D RELEASE
End of Phase I production to release.
DAISY SLED
A test sled which is decelerated to simulate a
crash condition (see Holloman tests).
DAMAGE FREE CAR
Car equipped with special bracing devices to
decrease the possibility of damage to lading.
Usually called "DF" car.
DAMPED
Damped systems are those in which energy is
dissipated by forces opposing the vibratory motion. Any means associated with a vibrating system to balance or
modulate exciting forces will reduce the vibratory motion, but are not
considered to be in the same category as damping. The latter term is applied to an inherent characteristic of the
system without reference to the nature of the excitation.
DAMPING DEVICES
As distinct from specific types of damping, damping
devices refer to the actual mechanisms used to obtain damping of suspension
systems.
DAMPING RATIO
The ratio of the amount of viscous damping present
in a system to that required for critical damping.
DASHBOARD
A board on the fore part of a buggy or other
vehicle to intercept water, mud or snow. Sometimes used, incorrectly, as a
synonym for instrument panel.
DC
Direct current
DDEC
DEAD AXLE
An un-powered axle used to increase the legal
weight capacity of a vehicle.
DEAD RAIL
A second set of tracks over a scale used when cars
are not being weighed.
DEADHEAD
1) Fireman's term for brakeman. 2) Employee riding on a company pass or on
company business. 3) Train and / or engine crew moved without performing
service, from one terminal to another at railroad convenience and for which
they are paid.
DEAD-HEADING
Running empty, without cargo.
DEADMAN
A buried timber, log or beam designed as an anchor
to which a guy wire or cable is fastened to support a structure, as a wood or
steel column, derrick or mast.
DEADMAN CONTROL
A foot pedal or brake valve which must be kept in a
depressed position while the locomotive is operating. A release from this depressed position initiates an air brake
application after a short time delay.
DEBRIS
Any accumulation of broken and detached
matter. Debris can be left in a pile or
scattered over a large area. Usually a
poor indicator of area of impact but can sometimes be an indicator of velocity
and direction of travel.
DECAL
(Decalcomania) A decorative or informative transfer
sheet used for wood graining, labeling, etc.
DECELERATION:
Negative acceleration.
DECIBEL (dB)
Measures the intensity (loudness) of sound.
DECISION
Determination of what action to take after
perceiving a situation; choice of driving strategies or evasive tactics.
DECK
Floor of locomotive cab or cars.
DECKLID
A hinged panel providing access to the luggage
compartment.
DEFECT CARD RECEPTACLE
A small metal container, placed underneath the car
for protection from the weather, in which defect cards are placed.
DEFENSIVE DRIVING
Driving in a way that avoids conflicts that may be
caused by the mistakes of others while making no mistakes yourself.
DEFLECTION
(static)
The radial difference between the undeflected tire radius and the static
loaded radius, under specified loads and inflation.
DEFLECTION RATE
Generally refers to rate of spring deflection in
inches per 1000 lb.
DEFORMATION
The alteration of form or shape, as a result of
collision.
DEGREE OF CURVE
The number of degrees of central angle subtended by
an arc of 100 feet on the circumference; 5730 feet. Divided by the degree of a
curve equals the radius the curve.
DEGREE OF FREEDOM
The number of degrees of freedom of a vibrating
system is the sum total of all ways in which the masses of the system can be
independently displaced from their respective equilibrium positions. Examples: A single rigid body constrained to move only vertically on
supporting springs is a system of one degree of freedom. If the same mass is also permitted angular
displacement in one vertical plane, it has two degrees of freedom; one being
vertical displacement of the center of gravity; the other, angular displacement
about the center of gravity.
DELAYED PERCEPTION
Delayed perception is a phrase which expresses the
fact that the point of actual perception does not coincide with the point of
possible perception, but rather, actual perception is delayed owning to driver
inattentiveness. Delayed perception
does not include reaction time.
DELIVERING CARRIER
1) The carrier which delivers a shipment to the
consignee. 2) The transportation company that delivers a shipment.
DELIVERY
The act of transferring possession of a
shipment. This could be from consignor
to carrier, one carrier to another or carrier to consignee.
