Copyright by Goodheart-Willcox Co., Inc.
200 Automatic Transmissions and Transaxles
Steering column lever
Front rod
Torque
shaft
Swivel
assembly
Rear
rod
Transmission
control lever
Figure 9-19. Linkage transfers movement of the steering
column-mounted gear selector lever to the manual valve in the
transmission. Some vehicles use a cable instead of the rods and
levers shown here. (Chrysler)
Manual valve
Throttle
valve
Manual
valve
linkage
Throttle valve
linkage
Figure 9-20. Note the position of the levers inside and outside
the case. The manual valve lever has a projection that fits
between two lands of the manual valve. The throttle lever
pushes on the spring-loaded throttle valve. (Ford)
The outer manual lever is attached to the shift rod or cable
from the shift selector lever. Movement of the outer manual
lever is transferred through the shaft passing through the
case to move the inner manual lever. This lever connects to
the manual valve in the valve body. The manual valve
opens and closes passageways that direct fluid to the differ-
ent circuits in the transmission, as needed for the selected
operating range.
Note that a hole runs through the shaft of the outer
manual lever and shaft assembly shown in Figure 9-20.
Through this hole passes another shaft having levers at each
end. The outer throttle valve lever is connected, by linkage,
to the engine throttle, and the inner throttle valve lever is
connected to the throttle valve. The inner lever usually
contacts the throttle valve directly. Seals at the case and
throttle shaft prevent transmission fluid leaks.
The inner manual lever holds the manual valve in posi-
tion. If the manual valve were not held in place, hydraulic
pressure and vibration could cause the valve to move out of
position. A series of detents, sometimes called a cockscomb,
is part of the inner manual lever. This can be seen in
Figure 9-20. A spring is used to hold a roller or ball against
the detents. Spring pressure holds the lever in position; how-
ever, the spring is not strong enough to prevent movement of
the lever when the driver moves the selector lever.
Neutral Start Switch
A neutral start switch is shown in Figure 9-21.
Sometimes called a neutral safety switch, this switch pre-
vents starting the engine when the selector lever is in any
position but Park or Neutral. The switch may be transmis-
sion mounted or console mounted. (The column-shift
safety mechanism is usually in the ignition switch. The igni-
tion key will not turn to start the vehicle unless the selector
lever is positioned in Park or Neutral.)
If the engine were to start when the selector lever was
in any position but Park or Neutral, the vehicle would lurch
forward, possibly causing an accident or injury. The switch
is activated by movement of the shift linkage, and current is
allowed only when the selector lever is in Neutral or Park.
Otherwise, the switch contacts are open, and circuit cur-
rent cannot flow. The vehicle’s ignition switch is wired to
the starter solenoid through the neutral start switch. If the
ignition switch is operated when the selector lever is in any
Drive gear or Reverse, current will not flow to the starter
motor and the motor will not turn.
Note that in some cases, the neutral start switch has an
integral backup-light switch. The shift linkage makes con-
tact with a plunger within the switch when the selector
lever is in Reverse. Moving the plunger causes a second set
of contacts within the switch to close, completing the
backup-light circuit and causing the lights to go on.
Parking Gear
Figure 9-21 also shows part of the linkage that locks
up the parking gear, which is a toothed wheel splined to
the output shaft. The linkage extends to the rear of the
transmission and locks the output shaft to the case. A lever
with a parking pawl, Figure 9-22, is attached to the trans-
mission extension housing. The pawl moves in and out of
engagement with the parking gear. When the driver shifts to
the Park position, the shift linkage pushes on the parking