Section IV. SYSTEM HYDRAULIC
d. The hydraulic system provides a constant
23-11. Purposes. The hydraulic system serves four
fresh supply of oil to all critical wearing surfaces of the
a. The planetary holding devices (clutches and
23-12. Supply System (Fig. 23-10). The supply
brake bands) are all actuated by hydraulic pressure from
the hydraulic slave circuits.
system provides a clean pressure-regulated supply of oil
for the hydraulic system of the automatic transmission.
b. The shifting pattern of the transmission is
Early automatic transmissions used a combination of an
engine-driven pump that worked in conjunction with an
controlled by the hydraulic system. This is done by
output shaft-driven pump. This configuration no longer is
switching hydraulic pressure to programmed
used and, therefore, will not be covered. The operation
combinations of the planetary holding devices based on
and construction of a typical system is described below.
vehicle speed and engine load indicators.
a. Hydraulic Pump (Fig. 23-11). The typical
c. The hydraulic system circulates the oil
hydraulic pump is usually a standard-type internal-
through a remote cooler to remove excess heat that is
external rotor-type pump (para
generated in the transmission and torque converter.
Figure 23-10. Typical Hydraulic Supply System