DEMOUNTABLE RIM
A rim with valve locaters which is used with a cast
spoke wheel to provide the method of attaching tires to the vehicle.
DEMURRAGE
detention of a freight vehicle or container beyond
a stipulated time. Also the payment
made for such delay.
DENSITY
The weight of an article per cubic foot. The ratio of mass to bulk or volume.
DEPARTMENT OF TRANSPORTATION (DOT)
The federal agency responsible for the
administration of the Federal Motor Carrier Safety Regulations. See Bureau of Motor Carrier Safety.
DEPLOYMENT THRESHOLD
The level of crash severity at which ACRS system
actuation should occur.
DEPOSIT
An imprint consisting of material deposited on the
road surface from tire grooves.
Sometimes found where a tire stops sliding.
DEPOSITION
Pre trial questioning of witness, under oath,
subject to cross examination for the purpose of discovering evidence or
perpetuating testimony; a document in which a deposition is recorded.
DEPRESSED CENTER FLAT CAR
A flat car with the section of the floor between
the trucks depressed to permit loading of high shipments within over head
clearance limits. Also called a well
flat.
DEPTH OF FIELD
The range or distance from the nearest object to
the farthest object in a scene that must be clear in a photograph; desired zone
of sharpness.
DEPTH OF FOCUS
The range of distances which are in acceptably
sharp focus for any lens setting; the effective area of sharpness.
DEPTH PERCEPTION
The ability to Judge distances.
DERAIL
A track safety device designed to guide a car off
the rails at a selected spot as means of protection against collision or other
accidents; commonly used on spurs or sidings to prevent cars from fouling the
main line.
DESCRIPTION
Designation of an object, a condition, or an event
according to the appropriate category in each of a number of classifications.
DESIGN AID
A full size model of a vehicle, or portion thereof,
with components simulated of the most practical materials (wood, plastic,
etc.). This is the first three-dimensional representation of designs (well in
advance of prototype vehicles) and is updated with facsimiles of the latest
designs until prototype or design check vehicles are available. One of the
prime objectives of the design aid is to provide design visibility to promote
early design concurrence between the various areas. Another prime objective is
to provide a mock-up where wiring harness routing and component location can be
experimentally determined.
DESIGN CHECK VEHICLE
An experimentally assembled vehicle consisting of
prototype and current production material. This vehicle, or portion thereof, is
used for the design check of components for fit, clearance and functions not
requiring the total operation of the vehicle. All RPOs and accessories are also
included as port of the design check vehicle specifications. It is the intent
that these vehicles will provide the affected design activities with the
visibility required for the determination and investigation of design discrepancies
and potential production and service problems.
DESTINATION
The plies to which a shipment is to be delivered.
DETAILED STATEMENT
A concise written summary of what a particular
person has to say about a traffic accident or circumstances connected with
it. A detailed statement is usually not
a verbatim report of the information obtained from an informant.
DETECTOR
A switch used in the ACRS sensor assembly which
responds to "G" forces.
DETENTION
See demurrage.
DETONATION
Sharp knock resulting from too rapid burning of
fuel charge in combustion chamber.
DETONATOR
An
electronically actuated percussive device (I.e. to open the ACRS
inflator valve).
DFA
Design for Assembly - Design to make assembly
easier.
DFMA
(Design for Manufacture and Assembly) is the
pursuit of product simplification by evaluating and improving products in the
design stage. Part features which affect ease of assembly, cost and
productivity.
DFMEA
(Design Failure Mode and Effects Analysis) is a
disciplined analysis of the part design with the intent to identify and correct
any known or potential failure modes before the first production runs occur.
DIAG RECORDS
Diag Records indicates the count of Diagnostic Trouble Codes that became active during the trip. ( Detroit )
DIAGNOSTICS
Electronic means of checking ACRS system electrical
continuity and inflator pressure.
DIE
Mating metal part containing desired form
impressions.
DIE CAST
Forcing molten metal into steel die to form
casting.
DIE MODEL
A three-dimensional representation made of hard
wood from approved engineering drawings and aluminum templates.
DIESEL
Commonly referred to as diesel-powered vehicle.
