Mil-Spec Connector Coupling Styles

Make a Reliable Connection

A connector’s coupling style describes the way in which the plug and receptacle mate. Bayonet coupling is used in MIL-DTL-26482, MIL-DTL-38999 Series I, and MIL-DTL-38999 Series II. Threaded coupling is employed in MIl-DTL-5015, MIL-DTL-22992 Class L, and MIL-DTL-38999 Series III. MIL-DTL-83723 Series III offers bayonet and threaded coupling. Both styles are designed to remain securely coupled, even during severe vibration, yet be easily disconnected by hand without the need for tools. The shells are polarized with keys and suitable keyways to properly align shells and contacts with their counterparts prior to mating; this prevents mismatched contacts or shell binding during coupling. Once shells have been properly aligned, a clockwise motion of the knurled coupling ring brings the two connector faces together and securely engages both sets of contacts.

Bayonet Coupling

Bayonet coupling is often referred to as a “quick-disconnect” because complete coupling or decoupling is achieved with a quick one-third turn of the coupling ring. Rather than threads, bayonet coupling uses bayonet pins and ramps to mate. The receptacle’s perimeter contains three equally spaced passivated stainless steel bayonet pins that slide through the ramps on the plug’s coupling ring and are spring-loaded into their locking detents. Tactile, audible, and visual cues confirm complete coupling. A clear “click” can be felt and heard when the connectors have fully mated, which is particularly helpful in blind-mate applications. Inspection holes on the coupling ring allow for visual confirmation that the bayonet pins are in their locked position. These connectors are recommended for high-vibration environments, blind-mate applications, or where quick coupling/uncoupling is required.

  • Complete coupling in 1/3 turn
  • Audible & tactile “click”
  • Visual inspection holes
  • Secure under high-vibration

Threaded Coupling

Single-start A-threads are the most traditional and field-proven coupling design, although thread type may vary between connector series. Basic threaded connectors fully couple after four turns of the coupling ring and are recommended for all general-duty applications requiring secure coupling at an economical cost. Lockwire holes are provided along the perimeter of the coupling ring for added safety. D38999 connectors provide an advanced threaded coupling design that features triple-start threads and a ratcheting coupling to ensure positive mating in high-vibration environments.

  • Complete coupling in 4 turns
  • Economical design
  • Simple locking mechanism
  • Lockwire holes on coupling rings