MANUAL TRANSAXLE <4WD> - Viscous Coupling .(VClJ)21-13In contrast, the inner plates have no such spacer rings, and
each can slide to some extent over the hub spline shaft
between the outer plates.
The space between the housing and outer and inner plates is
filled with mixture of silicone oil and air.
Plate A
Moving atvelocity V*
OPERATION OF THE VISCOUS COUPLINGPrinciples of operation
The viscous coupling is a kind of fluid clutch that uses viscous
resistance (shear stress) of the fluid to transmit power or limit
differential action.
For this purpose, the viscous coupling uses silicone oil whose
viscosity is less variable with temperature changes.
The principles of operation are described below, using an
enlarged model consisting of two parallel plates with fluid filling
the space between them.
Assume that fluid fills the space between plates A and
B.When plate A moves at velocity V, the fluid that is in contact
with plate A also moves at velocity V. The velocity of the fluid
decreases gradually in area closer to plate B; the area that is in
contact with plate
B is stationary. Thus there occurs a velocity
gradient in the fluid. As the fluid is viscous, the faster moving
fluid molecules develop a force (shear stress) to pull or
separate the more slowly moving molecules if there occurs
velocity gradient.
This force acts as resistance to the plate that is moving at
velocity
V (plate A) and as force to the stationary plate to move
it in the same direction as plate A.
In other words, shear stress works to reduce velocity differ-
ence of the two plates.
1 Torque characteristics
Rotating speed differenceWhen differential action occurs in the center differential, a
rotating speed difference occurs between the inner and outer
plates of the viscous coupling, and the oil between plates is
sheared, developing viscous resistance (differential limiting
torque).This viscous resistance changes with the rotational speed
difference as shown at the left. Namely, the differential limiting
torque increases with rotating speed difference.
i73BODY
- Doors23-19The doors are front hinged, sash doors opening
Lowards the rear with the following features.
lThe sash is flush with the body and has had its
height difference with the glass
surface mini-
mized to reduce wind noise.
* By effectively employing reinforcements, the
regularorrigidity of the outer panels and the rigidity of thebeltline openings have been improved.
lA two-step door check has been adopted to hold
the door securely at the midway position.
l The window regulator is of a compact and
light-weight wire winding type.
Door beltline innerreinforcement
Door beltline outer
reinforcement
Door lower
hinr-reinforcement *-lentDoor side impact bar
l6A0463
16AO462Door lower hinge
