Ford F-250 Owner's Manual page 168

Seating and Safety Restraints
2. To unfasten, push the release
button and remove the tongue from
the buckle.
Restraint of pregnant women
WARNING: Always ride and drive with your seatback upright and
the safety belt properly fastened. The lap portion of the safety belt
should fit snug and be positioned low across the hips. The shoulder
portion of the safety belt should be positioned across the chest. Pregnant
women should also follow this practice. See figure below.
Pregnant women should always
wear their safety belt. The lap belt
portion of a combination lap and
shoulder belt should be positioned
low across the hips below the belly
and worn as tight as comfort will
allow. The shoulder belt should be
positioned to cross the middle of
the shoulder and the center of the
chest.
Vehicle sensitive mode
Combination lap and shoulder belts in normal retractor mode allow free
shoulder belt length adjustment to your movements and locking in
response to vehicle movement. For example, if the driver brakes
suddenly or turns a corner sharply, or the vehicle receives an impact of
approximately 5 mph (8 km/h) or more, the combination safety belts will
lock to help reduce forward movement of the driver and passengers.
Belt sensitive mode
Combination lap and shoulder belts can also be made to lock manually by
quickly pulling on the shoulder belt.
168
2011 F-250/350/450/550 (f23)
Owners Guide, 3rd Printing
USA (fus)