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Dowson gas

A mixture of producer gas and water gas obtained by passing steam and air
over heated coal or coke in a Dowson producer.

Dowson producer

A furnace used for the manufacture of producer gas. Fay

Dowty hydraulic tub retarder

A retarder that consists of lengths of steel channel with attached rubbing
strips that operate on the face of the wheels above center. The action is
controlled by a hydraulic cylinder containing opposed pistons. The
hydraulic pressure is supplied from an accumulator in which pressure is
maintained by means of a 5-hp (3.7-kW) electric motor-driven pump that is
sufficient for 10 retarder unit. Mason

Dowty prop

A prop that is in effect a self-contained hydraulic jack consisting of two
tubes, the upper one telescoping into the lower. The upper (or inner) tube
acts both as a reservoir for the oil and as a container for the pump,
yield valve, and other accessories. Nelson

Dowty roofmaster

A self-contained, oil-operated steel support for use on a mechanized
long-wall face. It has support frames constructed of rigid roof and floor
members supported by yielding hydraulic props. Two- and three-prop units
are connected alternately to the armored conveyor by means of jacks
mounted in the floor members, to carry long and short cantilever roof
beams, respectively. See also:self-advancing supports

dozer

Abbrev. for bulldozer; shovel dozer. See also:bulldozer
Nichols, 2

dozer shovel

A tractor equipped with a front-mounted bucket that can be used for
pushing, digging, and truckloading. Nelson

dozzle

See:core.

D.P. reagents

Flotation reagents made by DuPont are D.P. 243, a 50% aqueous paste of
lorolamine (lorol being a mixture of primary straight-chain alcohols) and
D.P.Q., lauryl trimethyl ammonium bromide. Others include D.P.Q.B.,
D.P.C., D.P.N., and D.P.L.A. Pryor, 3

dradge

Corn. The inferior portions of ore separated from the best ore by cobbing.
Fay

draft

A survey line in a traverse. Syn:leg

draft engine

Corn. An engine used for pumping.

draft gage

An instrument used to measure the small pressure differentials below
atmospheric; e.g., an inclined manometer to measure the pressure
difference between a flue and the atmosphere for combustion control.
ACSG, 2

draft hole

An opening through which air is supplied to a furnace. Fay

draftsman

In petroleum production, one who specializes in drawing subsurface
contours in rock formations from the data obtained by a geophysical
prospecting party. The draftsman plots maps and diagrams from computations
based on recordings of seismograph, gravimeter, magnetometer, and other
petroleum prospecting instruments, and from prospecting and surveying
field notes. DOT

drag

a. The frictional resistance offered to a current of air or water;
resistance created by friction. Fay
b. Fragments of ore torn from a lode by a fault. Such fragments are
scattered along the line of the fault and are usually inclosed within
crushed or brecciated pieces of the rock traversed by that fault.
c. The flexuring of strata associated with faults. In a normal fault, the
coal seam often bends upward on the downthrow side and downward on the
upthrow side. Thus, drag is an indication of direction of displacement of
the beds. Also called terminal curvature. See also:coal lead
Nelson
d. In an inclined stope, the weight of the arch block is resolved into two
components, one at right angles to the dip, which tends to close the
opening, and one parallel to the dip, which tends to produce movement of
the hanging wall with respect to the footwall. This movement is known as
drag, or creep. Syn:creep
e. See also:drag ore
f. An appliance to be attached to the rear of a loaded train of cars to
prevent the cars from running down the incline or grade in case the cable
should break. See also:backstay
g. The uptilted or downtilted curve in rock beds or strata adjacent to a
fault. Long
h. The force exerted by a flowing fluid on an object in or adjacent to the
flow. AGI
i. The bending of strata on either side of a fault, caused by the friction
of the moving blocks along the fault surface; also, the bends or
distortions so formed. CF:bull

drag angle

The angle at which the leading surface of a cutting plane or point meets
the surface to be cut. If less than 90 degrees , the angle is said to be
negative; if over 90 degrees , it is called a positive rake or drag angle.
CF:rake

drag bit

a. A noncoring or full-hole boring bit that scrapes its way through strata
that must not be too hard. It may be a two-, three-, or four-bladed
pattern with various curves and cutaways. The drilling fluid passes down
through the hollow drill stem to the cutting point.
See also:roller bit
b. Various kinds of rigid steel bits provided with fixed (as contrasted to
the movable or rolling cutting points of a roller bit) and sometimes
replaceable cutting points, which are rotated to drill boreholes in soft
to medium-hard rock formations. See also:bit; fishtail bit; mud bit.
Long

drag bolt

A coupling pin. Standard, 2

drag brake

On a revolving shovel, the brake that stops and holds the drag (digging)
drum. Nichols, 2

drag breccia

Fragments of rock in the brecciated zone of a fault. Long