Abstract: A door is supported for shifting between first and second positions, respectively opening and closing a doorway. A fluid actuator, such as a pneumatic cylinder, is used to shift the door between such positions. The fluid actuator reduces the velocity of the door as the door approaches at least one of the open and closed positions. In the case of a pneumatic cylinder, both sides of the cylinder may be subjected to relatively high air pressure when the door is stationary. To reduce the velocity of the door as it approaches the open or closed position, the rate of bleeding of air from one side of the cylinder is reduced.

Abstract: A sliding door suspension system and a sliding door assembly for supporting a heavy sliding door from a door frame includes a rail horizontally mounted to the door frame. The suspension system includes a roller assembly which rollingly engages the rail and supports the heavy door. The roller assembly includes an axle or shaft having a bearing surface. The axle has at least one threaded end for securing the roller assembly and for attaching the roller assembly to a door hanger from which the heavy door is suspended. The roller assembly further includes a roller with a concentric hollow bore for seating a bearing assembly or bushing through which the axle extends in supportive engagement with the bearing assembly. The rail has a convex arcuate upper roller guide surface. The roller has a concave arcuate roller guide engaging surface which conforms to and engages the upper surface of the rail. The roller assembly also includes a door height and alignment adjusting member which threadably engages the axle.