MIL-PRF-22710 Switches, Code Indicating Wheel \(Printed Circuit\), Thumbwheel And Push-Button, General Specification ForThis specification covers the general requirements for illuminated and non-illuminated, thumbwheel \(see 6.4.1\), and push-button, printed circuit rotary switches having unsealed and sealed modules and the associated hardware. These switches are designed for low power alternating current \(ac\) and direct current \(dc\) switching applications for use in electronic and communication equipment. Procurement of switches and mounting hardware will require additional data, giving detailed electrical and mechanical requirements, tolerances, and applicable additions and exceptions to the general requirements and tests specified herein \(see 6.2\).

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MIL-PRF-22710H

4.5.22 Life (rotational) (see 3.25). Switches shall be tested in accordance with 4.5.22.1, and when applicable (see

3.1), in accordance with 4.5.22.2.

4.5.22.1 At atmospheric pressure. Switches shall be tested in accordance with method 206 of MIL-STD-202. An

actuating mechanism shall be used that basically duplicates the function of the mechanism described in method 206

for the switches. The following details and exception shall apply:

a. Test potential and load: Each switch section shall be energized by the specified test loads (see 3.1), with

each load applied to approximately the same number of sections. The first and last section shall be

energized with the resistive load of the highest voltage rating. The specified load for each section shall be

wired to the contacts which are subject to making or breaking the circuit during rotation of the switch shaft as

follows:

(1) Nonshorting type section: All contacts.

(2) Shorting type section: Alternate contacts only. The first and last section shall be energized with the

resistive load of the highest voltage rating. The specified load for each section shall be wired to each

contact of the section, which is subject to making or breaking during rotation of the switch shaft. Where

there are insufficient switch sections to accommodate all rated loads, the loads shall be apportioned,

approximately equally, among the other switches being subjected to the life (rotational) test.

b. Cycling and cycle rate: Manually actuated switches shall be cycled at the rate of 10 cycles per minute. At the

option of the contractor, cycling may be interrupted, periodically, after each 5,000 cycles of operation. Each

shaft of concentric shaft switches shall be rotated the total number of cycles prescribed.

c. Test-condition letter: As specified (see 3.1).

d. Operate cycle: The monitoring apparatus shall record the number of operating cycles. The test switches

should be manually operated, and contact resistance readings taken, at the beginning of the test and

immediately following the conclusion of each of the environments listed below, and changes in contact

resistance exceeding the maximum specified shall be noted. Unless otherwise specified (see 3.1), the test

shall be conducted in the following sequences and environments:

(1) 25 percent of the test cycles at room ambient temperature.

(2) 25 percent of the test cycles at maximum rated temperature.

(3) A 2-hour noncycling period at minimum rated temperature.

(4) 25 percent of the test cycles at minimum rated temperature.

(5) 25 percent of the test cycles at room ambient temperature.

4.5.22.2 At reduced barometric pressure. Switches designed for operation above 10,000 feet shall be tested as

specified in 4.5.22.1, and in accordance with method 105 of MIL-STD-202, except that the temperature condition

shall be room ambient. The following details shall apply:

a. Method of mounting: On a vertical corrosion-resistant panel.

b. Test-condition letter: C or D, as applicable (see 3.1).

c. Tests during subjection to reduced pressure: Switches shall be operated at the applicable test loads (see

After the test, switches shall be examined for broken, deformed, displaced, or loose parts.