What is a fifth wheel?

Question

What is a fifth wheel?

Answer 1

Not sure if you mean in a rail transport definition or social definition.

In a social definition.

It's origin is that 4 wheels make up a vehicle and any more is useless. It's a derogatory term used to describe a person who has a habit of hanging on to a group of two or more people whether invited or not.

In a rail definition a fifth wheel can be for one of a number of purposes. The first is as an electrical power pickup to reduce wear and tear that a sliding metal pickup creates. The second use is on carriages to spin on the rails and run a generator to provide power for the carriage or even provide air pressure or vacuum to operate the train. The final purpose is to spin and act as a sensor for the speed of the train.

Answer 2

It is a term used to say something is unneeded or unwanted.  

Cars have four wheels - a fifth wheel would not make any sense or achieve any benefits to the car - so it is useless addition to the car (unless it is in the boot / trunk of the car - but guess you understand what i mean).

Answer 3

A wheel or portion of a wheel placed horizontally over the forward axle of a carriage to provide support and stability during turns.

A similar device over the rear axle or axles of a tractor or pickup truck, serving as a coupling for a semitrailer.

An additional wheel carried on a four-wheeled vehicle as a spare.

An extra and unnecessary person or thing.

Answer 4

a fifth wheel is a pancake type coupling (hitch) which is on the rear of a semi tractor or in the bed of a pickup truck to connect and tow a trailer of some sort.

Answer 5

A tag-a-long. Usually in a group or date setting...an extra person whose company is not really wanted.

Answer 6

When you are on a double date the 5th wheel is that person who has no date and is just tagging a long. Also works for the 3rd wheel on a single date.

Answer 7

A saved tire in the car .

Answer 8

The third leg.

Answer 9

the thing on the back of a truck where the trailer goes into

Answer 10

A fifth wheel is used to hook up something like a tractor on a transport truck. Also used as an extra person.

Answer 11

Semi-trailer truck

Answer 12

the odd person out when hanging out with 2 couples

Answer 13

one more than a fourth wheel.... duh.