N

 

 

NAEPIS

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

Natural frequency of a body of system is a frequency of free vibration.

 

NATURALLY ASPIRATED

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.

 

NEGATIVE PROOF

Proof that an event or sequence of events could not  have occurred.

 

NESTED

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

2,000 pounds.

 

NET TON MILE

The movement of a ton of freight one mile.

 

NET WEIGHT

(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

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.

 

NEUTRAL STEER

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.

 

NHTSA

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.

 

NOMOGRAPH

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.

 

NON-CENTRAL COLLISION

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

 

NON-COLLISION

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.

 

NON-FIXED OBJECT

Objects that are moveable or moving but are not motor vehicles, pedestrians, pedal-cyclist, animals, or trains.

 

NON-SEQUENTIAL WARNING

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.

 

NORMAL

Perpendicular  At right angle to a given line or plane

 

NORMAL ACCELERATION

The component of the vector acceleration of a point in the vehicle in the z-direction.

 

NORMAL FORCE

(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.

 

NORMAL SPEED

The maximum authorized speed shown in the time table.

 

NORMAL SURFACE

General contour of a part excluding local deformations.

 

NORMAL VELOCITY

Normal velocity (w)  of a point in the vehicle is the component of the vector velocity in the z-direction.

 

NOTCHBACK

Body styling where the backlight is in a noticeably different plane than both the roof and the deck.

 

NOZZLE

Injector tip with venturi to atomize fuel.

 

NTSB

NTSB is an abbreviation for the National Transportation Safety Board

 

NVH

Noise, Vibration, Harshness

 

NVH TERMINOLOGY

Terms describing NVH problems as developed and used by Ford Customer Service (See Below)

NVH TERMINOLOGY

BOOM - Low pitched sound like a drum roll or distant thunder. May cause pressure on the ear drum.

NVH TERMINOLOGY

BUZZ - Low pitched sound, something like a bee. Usually associated with vibrations.

NVH TERMINOLOGY

CHATTER - Rapidly repeating metallic sound.

NVH TERMINOLOGY

CHIRP - High-pitched rapidly repeating sound, like chirping birds.

NVH TERMINOLOGY

CHUCKLE - Rapid noise that sounds like a stick against the spokes of a spinning bicycle wheel.

NVH TERMINOLOGY

CLICK - Light sound, like a ball point pen being clicked.

NVH TERMINOLOGY

CLUNK/THUMP - Heavy metal-to-metal sound, like a hammer striking steel.

NVH TERMINOLOGY

GRIND - Abrasive sound, like a grinding wheel or sandpaper rubbing against wood.

NVH TERMINOLOGY

GROAN/MOAN - Continuous, low-pitched humming sound.

NVH TERMINOLOGY

GROWL/HOWL - Low,   guttural sound, like an angry dog.

NVH TERMINOLOGY

HISS - Continuous sound like air escaping from a balloon.

NVH TERMINOLOGY

HUM - Continuous sound of varying frequencies, like a wire humming in the wind.

NVH TERMINOLOGY

KNOCK - Heavy, loud, repeating sound like a knock on a door.

NVH TERMINOLOGY

PING - Similar  to knock, except at higher frequency.

NVH TERMINOLOGY

RATTLE - A sound suggesting looseness, such as marbles rolling around in a can.

NVH TERMINOLOGY

ROAR - Deep, long, prolonged sound like an animal, or winds and ocean waves.

NVH TERMINOLOGY

RUMBLE - Low, heavy, continuous sound like that made by wagons or thunder.

NVH TERMINOLOGY

SQUEAK - High-pitched sound, like rubbing a clean window.

NVH TERMINOLOGY

SQUEAL - Continuous, high pitched sound, like running finger nails across a chalkboard.

NVH TERMINOLOGY

TAP - Light, hammering sound like tapping a pencil on the edge of a table. May be rhythmic or intermittent.

NVH TERMINOLOGY

WHIR/WHINE - High-pitched buzzing sound, like an electric motor or drill.

NVH TERMINOLOGY

WHISTLE - Sharp, shrill sound, like wind passing a small opening.