Gender of connectors and fasteners
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In
The assignment is a direct analogy with male and 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
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. air gaps 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[3]
- 18th-century dictionaries and encyclopedias mention male and female screws or cochleae.[4] 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.[5]
Mechanical fasteners
In mechanical design, the prototypical "male" component is a threaded bolt,
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.[7]
For example, the canonical
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
Hermaphroditic connections, which may 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 § Genderless (hermaphroditic), below. Interchangeable garden hose fittings made by GEKA are also hermaphroditic, relying on a rubber gasket to make the final connection.
Downspout
Ductwork
Electrical and electronic
Although the gender of tubing and plumbing fittings is usually obvious, this may not be true of
Further confusion can be caused by the term "
A connector in a fixed location is a "jack", and a moveable connector is a "plug".[8][10] The distinction is relative, so a portable radio is considered stationary compared to the cable from the headphones; the radio has a jack, and the headphone cable has a plug. Where the relationship is equal, such as when two flexible cables are connected (an "inline" connection), each is considered a plug. Jacks use the reference designator prefix of J and plugs use the reference designator prefix of P.[8][10]
It is common practice to use female connectors for jacks, so the informal gender-based usage often happens to agree with the functional description of the technical standards. However, this is not always the case; often-seen exceptions include a computer's AC Power Inlet and EIA232 DE9 Serial Port, or the male coaxial power jacks for connecting external power adapters to portable equipment.
To summarize, it is considered best practice to use "male" and "female" for connector gender, and "plug" and "jack" for connector function or mobility. [citation needed]
Variant usages
In the United Kingdom, many
For example, in the UK, the connector on the end of a headphone lead is known as a "jack", that plugs into a socket on the main unit. The same usage also generally occurs in Italy, where the English word "jack" is commonly used to indicate the connector on the end of a headphone lead.[citation needed]
In Romania, female connectors are known as mamă ("mother") and male connectors are tată ("father").[citation needed]
Abbreviations and alternate terminology
The standard letters "M" and "F" are commonly used in part numbers to designate connector gender. For example, in Switchcraft XLR microphone or hydrophone connectors, the part numbers are denoted as follows:
- A3F = Audio 3-pin Female connector;
- A3M = Audio 3-pin Male connector.
The terms plug, pin, and prong are also often used for "male" connectors, and receptacle, socket, and slot are used for "female" connectors. In many cases these terms are more common than male and female, especially in documentation intended for the non-specialist. These nearly synonymous terms can cause a fair amount of confusion when the designations are shortened in labels.
For example, a female high-density D-subminiature connector with a size 1 shell can be named DE15F or DE15S (see accompanying pictures). Both terms mean the same thing but could be construed to be completely different items. Similarly, a male standard-density D-sub with a size 1 shell can be named DE9M or DE9P; a female standard-density D-sub with a size 2 shell can be named DA15F or DA15S; a male high-density D-sub with a size 3 shell can be named DB44M or DB44P; and so forth.
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A panel-mountedIEC 60320 C14male connector jack designed to accept AC line power
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A male 50 ohm BNC connector plug. Three circular projections (including the central pin) interlock with two rings of the female jack.
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Triaxial BNC connector, a male plug
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Twinaxial cable connector, a male plug
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Coaxial Type N connector, a male plug
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Female (left) and male weatherproof plugs for photovoltaic solar panels
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This HDMI plug is conventionally assigned to male gender
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Toslink male plug optical fiberconnector
Gender selection in electronic design
Electronic designers often select female jack connectors for fixed mounting on electronic equipment they design. This is usually done because female connectors are more resistant to damage or contamination, by virtue of their concealed or recessed electrical contacts. A damaged motherboard connector can result in the scrapping of an expensive piece of electronic equipment. The risk of damage is reduced by relegating the more exposed male contacts to connecting cables, which can be repaired or replaced at lower cost.
For example, in an RS-232 serial port, the male connector is more mechanically fragile than the female connector.[11] Cost and reliability considerations probably drove the design decision to use female jack connectors on many computer terminals (and some personal computers) for the serial port, despite being in direct violation of the connector gender convention explicitly specified in the RS-232 standard for "DTE" (data terminal equipment) connections. This confusing reversal of the RS-232 connector gender convention has caused many hours of frustration for ill-informed end users, as they tried to troubleshoot non-functional serial port equipment connections.[citation needed]
Safety
In electrical connections where
In the case of consumer-level AC power, connector gender is used to implicitly enforce safe use of power connectors. Because of this consideration, it is illegal under electrical code to make or use any gender changers to connect AC line power to consumer-level equipment.
