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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
GENERAL INFORMATION
GLOSSARY OF TECHNICAL AND MECHANICAL TERMS
Absorption
The action of a material in extracting substance from
the atmosphere (water from air, etc. ).
Allowance
Covers variation in dimensions to allow for different
qualities of fits.
Alloy Steel
A steel which owes its characteristic properties chiefly
to the presence of one or more elements other than carbon;
i.e., nickel, chromium, vanadium, molybdenum, etc.
Angle
The difference in direction of two lines which meet or
tend to meet. The lines are called sides, and the point of
meeting' the vertex of the angle. They are measured by
degrees and by radians. One degree is equivalent to the
angle at the center of a circle, subtended by an arc whose
length equals one three hundred sixtieth (1/360) of the
circumference. One radian is equal to the angle at the center
of a circle when subtended by an arc equal in length to the
radius of the circle. One radian equals 57.2958 degrees; also
1 radian equals 180/ r.
The protractor is used for the measurement of angles.
A right angle is one which is formed by the radius moving
through 1/4 of the circumference. It is a square angle and
contains 90°.
An acute angle is one containing less than 90°. An
obtuse angle is one containing more than 90°.
An oblique angle may be any other than a right angle.
A reflex angle is one containing more than 180°
.
A helical angle is the angle of a thread at the pitch line
with the axis of a threaded part; the lead angle of a thread is
the total or included angle between the sides or walls of a
thread measured on the axial line.
A dihedral angle is one formed by the opening between
two intersecting planes.
The vertex of an angle is the point of intersection of the
two lines which form the angle.
Brinell Test
A hardness-testing instrument, employing the hardened
steel ball indentation method.
B.T.U.
Abbreviation for British Thermal Unit which represents
the amount of heat required to raise the temperature of one
pound of water one degree Fahrenheit at or near 37°F. There
are 778 foot-pounds of energy in a B.T.U. and 42.4 B.T.U. to
one horsepower.
Calibrate
To ascertain the accuracy of and to rectify same, as
regards a precision measuring instrument, etc.
Calorie
Any of several thermal units, as: (a) The amount of
heat (small calorie) required to raise the temperature of one
gram of water one degree Centigrade. (b) The amount of heat
(large or great calorie) required to raise a kilogram of water
one degree Centigrade. (1 great calorie equals 1000 small
calories.)
Cantilever
A projecting beam, bar, or member supported at one
end only.
Center of Gravity
That point in a body about which all the parts exactly
balance each other.
CTS-2128-L Page 7
PRINTED IN UNITED STATES OF AMERICA
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