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Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 87
the wheel to slow or stop its rotation.
brake (sheet metalworking tool). A metalworking shop tool used to make straight bends across sheets of
metal. Brakes can be adjusted to make bends with the proper bend radius and bends having the correct
number of degrees.
See box brake, cornice brake, finger brake, and press brake.
brake back plate (aircraft landing gear component). A floating plate in an energizing-type brake to
which the wheel cylinder and the brake shoes attach.
brake caliper (disk brake component). A hydraulically operated clamp that holds the brake linings on
either side of a brake disk. When the brakes are applied, the calipers squeeze the linings tight against the
disk to produce the required friction.
brake horsepower. See BHP.
14 CFR Part 1: “The power delivered to the propeller shaft (main drive or main output) of an
aircraft engine.”
brake lining (aircraft landing gear component). A material with a high coefficient of friction and the
ability to maintain its friction and strength when it is hot. Brake linings were at one time made with
asbestos, but modern brake linings contain no asbestos.
brake mean effective pressure. See BMEP.
brake specific fuel consumption. See BSFC.
braking action advisories. A condition noted in an ATIS broadcast when the tower has received a runway
braking action report of “poor” or “nil.” When a braking action advisory is in effect, ATC will issue the
latest braking action report for the runway in use to all arriving and departing pilots.
braking action report. A report of conditions on the airport movement area providing a pilot with a
degree/quality of braking that he might expect. Braking action is reported in terms of good, fair, poor, or
nil.
brashness (wood condition). A condition of wood which causes it to have low shock resistance so that it
fails abruptly when it is bent.
brass. An alloy of copper and zinc made up of approximately 67% copper and 33% zinc. Brass is
malleable and ductile and is used for certain types of aircraft hardware and locking wire (safety wire) where
corrosion resistance is important.
Brayton thermodynamic cycle. The constant-pressure cycle of energy release used to describe the action
of a gas turbine engine. Fuel is added to the air passing through the engine and is burned. Heat from the
burning fuel-air mixture expands the air, and since this air is not confined, it accelerates as it moves
through the engine.
The Brayton cycle, a constant-pressure cycle, is an open cycle because all the events, compression,
combustion, expansion, and exhaust take place at the same time, but in different locations within the
engine.
The Brayton cycle differs from the Otto cycle used in reciprocating engines because the Otto cycle
is a constant-volume cycle. See Otto thermodynamic cycle.
braze welding. A method of joining pieces of metal by wetting their surfaces with a molten brass alloy.
The brass rod used for braze welding melts at a temperature above 800°F, but below the melting
temperature of the metals being joined.
Braze welding differs from brazing in that it does not use capillary action to pull the molten alloy
between the pieces of metal being joined.
brazier-head rivet. A thin protruding-head rivet that was at one time popular for aircraft sheet metal
construction. Brazier-head rivets have been superseded and may be replaced by MS20470 (AN 470)
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 88
universal-head rivets.
brazing. A method of joining metals by allowing capillary action to pull molten, nonferrous filler metal
between close-fitting parts. When the filler metal solidifies, it holds the parts together.
Brazing differs from soldering in the melting temperature of the filler metals used. Soldering uses
filler metals that melt at temperatures below 800°F, and brazing metals melt at temperatures above 800°F.
breadboard (electrical circuit). A device for building experimental electrical circuits that allows the
components to be temporarily connected into the circuit, making it easy to exchange components. After a
circuit functions as it should on the breadboard, and all the correct components are chosen, the circuit is
redesigned into its final configuration.
Many modern circuits are first built on solderless breadboards that allow the substitution of parts
without their having to be soldered into the circuit.
break-before-make switch (type of electrical switch). A form of double-throw switch that breaks one
circuit before it makes contact with the other circuit.
　
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