THE INSIDE PNEUMATIC CIRCUIT GOES DIRECT TO THE AIR FEEDING LINES AND TO THE PUMPS (THROUGH THE FREQUENCY GENERATOR). WHEN THE SOLENOID VALVE IS ENERGIZED THE PUMPS CAN CYCLE (ADJUSTABLE WITH THE FREQUENCY GENERATOR) AND AIR IS SENT CONTINUOUSLY TO THE TOOL. THE SOLENOID VALVE HAS TO BE ENERGIZED BEFORE THE TOOL WILL BEGIN TO MACHINE AND SHUT DOWN WHEN THE TOOL WILL FINISH TO MACHINE.