Great Wall hover, Service Manual

Page: 89 / 425

Automatic transmission-13
Symbol of solenoid valve (On/off solenoid valve)
Figure 3.5 Normal-opened type
1.Variable pressure regulating valve regulating system
The shifting pressure of abrasion unit is controlled by the variable pressure regulating valve.
The line pressure is independent of the shifting pressure and determined by the thro
position, shifting status and engine speed.
S5 is a proportional or variable pressure regulating valve which provides the pressure signal control shifting pressure for
the clutch and brake belt regulating valve.
In automatic shifting period, it process the integral times enlarging and contracting
regulation for the clutch regulating valve, brake belt regulating valve, torque converter regulating valve and VPS.
The hydraulic pressure generated by variable pressure regulating valve is in inverse ratio with current. During the shifting, TCU
will increase or decrease the current of solenoid valve according to the program. The current is variable in the range of 200mA
to 1000mA. The increasing of the current will decrease the S5 output pressure; the decreasing of current will increase the output
pressure of S5.
Lin 500 pressure (about 440 to 560kPa) is the reference pressure of VPS, meanwhile, the VPS output pressure equals to the
pressure on line 500 always.
When the VPS is in waiting status, it means there is not the generation of shifting action. VPS current is 200mA. At this time,
it gives the maximum output pressure.
In stable status, the brake belt and clutch regulating solenoid valve is in closed status. In this condition, the pressure of line 500
is applied on the piston. For the line 500 pressure is more than S5 pressure always, so it pushed the oil in S5 to the place
between the regulating valve and piston. At this time, oil pressure applied on the friction unit equals to the product of pressure
on line 500 and magnification factor.
During the starting of shifting, the used on/off solenoid valve is in opened status which cut off the oil loop supply from line 500
to piston.
At the same time, VPS pressure is decreased to starting pressure valve, pressure set by regulating valve and pressure setting
value required by execution of VPS by pushing the piston from the valve. The shifting is finished through the on/off solenoid
valve, VPS returns to the waiting status
Pointed to each gear-position, the system can make the brake belt; clutch or both realize
the electronic control.
Mode indicator lamp: the mode indicator lamp can be used to indicate the current selected and whether the overpeed status
exists. The mode indicator lamp is located in instrument panel generally. (Refer to Part 2.3)