Spicer Steer Axles Application Guidelines - Manual (Page 43)

AXAG400 – February 2007 front < 37 >
Integral knuckle – one piece steel knuckle forging made with both steer and tie rod arms forged into one
piece.
Jam Nut – second nut on a screw or bolt which 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.
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.
Knuckle – integral with the spindle, the inner portion of which is affixed to and pivots on the kingpin.
Knuckle 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 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 Index.
Lift able 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 for bridge laws.
Limited access – roads where access is controlled and limited to entrance and exit in designated areas
such as highway ramps; see also Turnpike.
Line Haul – trucking involving moving different types of freight in high mileage operation (over 60,000
miles/year).
LMS – Low Maintenance System that eliminates wheel-bearing adjustment and increases service
intervals using a combination of lube, bearings and seals.
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.
OAW – OverAll Width across the widest portion of the vehicle/axle/etc.
OEM – Original Equipment Manufacturer.
Off Highway – operation exceeding 10% of the time on unimproved surfaces such as loose dirt, mud and
sand.
On Highway – refers to trucking performed on turnpike quality roads, freeway or expressway.
On/Off Highway – refers to trucking operations that involve traveling both on highway and on roads of
lesser standards, for example timber hauled out of the woods on forest roads and then on the
highway to the mill.
Pitman arm – arm attached between the steering gear sector shaft and the drag link which transmits the
steering force from the cross shaft to the steering linkage system; this is how the rotary motion of the
steering wheel is turned into lateral movement of the arm.
Pusher axle – a "dead axle" (no driving capability) used to give vehicle more weight carrying capacity; a
pusher axle is ahead of the drive axle; a tag axle is behind the drive axle; this type of axle may have
the capability of being raised or lowered and some are made to be “steerable”.
Regional Haul – on-highway usage within a region, typically a one day round trip.
Relief pressure – maximum pressure where the steering gear is protected from providing too much load
into the steering system.
Rolling radius – distance from center of the tire to the ground under rated axle capacity.
Secondary – roads that are typically well maintained gravel or crushed rock, surface conditions are not
as favorable as on primary roads.
Sensor sleeve – rigid steel sleeve mounted in the knuckle to provide a pilot for the ABS sensor to be
mounted in close proximity to the tone ring on the hub.
Shims – spacers used to fill in the space between knuckle and top of beam after thrust washer is
installed on the bottom side of the beam.
SLR – Static Loaded Radius; distance, expressed in inches, from the center of a tire/wheel assembly to
the pavement, measured when mounted on a vehicle and loaded to its maximum rated capacity.
SMC – Spring Mounting Center; distance between frame rails where beam is mounted in the vehicle.
Spring pad – flat locator surface on the beam is drilled for the specific mounting pattern for the U-bolt
connect to the leaf spring.
Steer arm – rigid connection between the steering mechanism and the steer knuckle.
Steer arm swing radius – radius created when the steer knuckle rotates from stop to stop; establishes
clearance window.
Steering gear – the mechanism that translates the steering wheel rotation into movement at the steer
knuckle through the draglink.