Spicer Drive Axles Application Guidelines - Manual (Page 98)

AXAG-0200 June 2009 98
Glossary
GAWR (Gross Axle Weight Rating)
- The total weight
capacity of an axle (single, tandem , or tridem ).
GCW (Gross Combination Weight)
- The weight of a
truck and trailer combination and its entire contents.
GCWR (Gross Combination Weight Rating)
- The total
weight capacity of a truck and trailer combination and its
entire contents as determined by axle ratings.
Gear Ratio, Axle
- Ratio of the speed of the propeller
shaft to the speed of the rear axle shaft .
Glad-hand
- A separable mechanical connector used to
join air line hoses when combination vehicles are coupled
together.
Grade
- The degree of inclination of a road. Typically
specified in percent (rise/100 ft run).
Gradeability
- Percent grade that a vehicle will negotiate.
Grease-stained Drum
- A brake drum with discoloration
of friction surface caused by, for example, improper
greasing of brake camshaft or wheel seal leakage.
Gusset
- A reinforcement welded to the camshaft bracket
to provide additional support for severe service
applications.
GVW (Gross Vehicle Weight)
- The total weight capacity
of a single vehicle.
GVWR (Gross Vehicle Weight Rating)
- The total
weight capacity of a single vehicle as determined by axle
ratings.
Hand valve
- See " Trailer Control Valve ".
Heat-checked Drum
- Brake drum with hairline cracks on
friction surface caused by thermal cycling. Mild checking
normally does not require drum replacement.
Heat-spotted Drum
- Brake drum with a pattern of hard,
slightly raised dark spots of martinsite on its friction
surface. Caused by localized overheating and sudden
cooling, those spots should be ground off to prevent drum
cracking, uneven lining wear and loss of braking
efficiency. If spots cannot be removed, the drum should be
discarded. Heat spotting is promoted by light and steady
braking on downgrades.
Helper Spring
- Additional spring device permitting
greater load on axle.
High Articulation Suspension
- Type of suspension for
off-road activity. Greater articulation or suspension travel
is required to keep tires in contact with the ground.
High Entry Single
- Front tandem axle used as a single
axle.
Highway
- A major road used for any form of motor
transport, typically outside of any city limits and with road
surfaces of good to excellent concrete or asphalt.
Hold-off Spring
- A spring within a relay valve or quick
release valve that's designed to retard valve operation until
a predetermined amount of air pressure is exerted. See
" Crack Pressure ".
Horse Power
- English unit used denote the amount of
work done in a given period of time, equal to 33,000 foot-
pounds per minute.
Housing
- A casing or container for mechanical
components.
Housing Box
- Cross section of square-armed or
rectangular-armed axle housing.
Hub Mount Wheel
- Wheels that are designed to center
on the hub at the bore of the wheel. These wheels generally
have straight-through bolt holes, since the bolt holes only
supply clearance for the stud. Hub mount wheels are used
with two-piece flange nuts.
Hypoid Gear
- Modified Spiral Bevel Gear that allows the
pinion to be positioned below the ring centerline.
Hysteresis
- Difference between the amount of pressure
needed to open a valve and the pressure drop needed to
close it.
I-Beam
- Forged steel structural beam constructed in the
shape of an "I".
Inertia Excitation
- Excitation produced by the oscillating
torque loads resulting from the drive shaft inertia being
accelerated through non-uniform motion.
Inset Wheels (or Negative Offset)
- The wheel centerline
is positioned inboard of the wheel mounting surface.
Installation Angle
- Angle that the drive shaft enters the
differential relative to horizontal.
Integral Coach
- Designed to carry passengers, the cab
and body of this style coach are built as one, most often
with rear engine design.
Integral Knuckle
- One piece steel knuckle forging made
with both steer and tie rod arms forged into one piece.
Interaxle Differential
- Gear device dividing power
equally between axles and compensating for unequal tire
diameters.
Interstate
- One of a system of limited access highways
extending between the major cities of the 48 contiguous
United States.