What are the Different Types of Connector Locking Mechanisms?

Most connectors are equipped with a locking mechanism or ‘coupling system’ that allows the mating halves to be fixed together securely. This mechanical system holds the connectors in place to ensure a continuous connection, preventing accidental uncoupling.

With so many types of electrical connectors and specifications available, it can be difficult to find the most reliable option for your applications needs. 

The most popular types of connectors are referred to as circular connectors and rectangular connectors due to their shapes - let’s take a look into the common locking mechanisms available for these formats.

Bayonet locking

Most people will know a bayonet as a weapon – a blade that can be fixed to a firearm – but this military use also inspired the engineering term. A bayonet coupling system uses a plug or pin on one side and a receptacle or hole on the other, which requires rotating to engage or disengage.

Bayonet connectors are easy to operate by pushing the aligned parts together and rotating until an audible clicking sound is heard. Not only is it quick to secure, but it’s also quick to decouple, as a 1/3 turn can swiftly lock or unlock the connector.

As rotation is required, bayonet locking mechanisms are typically used by circular connectors. These durable systems can then be used to transmit power or signals in a variety of applications. Its resistance to shock and vibration makes it ideal for use in outdoor equipment.

Screw locking

Screw locking is another term for threaded coupling, which is a simple and universally recognisable system that allows parts to be tightened to a specific torque. Typically, one part has multiple pins or sockets that insert into the opposing part, and the coupling ring on one half is turned to engage the threads. 

Again, in order to twist the connector and engage the locking mechanism, the connector has to be circular.  However, there are also rectangular connector designs that use screw locking mechanisms, though these operate a bit differently.

Central screw mechanisms for rectangular connectors tend to have guide pins on one part and a central screw on the other, which connect in more of a push-pull style and may have a spring-loaded mechanism to prevent the central screw from loosening under vibration.

Jack screw (or jackscrew) mechanisms for rectangular connectors are most often used with d-sub miniature backshells. Usually, the backshell has a jack screw on either side, and the panel connector houses internal threads for them to mount into. 

Snap-in locking

Lightweight, low-cost, and user-friendly – snap-in mechanisms simply snap into place by gently aligning and forcing the male half into the female counterpart. Separating them is as easy as pulling them apart the same way, but in reverse. 

Also known as snap-on or sometimes slide-on interfaces, the coupled parts are secured in place with a retention mechanism. However, as they are easier to pull apart, there can be a higher risk of accidentally unplugging connectors with this locking style.

This swift disconnect can be useful when fast and frequent coupling and uncoupling is required, such as with electrical equipment testing. This locking mechanism is usually found in circular connectors and implemented in environments with limited space.

Push-pull locking

Also known as push-fit or push-and-press mechanisms, push-pull coupling is a simple yet strong method of securing connectors. The system uses a plug with inner latches that retract as the parts slide together until they slot into grooves with matching profiles inside the receptacle.

With the parts locked into place, you cannot accidentally disconnect them just by pulling. To break the connection, you have to squeeze the connector body and pull at the same time to disengage the latches, or pull back an outer sleeve to access it.

As some of these are rotate-and-pull systems as well as squeeze-and-pull, they are also typically used for circular connectors, though many rely on axial force rather than rotational force. 

Being small and space-saving in addition to easily mated and difficult to accidentally disconnect, this type of connector locking mechanism is often used in busy settings where efficiency is important but unintentional decoupling could have serious consequences, such as healthcare.

Latch locking

A spring latch is a mechanism that prevents two components from moving or separating once they are joined together. Spring compression prevents the parts from disconnecting, as the latch or lever needs to be pulled, pressed, or rotated with the appropriate force and in the right direction to release the connector.

There are various styles of spring latches, from bolts to toggles, and they can be made from a variety of materials, too. Spring latches for circular connectors are often made of metal, particularly steel. These are mostly designed for field use with rapid coupling and high mating cycles.

Latch systems are also available for rectangular connectors, though these are normally much simpler plastic latches designed for low-cost and light-duty applications, as they aren’t as rugged as metal spring latches.

Lever locking

Some rectangular connectors make use of an external latching mechanism rather an internal one, such as a clamp-style lever. This assembly typically uses a pivoting arm that lifts to allow the two halves to connect, then lowers and clicks into place to hold the parts together securely.

One half will have a specifically shaped lever arm, which corresponds to a groove on the other half where it will hold the two together when the lever is engaged. The action of securing the connection is easy and fast, aided by an audible click, and the mechanism then improves the connection’s resistance to shock and vibrations.

This more robust style is suited for heavy duty connectors used in environments with many connectors assembled in rows, and is common in production control and automotive sectors.

Find out more

When browsing the Northern Connectors website, you can filter by locking mechanism type on each category page to narrow down your choices. If you have trouble finding a suitable connector, feel free to call our team of specialists on 01744 815001, or complete our online contact form and we will be in touch at the nearest opportunity.