Shift Pressure (p-S)
The shift pressure is determined by the shift pres-
sure regulating solenoid valve and the shift pressure
regulating valve. The shift pressure:
• Regulates the pressure in the activating shift
element during the shift phase.
• Determines together with the modulating pres-
sure the pressure reduction at the deactivating shift
element as regulated by the overlap regulating valve.
• Initializes 2nd gear in limp-home mode.
Modulating Pressure (p-Mod)
The modulating pressure influences the size of the
working pressure and determines together with the
shift pressure the pressure regulated at the overlap
regulating valve. The modulating pressure is regu-
lated at the modulating pressure regulating solenoid
valve, which is under regulating valve pressure. The
modulating pressure is variable and relative to the
engine load.
Regulating Valve Pressure (p-RV)
The regulating valve pressure is regulated at the
regulating valve pressure regulating valve in relation
to the working pressure (p-A) up to a maximum pres-
sure of 8 bar. It supplies the modulating pressure
regulating solenoid valve, the shift pressure regulat-
ing solenoid valve and the shift valve pressure regu-
lating valve.
Shift Valve Pressure (p-SV)
The shift valve pressure (p-SV) is derived from the
regulating valve pressure (p-RV), is regulated at the
shift valve pressure regulating valve and is then
present at the:
• 1-2 and 4-5 shift solenoid valve.
• 3-4 shift solenoid valve.
• 2-3 shift solenoid valve.
• Torque converter lockup solenoid valve.
• 3-4 and 2-3 shift pressure shift valve.
The shift valve pressure (p-SV) controls the com-
mand valves via the upshift/downshift solenoid
valves.
Overlap Pressure (p-Ü)
The overlap pressure controls the shift component
pressure reduction during a shift phase. The pres-
sure in a shift element as it disengages is controlled
during the shift phase depending on engine load
(modulating pressure) and the pressure in the shift
element as it engages. The adjusted pressure is
inversely proportional to the transmission capability
of the shift element being engaged (controlled over-
lap).
Working Pressure Regulating Valve (Operating Pressure)
The working pressure regulating valve (Fig. 64) is
located in the valve housing of the shift plate. It reg-
ulates the primary pressure of the hydraulic system.
Fig. 64 Working Pressure Regulating Valve
1 - PRESSURE FROM K1/K2
2 - END FACE
3 - ANNULAR SURFACE
4 - WORKING PRESSURE REGULATING VALVE
21a - 58 TRANSMISSION AND TRANSFER CASE WG
ELECTROHYDRAULIC UNIT (Continued)
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