During the pre-trip inspection of a combination vehicle, what should the driver check about the sliding fifth wheel (if equipped)?

SLIDING FIFTH WHEELS allow the fifth wheel position to be adjusted forward and backward on the tractor frame. This is used for axle weight distribution — moving the fifth wheel forward puts more weight on the steer axle, moving it back puts more on the drives. INSPECTION REQUIREMENTS: LOCKING MECHANISM: The slide must be fully locked before driving — inspect the locking pins or teeth to verify they are fully engaged with the slide rail; pull on the fifth wheel assembly to test for any movement; if the fifth wheel can slide, it is NOT properly locked; POSITION MARKING: Note the position indicator markings; the position should match the weight distribution requirements for the load; BRACKET AND RAIL CONDITION: Check for cracking, deformation, or damage to the slide rail and mounting brackets; damaged slides can fail under load; AIR-OPERATED SLIDES: Some sliding fifth wheels are air-operated; check that the air supply is connected and the air-operated release valve is in the locked/closed position; CONSEQUENCES OF UNLOCKED SLIDE: If the fifth wheel slides forward while loaded at highway speed, it can cause: sudden steer axle overload; loss of steering control; potential collision; if it slides back, it can reduce steer axle weight to the point of steering instability; an unlocked slide can allow the combination to fold or jackkife if the fifth wheel moves suddenly during braking or turning.