FWD-4WD Shift Mechanism (4WD)

ECVT Shift Mechanism (FWD):

ECVT Shift Mechanism (4WD):

OPERATION
Shifting from FWD (front-wheel drive) to 4WD (4-wheel drive), or vice versa, is accomplished by a button switch. This switch controls the line pressure to move the fork via the piston and rail.

When current does not flow through the 4W0 solenoid valve ("OFF"), the transfer valve moves to the right due to tension from spring 1. This causes line pressure to flow from circuit "1" to oil chamber "3" so that the piston moves to the left. Movement of the piston disengages the FWD-4WD clutch to set the circuit in the FWD mode.

When current flows through the 4WD solenoid valve ("ON"), the solenoid valve overcomes the tension of spring 1. This causes the transfer valve to move to the left. Line pressure then flows from circuit "1" to oil chamber "2" so that the piston moves to the right. Movement of the piston engages the sleeve and coupling to set the circuit in the 4WD mode.

However, when the line pressure control solenoid valve "4" is "OFF" (i.e., current does not flow through it), line pressure in circuit "1" is discharged from drain port "5" of line-pressure control solenoid valve "4". As a result, shifting between FWD and 4WD cannot be accomplished.