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Alternative forms[edit]


eighteen-wheeler (plural eighteen-wheelers)

  1. A tractor-trailer with eighteen wheels, normally with two steerable wheels on the first axle and four wheels on two fixed axles of the tractor and two fixed four-wheel axles on the rear of the trailer.


See also[edit]

Side view and underside view of a conventional 18-wheeler semi-trailer truck with an enclosed cargo space. The underside view shows the arrangement of the 18 tires (wheels). Shown in blue in the underside view are the axles, drive shaft, and differentials. The legend for labeled parts of the truck is as follows:
1. tractor; tractor unit
2. semi-trailer (detachable)
3. engine compartment
4. cabin
5. sleeper (not present in all trucks)
6. air dam
7. fuel tanks
8. fifth wheel coupling
9. enclosed cargo space
10. landing gear - legs for when semi-trailer is detached