DIESEL ELECTRIC LOCOMOTIVE
A locomotive in which one or more diesel engines
drive electric generators which in turn supply electric motors (usually series
D.C.) which are geared to the driving axles.
DIESEL ENGINE
An internal combustion engine that uses compression
to raise air temperature to the igniting point, whereas fuel is ignited by a
spark in a gasoline engine.
DIFFERENTIAL
The part of the power train that permits one wheel
to turn at a different rate of speed from the other, as occurs when going
around a turn.
DIFFERENTIAL LOCK, INTERAXLE TYPE
Used on twin-screw tractors, this valve can be set
to lock both rear axles together so that they pull as one for off-the-road
operation. Never used for over-the-road
operation.
DIFFUSER
A tube with slotted ports to distribute the
inflating gas into the air cushions.
DILUTION
To render more liquid or weaken solution.
DINKY
(slang) A small engine used around round house or
back shops for switching.
DI-NOC
Trade name for a decal material consisting of three
layers - decal, glue and paper. The outer portion can be painted with a special
elasticized paint. When applied to the surface of a model, the Di-Noc is first
soaked in warm water. The wet paper backing is separated from the decal, which
takes the form of the clay surface and gives the model the effect of a painted
car.
DIRECT CURRENT
Electrical current that always flows in one
direction only and is the type used in automotive equipment.
DIRECT DAMAGE
Is the definition associated with displacement of
sheet metal and / structure under the direct contact of collision forces.
DIRECT DRIVE
Refers to a condition in which the transmission is
in a gear having a 1:1 ratio, that is, when the engine crankshaft is turning at
the same rate as the vehicle drive shaft.
See overdrive and under drive.
DIRECTION OF FORCE
The direction of the principle force sustained by a
vehicle at impact and resulting in the vehicle damage. (See collision deformation classification SAEJ244).
DIRT BIKE
A motorcycle designed for off highway use.
DISC BRAKES
Disc brakes are a type of brake system wherein the
friction material is a flat pad. The
friction pads bear against a flat brake disc, or rotor, mounted in a plane
perpendicular to the axle axis.
DISC WHEEL
A single unit that combines a rim and a wheels
DISCRIMINATIVE REACTION
A reaction to perception of an unfamiliar hazard or
other situation, which requires additional information than that immediately
available to make a decision or which presents several choices of possible
evasive tactics. Time required is 1.5
seconds or more, possibly much more.
DISENGAGEMENT
The final touching of objects in a collision before
separation; the time and place on a traffic unit or traffic way where this
touching occurs. If colliding objects
do not separate, there is no last contact.
DISPATCHER
Person in charge of dispatching.
DISPLACEMENT
The stroke of the piston multiplied by the area of
the cylinder bore, the product multiplied by the number of cylinders in the
engine.
DISTANCE TO SWERVE
(d): The longitudinal distance necessary to change
direction and return to a parallel course
while traversing a given lateral distance(dlat).
DISTRIBUTOR
An engine-driven device in ignition system to
produce, time, and deliver spark to the spark plugs.
DISTURBANCE RESPONSE
The vehicle motion resulting from unwanted force or
displacement inputs applied to the vehicle.
Examples of disturbances are wind forces or vertical road displacements.
DIVERGENT INSTABILITY
Divergent instability exists at a prescribed trim
if any small temporary disturbance or control input causes an ever increasing
vehicle response without oscillation.
DLO
(Day Light Opening) - line defining the areas
through which light will pass in glazed areas.
DOCK
A platform where trucks load and unload.
DOCK RECEIPT
Receipt given for a shipment received or delivered
at a pier or dock. When delivery of a
foreign shipment is completed, the dock receipt is surrendered to the
transportation line and a bill of lading is issued.
DOCUMENT
Anything printed, written, etc., relied upon to
record or prove something.
DOCUMENTATION
(1; the supplying of documents (2) the documents that are supplied.
DOE
Design of Experiment - Evaluate key criteria to
evaluate contribution to problem.
DOG CHASE
A relief crew went out to bring in a train which
can not be legally moved by its own crew.
