190303jA Flashcards
Drive Axle and Carrier Fundamentals and Service- Part A
What is sprung vs unsprung weight?
sprung weight: anything supported by suspension
unsprung weight: anything not supposed by suspension
an off road assembly must withstand and support the weight of the equipment and load that has been passed through the suspension system to drive axle assemblies
T or F
True
off road equipment must be able to handle the loads and stresses applied by _____________ and the extreme applications the machines are designed for
working conditions
the rear axle assembly must be able to withstand the forces applied while the box is _______
raised
the drive axle changes the direction of power flow by how many degrees?
90 degrees
what provides the final gear reduction in the powertrain?
the drive axle
what does GAWR stand for?
gross axle weight rating
what is the GAWR?
manufacturer says how much an axle can safely carry
gross axle weight refers to the weight the axle must be able to carry. what does it not refer to?
the weight it must propel
what determines the construction of the housings, bearings, axles, and wheel ends?
the gross axle weight rating
what torque ratio does the drive axle provide?
reduction
how does the drive axle change the path of power to 90 degrees?
with bevel gears
what is the path of power in a single reduction drive axle diff?
input pinion
crown (bevel) gear
diff case halves
cross shaft (spider)
diff pinion gear (spider gears)
axle side gears
axle
what is the math equation to find bevel rpm?
left rpm + right rpm / 2= bevel rpm
you won’t lose speed in a differential
if the machine travelled in a straight line, there would be no need for a speed difference between the?
wheel ends
ways traction control can be activated?
by operator manually
automatic differential
limited slip differential
what do the automatic/limited slip differentials allow the diff to do?
auto lock when traction is bad on one side of the machine, but allows diff to work normal while cornering
Function of the carrier housing (differential case)?
hold the internal gear components (pinion, bevel, diff case, diff assembly)
carrier must be able to handle?
all torque created through the engine and powertrain
why does the carrier have 2 removable caps at the rear?
to secure diff case bearings and adjusters
where is the differential carrier located?
in rear axle housing behind tranny
what does the differential thrust pin do?
prevent diff movement during high thrust loads
what type of equipment runs an integral input pinion?
smaller equipment, limits torque applied to carrier
what type of equipment runs a carrier mounted pinion?
large equipment, need breakout torque forces. torque multiplies through differentials
Characteristics of a full floating axle shaft?
only transmits torque, does not carry machine weight
what is the main function of a full floating axle shaft?
drive the final drive and hub assembly
on a full floating axle, how is the weight and load transmitted?
through the drive axle housing, bearing arrangement, hub assembly, wheels
benefit of a full floating axle while disassembling?
can remove the axle while keeping the vehicle weight on the tires
characteristics of a semi floating axle shaft?
transmits torque and carries weight of machine
what is the common arrangement for planetary final drives?
inout on sun, output on carrier, ring held, carrier turns sun, carrier output, ring held
what can a machine produce while using double reductions?
great amounts of breakout torque, axle component stress minimal
what axle design is the only application that can handle extreme forces created at the wheel end?
full floating axle design
what is the drive axle housing made form?
cast steel
what does the axle housing provide?
frame for mounting carrier assembly and attached components
what is the opening called in the middle of the drive axle housing?
the bowl
what is the carrier housing made from
cast steel
what is the main function of the carrier housing?
hold internal gear components
the carrier must be sturdy enough to support components and withstand what forces?
forces trying to separate the gears
what does th opinion bearing cage house?
bearings that support the pinion
why are tapered roller bearings on the pinion put under preload?
to keep pinion located properly, ensure bearings rotate while under torque
what determines bearing preload?
selective spacer, designated thickness
how can you adjust pinion depth?
with shims between pinion bearing cage and carrier housing
what prevents lube from escaping?
input pinion seal
what provides the final gear reduction in the powertrain?
the pinion and bevel gear
what does an overhung pinion look like?
has a flat surface at the end of the pinion gear
where does the pinion sit in an abmoid pinion position?
