Moveable Civic Arena Roof Rolls on Wheels Designed by Heyl & Patterson
Bulk Transfer Division
Heyl & Patterson worked with the Pittsburgh Public Auditorium Authority and the Allegheny County government in 1960 to develop a system to open the stainless steel roof of the Civic Arena.
The auditorium roof is a dome, made up of eight equal leaves arranged in two sets of four each. The leaves in each set are at different levels so they can telescope over each other. The bottom leaf in each set is adjacent to the roof's supporting cantilever girder and is stationary, while the other three leaves are moveable. When the six moveable leaves are in the closed position, a complete cover is provided for the auditorium. When they are in the retracted position, there are three moveable leaves stacked above each of the two fixed leaves. A total of 42 trucks mounted on 78 wheels, of which 30 are individually driven, support and move the six moveable leaves. These trucks permit opening or closing of the roof in 2.5 minutes. A double acting, self-contained hydraulic buffer is provided at each edge of each moveable leaf to prevent the leaves from hitting fixed bumpers or the cantilever girder at high speed in the event of a control failure.
The two top moveable leaves each have a one-wheel idler truck at the lower end of the rib along the leaf's edge nearest the supporting cantilever girder, and a two-wheel driving truck at the lower end of each of the leaf's six remaining ribs. The four lower moveable leaves each have a one-wheel idler truck at the lower end of each of its two outside ribs, and a two-wheel driving truck at the lower end of each of its five intermediate ribs.
All trucks have welded structural steel frames mounted on one or two 30" diameter double-flanged rim-toughened wrought steel wheels. Each wheel is fitted with anti-friction bearings and turns on its own individual carbon steel axle. The one-wheel trucks have fixed, bolted connections to their roof ribs, while each two-wheel truck is connected to its rib through a lubrite bronze bushed forged carbon steel equalizer pin in a cast carbon steel housing bolted to the lower end of the rib.
One wheel of each driving truck is individually driven by a Westinghouse right-angle gearmotor through a chain transmission consisting of finished roller chain, a sprocket keyed to the low speed shaft of the gearmotor, and a sprocket cap screwed to the truck wheel. The gearmotors are mounted on the bottom sills of the roof leaves, and each is equipped with a disc-type electric brake. To provide additional braking, the idler wheel in each driving truck is connected by a chain transmission to a right-angle gear reducer equipped with a disc-type electric brake, and mounted on the bottom sill of the roof leaf.
To provide moving of the roof leaves at different speeds such that they will all reach their closed or open positions simultaneously when operated from a single central control station, a Westinghouse Electric Corporation reactor-controlled AC motor is provided for the gearmotors, and is designed for operation on a 480-volt, 3-phase, 60-cycle power system.