Space-a Truckers

Ch 23 Truck Axles

amboid gear set
a gear arrangement where the axle of the drive pinion gear is located above the radial center line of the crown gear it drives
axle range interlock
used to prevent axle ratio shifting when inter-axle differential action is locked out
axle shaft
used to transmit drive torque between the differential carrier assembly and the drive wheels
banjo housing
differential axle carrier housing that’s in the shape of a bango
controlled traction
different gearing that uses a friction plate assembly to transfer drive torque from a slipping wheel to its opposite
crown gear
a large disc shaped gear driven at right angles by a smaller pinion gear. it alters the torque path direction in a final drive carrier by 90 degrees so that a longitudinal drive shaft can deliver transverse torque to the driving wheels.
dead axles
a term used to describe any axle that does not have gearing to drive the vehicle. Lift axles, trailer axles, and steering axles fall into this category.
differential
drive axle gearing that transmits drive-line torque to axle shafts and the drive wheels, and allows the opposing wheels to rotate at different speeds for cornering and traction.
differential carrier
the drive axle assembly that houses the differential gearing.
differential lockout
driver-controlled means of locking out differential action to improve traction on a slippery surface
double-reduction axle
a differential carrier gear set that uses a pair of gear sets for greater speed reduction and increased drive wheel torque. used in severe service applications such as cement mixers, construction dump trucks.
final drive carrier
a drive axle assembly that contains gearing to alter the direction of the torque path by 90 degrees and incorporates differential gearing. (also called differential carrier)
full floating
a component that performs independently of the subsystem that contains it; for instance, this axle shaft imparts drive torque to a wheel assembly and does not support vehicle weight in any way.
hypoid gear set
a gear arrangement in which the axis of the drive pinion gear is located below the radial center line of the crown gear it drives. it’s often used in truck differential carrier gearing because its spiral bevel gear geometry allows the absorption of driving torque to be spread over a greater number of teeth, meaning that it is both tougher and quieter.
inter-axle differential
differential gearing used between the drive axles on a tandem drive, highway tractor: it divides torque between the two drive axles (also called a power divider)
inter-axle differential lock
driver actuated way of locking out inter-axle differential gearing actin to temporarily gain better traction
live axle
used to describe an axle that contains drive gearing. it is functionally opposite to a dead axle
pinion
a smaller, stub-shaped gear used to drive a larger gear in an arrangement such as crown and pinion gearing in final drive carriers or the starter motor pinion that engages with the flywheel ring gear.
planetary double-reduction axle
a drive axle using two reductions. The first reduction takes place at the pinion and crown gear-set, and the second reduction is achieved by a planetary gear-set
power divider
inter-axle differential gearing used in tandem drive,highway tractors to split torque between the two drive axles. (also called inter-axle differential)
pusher axle
a truck dead axle located in front of a drive axle that may or may not be a lift axle
single-reduction axle
drive axle gearing that uses only one stage of reduction gearing achieved by the pinion and crown gear set ration
spigot
a pilot bearing straight roller bearing mounted on the head of a shaft. Also a dump valve/tap assembly used on air tanks.
spin-out
this occurs when differential action allows one drive wheel on a slippery surface to spin while the other remains stationary and receives no driving torque. On tandem drive trucks (because of the additional differential action between the drive axles) it is possible to turn a spinning wheel at 4x its normal speed. this can take out the inter-axle differential or carrier differential. it is a driver abuse failure of differential carriers.
spiral bevel gear
helical gear set arrangement that has a drive pinion mesh with a crown gear at the radial center-line of the gear
tag axle
a truck dead axle located behind a drive axle may or may not be a lift axle
tandem drive axle
one of a pair of drive axles used in tandem drive highway trucks
torque proportional differential
Mack Trucks power divider that can vary the distribution of torque between the two drive axles of a tandem drive set. its known for its superior ability to contain potential spin-out conditions