Monday, May 21, 2012

Gravity-- Think about it

Gravity

The invisible force that pulls objects to the center of the earth is called GRAVITY. This force gives objects their weight and keeps them in contact with the ground. Without gravity a vehicle could not accelerate, brake or steer. In certain situations, uphill and downhill, you must compensate for this force acting upon the vehicle.

DRIVING UPHILL: The force of gravity will slow your vehicle; the steeper the grade, the greater the effect. Thus, as you approach the hill, you must choose appropriate gear that will provide power to climb. In a standard, downshift; in an automatic, use the transmission kick down on a short grade or select a lower gear on a longer grade. (2nd gear = 20 to 40 mph; 1st gear > 20 mph.) Avoid shifting on the hill. Driving uphill, maintain speed by increasing pressure on the accelerator.

Near the crest, ease up on the accelerator (reduced forward sightline) and keep to lane position 3 (right position) until your sightline is restored. When you return to level ground, select the appropriate gear.

To stop on the upgrade, your stopping distance will be much shorter. Adjust brake input to stop in the correct place.

DRIVING DOWNHILL: The force of gravity will cause your speed and braking distance to increase. Approaching a downgrade, (signs warn of the hill, length and grade) check the brakes by applying slight pressure. If the hill is steep, downshift in keeping with the speed required. As you descend the slope, take advantage of the engine compression for braking and, if necessary, apply the brakes as well, gently and intermittently. Increase the following distance and, if you must stop, input braking pressure sooner and more firmly.

Your vehicle’s CENTER OF GRAVITY is the point around which all of its weight is balanced. Most modern automobiles have a very low center of gravity; this gives them excellent road-handling characteristics. Pick-up trucks, jeeps, four wheel drive vehicles and cars with rooftop carriers tend to have higher centers of gravity. This must be taken into consideration otherwise braking and steering maneuvers become dangerous.

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