History
From the Archives: April 3, 1958
This 1958 image shows an operator manning hydraulically powered collapsible forms for lining the North Central Outfall Sewer Tunnel in Los Angeles.
It was operated in conjunction with a pneumatic concrete placing system developed by M.E. Kemper. The 16-ft-long, plastic-lined, collapsible forms are made up of five hinged sections—a top, two sides and two skirts.
The invert forms are separate. The unit is maneuvered by a hydraulically powered jumbo. Double-acting positioning rams place the side forms while the skirts are raised or lowered with pneumatic chain hoists.
For the concreting phase, four 3-cu-yd capacity placer cars are linked, rail-mounted and powered by a locomotive.
The mix is fed to the forms through an 8-in.-dia discharge line. The sewer project included two tunnels, one 4 miles long and another 1,500 ft long.
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