North American Engineering Parts Inquiry System
NARROW GAGE (track)
When the distance between the heads of the rails is less than 4' 8". See Board gage, Standard gage, and gage of track.
Natural frequency of a body of system is a frequency of free vibration.
Refers to a diesel engine in which the charge air enters the cylinders by atmospheric pressure, I.e., 101.2kPa (14.7 psi), which is known as 1 atmosphere.
Proof that an event or sequence of events could not have occurred.
Packed one within another net ton 2,000 pounds. Also called a short ton.
NET CONTACT AREA
The area enclosing the pattern of the tire tread in contact with a flat surface, excluding the area of grooves or other depressions.
NET HOLE DOOR CONCEPT
A process using precision pierced holes in the door hinge which align to precisely located topping plates on the body for a non-adjustable door installation. Process can be applied to other modular assembly installations.
NET TON MILE
The movement of a ton of freight one mile.
(a) The weight of an article clear of packing and container (b) as applied to a truckload, the weight of the entire contents of the truck.
NEUTRAL SAFETY SWITCH
A switch which completes the starter circuit and the backup lamp circuit and provides power to the belt warning system, depending on which gear the driver selects.
Neutral stability exists at a prescribed trim if, for any small temporary change in disturbance or control input, the resulting motion of the vehicle remains close to, but does not return to, the motion defined by the trim.
A vehicle is neutral steer at a given trim if the ratio of the steering wheel angle gradient to the overall steering ratio equals the Ackerman steer angle gradient.
NEUTRAL STEER LINE
The set of points in the x-z plane at which external lateral forces applied to the sprung mass produce no steady-state yaw velocity.
NEUTRAL STEER POINT
The neutral steer point is the hypothetical point about which the tire lateral forces are balanced
NEWTON'S FIRST LAW
An un-accelerated body remains un-accelerated unless it is caused to change that state by forces exerted on it by the environment.
NEWTON'S SECOND LAW
The acceleration of a particle is equal to the ratio of the net force acting on the particle to the internal mass of the particle. A =f/m
NEWTON'S THIRD LAW
To every action there is always an opposed equal reaction. The action forces and reaction forces are on different bodies.
National Highway Traffic Safety Administration
95 PERCENTILE MANIKIN
Two or three dimensional manikin of the human body with dimensions as large as 95 percent of the population.
A chart on which three or more scales are arranged so that a straight line drawn through values on any two will cross the third at a corresponding value; nomograph; a graphic calculator.
A non-central collision is a collision between two vehicles, or a vehicle and a fixed object, in which the principle force is not directed through the centers of mass of the involved vehicles
Includes, but not limited to; overturn, jack-knifing, fire / explosion, gas inhalation, a fall from a vehicle, an injury inside a vehicle not associated with a collision.
Objects that are moveable or moving but are not motor vehicles, pedestrians, pedal-cyclist, animals, or trains.
A type of belt warning system which only senses whether or not the belt is fastened, not in which sequence the belt is fastened and the seat is occupied.
Perpendicular At right angle to a given line or plane
The component of the vector acceleration of a point in the vehicle in the z-direction.
(y): The perpendicular component of the force exerted by a supporting surface on a surface resting or sliding on the supporting surface.
NORMAL FORCE COEFFICIENT
(C z) is based on the aerodynamic force acting in the z direction.
The maximum authorized speed shown in the time table.
General contour of a part excluding local deformations.
Normal velocity (w) of a point in the vehicle is the component of the vector velocity in the z-direction.
Body styling where the backlight is in a noticeably different plane than both the roof and the deck.
Injector tip with venturi to atomize fuel.
NTSB is an abbreviation for the National Transportation Safety Board
Noise, Vibration, Harshness
Terms describing NVH problems as developed and used by Ford Customer Service (See Below)
BOOM - Low pitched sound like a drum roll or distant thunder. May cause pressure on the ear drum.
BUZZ - Low pitched sound, something like a bee. Usually associated with vibrations.
CHATTER - Rapidly repeating metallic sound.
CHIRP - High-pitched rapidly repeating sound, like chirping birds.
CHUCKLE - Rapid noise that sounds like a stick against the spokes of a spinning bicycle wheel.
CLICK - Light sound, like a ball point pen being clicked.
CLUNK/THUMP - Heavy metal-to-metal sound, like a hammer striking steel.
GRIND - Abrasive sound, like a grinding wheel or sandpaper rubbing against wood.
GROAN/MOAN - Continuous, low-pitched humming sound.
GROWL/HOWL - Low, guttural sound, like an angry dog.
HISS - Continuous sound like air escaping from a balloon.
HUM - Continuous sound of varying frequencies, like a wire humming in the wind.
KNOCK - Heavy, loud, repeating sound like a knock on a door.
PING - Similar to knock, except at higher frequency.
RATTLE - A sound suggesting looseness, such as marbles rolling around in a can.
ROAR - Deep, long, prolonged sound like an animal, or winds and ocean waves.
RUMBLE - Low, heavy, continuous sound like that made by wagons or thunder.
SQUEAK - High-pitched sound, like rubbing a clean window.
SQUEAL - Continuous, high pitched sound, like running finger nails across a chalkboard.
TAP - Light, hammering sound like tapping a pencil on the edge of a table. May be rhythmic or intermittent.
WHIR/WHINE - High-pitched buzzing sound, like an electric motor or drill.
WHISTLE - Sharp, shrill sound, like wind passing a small opening.