Tandem

{{Short description|Arrangement, one in front of the other}} {{Use dmy dates|date=August 2024}} {{other uses}} [[File:NK Traditioneel Gerij 2014 (21).jpg|thumb|Horses hitched in tandem pulling a carriage]] '''Tandem''', or '''in tandem''', is an arrangement in which two or more animals, machines, or people are lined up one behind another, all facing in the same direction.<ref name=OED>{{OED|Tandem}}</ref> ''Tandem'' can also be used more generally to refer to any group of persons or objects working together, not necessarily in line.<ref name=OED/>

The English word ''tandem'' derives from the [[Latin]] [[adverb]] {{Lang|la|tandem}}, meaning ''at length'' or ''finally''.<ref name=Wordinfo.com>{{cite web | url = http://www.wordinfo.info/words/index/info/view_unit/2083 | title = Tandem | publisher = Wordinfo.com | access-date = 2009-01-28}}</ref> It is a [[word play]], using the Latin phrase (referring to time, not position) for English "at length, lengthwise".<ref>{{cite web |url=https://www.etymonline.com/word/tandem |title=tandem |date=2014-01-14 |first=Douglas |last=Harper |website=[[Online Etymology Dictionary]] |access-date=2022-10-16 }}</ref>

== Horse driving ==

[[File:Beverley Gas Works, Old Hull Road 1910 (archive ref DDX1544-1-11) (28284430335).jpg|thumb|[[Draft horse]]s chain-hitched in tandem; ''carter'' standing in usual position beside rear horse]] When [[Driving (horse)|driving horses]], ''tandem'' refers to one horse harnessed in front of another to pull a load or [[Horse-drawn vehicle|vehicle]]. A tandem arrangement provides more pulling power than a single horse, such as for pulling a heavy load up a steep hill, out of heavy mud or snow, or pulling heavy loads on narrow tracks or through narrow gates and doorways (too wide for a pair of horses side-by-side).{{r|smith|p=52,75}} For example, a Brewer's van fully loaded with 25 barrels might weigh 8 tons, requiring 2 or 3 horses.{{r|walrond79|p=45}}

In ''carting'', when pulling heavy loads with tandem harness, the ''carter'' walks to the left of the shaft horse holding its left rein with his right hand, and holding the reins of the lead horse in his left hand.{{r|attelerenfile}}{{r|walrond79|pp=62-63}}

The harness for the leader (front horse) is slightly different than for the wheeler (rear horse). For instance, the leader doesn't have shafts, so shaft holders are not needed, but often there are straps to support the traces (pulling straps) from sagging too low. Any straps running across the back of the leader should be sewn or use special buckles which don't leave a loose tab that might catch a rein in it.{{r|walrond79|pp=14,20,267}} In [[carriage driving]], the driver should carry a whip long enough to reach the shoulder of the leader.{{r|walrond79|p=63}}

[[File:Skeleton-Tandem-Cart.jpg|thumb|The driver sits high enough to see over the leader and is carrying a whip long enough to reach the lead horse's shoulder]] A ''tandem cart'' is constructed in the style of a [[dogcart]] and used mainly for show, and should be tall enough for the driver to look over the head of the lead horse.{{r|smith|pp=159}}{{r|walrond79|p=263}}{{r|walrond95|p=23}} A ''drayel'' is hardware at the tip of the shafts to attach the traces (pulling straps) from the front horse.{{r|smith|pp=185}} Alternative to using a drayel, the leader's traces are hooked or buckled into the forward end of the wheeler's traces.{{r|walrond79|p=267}}

Driving a tandem is challenging and led to the creation of tandem [[driving club]]s and matches in the 19th century.{{r|walrond79|p=264}}

{{Blockquote |text=The art of tandem driving requires an alert brain and sensitive fingers. It has been compared with playing a harp. It is, in many ways, more difficult than driving a team [of four horses]. Whereas the leaders of a team balance one another and keep each other straight, there is nothing other than the skill of the Whip (driver) to prevent a tandem leader from turning to face his driver. |author=Sallie Walrond {{r|walrond79|p=264}} }}

Three horses in a row is sometimes called a ''randem/random'' or ''trandem/trandom''.<ref>{{Cite journal |url=https://www.carriageassociationofamerica.com/tandem-vs-randem/ |title=Tandem vs Randem |journal=[[The Carriage Journal]] |volume=21 |issue=1 |year=1983}}</ref>{{r|walrond79|p=222}}{{r|smith|p=19}}

== Bicycles ==

[[File:Flory och Elin.jpg|thumb|upright|Tandem bicycle]] [[Tandem bicycle]]s are named for their tandem seating, a more common arrangement than side-by-side "[[sociable]]" seating. Tandem bikes are also used in [[road bicycle racing|road racing]], [[track cycling|track racing]], and [[Tandem (UCI)|para-cycling]].