DOG LEG
A right-angle bend, as in the angle made by the
side and bottom of windshields of the mid-fifties.
DOLLY
A small platform mounted on wheels that is used in
a warehouse to move objects. Also used
in reference to (1) The coupling device composed of one or two axles and a
fifth wheel used to convert a semi-trailer to a full trailer so it can be
coupled to the rear of a tractor-trailer unit, making the combination into a
double-bottom rig; (2) landing gear on a trailer.
DOLLY HITCH
Coupling device between leading trailer and dolly
consisting of pintle hook and drawbar connection.
DOOR CHECK
A device, part of the door hinge assembly, to
prevent the door from opening beyond the designed full-open position.
DOT
Federal Department of Transportation
DOUBLE BOTTOMS
See doubles
DOUBLE CAP NUT
The inner and outer nuts used to secure stud-mount
wheels to a vehicle. The inner dual wheel is attached by an inner cap nut with
a spherical radius and the outer dual wheel is attached by an outer cap nut
with a spherical radius.
DOUBLE DECK (stock car)
A car with a second floor (often made removable)
half way between the ordinary floor and the roof, to increase the carrying
capacity of the car for small livestock, such as pigs as sheep.
DOUBLE DROP FRAME
A drop frame trailer with one drop behind the kingpin
and one in front of the rear axles. See
drop frame.
DOUBLE-AXLE
See tandem axle.
DOUBLE-CLUTCHING
Shifting the gears of a non synchronized truck
transmission without clashing them, by depressing and releasing the clutch
pedal twice.
DOUBLE-REDUCTION REAR AXLE
A rear end that reduces the drive line rpm in
relation to the rear wheel rpm by means of a double. Dual gear reduction
generally used in rear axles.
DOUBLES
A combination vehicle consisting of a tractor, a
semi trailer and a full trailer, coupled together. Also called twins, twin trailers and most often double bettors.
DOWEL PIN
A pin aligning or securing two parts to prevent
movement between them.
DOWN TUBES
The lower frame portion extending from the steering
head down and under the engine to the swing arm pivot.
DOWNSHIFT
A shift which results in an increase in torque
ratio and decrease in speed ratio.
"D" PILLAR
Vertical or diagonal structural pillar between roof
and body at the rear corner of a station wagon.
"D" POINT
Lowest point on a manikin's buttocks contour.
DPSR
Daily Problem Status Report
DQR DRAG TEMPLATE
Durability, Quality and Reliability. A pattern or
guide of a particular of the body section - bumper, molding, etc.
DRAFT GEAR
A unit which forms the connection between the
coupler rigging and the center sill.
The purpose of this unit is to receive the shocks incidental to train
movements and coupling of cars, and so cushion the force of impact.
DRAG
Lowest part of flask used in casting.
DRAG FACTOR
(f): A number representing the acceleration or
deceleration of a vehicle or other body as a decimal fraction of the
acceleration of gravity; the horizontal force needed to produce acceleration in
the same direction divided by the weight of the body to which the force is
applied. When a vehicle slides with all
wheels locked, on a level surface, the coefficient of friction and the drag
factor have the same value.
DRAG LINE
A method of moving freight carts around a carrier's
terminal. Refers to a moving cable (the
line) that operates either from a suspended position overhead or in a slot in
the floor. The line supplies the motive
power (drag) to the carts when they are attached to the line.
DRAG LINK
The term "drag link" in a typical
steering system is a rod connected at its end points to the idler arm and the
pit man arm. The drag link, the tie
rods, the idler arm and the steering knuckles comprise the steering linkage.
DRAIN LINES
In some fuel systems, unburned fuel is returned to
the supply tank through the drain lines.
Not found on all tractors.
DRAW DIE
An operation in which a flat sheet metal blank is
restrained around its periphery and caused to flow into a female configuration.
Action may be air or toggle.
DRAW FORMING
To form parts from flat stock by distortion or
stretching in a die.
DRAW LINE
The inner extreme of draw marks caused by the blank
traversing through spleens, binder radii, and steps in the cavity (female) of
draw dies. Objectionable surface defect if it carries into an exposed area of a
panel.