A double-ended male connector for utility-supplied ("mains") electrical power is extremely dangerous, and sometimes is called a suicide cable or widowmaker cord.[12] Some hardware shops explicitly refuse to make or sell them when asked by customers who have mistakenly hung a string of Christmas lights backwards and wish to connect the socket end to a wall socket,[13] or who intend to connect a generator or inverter to their home's electrical circuit in the event of a utility power outage.[12] The exposed prongs on the live end of the cable pose serious electrical shock and fire hazards, and when improperly used in a generator setup may cause the equipment to burn out when utility power is restored.[12] It can also backfeed power into the grid, potentially damaging utility equipment or even electrocuting linemen attempting to restore power.
Similarly, an exposed connection on a jumper cable for a 12V automotive battery can be hazardous, because of the potentially high current and energy involved. Accidental shorting of the wire to vehicle ground can cause sparks, rapid heating, or even a battery explosion.
In
An example of a design tradeoff in power connector selection is a coaxial power connector, which is usually set up so that power is fed from the female plug into the male jack (which is typically a part of the electronic device accepting the power). Although the plug is female, with a partially recessed center contact, it is still possible for casual accidental contact with a metallic object to short-circuit the power source. Depending on the design of the power adapter, it may react to a short circuit by shutting down temporarily, or instead by blowing out an internal safety fuse.
In this example, the marginal reliability of the connector choice was deemed to be acceptable by the equipment designer, since the power adapter supplies low voltage that does not pose an electric shock hazard. The potential fire hazard from accidental short-circuiting is addressed by the internal safety fuse, although this requires that a failed power adapter must be completely replaced. In a different design, if the power adapter were intended to supply a voltage sufficient to cause electrical shock, the semi-exposed center contact of the female plug would be considered unacceptably hazardous, requiring a different choice of power connector.
Ambiguous gender
Some electrical connectors are hermaphroditic because they include both male and female elements in a single unit intended to interconnect freely, without regard for gender. See the discussion of genderless connectors in this article for more detailed information.
As an additional complication, certain electronic connector designs may incorporate combinations of male and female pins in a single connector body, for mating with a complementary connector with opposite gender pins in corresponding positions. In these unusual cases, gender is often defined by the shape of the connector body, rather than the mixed-gender connector pins and sockets. These types of connectors are not strictly speaking hermaphroditic, since mating connectors are not freely interchangeable. An informal term that has been used for these connectors is "bisexual", in addition to the more official terminology, mixed-gender. Thus, for example, one can have a mixed-gender female plug that connects to a mixed-gender male jack (though a reversed gender assignment of connectors would be a more typical design choice in this example).
Male connector pins are often protected by a shell (also called a shroud, surround, or shield), which may envelop the entire female connector when mated. RF connectors often have multiple layers of interlocking shells to properly connect the shields of coaxial and triaxial cable. In such cases, the gender is assigned based on the innermost connecting point. With the exception of reverse polarity BNC or TNC, where the outer shell determines the gender and the innermost connecting points are opposite to a standard connector, for example a female RP-TNC connector has a solid innermost pin.
Another ambiguous situation arises with the connectors used for
A casual glance at a USB "Type A" plug connector may give the false impression that it is hermaphroditic. However, a physical attempt to mate two USB "Type A" cables with each other reveals the fact that the connectors will not interconnect. Classifying according to mathematical
An example of a connector where the contacts themselves are hermaphroditic is the ELCO Varicon, wherein the contacts are bifurcated in recessed cross-shaped wells, and mate with one another axially at a 90 degree rotation. In this example, the plugs have the contacts oriented transversely and the sockets are arranged longitudinally.
Genderless (hermaphroditic)
By definition, a
Another closely related type is the stackable connector for electronics, which typically has male pins on one surface and complementary female sockets on the opposite surface, allowing multiple units to be stacked up like plastic milk crates. Examples of this include stackable banana plugs, and interconnect cables specified for the IEEE-488 instrumentation bus. Stackable mezzanine bus connectors are used on some modular microcomputer accessory boards for systems such as the Arduino add-on daughterboards called "shields". The older PC/104 embedded PC modules use a similar stackable format for interconnection. Stackable connectors are not classified as hermaphroditic in the strictest sense, but are often described as such in looser usage.
The hermaphroditic design is useful when multiple complex or lengthy components must be arbitrarily connected in various combinations. For example, if hoses have hermaphroditic fittings, they can be connected without having to pull a lengthy hose and reverse it because it has the wrong gender to connect to another hose. Some military fiber optical cables also have hermaphroditic connectors to prevent "wrong gender" connector problems in field deployments. In a similar fashion, railcars are usually equipped with hermaphroditic railway coupling mechanisms that allow either end of the vehicle to be connected to a train without having to turn the railcar around first. For the same reason, several
In the absence of genderless connectors, gender changer fittings might be used to enable certain connections. The designer of a connection system may use one or both schemes to allow arbitrary connectivity, or even combine both schemes into a single system.
