Gender Of Connectors And Fasteners

In electrical and mechanical trades and manufacturing, each half of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. The female connector is generally a receptacle that receives and holds the male connector. Sometimes the terms plug and socket or jack are used, particularly in reference to electrical connectors. In some cases, the pins on the connector may have the opposite nominal gender to the mounted connector, such as the RCA connector.

The assignment is a direct analogy with male/female genitalia, the part bearing one or more protrusions or which fits inside the other being designated male, in contrast to the part containing the corresponding indentations, or fitting outside the other, being designated female. Extension of the analogy results in the verb to mate being used to describe the process of connecting two corresponding parts together.

In some cases (notably electrical power connectors), the gender of connectors is selected according to rigid rules, to enforce a sense of one-way directionality (e.g. a flow of power ''from'' one device ''to'' another). This gender distinction is implemented to enhance safety or ensure proper functionality by preventing unsafe or non-functional configurations from being set up.

In terms of mathematical graph theory, an electrical power distribution network made up of plugs and sockets is a directed tree, with the directionality arrows corresponding to the female-to-male transfer of electrical power through each mated connection. This is an example where male and female connectors have been deliberately designed and assigned to physically enforce a safe network topology.

In other contexts, such as plumbing, one-way flow is ''not'' enforced through connector gender assignment. Flows through piping networks can be bidirectional, as in underground water distribution networks which have designed-in redundancy. In plumbing situations where one-way flow ''is'' desired, it is implemented through other means (e.g. gravity feed or one-way check valves), and not through male-female gender schemes.

Early mentions of the metaphor

*The Talmud describes arrow heads and mating shafts as potentially being either male or female, depending on their construction, i.e. a prong on a male arrow head fits into a hollowed out shaft and vice versa. This is owing to a prohibition on a female shaft, from its susceptibility as a receptacle for impurity, for use as s'chach
*18th-century dictionaries and encyclopedias mention male and female screws or cochleae. A 1736 builder's manual mentions screw genders as metaphors for convex and concave shapes:

If the furrowed surface be convex, 'tis called a ''Male Screw''; if concave, ''a Female''; and where Motion is to be generated, the Male and Female are always join'd.

Mechanical fasteners

In mechanical design, the prototypical "male" component is a threaded bolt, but an alignment post, a mounting boss, or a sheet metal tab connector can also be considered as male. Correspondingly, a threaded nut, an alignment hole, a mounting recess, or sheet metal slot connector is considered to be female.

While some mechanical designs are "one-off" custom setups not intended to be repeated, there is an entire fastener industry devoted to manufacturing mass-produced or semi-custom components. To avoid unnecessary confusion, conventional definitions of fastener gender have been defined and agreed upon.

Modular construction toys

Although this aspect is not highlighted in their promotional literature, several common construction toys embody gendered (and in some cases, genderless) mechanical interconnections. This should not be surprising, since these toys feature the nearly infinite flexibility and versatility of shape that a modular interconnect architecture can enable. Mathematicians have begun to classify well-known construction sets using group theory to study the combinatoric possibilities of structures that can be built.

For example, the canonical LEGO plastic blocks have "female" indentations on the lower surface, and "male" bosses or protrusions on the upper surfaces. Meccano and Erector have many gendered connections, starting with the nut-and-bolt fasteners they use frequently.

Stickle bricks, using interlocking plastic protrusions, are effectively genderless. Lincoln logs use a very simple form of genderless connections. Kapla or KEVA planks are extremely simple genderless systems interconnected only by gravity.

Plumbing

In plumbing fittings, the "M" or "F" usually comes at the beginning rather than the end of the abbreviated designation. For example:
* MIPT denotes ''male iron pipe thread'';
* FIPT denotes ''female iron pipe thread''.

A short length of pipe having an MIP thread at both ends is sometimes called a nipple. A short pipe fitting having an FIP thread at both ends is sometimes called a coupling.

Hermaphroditic connections, which include both male and female elements in a single unit, are used for some specialized tubing fittings, such as Storz fire hose connectors. A picture of such fittings appears in , below.

Downspout

Downspout