DEADHEADING— Traveling without a load, exceptwhen traveling from the dumping area to the loadingpoint.DENSITY— The ratio of the weight of a substance to itsvolume.DIESELING— In a compressor, explosions of mixturesof air and lubricating oil in the compressionchambers and/or other parts of the air system.DOLLY— A unit consisting of a draw tongue, an axlewith wheels, and a turntable platform to support agooseneck trailer.DOUBLE-CLUTCHING— Disengaging and engagingthe clutch twice during a single-gear shift (changeof gears) to synchronize gear speeds.DOWNSTREAM FACE— The dry side of a dam.DOZER— Abbreviation of bulldozer.DRAFT— Resistance to movement of a towed load.DRAGLINE— A crane with a dragline attachment, usedto excavate material from below the grade on whichthe crane is sitting.DRAWBAR— A fixed or hinged bar, extending to therear of a tractor and used as a fastening for lines andtowed machines or loads.DRAWBAR HORSEPOWER— A tractor’s flywheelhorsepower minus friction and slippage losses in thedrive mechanism and the tracks or tires.DRAWBAR PULL— The pull that a tractor can exert ona load attached to the drawbar. Depends on power,weight, and traction.DRILL COLLAR— Thick-walled drill pipe, usedimmediately above a rotary bit to provide extraweight.DRILL, PERCUSSION— A drill that hammers androtates a steel and bit. Sometimes limited to largeblast hole drills of the percussion type.DRILL PIPE— The sections of a rotary drilling string,connecting the kelly with the bit or collars.DRIVE SPROCKET— A drive roller with teeth thatengage matching recesses or pins (bushings) in thetrack assembly.DROP HAMMER— A pile-driving hammer that islifted by a cable and that obtains striking power byfalling freely.DRUM, SPUDDING— In a churn drill, the winch thatcontrols the drilling line.EJECTOR— A clean-out device, usually a sliding plate.EMBANKMENT— A fill whose top is higher than theadjoining surface.EROSION— Wear caused by moving water or wind.FACE— (1) The more or less vertical surface of rockexposed by blasting or excavating or the cutting endof a drill hole. (2) An edge of rock used as a startingpoint in figuring drilling and blasting. (3) The widthof a roll crusher.FACTOR OF SAFETY— The ratio of the ultimatestrength of the material to the allowable or workingstress.FAIRLEAD— A device which lines up cable so that itwill wind smoothly onto a drum.FEATHER— To blend the edge of new material into theold surface smoothly.FIFTH WHEEL— The weight-bearing swivelconnection between highway type of tractors andsemitrailers.FILL— An earth or broken rock structure orembankment. Soil or loose rock used to raise agrade. Soil that has no value except bulk.FLOAT— In reference to a dozer blade, to rest by its ownweight or to be held from digging by upwardpressure of a load of dirt against its moldboard.FOOT— In tamping rollers, one of a number ofprojections from a cylindrical drum.FOOT-POUND— Unit of work equal to the force inpounds multiplied by the distance in feet throughwhich it acts. When a 1-pound force is exertedthrough a 1-foot distance, 1 foot-pound of work isdone.FOUR BY FOUR (4 x 4)— A vehicle with four wheelsor sets of wheels, all engine-driven.FREE FALL— Lowering of the hook (with or without aload) without it being coupled to the power trainwith the lowering speed being controlled by aretarding device, such as a brake.FRONT-END LOADER— A tractor loader with abucket that operates entirely at the front end of thetractor.FROST— Frozen soil.FROST LINE— The greatest depth to which ground maybe expected to freeze.AI-4
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