Spicer Drive Axles Application Guidelines - Manual (Page 99)

AXAG-0200 June 2009 99
Glossary
Inversion Valve
- Valve used on trucks to release air from
the parking brake chambers and apply the rear brakes if the
rear air reservoir fails, modulated by the brake pedal.
Jackknife
- Uncontrollable articulation of a tractor-trailer
typically resulting from lock-up or spinning of tractor drive
axle(s). The risk of jackknife is greatest on a slippery road
with an empty or lightly laden trailer in tow.
Jake Brake
- Trademark of engine brakes by the Vehicle
Equipment Division of The Jacobs Manufacturing Co. See
" Engine Brake ".
Jam Nut
- Second nut on a screw or bolt that locks against
the first nut (i.e., jams against it) so that the nut won't come
loose.
Kingpin
- Front axle pin allowing wheels to steer vehicle.
Also called knuckle pin.
Kingpin Angle
- Angle of the kingpin in relation to a
vertical line at the point of intersection on the ground at tire
contact as viewed from the front or back.
Kingpin Cap
- Bolt on or threaded in cap used to seal the
outer sides of the upper and lower portion of the steer
knuckle. This cap is used to prevent contamination from
getting into the kingpin joint area.
Knuckle
- Integral with the spindle, the inner portion of
which is affixed to and pivots on the kingpin.
Knuckle Cap
- See " Kingpin Cap ".
Knuckle Pin
- See " Kingpin ".
Knuckle Seal
- Seal built into inner side of the upper and
lower portion of the steer knuckle. This seal is used to
prevent contamination from entering the areas between the
kingpin, the knuckle and the beam.
KPI (Kingpin Intersection)
- The distance between the
intersection points of LH and RH steer knuckles pivot, or
the points where the spindle axis crosses the king pin axis.
Leak-down Test
- A common method of checking for air
leaks. With the engine off, vehicle stationary, the air
system at maximum governed pressure and all service
brakes fully applied, there should be no more than a 3 psi/
min. air loss noted on the dash-mounted pressure gauge for
straight trucks ; 4 psi/min. for combination vehicles.
Liftable Axle
- Axle that is capable of lifting off the
ground and reducing load during parking maneuvers and
lowering to the ground and reducing the load from bridge
laws. See " Pusher Axle " & “ Tag Axle ”.
Limited Access
- Roads where access is controlled and
limited to entrance and exit in designated areas such as
highway ramps. See " Turnpike ".
Limited-slip Differential
- Mechanical action that resists
the free working of an ordinary differential, thus
distributing a greater torque to the slower-turning wheel or
axle.
Line Haul
- Trucking involving moving different types of
freight in high mileage operation (over 60,000) miles/year.
Lining Swell
- Temporary swell of brake lining that occurs
with heat, but returns to original when cooled.
Lining Growth
- Permanent swelling of brake lining
resulting from heat exposure. Occurs in new lining only.
LMS (Low Maintenance System)
- Optional packages
are either lube for life or annual lube.
Locator Dowel Hole
- Drilled hole located centrally on the
spring pad drilling that is used to locate the caster block
used to attach the springs to the steer axle.
Lockout Assembly
- A shift unit that controls the
operation of the interaxle differential in tandem drive
axles. The operation of this unit is controlled from the
vehicle cab by the driver and is activated by either air
pressure from the vehicle's air reservoir (brakes) or by
electrical means in.
Long stroke Chamber
- A brake chamber designed to
have longer-than-normal push rod travel, adding safety
factor to chamber stroke. For example, a regular, clamp-
type, Type 30 chamber has a readjustment limit of 2 in and
a maximum stroke of 2.5 in. A long has a readjustment
limit of 2.5 in and a maximum stroke of 3 in.
Low Maintenance System
- See " LMS ".
Low Pressure Warning Device
- Pressure-sensitive
electrical switch that actuates an in-cab buzzer and
warning light when air pressure falls below a
predetermined level (typically, 60 psi).
Marion Support
- A "tear-drop" shaped support that fits
over the camshaft barrel located between the chamber
bracket and the automatic brake adjuster (ABA). The
Marion Support is welded to the axle housing after the
brake assembly is mounted to the axle. This is an optional
means of support where the BCCC dimension is 13.5" or
longer.
Mechanical Suspensions
- A suspension that is not an air
ride suspension.
Michigan Special Gravel Trains
- An eleven axle
combination permitted in Michigan with gross weights as
high as 164,000 lbs.