafts of D length, the flatted surface shall start 0.031 (0.79 mm)

inches �0.005 inches (0.13 mm) from the retaining ring and extended to the free end of the operating shaft (see 3.1).

FIGURE 1. Position of flatted surface of flatted operation shaft.