Spicer Drive Axles Application Guidelines - Manual (Page 105)

AXAG-0200 June 2009 105
Glossary
Trailing Arm Suspension
- A suspension with a total of
two trailing arms. This suspension forces the axle to travel
in an arc which results in a caster change and also torques
the axle as the suspension goes into roll.
Trailing Axle
- See " Tag Axle ".
Transfer Case
- Split power gear box transmitting drive to
front and rear axles.
Transmission (Main)
- Selective gearbox providing
various combinations of gear ratios.
Transmission (Auxiliary)
- Additional gearbox increasing
the gear ratio combinations when used with main
transmission or multi-speed axles.
Treadle Valve
- Foot-operated brake actuation valve.
Tridem Axle
- A combination of three axles having a
common suspension.
Tri-drive
- See " Tridem Axle ".
Trolley Valve
- See " Trailer Control Valve ".
Trunnion
- Journals allowing pivoting or turning.
Tubular Beam
- Beam constructed of a seamless / hollow
tube with forged steel beam ends welded on the ends to
create the foundation of a steer axle.
Turned Drum
- A brake drum that has been resurfaced on
a lathe to remove scoring or other defects. The diameter
must stay within manufacturer's limits.
Turnpike
- Expressway or freeway.
Two-speed Axle
- A rear-axle assembly that has two
different output ratios from the differential carrier
assembly. Used primarily for export and most popular with
5-speed transmissions to provide a fast ratio for top speed
and a slower ratio for greater pulling power. These ratios
are controlled by the vehicle driver from the cab at the
driver's discretion. This axle is sometimes called a dual
range unit.
Two-spring Suspension
- A standard leaf spring
suspension.
Underslung Suspension
- A trailing arm suspension in
which the trailing arm is mounted to the bottom of the axle.
Unitized Hub System
- Hub system that is factory filled
with synthetic grease and sealed to avoid lubrication
intervals, bearing adjustment, and seal replacement -
eliminating hours of typical maintenance.
Vocation
- Specific usage of a vehicle in a defined industry.
Vocational
- Dedicated to one specific type of service (i.e.
mining, oil field, logging etc.).
Walking Beam Suspension
- A mechanical suspension
that attaches two axles together with the use of a leaf spring
or structural beam that pivots about a trunnion tube.
Warning Light, ABS
- An indicator light on the truck or
tractor instrument panel that illuminates to indicate the
status of the ABS system. On trailer ABS, the indicator
light may be located on the trailer body where the driver or
maintenance personnel can easily see it.
Wedge Brakes
- As opposed to a brake applied by an S-
cam, this type of brake is applied by a single or double
wedge-type mechanism. This type of brake is self-
adjusting and, as such, does not utilize an external brake
adjuster.
Wet Tank
- Also known as the supply air tank, that
reservoir nearest to the air compressor where water and oil
are most likely to accumulate (assuming the lack of a
functional air dryer).
Wheelbase
- Distance between centerlines of front steer
and rear drive axles or to centerline of tandem axles.
Wheel Bearing
- Typically a set of two opposing tapered
roller bearings that provide radial and thrust load capability
while at the same time providing rolling motion.
Wheel Inset, Negative
- The rim centerline is positioned
inboard of the wheel mounting face.
Wheel Offset
- See " Wheel Inset " or " Wheel Outset ".
Wheel Outset, Positive
- The rim centerline is positioned
outboard of the wheel mounting face.
Wide Base Tire
- See " Super Single Tire ".
Wide Brake Package
- An optional package consisting of
16.5 x 5 (12K steer) and 16.5 x 8-5/8; (20K/23K drive
axle). The greater width will reduce brake-operating
temperatures thus increasing brake life.
Wide Track
- Axle that is wider than standard maximum
96" overall width.
Wide Track Housing
- Extended length housing used to
meet increased track and stability requirements.
Woodruff Key
- A half-moon shaped piece of metal used
to secure something to a shaft that has a notch cut in the
shaft to accommodate the key.
Worm Gear
- Component of brake adjuster. The worm and
worm gear provide for adjusting lining-to-drum clearance.