Page 38 - Hydra-matic 6 Speed RWD Technician's Guide (October 2005)

HYDRAULIC CONTROL COMPONENTS

FLUID PUMP ASSEMBLY
TORQUE
CONVERTER PUMP
HOUSING SLIDE SLIDE
(203) FLUID PIVOT VANE COVER
SEAL SLIDE SLIDE PIN (216) ASSEMBLY
RING O-RING (212) (215) (219)
VANE ROTOR (209) SEAL
RING GUIDE (210)
(207) (208)

VANE
SLIDE ROTOR
OUTER RING (217)
SPRING SLIDE SLIDE (207)
(211) SEAL SEAL
SUPPORT (213)
(214)

FLUID PUMP ASSEMBLY
The fluid pump assembly contains a variable displacement, vane
PRESSURE RELIEF
VALVE type pump, located in the torque converter housing (203). When
(LOCATED IN PUMP)
the engine is cranking, the torque converter pump hub, which is
keyed to the fluid pump rotor (217), turns the rotor at cranking
speed. As the fluid pump rotor and the fluid pump vanes (216)
begin to rotate, the volume of fluid between the vanes is at its
1
maximum, creating a vacuum at the pump intake port. The
SLIDE vacuum allows atmospheric pressure, acting on the fluid in the
PIVOT bottom pan, to prime the pump quickly and pressurize the hy-
PIN
(215) draulic system when the engine is running.
LINE
Fluid from the transmission bottom pan (29) is drawn through
2
the fluid filter assembly (26) and into the fluid pump intake
(suction) fluid circuit. This fluid is then forced to rotate around
SLIDE the fluid pump slide (212) to the pump outlet port where the
(212) clearance between the fluid pump slide and the fluid pump rotor
decreases. Decreasing the volume pressurizes the fluid and forces
the fluid into the line pressure fluid circuit. This fluid is directed
to the pressure regulator valve and becomes the main supply of
DECREASE VANE fluid to the various components and hydraulic circuits in the
(216)
transmission.
LINE
The events described above occur when the pump is operating
at maximum output. Since most normal driving conditions do
ROTOR not require maximum output, the pressure regulator valve will
(217)
move far enough against spring force to allow pressurized fluid
to enter the decrease fluid circuit. Decrease pressure is applied
VANE FLUID
RING to the backside of the fluid pump slide, and moves the slide
(207) PAN against pump slide spring (211) pressure to lower the output of
(29)
SLIDE the pump. The result is a control of the pump’s delivery rate of
OUTER fluid to the hydraulic system.
SPRING
(211)
Pump Related Diagnostic Tips
• Transmission Overheating
• Loss of drive
FLUID FILTER • High or low line pressure
ASSEMBLY
(26) • Slipping clutch or harsh apply

Figure 29 29