DRAWHEAD
The head of an automatic coupler, exclusive of the
knuckle, knuckle pins and lock.
DRAWING QUALITY STEEL
(DQ) Cold reduced, box annealed last (also tempered
in exposed grades) drawing quality sheet steel for parts having a severe draw.
DRAYAGE
The charge made for carting, draying, or trucking
freight.
DRIBBLE
Liquid debris from a vehicle or its cargo that
drops to the ground, often leaving a trail, if the vehicle is moving, from a
spatter area to a puddle.
DRIFT TIME
The time required for a vehicle or combination to
coast, with engine disengaged, from a specified higher speed to a lower
specified speed, without the use of brakes.
DRILL TRACK
A track connecting with the ladder track, over
which engines and cars move back and forth in switching.
DRILLING (car)
The handling or switching of cars in freight yards.
D-RING
The hook or ring latch located in the vicinity of
the occupants shoulder, often on the B or C pillars and used for directing the
shoulder belt from the retractor mechanism over the shoulder.
DRIP MOLDING
(Drips) an exposed channel applied to the roof over
the side windows to direct water away from the windows and to cover structural
welding.
DRIVE
Every person who drives or is in actual control of
a vehicle.
DRIVE AXLE
An axle that transmits power to the wheels. A drive axle is a powered axle that actively
pulls the load.
DRIVE SHAFT
A heavy-duty tube that connects the transmission to
the rear end assembly of the tractor.
DRIVE TRAIN
A series of connected mechanical parts for
transmitting motion.
DRIVABLE MODEL
A fiberglass body mounted on a chassis and used to
evaluate the model in motion.
DRIVELINE
The universal joints, any bearings, and the
driveshaft(s) that transmit power from the transmission to the drive axle.
DRIVER
Driver Identification at the time of the data extraction. ( Detroit )
DRIVER ACRS
An air cushion restraint system used to protect the
driver in a vehicle crash.
DRIVER INCIDENTS
Latest driver incidents recorded, up to five. ( Detroit )
DRIVER INCIDENTS TOTAL
Total number of driver entered incidents. ( Detroit )
DRIVER MODULATION
The use of steering or brake release and
reapplication or combination of both to maintain directional stability.
DRIVER PERCEPTION REACTION TIME
The interval of time lapse between the instant a
driver first perceives a reason to stop or maneuver his vehicle and the instant
he takes action.
DRIVERS
(Slang) The drive wheels of a tractor.
DRIVERS
Transistors used as amplifiers. Taking a small
current from an integrated circuit to control the much larger current of the
interlock relay or the elt warning system.
DRIVER'S DUTY STATUS RECORD BOOK
See log book, driver's dally.
DRIVER'S LOG
See log book, driver's dally.
DRIVERS PERCEPTION REACTION DISTANCE
The distance traveled by a vehicle during the time
that elapses from the instant the driver detects a hazard until he applies the
brake or makes an evasive maneuver.
DRIVEWAY ACCESS
A roadway by which motor vehicles may enter or
leave a trafficway and limited to that portion that is entirely within the
confines of the trafficway.
DRIVING
Engine on time when the vehicle speed was greater than 1.5 mph. ( Detroit )
DRIVING ECONOMY
Trip Distance divided by Driving Fuel. ( Detroit )
DRIVING FORCE
The longitudinal force resulting from driving
torque application.
DRIVING FORCE COEFFICIENT
The ratio of the driving force to the vertical
load.
DRIVING FUEL
Trip fuel minus Idle Fuel. ( Detroit )
DRIVING PERCENT
Driving Time divided by Trip Time ( Detroit )
DRIVING TIME
Trip time minus Idle Time. ( Detroit )
DROMEDARY TRACTOR
A long-wheelbase tractor with a cargo body placed
between the fifth wheel and the cab.
DROP
Switching movement in which cars are cutoff from an
engine and allowed to roll free into a track.
DROP BOTTOM CAR
A gondola car with a level floor, equipped with a
number of drop doors for discharging the load.
DROP BRAKE SHAFT
A brake shaft for flat cars which normally extends
above the floor, but can be dropped down should conditions of the lading require.
