Copyright by Goodheart-Willcox Co., Inc.
Chapter 9 Automatic Transmission Control Components 187
Oil
seal
O-ring
Vent
baffle
Oil pump
body
Outer gear
Inner gear
Gasket
Reaction
shaft
support
Seal rings
#1 Thrust washer
(selective)
7
201
210
209
202
No. Description
7 Seal, pump/case
201 Body, pump
202 Cover, pump
209 Gear, pump drive
210 Gear, pump driven
A
B
Figure 9-2. Three types of transmission oil pumps are shown here. Note the stator shaft, which extends forward from oil pump. It
supports the torque converter stator. The shaft extending back from oil pump is the support and fluid feed for some transmission
clutches. A—Gear-type oil pump. The pump housing also contains built-in converter clutch and pressure regulator valves. The
pressure regulator valve lowers pump pressure by decreasing pump capacity. B—Rotor-type oil pump. The pump cover contains the
stator and clutch support shafts. (continued)
There are several types of transmission oil pumps, all
of which consist of elements—gears, rotors, or vanes—that
rotate inside a housing, Figure 9-2. (The types of hydraulic
pumps used in automatic transmissions were discussed in
Chapter 6.) As the elements rotate, they come together on
one side of the pump housing and move apart on the other.
As they move apart, a low-pressure region is created on the
inlet side of the pump. As a result, transmission fluid is
drawn from the sump, or oil pan, through the transmission
filter and pump inlet, and into the pumping chamber. The
fluid is then carried around the pumping chamber to the
pump outlet. The fluid is discharged into the hydraulic