MAXIDRY MAXI200, Installation Manual, Page: 41 / 78

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E. COMPRESSED AIR SUPPLY SYSTEM
The compressed air system of the tilting dryer consists of a number of pneumatic pistons located throughout the dryer.
The pistons are actuated by solenoid and flow control valves that are under computer control. The pneumatic pistons
are used to:
• Tilt the Dryer for Loading and Unloading
• Open and Close the Load and Unload Doors (for Dryer Models Equipped with Automatic Doors)
• Operate the Steam Coil Damper (for Steam Heated Models Only)
1. Filter/Regulator/Gauge Assembly
The compressed air supply to the dryer is connected into the 3/8” F.P.T. fitting of the filter/regulator/gauge
assembly, which is located at the bottom rear of the right side of the base.
The filter/regulator/gauge assembly performs three (3) essential functions. The filter removes most solids and
liquid particles from the compressed air stream and traps them in its bowl, where this waste can be readily
removed through the drain valve at the bottom of the bowl.
The filter bowl
should be
cleaned monthly.
The regulator will maintain a nearly constant outlet air pressure so that the dryer’s air pistons will function
normally despite upstream air pressure variations. After the compressed air is connected into the filter/regulator/
gauge assembly, adjust the regulator knob so that the gauge needle reads 80 psi (5.51 bar).
2. Tilting-Piston Solenoid Valves
A 2-way tilt dryer has two (2) of these solenoid valves … one to control the front set of tilting pistons and a
second to control the rear set of tilting pistons. A one-way tilt dryer has only one (1) solenoid valve.
Each valve has five (5) 3/8” F.P.T. ports and two (2) electric solenoid operators, one (1) on each side of the valve.
To tilt the dryer forward, a 24 volt signal is applied to the rear pistons solenoid connector “12” and no voltage is
applied to the solenoid connector “14”. The internal spool in the valve will move and 80 psi (5.51 bar) of air will
enter the bottom port of the rear tilting pistons, extending the rear tilting piston rods and tilting the dryer forward
for unloading. The top piston ports are bled to the atmosphere.
To level the dryer, the voltage signals are reversed. No voltage is applied to the “12” solenoid, and 24 volts is
applied to the “14” solenoid. The valve spool will now move so that 80 psi (5.51 bar) of air is applied at the top
piston ports, while the bottom piston ports are bled to the atmosphere. The piston rod will now retract, leveling
the dryer. On rear tilt dryers, the front tilting piston solenoid valve acts in the same manner.
The tilting piston valves are 5 port/3 piston valves. If no voltage is applied to both the “12” and “14” solenoids,
ALL
five (5) valve ports are blocked. This means that, if the dryer is tilting or leveling and power to the dryer is
shut off, the pistons will lock in position, holding the dryer in a partially tilted position.
The dryer can be made to tilt faster or slower by adjusting the tilting pistons 3/8” flow control valves, which are
located on the pneumatic control panel.
The tilting piston valves and flow control valves are located on the pneumatic plate in the rear of the dryer’s base.