Patent ID: 6749268
Filing Date: 2004-06-15
Classification: B60P

Abstract:
A door closing apparatus for a hopper with a bottom discharge opening for discharging material therefrom and first and second pendulum doors connected to the hopper and moveable between a closed position preventing discharge of material from the hopper through the bottom discharge opening and an open position allowing discharge of material from the hopper through the bottom discharge opening, a framework in the discharge opening, said door closing apparatus comprising:a first gear wheel mounted on a first shaft and a second gear wheel mounted on a second shaft, said first and second shafts journaled in the framework in the discharge opening and said first and second gear wheels having teeth in mesh, a torsion spring having first and second spring arms and an initial tension, said first spring arm attached to one of said first or second shafts and said second spring arm stopped from rotation by the framework, a first crank arm attached to the first gear wheel and a second crank arm attached to the second gear wheel, each of said first and second crank arms having a free end, a lever arm with a free end, said lever arm attached to one of the first or second crank arms, a first connecting link pivotally attached to the free end of the first crank arm and pivotally attached to the first pendulum door and a second connecting link pivotally attached to the end of the second crank arm and pivotally attached to the second pendulum door, said first and second crank arms generally oppositely directed when the pendulum doors are in the closed position and generally parallel when the pendulum doors are in said open position, a bidirectional pneumatic cylinder with a piston rod for connection with a source of pressurized air, said cylinder pivotally attached to the framework above the first and second gear wheels, said piston rod pivotally attached to the free end of the lever arm, whereby the initial tension of the torsion spring damps movement of the pendulum doors by the pneumatic cylinder and resists opening of the pendulum doors if the pneumatic cylinder loses pressure.