MIL-DTL-38999 Series IV Wall Mount Receptacle — Breech Coupling

Specifications

Cross-Reference

Applications

D38999/40 is the wall-mounting flange receptacle of MIL-DTL-38999 Series IV — the breech-coupling generation. Where Series III relies on a triple-start thread that takes several turns to seat, Series IV mates with a 90-degree quarter turn of a breech-lok ring, and the engagement is confirmed by sound, touch and a visible indicator. Mechanically, the mating force is spread across a channelled metal flange rather than concentrated in a thread, which is why Series IV is quoted at a 1000 lb-in bend moment and is the family specified where a connector has to survive heavy cable loads: armoured vehicle harnesses, towed arrays, and mounted equipment exposed to impact. Electrically and environmentally it is the familiar 38999 system — rear-release crimp contacts on the M39029 pattern, shell classes F/W/G/Y/N, 500 mating cycles, and -65 C to +200 C operation — and the shell sizes and insert arrangements intermate with Series III, so a Series IV receptacle can be paired with a Series III plug of the same arrangement.