A fifth wheel includes a top plate having a throat that is adapted to receive a kingpin of a trailer. The fifth wheel is equipped with a locking mechanism including a jaw slidably connected to the top plate and slidable between a closed position where the jaw blocks passage of a kingpin out of the throat of the fifth wheel and an open position where a kingpin may pass into and out of the throat of the fifth wheel. The jaw has an edge adapted to engage a kingpin positioned in the throat of the fifth wheel when the jaw is in the closed position. A bias device urges the jaw towards the closed position. The fifth wheel further includes a mechanism for moving the jaw between the open and closed positions. Further, the top plate of the fifth wheel is configured to allow service and/or replacement of the jaw from the top of the fifth wheel while it is assembled to a vehicle.