Page 39 - Hydra-matic 6 Speed RWD Technician's Guide (October 2005)

HYDRAULIC CONTROL COMPONENTS

PRESSURE REGULATION
The main components that control line pressure are the line Pressure Regulation
pressure control (PC) solenoid and the pressure regulator valve. The line PC solenoid regulates fluid pressure as a function of
The fluid pressure required to apply the clutches varies in relation engine torque (minimum signal pressure at low torque, maximum
to throttle position and engine torque. At the pressure regulator signal pressure at high torque). Line pressure, acting on the end
valve, line pressure is regulated in response to the following: of the pressure regulator valve, moves the valve against spring
force and PC solenoid line fluid pressure to a point where line
- Fluid pressure routed from the line PC Solenoid (This fluid pressure enters both the converter feed and the decrease fluid
pressure is proportional to engine torque – see page 46). circuits. Decrease fluid pressure moves the pump slide (212)
PC solenoid line fluid pressure moves the isolator valve against spring force and toward the center of the pump cavity.
(236) against the pressure regulator valve inner spring (235) This decreases eccentricity between the pump slide and the
which acts against the pressure regulator valve (233). rotor which, as a consequence, decreases the pump output
capacity. Decrease pressure and the position of the pump slide
- Pressure regulator valve outer spring (234) force.
constantly varies depending on driving conditions and the amount
of fluid pressure and volume needed to operate the transmission.
The pressure regulator valve routes line pressure into both the
converter feed and the decrease fluid circuits. Converter feed
fluid is routed through the converter feed limit valve (220) and
the TCC control valve (227) to the torque converter release, and
the cooler fluid circuits. Decrease fluid pressure moves the fluid Pressure Regulator Related
pump slide against the force of the pump slide outer spring
(211). Diagnostic Tips
A stuck or damaged pressure regulator valve could cause:
• High or low line pressure
• Slipping clutches or harsh apply
• Transmission overheating
• Low or no cooler/lube flow

PRESSURE RELIEF PRESSURE RELIEF
VALVE VALVE
(LOCATED IN PUMP) (LOCATED IN PUMP)

1 1

LINE LINE
2 2
212 212
CONV FD CONV FD

PRESSURE REGULATOR VALVE 3 LINE PRESSURE REGULATOR VALVE 3 LINE

LINE
LINE
2a EXH FLUID 2a DECREASE FLUID
DECREASE
PUMP
PUMP
EXH
SLIDE
SLIDE
AND
AND
ROTOR
➤ ROTOR ➤ ➤
➤
ISOLATOR ISOLATOR
PCS LINE SUCTION PCS LINE SUCTION
5 5
ACT FD LIM PCS LINE ACT FD LIM PCS LINE
ISOLATOR ISOLATOR
VALVE VALVE
LINE LINE
PRESSURE PRESSURE
CONTROL CONTROL
SOLENOID SOLENOID
N.H. N.H.
MINIMUM PUMP OUTPUT MAXIMUM PUMP OUTPUT

30 Figure 30