14
D. AIRLOCK
T
he last valve section of the manifold runs the airlock. The spool in the valve is factory-set so the
airlock turns at about 12 rpm. The proportional valve in combination with the control box, provides
adjustment of the airlock speed. There is a pressure switch on the forward circuit that is set for
2,400 psi (16,547 kPa) that triggers the auto-reverse function on the airlock. Normal rotation of
the airlock is clockwise if viewing from the driver side of the machine.
SUBSYSTEM 3: HYDRAULIC CONTROL SYSTEM
The hydraulic control system is an electrical system that controls all the hydraulic functions on the
Bark Blower. This 12-VDC system runs off the engine electrical system. It is a programmable
logic control (PLC) system located in the electrical control box on the passenger-rear side of the
machine. This module controls the solenoid valves in the hydraulic system. The solenoids are
energized by way of the white DIN connectors mounted on each solenoid. The DIN connectors
each have a small red light in them that illuminates if the circuit is active. This is an easy way to
check if a particular circuit has electrical power.
When Material Start is selected from the PANEL OPERATE screen, the proportional solenoid on the
airlock valve section is energized, which starts the airlock. If the floor toggle switch is in the ON posi-
tion, the floor and feed roll solenoid is also energized after a factory-set 1.5 second delay. This delay
ensures that the airlock has a chance to clear itself. After the delay, the floor and feed roll will begin
to move at the speed relative to the Floor Speed %. This speed can be set by using the Material
Increase and Material Decrease buttons on the PANEL OPERATE screen. The default adjustments
are in 5% increments which can be changed in the USER SETTINGS screen.
As material drops into the top of the airlock, the pressure required to cut the material is monitored
by the pressure switch. This switch is located on the forward port of the airlock valve section, in the
manifold labeled AL1G (see Figure 3 on page 13). The switch is normally open. When the airlock
motor stalls due to the rotor encountering an object it cannot cut, high pressure is created in the
airlock circuit and the pressure switch closes. The amount of time the pressure switch is closed is
monitored by a setting in the PLC box. If the switch remains closed for more than 0.5 second, the
system automatically reverses the rotor by energizing the reverse solenoid. It also de-energizes the
floor solenoid, thus shutting off the floor and the feed roll. The airlock will remain in reverse for ap-
proximately 1.5 second. The system will then restart the floor and feed roll after allowing the airlock
to clear itself.
The agitator is also controlled through the PLC box. The agitator will start on a 3-second delay (in
a similar manner to the floor) and will stop during an auto-reverse. The agitator circuit on the Bark
Blower also has an auto-reverse feature for when the agitator may bog down and become unable to
turn itself. This most often occurs at the beginning of a load when the hopper is completely full of wet
or packed down mulch. The PLC system receives a signal from the pressure switch on the forward
port of the agitator circuit labelled A1G when the agitator motor stalls. When this signal is received,
the system automatically de-energizes the solenoid before the pressure switch and energizes the
reverse solenoid on the valve circuit, causing the agitator to rotate in reverse. The reverse-rotation
time is set for 10 seconds, after which the forward solenoid will energize and the agitator will return to
its normal rotation. This process may be repeated several times until the agitator sufficiently breaks
up the packed mulch material. The agitator auto-reverse process does not interrupt or affect any
other function(s) on the Bark Blower.
When the Material Stop is activated, power is shut off to solenoids controlling the hydraulic motors
on the floor, airlock, feed roll, and agitator. The hydraulics can also be stopped by turning the ignition
key OFF. Please note that the hydraulics will also stop if the folding door on the feed roll housing is
opened and cannot be restarted until they are closed and the Material Start is activated.
Summary of Contents for Bark Blower BB1216
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