DROP END GONDOLA CAR
A gondola car with end doors which can be dropped
when the car is used for shipping long material which extends over more than
one car.
DROP FRAME
A trailer frame that drops downward to increase
cargo capability without increasing the vertical clearance of the vehicle. Consists of two types: single drop and double drop.
DROP IT ON THE NOSE
Uncoupling a tractor from a semi-trailer without
lowering the landing gear to support the trailer's front
DROP OFF
The edge of pavement where it is more that about 2
inches (about 5 cm) higher than the abutting shoulder.
DROP THE BODY
(Slang) Unhook and drive a tractor away from a
parked semi-trailer.
DROP-IN UNIT
Generally refers to rear axle gear assembly located
in axle housing by drop-in.
DRUM BRAKES
Drum brakes are a type of brake system wherein the
friction material of the brake shoes is arranged cylindrically around the axle,
and bears against a cylindrical brake drum.
DRY FREIGHT
Freight that does not need to be shipped at a
specific temperature to prevent spoilage.
DRY TANK
Part of brake system. Air passes from wet tank to dry tank. Dry tank is the air reservoir from which the air is drawn for
operating the brake system.
DUAL AXLE
Tandem axle or two axles in combination.
DUAL SPACING
Lateral distance from wheel centerline to wheel
centerline in a dual wheel arrangement. It is determined by adding two offsets
(disc wheels) or two offsets plus one spacer bandwidth (demountable rims).
DUAL-LEVEL INFLATOR
An air cushion inflator comparing two magnitudes of
inflating energy which can be timed to provide variable inflation.
DUALS
A pair of wheels and tires mounted together on the
same side of one axle.
DUMMY COUPLER
A fitting used to seal the opening in an air brake
hose connection (glad hands) when the connection is not in use. Sometimes called a dust cap.
DUMP BODY (CAR)
Truck, car or trailer body of any type which can be
tilted to discharge its loads
DUNNAGE
The material used to protect or support freight in
trucks. The weight of dunnage is shown
separately on the bill of lading since it is material used around a cargo to
prevent damage. Often it is transported
without charge.
DURABILITY AND FINAL
Certifies that durability, reliability and all
other program requirements not met at the time of sign off.
DURAMETER
An instrument which measures the hardness of
rubber. Measures hardness by the deflection of a steel probe into a material. (
see ASTM D2240 )
DUSK
The beginning of darkness in the evening.
DUST CAP
See dummy coupler.
DUST SHIELD
Sheet metal shield on brake assembly used to keep
debris from brakes.
DUTY
A tax levied by a government on imports and
exports.
DVP & R
Design Verification Plan and Report
DYING DECLARATION
A statement made by the victim of a homicide while
about to die, in expectation of death and without any hope of recovery, and
concerning the facts and circumstances under which the fatal injury was
inflected.
DYNAMIC BALANCE
The balance of an object when it is in motion.
DYNAMIC BRAKING
A means of braking a locomotive or car having
electric motors or by using the motors as generators and dissipating this power
through resistors. It may be used to
control train speed and to brake a train to low speed after which air brakes
bring it to a full stop.
DYNAMIC CRUSH
The maximum exterior deformation suffered by a
vehicle in impact with another vehicle or object and, due to the elastic
properties of vehicle bodies, will be slightly greater than the post impact
measurement. The maximum deformation
that a vehicle would experience during the event. The dynamic crush is often 10 - 20 % greater than the static
crush. The difference being the bounce
or coefficient of restitution.
DYNAMIC INDEX
(k /ab ratio) is the square of the radius of
gyration (k) of the sprung mass about a transverse axis through the center of
gravity, divided by the product of the two longitudinal distances (a and b)
from the center of gravity to the front and rear wheel centers.
DYNAMIC RATE
Dynamic rate of an elastic member is the rate
measured during rapid deflection where the member is not allowed to reach
static equilibrium.
DYNAMICS
The physical behavior of an object in motion.
DYNAMOMETER
A device for measuring the work output of an
engine. See brake horsepower.
References
Detroit Diesel
Caterpillar User's Manual