Hudson 1948 Commodore, Service Manual

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double action hydraulic top operating cylinders.
The electric pump motor is operated through a solenoid
switch incorporated in the cylinder.
To make a complete check, both the ELECTRICAL
system and the HYDRAULIC system must be considered.
The hydraulic system includes the hydraulic pump, pressure
relief valve and fluid reservoir, the top operating valve, top
and window operating cylinders, fluid lines, and the hydrau-
lic fluid. The electrical system includes the battery, circuit
breakers, top operating valve and switch assembly, window
switches, motor solenoid, motor, window cylinder solenoid
valves, and all connecting wires.
The first step in checking any Hydro-Lectric system that
fails to operate, or which operates slowly, is to check the
battery gravity reading, Figure 182. For efficient operation,
the battery reading should not be lower than 1.225. A low
battery may result in slow operation of the pump motor or
faulty operation of the motor solenoid switch and the win-
dow cylinder solenoid valves.
FIGURE 182
CAUTION: Before any check of fluid level, disconnect
negative cable at negative battery terminal. Since the hy-
draulic fluid is inflammable, any accidental sparks may
ignite spilled fluid.
If the pump motor operates and the battery gravity read-
ing is at least 1.225 at 70°F, unsatisfactory operation may be
due to low fluid level in the fluid reservoir. Low fluid level is
usually
usually indicated when the pump operation is noisy or
when it is impossible to raise all the windows; that is, one,
two, or three windows may go up satisfactorily, but pump
may become noisy and only partially close the fourth win-
dow while the other three are up.
To check the fluid level in the reservoir, lower all win-
dows and raise the car.
FIGURE 183
NOTE: It is not necessary to lower the top to check fluid
level. Since the top operating cylinders are double action
cylinders, the amount of fluid in the cylinders remains
constant.
Remove the plate from bottom of pump well and re-
move fluid reservoir. If the fluid level is low, add enough
fluid to bring the fluid level up to the line on the fluid
reservoir. If the fluid is dirty, the system should be drained
as explained on Page 98, and new fluid substituted.
ELECTRICAL SYSTEM CHECKS
Inoperative solenoids or switches shorted, grounded, or
open circuits will cause failure of the electrical system as
will a low battery.
CIRCUIT BREAKER
If the hydraulic pump motor fails to operate when the
top operating knob is moved in
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