Selectable Four Wheel Drive (S4WD) Front Axle Description and Operation
The Selectable Four Wheel Drive (S4WD) Front Axle consist of the following
components:
• | Differential Carrier Housing |
• | Differential Case Assembly |
• | Intermediate Shaft Bearing Assembly (located on the right side
of the oil pan) |
• | Electric Motor Actuator |
The front axle on Selectable Four Wheel Drive (S4WD) model vehicles
uses a disconnect feature mounted on the right side of the oil pan in order
to engage and disengage the front axle. When the driver engages the 4WD
system, the Transfer Case Control Module sends a signal to the electric
motor actuator to energize and extend the plunger inside. The extended
plunger moves the clutch fork and clutch fork sleeve across from the
clutch fork outer gear that is splined to the right side wheel drive shaft
to the clutch fork inner gear that is splined to the inner axle shaft.
The locking of the two gears allows the axle to operate in the same manner
as a semi-floating rear axle. A propeller shaft connects the transfer
case to the front axle. The differential carrier assembly uses a conventional
ring and pinion gear set to transmit the driving force of the engine
to the wheels. The open differential allows the wheels to turn at different
rates of speed while the axle continues to transmit the driving force.
This prevents tire scuffing when going around corners and premature
wear on internal axle parts. The ring and pinion set and the differential
are contained within the carrier. The axle identification number is
located on top of the differential carrier assembly or on a label on the
bottom of the right half of differential carrier assembly. The wheel
drive shafts are completely flexible assemblies consisting of inner
and outer constant velocity CV joints protected by thermoplastic boots
and connected by a wheel drive shaft.
Automatic Four Wheel Drive (A4WD) Front Axle Description and Operation
The Automatic Four Wheel Drive (A4WD) Front Axle consist of the following
components:
• | Differential Carrier Housing |
• | Differential Case Assembly |
• | Intermediate Shaft bearing Assembly (located on the right side
of the oil pan) |
The front axle on Automatic Four Wheel Drive (A4WD) model vehicles do
not have a disconnect feature in order to engage and disengage the front
axle. The Automatic Four Wheel Drive system uses the same differential
carrier assembly and intermediate shaft bearing assembly, but the clutch
fork, the clutch fork sleeve and the inner/outer gears have been replaced
with a single splined sleeve that connects the inner axle shaft directly
to the right side wheel drive shaft. This connection allows the right
side wheel drive shaft and the intermediate axle shaft to be directly
connected to the differential case assembly. It also results in having
the wheel drive shafts, the intermediate axle shaft and the propeller
shaft to spin continuously. When the transfer case is active, the clutch
assembly within the transfer case controls the amount of torque applied
to the front axle. The remaining components are the same as the selectable
four wheel drive axle.