above centreline
what is the better pinion mount, overhung or straddle?
straddle is stronger than overhung
what does a straddle mount pinion look like?
short stub shaft extends past the end of the pinion gear. has a bearing at the end
what design of pinion mount is better for high torque loads?
straddle mount
what does the stub shaft prevent the pinion from doing?
deflect away from bevel gear in high torque situations
where does a hypoid pinion set in relation to the centreline?
below the centreline
where does the spiral bevel pinion sit in relation to the centreline?
at the centreline
where does the bevel gear bolt to?
the differential case, diff case rotate when bevel gear rotates
what drive assembly does the drive pinion and bevel gear set act as?
an angle drive assembly
according to the book, can you swap out the drive pinion or bevel gear individually?
no, must be used in matched sets
where is the gear ratio stated on a pinion?
at the threaded end of the pinion, opposite the gear end
where is the pinion position number found on a pinion?
on the stub shaft/ at the head of the gear on the pinion
what does 39-6 mean on a gear?
the gear ratio, 39/6
what is used to prevent the bevel gear from deflecting away from the pinion in high torque load?
a thrust screw
where does the thrust screw sit and why does it sit there?
exactly opposite the pinion gear, on back side of bevel gear. sits bc that’s where max thrust load and deflection is
what’s another name for the differential cross shaft?
spider
what is the last component that makes up the diff case assembly?
the axle side gears
in a differential what gears can rotate at a different speed than the case?
the axle side gears
what are the 2 functions of a differential assembly?
split torque evenly to each shaft
deliver torque while allowing for difference in wheel speed side to side
what does the differential assembly act like?
a torque divider
torque is a function of resistance to?
movement
since the differential delivers the same amount of torque to each axle, the wheel that has good traction will only receive the amount of torque required to rotate the wheel with poor traction, because it goes off of resistance and it will take the path of least resistance
there is no answer that’s just good info
can speed or RPM of the axles be lost?
no, what comes in goes out. or is transferred to other side
while travelling straight ahead over even terriain, what is the differential gears doing?
all turning together
what happens to the wheels when you make a turn?
outer wheel goes faster than inner wheel, needs to travel a farther distance
when travelling in a straight line with uneven tire size or uneven terrain, what will happen?
diff gears will act like machine is cornering as one side will have to make up for the other side
when can extreme speed differences occur in a differential?
with really bad traction
how many differentials would a single motor scraper and single axle haul truck have?
one differential
what does a transfer case do?
drop flow of power down form tranny and then divide the power between the front and rear shafts
what does a transfer gear do?
split power to each axle group
how is a range shift collar actuated?
air pressure and solenoid valves
what does an interaxle differential help with?
splitting torque equally between front and rear drive shafts
how can you eliminate differential action to ensure both axles rotate at the same speed?
by locking the differential carrier to one axle side gear
what style of traction control provides more torque to the wheel with the greatest traction?
limited slip and no-spin
what traction controls don’t lock the carrier and axle to the extent that the locking differential does?
limited slip and no spin
what is a disadvantage of a locking differential?
shitty cornering
what are 2 types of diff locks?
jaw (dog) clutch
disc/plate clutch
how does a jaw style clutch work?
shift collar moves up and down with air, locks together to eliminate diff action
how can you limit damage when using a dog clutch?
operator low engine speed, travel straight ahead, don’t engage it when moving
on a plate and disc clutch diff lock, what is the normal position?
clutch released, oil applied spring released
what does a limited slip differential provide?
equal power and torque rot both shafts in normal conditions
if one wheel loses traction in a limited slip diff, where does the torque go?
to the wheel with more traction
how does the no-spin differential operate?
normally engaged and drives both wheels at same speed all the time, but when cornering it will unlock and allow that wheel to go faster
the bevel gear is bolted directly to the:
flanged case half
the differential pinions are driven by the:
cross shafts
the most common differential carrier assembly used today is the
single speed single reduction
