Pneumatic web guide

Apparatus for maintaining a traveling web of material in a predetermined path comprising:

• a double-acting actuator for moving said web, said actuator having a pressure responsive moveable wall forming a pair of chambers at opposite sides of said wall,
• a controller assembly having a sensor means in continuous engagement with an edge of said web,
• a source of fluid pressure,
• a pair of conduits continuously communicating said source of pressure with said controller assembly,
• said controller assembly being operative in a first position to prevent exhaust of fluid pressure from both of said conduits to the atmosphere when said web is in said predetermined path,
• said controller assembly including a rotatable valve element movable by said sensor means in one direction from said first position to modulate the exhaust of pressure from one of said conduits and to prevent the exhaust of pressure from the other of said conduits when said web moves in one direction from said predetermined path and being moveable in an opposite direction from said first position to prevent the exhaust of pressure from said one of said conduits and to modulate the exhaust of pressure from the other of said conduits when said web moves in the other direction from said predetermined path,
• said pair of chambers of said actuator being in separate communication with said pair of conduits, respectively, whereby exhaust of pressure from either of said conduits while maintaining pressure in the other of said conduits causes movement of said moveable wall and corresponding return movement of said web to said predetermined path.

Apparatus for maintaining a traveling web of material in a predetermined path comprising:

• a double-acting actuator for moving said web, said actuator having a pressure responsive movable wall forming a pair of chambers at opposite sides of said wall,
• a controller assembly including a sensor and a rotary control valve element, said sensor being movable to remain in engagement with said web during all lateral movement of said web and being directly connected to said control valve element to correspondingly rotate said valve element, said valve element having a pair of ports,
• a source of fluid pressure,
• first conduit means maintaining said source in continuous communication with one of said actuator chambers and one port of said pair of ports,
• second conduit means maintaining said source of fluid pressure in continuous communication with the other of said actuator chambers and the other port of said pair of ports,
• said rotary valve element having an initial position in which both of said ports are closed and being movable in a direction and for a distance corresponding to the movement of said web from said predetermined path to maintain one port closed and open the other port to exhaust air from the associated one of said first or second conduits whereby air is exhausted from the associated one of said chambers of said actuator to cause movement of said movable wall and corresponding return movement of said web to said predetermined path.