Operation and maintenance manual

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Section 120-0010

SM 2124 Rev 3 8-03

Lockup Clutch (Wk)

The transmission lockup clutch is automatically

engaged. Engine speed is picked up by turbine speed

sensor (8) which sends a signal to energise lockup

solenoid (3, Fig. 3) when turbine speed reaches a

predetermined level. Energising lockup solenoid

(3, Fig. 3) will move lockup valve (4, Fig. 3) across,

allowing oil to flow through the valve to engage

lockup.

Gear Selection

The transmission can be engaged and disengaged

under load by means of hydraulically controlled multi-

disc clutches. All gears run in antifriction bearings

and are constantly meshed. The gears, bearings and

clutches are lubricated with cooled oil.

The transmission is equipped with six multi-disc

clutches. These clutches are controlled via the six

proportional valves (6, Fig. 3). Each proportional

valve (6, Fig. 3) is composed of a pressure regulator

(Y1 to Y6, Fig.3), follow-on slide (5, Fig. 3) and

vibration damper (7, Fig. 3).

The control pressure of 9 bar for the actuation of the

follow-on slides (5, Fig. 3) is created by the pressure

reduction valve (2, Fig. 3). The pressure oil (16+2

bar) is directed via the follow-on slide (5, Fig. 3) to

the respective clutch.

Due to the direct proportional control with separate

pressure modulation for each clutch, the pressures to

the clutches, which are taking place in the gear

change, are controlled. In this way, a hydraulic

Transmission - Transmission and Mounting

SM - 1826

Y1 to Y6 - Pressure Regulators

1 - Main Pressure Valve 16+2 bar

2 - Pressure Reduction Valve 9 bar

3 - Lockup Solenoid

4 - Lockup Reduction & Shift Valve

5 - Follow-on Slide

6 - Proportional Valve (P1 to P6)

7 - Vibration Damper

8 - Harness Connection

Fig. 3 - Sectional View of Typical Control Unit with Lockup Clutch (Wk)

VALVE BLOCK

COVER

HOUSING

BREATHER

SYSTEM PRESSURE FROM

CONTROL UNIT