Pneumatic System 167
Introducing the Packer Air System
The hydraulic valve, which controls some of the hydraulic functions, is equipped with air actuators.
The packer air actuator pushes back and forth on the hydraulic spool of the valve, resulting in a
movement of the packer (extension or retraction).
Figure 7-6
Packer air actuator
As the packer reaches the end of a stroke, the proximity switch, located behind the packer, sends a
signal to the electronic module to indicate that the packer has reached the end of its stroke. The
multiplex module then operates the air solenoid valve, inside the air control box, with a 12volt signal
(one signal for packer extend, one signal for packer retract).
When receiving the 12-volt signal (extend or retract) from the module, the air solenoid valve enables
the air pressure to reach the actuator on the main control valve. The spool moves according to the
signal received.
Two quick exhaust valves, located close to the body main valve (see Figure 7-6), are designed to
release air pressure from the packer air actuator installed on the main control valve. They release air
when the packer reaches the end of a stroke, allowing the spool to move in the opposite direction and
accelerate air release in the actuator.
Quick exhaust valves
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