Dr

Draft Angle
A mandrel′s taper or angle for ease of part removal.
Draft Gauge
Instrument used to measure air movement by measuring air pressure differences.
Drag
Resistance of a vehicle body to motion through the air. A smooth surface has less drag than a rough one.
Drag Chute
A heavy-duty parachute attached to a vehicle and is used to rapidly add aerodynamic drag and to reduce the vehicle′s speed.
Drag Coefficient
A dimensionless value that allows the comparison of shape and orientation of different bodies.
Drag Link Steering System
Steering system used with solid axles.
Drain Cock
A tap provided for the purpose of draining off liquids from a tank or reservoir.
Drain Plug Spanner
A tool for removing and tightening drain plugs.
Drainage Basin
The area of land drained by a river system.
Drake Equation
A way of estimating the number of intelligent, technological species in existence in our Galaxy.
DRAM
Abbreviation of Dynamic Random Access Memory.
Drawbridge
The deck can be raised and lowered.
Drawing
A deformation technique used to fabricate metal wire and tubing.
Drawknife
Woodworking tool, two handed tool for shaping mainly in the round or curved sections.
Drawknife Bench
A purpose made seat or bench to hold the material while using a draw knife. The main details being that the worker sits down and uses his feet to control the gripping of the material.
Drawn Product
A product formed by pulling material through a die.
Dressing
The act of removing the glaze and dulled abrasives from the face of a grinding wheel to make it clean and sharp.
Drew, Charles Richard
American medical doctor and surgeon who started the idea of a blood bank and a system for the long-term preservation of blood plasma.
Drex
Used in the textile industry to measure the density of a single fiber of yarn.
Dribbling
Slow seeping of liquid from a control valve after it has been closed.
Drift
Motion of carriers caused by an electric field.
Drill Bits
Normally made of hardened or high speed steel with two cutting edges on the conical end with two helical flutes that act to move material away from the cutting edges.
Drill Chuck
A device used to grip drills and attach them to a rotating spindle.
Drill Chuck Arbor
Usually a tapered male and female fitting.
Drill Gauge
A flat steel plate drilled with holes of various sizes, each marked with the correct size or number into which small twist drills may be fitted to determine the size of their diameters.
Drill Jig
A jig that holds parts of a structure and by means of bushings, guides the drill so that the holes are properly located.
Drill Press
An upright power-driven machine for drilling holes in metal, wood, or other material.
Drinking Water
Water of sufficiently high quality that it can be consumed or used without risk of immediate or long term harm.
Drive Fit
One of several classes of fits in which parts are assembled by pressing or forcing one part into another.
Drive-By-Wire
Technology that replaces mechanical connections with electrical connections to reduce weight and provide more sophisticated and reliable responsiveness.
Driveline
An assembly of one or more driveshafts with provisions for axial movement, which transmits torque and/or rotary motion at a fixed or varying angular relationship from one shaft to another.
Driven Element
The element of an antenna connected directly to the transmission line.
Driveshaft
An assembly of one or two universal joints connected to a solid or tubular shaft member used to transmit rotational power.
Drivetrain
All of a vehicle′s components that create power and transmit it to the wheels, including the engine, transmission, differentials, and any interconnecting shafts.
Driving Point Measurement
A frequency response measurement where the excitation point and direction are the same as the response point and direction.
DRM
Abbreviation of Digital Rights Management.
Drogue Parachute
Parachute attached to a body, used to slow it down.
Drone
A pilotless aircraft, usually following a predetermined or programmed set of manoeuvres.
Drop Tank
An externally carried auxiliary tank, usually to contain fuel, which may be jettisoned if necessary.
Dropout
Any discrete variation in signal level during the reproduction of recorded data which results in a data-reduction error.
Dropping Point
The temperature at which a grease changes from a semi-solid to a liquid state under test conditions.
Dropsonde
A modified radiosonde package that is dropped by parachute from an aircraft to obtain temperature, pressure, and humidity profiles of the atmosphere below flight level.
Drought Severity Category
A measure of drought severity with categories denoted D0-D5 and higher numbers indicating a more severe drought.
Drug
A biologically active compound or mixture used to cure, prevent, or detect disease, to control biological processes, or to alter mental state.
Drum
Unit of volume sometimes used in the oil trade. The traditional standard drum of oil contains 55 U.S. gallons or about 208.198 litres.
Drum Brake
A brake that uses an enclosed rotating drum or can and stationary pads.
Drum Tower
A large, circular tower, usually low and squat.
Drum Type Armature
An efficient, popular type of armature designed so that the entire length of the winding is cutting the field at all times. Most wound armatures are of this type.
Drumming Noise
Often used to describe noise in the frequency range 30 to 60Hz.
Dry Air
Air without contained water vapour.
Dry Battery
A battery in which the electrolyte is immobilized, being either in the form of a paste or absorbed into the separator material.
Dry Bulb Temperature
The temperature of a gas or mixture of gases indicated by an accurate thermometer after correction for radiation.
Dry Bulb Thermometer
A thermometer used to measure the ambient temperature.
Dry Cell
A electrolytic cell also known as a Leclanché cell that uses a moist paste rather than a liquid as an electrolyte.
Dry Friction Damping
Coulomb damping is the dissipation of energy that occurs when a particle in a vibrating system is resisted by a force whose magnitude is constant independent of displacement and velocity, and whose direction is opposite to the direction of the velocity of the particle.
Dry Strength
Strength of an adhesive joint determined immediately after drying or after a period of conditioning in a specified atmosphere.
Dry Sump
A lubrication system in which the oil is pumped into the engine's sump under pressure and then pumped out again.
Dry Weight
The weight of a machine or vehicle without its lubricants or fuel.
Drystone Wall
Unmortared masonry wall.
Drywall
An interior facing panel consisting of a gypsum core sandwiched between paper faces, also called gypsum board or plasterboard.