Method and apparatus for regulating the closing speed of a rolling fire door

A rolling door comprising:

• a curtain having a plurality of interlocking horizontal slats;
• two guide assemblies, one positioned on each side of said curtain for guiding said curtain during vertical movement between an open position and a closed position;
• a horizontal first shaft operable to rotate at a first rotational speed and operatively connected to the top of said curtain for winding said curtain thereabout for raising said curtain to said open position and for unwinding said curtain to said closed position;
• and
• an apparatus for controlling closing movement of said door during an emergency condition comprising a second shaft operatively connected to said first shaft and operable to rotate at a second rotational speed which is greater than said first rotational speed upon closing movement of said door, and a viscous speed governor operatively connected to said second shaft for applying a damping torque to said second shaft to thereby regulate the first rotational speed of said first shaft during closing movement of the door during the emergency condition.

A method for regulating the closing speed of a rolling door during an emergency condition, comprising the steps of:

• providing a first shaft adapted to support the rolling door, said first shaft operable to rotate at a first rotational speed during closing movement of the rolling door;
• providing a second shaft operatively connected to said first shaft and operable to rotate at a second rotational speed which is greater than said first rotational speed upon closing movement of said door;
• and
• providing a viscous speed governor operatively connected to said second shaft for applying a damping torque to said second shaft to thereby regulate said first rotational speed of said first shaft during closing movement of the rolling door during the emergency condition.