What are Push-Pull Circular Connectors?

By Amy Goetzman | January 11, 2022

Meet the Connector: Push-pull Circular Connectors

Push-pull circular connectors feature a spring-action cylindrical sleeve surrounding or within the integral connector housing that self-latches when the connector is pushed into position. The connection is released through a squeeze-and-pull, rotate-and-pull, or other specific unlocking action that prevents accidental disconnection. Push-pull circular connectors are available in numerous sizes, voltages, and pin counts, and in coaxial, triaxial, fluidic, and pneumatic configurations.

Look around any healthcare setting and you will see push-pull circular connectors everywhere. The medical market relies on these versatile, user-friendly, dependable connectors to connect handheld devices and stationary equipment. They aren’t just for healthcare equipment, though; push-pull circular connectors serve the industrial, Test & Measurement, A/V, communication, and other markets where reliability and easy handling are equally important.

The push-pull circular connector was invented by engineer and LEMO Connectors founder Léon Mouttet after he attended a 1954 electronics exhibition in Milan. At the show, he surveyed the standard circular connector selection — mainly screw-thread or bayonet-locking circular connectors — and noticed a problem: Those connector types require time and two hands to mate. Mouttet developed a quick-locking alternative solution, taking inspiration from the spring action used in car cigarette lighters. His new circular connector design eventually became the Push-Pull LEMO B Series connector.

Since then, many connector companies have launched proprietary push-pull circular connectors with unique properties that serve specific markets and applications.

LEMO B Series push-pull circular connector

LEMO’s B Series Push-Pull Connector. When a surgeon told LEMO’s retired sales director Walter Straessle, “If your connector disconnects and we fail the operation, it will be your fault!” Straessle replied, “No problem, it will not disconnect.”

 Handling Advantages

Ergonomic handling is the hallmark of this circular connector type. The push-pull locking mechanism allows users to easily mate or disconnect equipment with just one hand or in blind mating situations. An audible or tactile “click” assures the user that the connection is complete and secure; no double-checking or visual confirmation is needed. This enables users at every skill level to quickly and reliably connect equipment. Keying, color coding, and LED options increase that reassurance.

 

ITT Cannon PL Series push-pull circular connector

ITT Cannon’s PL Series push-pull circular connectors are disconnected by pulling on a release sleeve on the outer shell.

Design Notes

  • Standards No single certification or standard guides the design of push-pull circular connectors, leading to a huge range of variation and very few examples of interoperability across manufacturers. Many push-pull products are designed and tested to meet market-specific standards such as the medical electrical safety standard IEC 60606-1 and the military durability standard MIL-STD-810F.
  • Mating Cycles Push-pull circular connectors are designed to have a minimum of 2,000 mating cycles for plastic versions and 5,000 mating cycles for metal versions, depending on manufacturer.
  • Spacing Since no bulky tools are needed to connect push-pull connectors they may be mounted closely together, as they only require two fingers to grip the shell to connect or disconnect. (Additional clearance is needed for push-pulls that require a twist motion to disconnect.)
  • Materials Metals used for circular push-push shell materials include copper, stainless steel, gold, and alloys. In the medical market, plastic or polymer options are favored for cleanability and aesthetics. The materials used in this market are typically crush-proof as well as able to withstand autoclave, UV sterilization, and other disinfection processes. In some cases, biocompatible materials may be required. Push-pulls used in space and other markets may need to meet outgassing requirements.
  • Ruggedization Push-pull circular connectors and their cable assemblies are available with specific durability attributes to ensure rugged performance in high-reliability and harsh environment applications, including those that feature temperature extremes, radiation, rough handling, chemicals, and other environmental factors.
  • Sealing Many manufacturers offer IP-rated protection against fluid and particulate ingress. Hermetic sealing within the connector can be enhanced with silicone O-rings and flexible polymer jacketing surrounding the cable assembly.
  • Interference Electromagnetic interference (EMI) or radio-frequency interference (RFI) is a significant concern for devices used in environments filled with electronic equipment, such as medical settings and aviation. The use of metal in the shell and ground terminal helps mitigate this concern and enhanced shielding is available from some manufacturers.
binder Subminiature Push-Pull circular connector

binder’s subminiature push-pull connector, suitable for industrial applications, weighs just 8g.

Markets, Sectors, and Applications

Medical (portable, handheld, diagnostic equipment), industrial (automation controls, robotics), Test & Measurement (analyzers, test equipment), A/V (event wiring, broadcast equipment), communications (antennas, radar, radio equipment), automotive (diagnostic and production equipment), mil/aero (soldier-worn equipment, portable devices), transportation (rail signaling, monitoring and control systems)

 

NorComp Quik LOQ push-pull circular connector

NorComp’s QUIK-LOQ push-pull circular connectors are available in a disposable option.

 

Suppliers

The circular push-pull is available in many variations from many manufacturers, including Amphenol Pcd, Bernier, binder, Fischer Connectors, Hirose Electric, ITT Cannon, LEMO, JAE, Molex, Neutrik, NorComp, PEI Genesis, and Samtec.

Some industrial push-pull connectors feature a rectangular or square body, such as HARTING’s PushPull.

 

Related Products

  • Circular DIN Connectors
  • Circular Metric Connectors
  • Circular MIL-Spec Connectors
  • Standard Circular Connectors (screw-type, bayonet locking, etc.)
  • M12-type push-pull connectors (used in rail and industrial applications)

Like this article? Check out our other Meet the Connector, circular connectors, and Market Update articles, our Medical Market Page, and our 2021 Article Archive

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