MIL-HDBK-143A
accessory power supply (aps) - A self-powered device used to supply electrical and/or
hydraulic power to accessory or other auxiliary equipment carried in a missile or aircraft
Accumulator - 1. In computer applications, a device which stores a number and which on
receipt of another number, adds it to the number already stored. 2. in hydraulic and
pneumatic applications, a device which stores liquid and gas under pressure for momentary
use at a time when additional energy is required.
acoustical system - A system adapted for the transmission of sound and consisting of one or
all of the following acoustical elements: acoustical resistance, inertance, and acoustical
capacitance.
activator, inertial - A mechanical device employing springs that absorb energy from a
velocity change and releases this energy to activate a circuit.
active homing - See: guidance, homing.
actual exhaust velocity - The real velocity of the exhaust gas leaving a nozzle, as determined
by making an accurate measurement at a specified point along the nozzle exit plane; the
velocity obtained when the kinetic energy of the gas flow produces an actual thrust. Cf:
exhaust velocity.
actuator - A self-contained power transmitting device designed to convert electrical,
chemical, or fluid dynamic energy into a controlled mechanical force.
ACTUATOR ELECTRO-MECHANICAL, LINEAR - A self-contained power transmitting
device designed to convert electrical energy into a controlled mechanical force, in the form of
linear (straight line) mechanical movement. Comprised of an electric motor(s), gear box(es),
screw-jack(s), limit switch (es), and such accessories as required for the specific moving and
positioning of other components. Excludes hydraulic and pneumatic cylinders and
screwjacks.
ACTUATOR ELECTRO-MECHANICAL, ROTARY - A self-contained power transmitting
device designed to convert electrical energy into controlled mechanical force in the form of
torque (rotation mechanical movement). Comprised of an electrical motor(s), gearbox(es),
limit switch(es), and such accessories as required for the specific moving and positioning of
other components. Excludes hydraulic and pneumatic cylinders and screwjacks.
ACTUATOR, EXPLOSIVE, LINEAR - A self-contained power transmitting device designed to
convert chemicalenergy into a controlled mechanical force in the form of linear mechanical
movement. The device is comprised essentially of a piston, powder charge, electrical bridge
wire. and contacts enclosed in a housing.
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