4WD SYSTEM


There are 2 types of 4WD system; easy select 4WD and super select 4WD.
Each 4WD system has following features:

EASY SELECT 4WD SYSTEM


For the easy select 4WD system, the double cone synchroniser has been adopted as the 2WD/4WD changeover mechanism. Thus, 2WD/4WD can be switched-over during driving, and the shift operation torque is reduced.

POWER FLOW


The easy select 4WD is composed of the 2WD/4WD changeover mechanism and high/low changeover mechanism as shown in the figure. With operating those, the drive torque transmission method can be selected.



2WD/4WD SWITCHING MECHANISM


The 2WD/4WD switching mechanism consists of the following parts: 2WD/4WD synchronizer hub, drive sprocket, 2WD/4WD synchronizer sleeve, outer ring, synchronizer cone, inner ring, synchronizer spring, and rear output shaft.
The 2WD/4WD synchronizer hub moves in mesh with the rear output shaft, outer ring and inner ring, while the drive sprocket is in engagement with the synchronizer cone.
The 4WD state is established when the 2WD/4WD synchronizer sleeve engages with the drive sprocket.


2WD OPERATION ("2H" POSITION SELECTED)

When "2H" is selected, the 2WD/4WD synchroniser sleeve is in the position shown as the figure. On this position, the drive sprocket does not rotate, and the drive torque does not transmit to the front differential. Therefore, the vehicle operates as a rear drive vehicle.

4WD OPERATION ("4H" OR "4L" POSITION SELECTED)

When "4H" or "4L" is selected, the 2WD/4WD synchroniser sleeve is in the place shown as the figure. On this position, the 2WD/4WD synchroniser hub and the drive sprocket are connected with the 2WD/4WD synchroniser sleeve for rotation, and the drive torque transmits to the front differential. Therefore, the vehicle operates as a four-wheel drive vehicle.

DOUBLE CONE SYNCHRONIZER


The synchroniser system is composed as shown in the figure.
The double cone synchroniser contacts both sides of the synchroniser cone (inner ring side and outer ring side) for synchronised operation. Then the capacity for synchronised operation increases to reduce the sift operation torque.


4WD INDICATOR-ECU
With the ON/OFF signals from each switch installed on the transfer and freewheel clutch, the drive state is determined, and the 4WD indicator lamp is controlled.

4WD INDICATOR LAMP
The 4WD indicator lamp indicates the currently selected mode of operation of the 4WD system. The 4WD indicator lamp is located in the combination meter.
Transfer shift position
 2H
 →
 4H
 →
 4L
 →
 4H
 →
 2H
Indicator lamp
 OFF
 Flash
 ON
 OFF
 ON
 OFF
 ON
 Flash
 OFF
Ignition switch
 OFF
 ON
 OFF
High/Low detection switch
 ON
 OFF
 ON
 OFF
 ON
4WD detection switch
 OFF
 ON
 OFF
Freewheel solenoid valve
 OFF
 ON
 OFF
 ON
 OFF
Freewheel engage switch
 OFF
 ON
 OFF

SUPER SELECT 4WD SYSTEM


The super select 4WD system houses a centre differential with VCU in the transfer, in addition to the High/Low switching mechanism and 2WD/4WD changeover mechanism. Thus, 4 drive types of 2WD, full-time 4WD, direct coupling high range 4WD, and direct coupling low range 4WD are selectable, enabling the 4WD system to cope with any driving conditions.

DRIVE METHODS
Transfer shift pattern
 Position
 2WD/4WD
 High/Low
 Centre differential
 Drive condition


2H
 2WD
 High
 -
 For driving on a dry ordinary road or highway. (Economical driving position)
4H
 4WD
 High
 Operating
 For ordinary and slippery road driving. (VCU functions to limit the differential operation)
4HLc
 4WD
 High
 Locked
 For driving on rough, sandy or snow-covered roads.
4LLc
 4WD
 Low
 Locked
 For greater traction torque as when climbing steep inclines.

POWER FLOW


The super select 4WD is composed of the 2WD/4WD changeover mechanism, high/low changeover mechanism, centre differential and VCU as shown in the figure. With operating those, the drive torque transmission method can be selected.



2WD/4WD SWITCHING MECHANISM


The 2WD/4WD switching mechanism consists of the following parts: differential lock hub, 2WD/4WD synchronizer hub, drive sprocket, 2WD/4WD synchronizer sleeve, outer ring, synchronizer cone, inner ring, synchronizer spring, front side gear and transfer drive shaft.
The differential lock hub is engaged with the transfer drive shaft, the 2WD/4WD synchroniser hub is engaged with the front side gear, outer ring, and inner ring, and the drive sprocket is engaged with the synchroniser cone. Each of them operates as a unit. The 2WD/4WD synchroniser sleeve switches the drive type by connecting them.


2WD OPERATION ("2H" POSITION SELECTED)

When "2H" is selected, the 2WD/4WD synchroniser sleeve is in the position shown as the figure. On this position, the drive sprocket does not rotate, and the drive torque does not transmit to the front differential. Therefore, the vehicle operates as a rear drive vehicle.

4WD OPERATION ("4H" POSITION SELECTED)

When "4H" is selected, the 2WD/4WD synchroniser sleeve is in the place shown as the figure. On this position, the 2WD/4WD synchroniser hub and the drive sprocket are connected with the 2WD/4WD synchroniser sleeve for rotation, and the drive torque transmits to the front differential. Therefore, the vehicle operates as a four-wheel drive vehicle.
At this time, even if rotation speeds differ between the front and rear wheels, the centre differential is effective because the differential lock hub is free. This allows the smooth drive. VCU incorporated in the centre differential limits the rotation speed difference to achieve the constant optimal drive force according to the rotation speed difference.

4WD OPERATION ("4HLC" OR "4LLC" POSITION SELECTED)

When "4HLc" or "4LLc" is selected, the 2WD/4WD synchroniser sleeve is in the place shown as the figure. On this position, the differential lock hub, the 2WD/4WD synchroniser hub, and the drive sprocket are connected with the 2WD/4WD synchroniser sleeve for rotation, and the drive torque transmits to the front differential. Therefore, the vehicle operates as a four-wheel drive vehicle.

DOUBLE CONE SYNCHRONIZER


The synchroniser system is composed as shown in the figure.
The double cone synchroniser contacts both sides of the synchroniser cone (inner ring side and outer ring side) for synchronised operation. Then the capacity for synchronised operation increases to reduce the sift operation torque.


4WD INDICATOR-ECU
With the ON/OFF signals from each switch installed on the transfer and freewheel clutch, the drive state is determined, and the 4WD indicator lamp is controlled.

4WD INDICATOR LAMP
The 4WD indicator lamp indicates the currently selected mode of operation of the 4WD system. The 4WD indicator lamp is located in the combination meter.