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The contents of this glossary are provided for informational purposes
only; no warranty is expressed or implied.
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Gauge -- an instrument or device for measuring, indicating or
comparing a physical characteristic.
Galling -- a form of wear in which seizing or tearing of the
surface occurs.
Gasohol -- a blend of 10% anhydrous ethanol (ethyl alcohol) and
90% gasoline, by volume. Used as a motor fuel.
Gear -- a cylindrical or conical part using a tooth or
screw-based surface configuration to mechanically transmit power from one
portion of a machine to another. Gear designs are based in part on the shaft
alignment: parallel, angled, over-and-under, etc. Selected gear types are:
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TYPE |
DESCRIPTION |
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Spur gear |
Has teeth on the outside of a cylindrical body that are
straight and parallel to the axis of rotation. |
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Helical gear |
Has teeth that spiral around the outside of a cylindrical body
at an angle. |
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Internal gear |
Has teeth on the inside of a hollow cylindrical shape. |
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Bevel or miter gear |
Has teeth on the outside of a conical body. They may be
straight cut (as in the plain bevel gear), or spiral cut
(as in the spiral bevel gear). Both transmit motion between
intersecting shafts at various angles. |
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Hypoid gear |
Has teeth cut in spiral bevel pattern, but set on
non-intersecting shafts crossing at a right angle
(over-and-under). |
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Worm gear |
Has threads that wrap around a cylindrical body. |
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Herringbone gear |
Has two separate rows of adjoining teeth on the same gear, cut
in the configuration of two connected helical gears with teeth
angled in a V-shaped alignment. |
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Crown gear |
Has teeth set in the rim perpendicular to the rotation plane of
the gear. |
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Straight gear (rack and pinion) |
Has a toothed bar into which a worm or spur type 'pinion'
meshes, normally used to translate rotating motion into
reciprocating motion. |
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Ratchet and pawl |
Has a toothed wheel or bar which catches a 'pawl' (a mechanical
device that allows rotation only in one direction). |
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Sprocket |
Has a gearlike wheel which drives or is driven by a chain as
opposed to direct mesh. |
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Gear train – group or sequence of gears which perform a
desired mechanical transfer of power. Selected gear train types are:
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TYPE |
DESCRIPTION |
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Transmission |
Gear train characterized by multiple selectable gear speed
ratios and the ability to uncouple the gear train from the power
source to permit starting and stopping the gear train without
stopping the power source. Used in applications where varying
speed/torque/output direction requirements must be satisfied by a
single geared system. |
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Differential |
Gear train characterized by the connection of two output shafts
or axles in the same line, with an epicyclic (one or more
parts travel around the circumference of another fixed or moving
part) gear arrangement permitting one output shaft to revolve
faster than the other. |
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Planetary |
Gear train characterized by a predominantly epicyclic
arrangement, consisting of a series of planet gears
rotating in a carrier between a central sun gear and
an outer ring gear (of internal gear type). A planetary
gearset may be configured in a variety of ways, depending on which
part of the gearset is used for power input, which part is held
stationary or braked, which part is used for power output, and the
actual number and arrangement of sun and planet gears. Generally,
the more planet gears the greater the torque capacity of the
system. |
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Speed increaser or reducer |
Gear train characterized by high to extremely high ratios of
input to output speed, for the purposes of large-scale RPM
increases or large-scale torque increases. Usually a single-speed
gear ratio; if multispeed, they differ from transmissions in that
they are shifted as often or as easily. |
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Generated contaminant -- created by internal processes such as
wear or progressive degradation of system fluids, rather than external
sources or inherent from assembly or maintenance.
Graphite -- a crystalline form of carbon having a laminar
structure, which is used as a lubricant. It may be of natural or synthetic
origin.
Gravimetric analysis -- a method of analysis whereby the dry
weight of contaminant per unit volume of fluid can be measured showing the
degree of contamination in terms of milligrams of contaminant per liter of
fluid.
Grease -- a lubricant composed of an oil or oils thickened with
a soap, soaps or other thickener to a semisolid or solid consistency.
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ALPHA-BOOKMARKED INDEX:
A - B - C -
D - E - F -
G - H - I -
K - L - M -
N - O - P -
R - S - T -
U - V - W -
Z
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