When an enforced sense of unidirectionality or "one-way flow" is required for safety or other reasons (for example, AC electrical power connections), a strict assignment of connector genders is implemented to prevent undesired configurations, and gender changers are banned.
Some commonly seen examples of hermaphroditic connectors include the
Some
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Hermaphroditic or genderless "claw" type hose connectors
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IBM Token Ringhermaphroditic connector with locking clip
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SAE hermaphroditic connector used for 12 V DC power
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GR-874 hermaphroditic coaxialRF connector
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Androgynous Peripheral Attach System spacecraft docking mechanism
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Anderson Powerpole 15/30/45 ampere genderless housings and contacts
Gender changers
Devices used for mating two connectors of the same gender have a wide variety of terms, including for example: "gender changer", "gender mender", "gender bender", and "gender blender".[16] A specific gender changer can be referred to by either the gender of its connectors, or the gender which it is designed to connect to, resulting in a thoroughly ambiguous terminology. Thus a "male gender changer" might have female connectors to mate two male ends, or male connectors to mate two female ends.
Adding to this potential for confusion, some gender changers also combine additional functions such as cross-over pin-outs. Active cables may incorporate embedded systems for communications protocol or logic level changes, which technically makes them "adapters", but this distinction is sometimes neglected in marketing materials or common usage.
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DA15 and DB25 D-subminiature gender changers
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A female to female BNC connector
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Pipe nipple male to male threaded pipe coupling
Examples
- Coaxial power connector, for low-voltage DC connections
- A power cord on an appliance terminates in a (male) plug; it connects to a (female) socket in a wall or on an extension cord.
- signals are normally terminated, at both ends, in a connectorcomprising an inner pin and an outer fixed or rotating shell; these are conventionally reckoned as male.
- A threaded nut is female and a bolt is male.
- Connectors for air brake hoses on heavy trucks and railroad equipment use genderless "gladhand connectors". In railroad air brake use, this makes the orientation of rolling stock irrelevant, and is used with the standard North American railroad coupler that connects cars together, also genderless.
See also
- Mating connection
- Piping and plumbing fittings
- Screw thread
- Sex bolt
- shipping containers
References
- ^ Simon Unwin: Metaphor: an exploration of the metaphorical dimensions and potential of architecture. Routledge 2019, p. 40.
- ^ Huggins, John S. (15 July 2009). "Jack/Plug – Jack, Plug, Male, Female Connectors". An Engineer's Review. Retrieved 1 July 2019.
- ^ Goldwurm, R. Hersh, Ed. Talmud Bavli: Tractate Sucah I, Schottenstein Edition. Brooklyn, NY: Mesorah Publications Ltd.
{{cite book}}
: CS1 maint: multiple names: authors list (link)Gemara p.12b - ^ Universal etymological english dictionary, London 1731, p. 180.
- ^ Richard Neve: Neve's The city and country purchaser and builder's dictionary, London 1736, p. 312; Google Books
- ^ "What are the different types of nuts and bolts?". www.essentracomponents.com. Retrieved 2023-03-07.
- ^ Calegari, Danny (2 December 2011). "Laying train tracks". Geometry and the imagination. Retrieved 2023-02-05.
- ^ a b c Graphic Symbols for Electrical and Electronics Diagrams (including Reference Designation Letters). IEEE. 1975.
- ^ Standard Reference Designations for Electrical and Electronics Parts and Equipments: IEEE-200-1975 (Reaffirmed 1988): Section 4.1.5.3. IEEE and ANSI, New York, NY. 1975.
- ^ a b c Reference Designations for Electrical and Electronics Parts and Equipment: ASME Y14.44-2008 : Section 2.1.5.3 (2). ASME, Fairfield, NJ. 2008.
- ^ Roedy Green. "RS-232C".
- ^ a b c Stanger, Tobie (20 October 2022). "Why 'Suicide' Extension Cords Are So Dangerous". Consumer Reports. Retrieved 17 November 2022.
- ^ Marco, Meg (18 March 2009). "Silly: ACE Hardware Is Tired Of People Asking For Double Ended Male Adapters". consumerist.com. Archived from the original on 2009-03-18. Retrieved 2 November 2021.
- ^ Live Sound International. Archives, April 2003. Connect Corner: The ins and outs of multipin connector designs. Peter Janis, Cabletek.
- ^ "EDAC. 516 Series Plug & Receptacle Rack & Panel Connectors with EDACON Hermaphroditic Contact Mating Design". Archived from the original on 2009-02-26. Retrieved 2008-09-30.
- ^ Jargon File: gender mender