Daewoo Musso. Manual - part 252

5A-40  AUTOMATIC TRANSMISSION

Converter Clutch Regulator Valve

The converter clutch regulator valve (refer figure 3.20) regulates
the pressure of the oil which applies the converter clutch. Input
oil from the line 500 circuit is regulated within the valve, with
the output pressure being variable according to the signal
pressure from the S5 circuit. Converter clutch apply and release
application is smoothed by electronically varying the S5 circuit
pressure.

Converter Clutch Control Valve

The converter clutch control valve (refer figure 3.21) is a two position valve which applies or releases the converter
clutch.

The switching of this valve is governed by the signal pressure from S7.

When the valve is in the off or released position, converter feed oil from the PRV is directed to the release side of the
converter clutch. After flowing through the converter, oil returns to the converter clutch control valve and is then
directed to the oil cooler.

When the valve is in the on or applied position, regulated oil from the converter clutch regulator valve is directed to
the apply side of the converter clutch. This oil remains within the converter because the converter clutch piston is
sealed against the flat friction surface of the converter cover. To provide oil flow to the cooler the converter clutch
control valve directs converter feed oil from the PRV directly to the cooler circuit.

Figure 3.21- Converter Clutch Control Valve

Figure 3.20 - Converter Clutch Regulator Valve

AUTOMATIC TRANSMISSION  5A-41

C1 Bias Valve

The C1 bias valve (refer figure 3.22) ensures that the converter lock-up clutch is only applied in third and fourth
gears. It uses C1 clutch oil pressure as the switching signal since C1 is only applied in third and fourth gears.

Line to 500 oil is routed through the C1 bias valve to S7. The C1 bias valve therefore acts as a safety feature to
ensure drivability in the event of S7 failure.

Figure 3.22- C1 Bias Valve

B1R Exhaust Valve

The B1R exhaust valve (refer figure 3.23) is a two position
spring loaded valve located in the transmission case directly
adjacent to the front servo. It permits the servo release oil to
be rapidly exhausted into the transmission case during
application of the front band (B1). This prevents the need to
force the oil back from the front servo through the valve body
and through the 3-4 shift valve. The spring positions the valve
to prevent oil entering the release area of the servo until the
B1R circuit oil pressure reaches approximately 100 kPa.

Figure 3.23 - B1R Exhaust Valve

5A-42  AUTOMATIC TRANSMISSION

POWER TRAIN SYSTEM

The Power Train System consists of:

l

A torque converter with single face lock-up clutch

l

Four multi-plate clutch assemblies

l

Two brake bands

l

Two one-way clutches

l

Planetary gearset

l

Parking mechanism

A conventional six pinion Ravigneaux compound planetary gearset is used with overdrive (fourth gear) being obtained
by driving the carrier.

The cross-sectional arrangement is very modular in nature. Four main sub-assemblies are installed within the case
to complete the build. These sub-assemblies are:

l

Gearset-sprag-centre support

l

C1 -C2-C3-C4 clutch sub-assembly

l

Pump assembly

l

Valve body assembly

One, or a combination of selective washers are used between the input shaft flange and the number

4 bearing to

control the transmission end float. This arrangement allows for extensive subassembly testing and simplistic final
assembly during production.

A general description of the operation of the Power Train System is detailed below. Refer to table 4.1 and figure 4.1.

First gear is engaged by applying the C2 clutch and locking the 1-2 One Way Clutch (1-2 OWC). The 1-2 shift is
accomplished by applying the B1 band and overrunning the 1-2 OWC. The 2-3 shift is accomplished by applying the
C1 clutch and releasing the B1 band. The 3-4 shift is accomplished by re-applying the B1 band and overrunning the
3-4 OWC. Reverse gear is engaged by applying the C3 clutch and the B2 band.

The C4 clutch is applied in the Manual 1,2 and 3 ranges to provide engine braking. In addition, the C4 clutch is also
applied in the Drive range for second and third gears to eliminate objectionable freewheel coasting. The B2 band is
also applied in the Manual 1 range to accomplish the low-overrun shift.

Both the front and rear servos are dual area designs to allow accurate friction element matching without the need for
secondary regulator valves. All the friction elements have been designed to provide low shift energies and high static
capacities when used with the new low static co-efficient transmission fluids. Non-asbestos friction materials are used
throughout.

Gear

First

Second

Third

Fourth

Reverse

Manual 1

Gear

Ratio

2.741

1.508

1.000

0.708

2.428

2.741

C1

X

X

C2

X

X

X

X

X

C3

X

C4

X

X

B1

X

X

X

B2

X

X

1-2

OWC

X

3-4

OWC

X

X

X

LU

CLUTCH

X*

X

ELEMENTS ENGAGED

* For Certain Vehicle Applications, Refer to the Owner's Manual.

Table 4.1 - Engaged Elements vs Gear Ratios

AUTOMATIC TRANSMISSION  5A-43

Figure 4.1 - Power Flow Diagram

TORQUE CONVERTER

The torque converter (refer figure 4.2) consists of a turbine,
stator pump, impeller and a lock-up damper and piston
assembly. As in conventional torque converters, the impeller is
attached to the converter cover, the turbine is splined to the
input shaft and the stator is mounted on the pump housing via
a one way clutch (sprag).

The addition of the damper and piston assembly enables the
torque converter to ‘lock-up’ under favourable conditions. Lock-
up is only permitted to occur in third and fourth gears under
specified throttle and road speed conditions.

Lock-up is achieved by applying hydraulic pressure to the
damper and piston assembly which couples the turbine to the
converter cover, locking-up the converter and eliminating
unwanted slippage. Whenever lock-up occurs, improved fuel

consumption is achieved. Torsional damper springs are
provided in the damper and piston assembly to absorb any
engine torque fluctuations during lock-up.

Figure 4.2 - Torque Converter Cross Section