Hydraulic System 279
To prevent cavitation, air pressure inside the hydraulic tank must be set between 3 and 3.5 PSI. A
gauge and a pressure regulator (see Figure 5-22) are installed to adjust air pressure inside the tank.
This gauge is located inside the frame rail on the curbside of the chassis; it can be accessed only when
the body is raised.
To adjust the pressure, turn the knob until the pressure reaches 3 to 3.5 PSI. The hydraulic tank is
also equipped with a 5-PSI relief valve and a 5-PSI pressurized screw on the breather cap (see Figure
5-21).
Figure 5-21
5-PSI relief valve and breather cap
Figure 5-22
Pressure gauge and regulator
Danger!
Install body safety prop before performing any work under the body.
Caution!
The air pressure inside the tank shall not exceed 5 PSI.
Relief
valve
Breather
cap
Pressure
regulator
Pressure
gauge