fifth wheel

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fifth wheel

a. A wheel or portion of a wheel placed horizontally over the forward axle of a carriage to provide support and stability during turns.
b. A similar device over the rear axle or axles of a tractor or pickup truck, serving as a coupling for a semitrailer.
2. An additional wheel carried on a four-wheeled vehicle as a spare.
3. An extra and unnecessary person or thing.

fifth wheel

1. (Mechanical Engineering) a spare wheel for a four-wheeled vehicle
2. (Mechanical Engineering)
a. the coupling table of an articulated vehicle
b. a steering bearing that enables the front axle of a horse-drawn vehicle to rotate relative to the body
3. a superfluous or unnecessary person or thing

fifth′ wheel′

1. a horizontal ring or segment of a ring, consisting of two bands that slide on each other, placed above the front axle of a carriage and designed to support the forepart of the body while allowing it to turn freely in a horizontal plane.
2. a superfluous or unwanted person or thing.

Fifth wheel

Before the advent of trucks, the fifth wheel was a semicircular iron ring attached to a wagon’s front axle to give additional support to the rest of the Running gear as the axle pivoted during turns.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.Fifth wheel - someone or something that is unwanted and unneededfifth wheel - someone or something that is unwanted and unneeded
redundance, redundancy - the attribute of being superfluous and unneeded; "the use of industrial robots created redundancy among workers"
2.fifth wheel - an extra car wheel and tire for a four-wheel vehicle
car wheel - a wheel that has a tire and rim and hubcap; used to propel the car
3.fifth wheel - a steering bearing that enables the front axle of a horse-drawn wagon to rotate
bearing - a rotating support placed between moving parts to allow them to move easily
References in periodicals archive ?
Additional products, including longer fifth-wheel trailers and shorter pop-up campers, are also planned.
The AxleCrutch works on travel trailers, fifth-wheel trailers, horse trailers, boat trailers, utility trailers and any other multiple-axle towed vehicle utilizing a conventional leaf-spring suspension.
McMahonae1/4AOs RV carries an extensive inventory of Class A, Class B and C motorhomes, travel trailers and fifth-wheel trailers.