== Motor vehicles ==

The [[Messerschmitt KR200]] was an example of a very small automobile that used tandem seating; one passenger behind the driver.

''Tandem parking'' means parking one car in front of the other.

The word tandem is also used to indicate a [[semi-trailer truck]] pulling more than one trailer.

''Tandem axles'' means one axle mounted closely in front of another. For trailers, the purpose is to bear heavier loads than a single axle provides.

{{Anchor|Trucks}}<!-- Other articles link here. --> In heavy trucks, tandem refers to two closely spaced axles. Legally defined by the distance between the axles (up to {{convert|2.5|m|ftin|frac=8|abbr=on}} in the European Union, {{convert|40|–|96|in|m|2}}<!-- lower limit questionable --> in the United States), mechanically there are many configurations. Either or both axles may be powered, and often interact with each other. In the United States, both axles are typically powered and equalized; in the European Union, one axle is typically unpowered, and can often be adjusted to load, and even raised off the ground, turning a tandem into a single-[[axle]].<ref>{{cite web|url=http://www.rsa.ie/Documents/Vehicle%20Std%20Leg/Vehicle%20regs/Weights_Dimensions_Leaflet.pdf|title=Guidelines on Maximum Weights...Criteria|publisher=[[Road Safety Authority]] (Ireland) |date=December 2011 |access-date=2013-05-20 |archive-url=https://web.archive.org/web/20130123035527/https://www.rsa.ie/Documents/Vehicle%20Std%20Leg/Vehicle%20regs/Weights_Dimensions_Leaflet.pdf |archive-date=January 23, 2013}}</ref><ref>{{cite web|url=https://ops.fhwa.dot.gov/freight/publications/brdg_frm_wghts/index.htm|title=Freight Management and Operations: Bridge Formula Weights|last=Federal Highway Administration|publisher=U.S. Department of Transportation |date=2006|access-date=2013-05-20}}</ref>

<gallery mode="packed"> File:Messerschmitt Kabinenroller Microcar.jpg|Messerschmitt KR200 Kabrio File:R+L Carriers truck with tandem trailer, Ypsilanti, Michigan.jpg|Tandem trailer configuration, pulled by a single tractor File:Trailer-tandemachse.jpg|A tandem axle on a small trailer File:18 wheeler.svg|The front tandem-axles are typically under power by the tractor. The rear tandem-axles, not powered, are supporting the rear of the trailer. </gallery>

== Aviation ==<!-- Other articles link here. --> [[File:US Navy 061017-N-7130B-030 An instructor pilot is joined by his student in the cockpit of a T-45A Goshawk on the flight deck aboard the Nimitz-class aircraft carrier USS Ronald Reagan (CVN 76).jpg|thumb|Instructor and student pilots in a [[McDonnell Douglas T-45 Goshawk]] aircraft]] The two seating configurations for trainer, night and all-weather interceptor or attack aircraft are pilot and instructor side by side or in tandem.<ref>{{cite book|title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=0-85045-163-9 |publisher=Frederick Fell, Inc. |publication-place=New York |date=1974 |edition=1st American |page=259}}</ref> Usually, the pilot is in front and the instructor behind. In attack helicopters, sometimes the pilot sits in back with the weapons operator in front for better view to aim weapons, as the [[Bell AH-1 Cobra]] was a tandem cockpit redesign which produced a much slimmer profile than the [[Bell UH-1 Iroquois]] on which it was based. Attack aircraft and all-weather interceptors often use a second crew member to operate avionics such as radar, or as a second pilot. Bombers such as the [[Convair B-58 Hustler]] seated three crew members in tandem. A common engineering adaptation is to lengthen the cockpit or fuselage to create a trainer with tandem seating from a single-seater aircraft.

