This image of 1958 shows an operator that manning hydraulically, drop -down forms for the coat of the northern sewerage tunnel in the center of Los Angeles.
It was operated together with a pneumatic concrete placement system developed by Me Kemper. The plastic shapes 16 feet in length, are composed of five articulated sections: one top, two sides and two skirts.
Inverted forms are separated. The unit is maneuver for a hydraulically powered jumbo. The double -performing positioning bouquets put the lateral shapes, while the skirts are raised or descended with pneumatic chain polists.
For the concrete phase, four capacity cars of 3 CU-YD are linked, mounted by rail and fed by a locomotive.
The mixture feeds on the shapes by means of an 8 in-day download line. The sewerage project included two tunnels, one 4 kilometers long and another 1,500 feet long.
