03 G-Force and Curve Dynamics Flashcards
______________ in the road are one of the greatest dangers a fire apparatus operator may face.
Curves
Lateral acceleration pushes the car from side to side and is noticeable to the driver and passengers as:
Centrifugal Force
Lateral acceleration is also commonly referred to as:
g-force or g’s
Vehicles that have a low center of gravity will rarely be able to generate enough lateral g-force to exceed their rollover threshold and roll over. Instead when a vehicle with a low center of gravity generates more lateral g-force than the available drag factor of the roadway, the tires break traction with the road and slide out.
The rollover threshold of a vehicle is a relationship between:
The height of the center of gravity and the track width.
NFPA requirement demonstrates that most modern-day fire apparatus will be able to absorb just ________ lateral g’s without rolling over.
0.50-0.60
Highway design engineers post curve advisory speeds which limit the amount of lateral g-force experienced by the driver to no more than:
0.15 - 0.20 g’s
Steering induced rollover
A driver who turns the wheel too sharply will create a curve in the road which may induce a rollover.
Reducing g-force will reduce weight shift and help maintain vehicle stability. This is especially important for fire apparatus that carry a water load because of a phenomenon known as liquid surge or slosh.
Slosh is especially dangerous in fire apparatus that operate with a partially loaded water tank, such as a wildfire tender that pumps and rolls as it fights wildfire.
Water slosh is a direct result of inertia.
Inertia is defined as the resistance of an object to any change in its speed or direction of motion.
Slosh has two main negatives:
Shifts the vehicles center of gravity
Increases stopping distance
Static stability factor
Rollover threshold calculation