=== Side-by-side seating ===<!-- Other articles link here. --> [[File:Hunter and meteor at kemble arp.jpg|thumb|Tandem seat [[Gloster Meteor]] (top right) and side-by-side seat [[Hawker Hunter]] (trainer)]] An alternative configuration is side-by-side seating, which is common in civil aircraft of all sizes, [[Trainer (aircraft)|trainers]] and large military aircraft, but less so in high performance jets and [[glider (sailplane)|gliders]] where drag reduction is paramount. The [[Boeing B-47 Stratojet]] and [[Boeing B-52 Stratofortress#Design effort|Boeing XB-52]] bombers used fighter-style tandem seating, but the final [[Boeing B-52 Stratofortress|B-52]] bomber series used a conventional side-by-side cockpit. The [[Grumman A-6 Intruder]], [[General Dynamics F-111 Aardvark]], [[Saab 105]], [[Sukhoi Su-24]] and the [[Sukhoi Su-34]] are examples of combat aircraft that use this configuration. For training aircraft, it has the advantage that pilot and instructor can see each other's actions, allowing the pilot to learn from the instructor and the instructor to correct the student pilot. The tandem configuration has the advantage of being closer to the normal working environment that a fast jet pilot is likely to encounter.<ref>{{cite web |url=http://testrakeaviation.editme.com/tandem-seat |title=Why Tandem Seating in the SGT-300? |date=2010-03-15 |work=testrakeaviation.}}</ref>

In some cases, such as the [[Northrop Grumman EA-6B Prowler]], a two-place aircraft can be lengthened into a four-place aircraft. Also, a single seat cockpit can be redesigned into a side-by-side arrangement in the case of the [[Douglas A-1 Skyraider]], [[Convair F-102 Delta Dagger|TF-102]] trainer or the [[Hawker Hunter]] training versions.

== Insects == During mating among [[odonata]] ([[dragonflies]] and [[damselflies]]), a male uses [[claspers]] at the end of his [[Abdomen#Other animals|abdomen]] to grab a female between the [[Head#Arthropods|head]] and [[Thorax (arthropod anatomy)|thorax]], forming a tandem. The pair may take flight while in tandem.<ref name="DuBois">{{cite book |last1=Dubois |first1=Bob |date=2005 |title=Damselflies of the North Woods |publisher=Kollath-Stensaas Publishing |isbn=0-9673793-7-7 |pages=5–6}}</ref><ref name="Mead">{{cite book |last1=Mead |first1=Kurt |date=2003 |title=Dragonflies of the North Woods |publisher= Kollath-Stensaas Publishing |isbn=0967379369 |ol=8556568M |page=5}}</ref>

<gallery mode=packed> Argia moesta-tandem.jpg|[[Powdered Dancer]]s in tandem Tramea lacerata-flying tandem flight.jpg|[[Black saddlebags]] tandem flight </gallery>

==References== <references>

<ref name="attelerenfile">{{Cite web |title=Atteler en file |language=fr |trans-title=Harness in line |first=Etienne |last=Petitclerc |date=February 16, 2026 |website=attelage-patrimoine.com |url=https://www.attelage-patrimoine.com/2026/01/atteler-en-file.html |quote=[Most often, when horses are driven in single file, each horse has its own {{Glossary link|glossary=Glossary of carriage and driving terminology|jerk line}}, except for the shaft horse, beside whose head the driver walks. For that horse, a short lead line is enough to guide him when needed.]}}</ref>

<ref name="smith">{{cite book |title=A Dictionary of Horse Drawn Vehicles |first=D.J.M. |last=Smith |year=1988 |publisher=J. A. Allen & Co. Ltd. |isbn=0851314686 |ol=11597864M}}</ref>

<ref name="walrond79">{{cite book |title=The Encyclopaedia of Driving |first=Sallie |last=Walrond |year=1979 |publisher=Country Life Books |isbn=0600331822 |ol=4175648M}}</ref>

<ref name="walrond95">{{cite book |title=Driving Questions Answered |first=Sallie |last=Walrond |year=1995 |publisher=Kenilworth Press |isbn=1872082807 |ol=8652287M}}</ref>

</references>

==External links== {{wiktionary|tandem}} {{Commonscat|Tandem arrangement (driving)}} * {{Cite web |url=https://www.carriageassociationofamerica.com/carriage-tour/tandem-cart/ |title=Tandem cart, circa 1890 |website=[[Carriage Association of America]]}}

[[Category:Carriages]] [[Category:Horse driving]] [[Category:Real object ordering]] [[Category:Seating]]