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8/6/2019 Automotive Transmission - 14
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
Axles were originally defined as rigid lateral connections between two wheelswhich could be steered together.
This type of axle helps ensure rolling stability and simplifies assembly by
providing a connection between the wheels and body.
the axle assembly includes the subframe, steering gear, stabilizer, anddifferential.
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Axles types
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
Rigid axles (dependent wheel control)
Independent suspension systems (independent wheel
control)
A third axle concept can be defined which lies between
the two types listed above:
Semi-rigid axles (twist beam suspension systems)
Placed front orrearof the vehicle (front axles, and rear axles)
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rigid Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
A rigid axle is defined as a lateral axle body that rigidly connects twowheels to one another and makes the motion of one wheel dependent
on the motion of the other.
This solution is also known as a solid axle, live axle, or dependent
wheel control system
found on a small number of cars and SUVs built for maximum off-road
performance
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Live and Dead Axle
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
A live axle is one that supports part of the weight of a vehicle
and drives the wheels connected to it.
A dead axle is one that carries part of the weight of a vehicle but does
not drive the wheels.
The wheels rotate on the ends of the dead axle.
Usually, the front axle of a passenger car is a dead axle and the rear
axle is a live axle.
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rear Drive Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
The rear drive axle connects the differential side gears to the drive
wheels.
The axle may or may not support the weight of the vehicle.
Rear axles are normally induction hardened for increased strength.
semifloating, three-quarter floating, and full floating.
Most automobiles use the semifloating type, whereas four-wheel drive
vehicles and trucks use full floating axles.
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rear Axle - Semifloating
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
The semifloating axle (fig. 13-21) used on mostpassenger cars and light trucks has its differential
case independently supported. The differential
carrier relieves the axle shafts from the weight of
the differential assembly and the stresses caused
by its operation. For this reason the inner ends of
the axle shafts are said to be floating. The wheelsare keyed to outer ends of axle shafts and the
outer bearings are between the shafts and the
housing. The axle shafts therefore must take the
stresses caused by turning, skidding, or wobbling
of the wheels. The axle shaft is a semifloating live
axle that can be removed after the wheel has beenpulled off
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rear Axle - Semifloating
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
The semifloating axle (fig. 13-21) used on mostpassenger cars and light trucks has its differential
case independently supported. The differential
carrier relieves the axle shafts from the weight of
the differential assembly and the stresses caused
by its operation. For this reason the inner ends of
the axle shafts are said to be floating. The wheelsare keyed to outer ends of axle shafts and the
outer bearings are between the shafts and the
housing. The axle shafts therefore must take the
stresses caused by turning, skidding, or wobbling
of the wheels. The axle shaft is a semifloating live
axle that can be removed after the wheel has beenpulled off
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rigid Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. KarthikeyanFour-wheel-drive off-road vehicle with rigidfront and rear axles
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rigid Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
Rigid driven rear axles are more common
and aregenerally used in heavier vehicles (SUVs,
vans, light
trucks) with reduced comfort expectations
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rigid Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
The properties of rigid axles are (Figure 4-3):
simplicity, economy, cost-effective integration of
the rear differential into the axle body (half-shafts
with no joints)
flat package shape wide loading surface for nondriven
axles
robustness, large load capacity
high roll center
identical orientation of both wheels during parallel
wheel travel (both wheels have the same toe and
camber)
large axle movements are possible (off-road use)
large unsprung mass (the entire axle moves withwheels), for driven axles up to twice as large as
that of an independent suspension system
the motion of one wheel affects the motion of the
other wheel during single-wheel compression
events (examples include tramping, wheel hop, and
a reduction in the wheels ability to compress) maneuver-de endant a lied wheel forces and
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rigid Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
The properties of rigid axles are (Figure 4-3):
simplicity, economy, cost-effective integration of
the rear differential into the axle body (half-shafts
with no joints)
flat package shape wide loading surface for nondriven
axles
robustness, large load capacity
high roll center
identical orientation of both wheels during parallel
wheel travel (both wheels have the same toe and
camber)
large axle movements are possible (off-road use)
large unsprung mass (the entire axle moves withwheels), for driven axles up to twice as large as
that of an independent suspension system
the motion of one wheel affects the motion of the
other wheel during single-wheel compression
events (examples include tramping, wheel hop, and
a reduction in the wheels ability to compress) maneuver-de endant a lied wheel forces and
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AutomotiveTransmission
AUTOMATIC TRANSMISSION
Rigid Axles
PSG College of Tech Dept of Automobile Engg.. Asst. Prof. R. Karthikeyan
The differential on a driven rigid axle can either be
integrated into the axle housing or attached to the
vehicles body separate from the axle.