Ammo wagon

Usage examples of caisson.

A bottomless caisson, serving as a sort of diving-bell, in which men can work when compressed air is introduced to keep out the water in proportion to the depth below the water-level, which is gradually carried down to an adequately firm foundation by excavating at the bottom of the caisson, and building up a quay-wall or pier out of water on the top of its roof as it descends.

Open iron caissons are frequently employed for enclosing the site of river piers for bridges, where a water-tight stratum can be reached at a moderate depth, into which the caisson can be taken down, so that the water can be pumped out of the enclosure and the foundations laid and the pier carried up in the open air.

Forth Bridge rest, were each erected within an open plate-iron caisson fitted at the bottom to the sloping rock, where ordinary cofferdams could not have been adopted.

The caisson at the bottom, forming the working chamber, is usually provided with a strong roof, round the top of which, when the caisson is floated into a river, plate-iron sides are erected forming an upper open caisson, inside which the pier or quay-wall is built up out of water, on the top of the roof, as the sinking proceeds.

Exposure to such pressures is apt to be followed by disagreeable and even dangerous physiological effects, which are commonly referred to as caisson disease or compressed air illness.

At this rate, the whole caisson would slough away and melt like butter, within an hour, under the weight of the Bridge above it.

Mounted on top of the caisson was a 5-ton Wilson crane, which would reach each shaft and also the muck cars standing on tracks on the ground level beside the caissons.

The average rate of lowering, when the cutting edge of the south caisson was passing through earth, was 0.

As the jacks lifted the caisson, the blocking was set for a lower position, to which the caisson settled as the jacks were exhausted.

The caisson usually rested on three sets of blockings on each side and two on each end.

When a sufficient number of posts had been placed, the blocking on which the caisson had rested was knocked or blasted out, and the rock underneath was excavated.

The tilt or level of the caisson was controlled by chopping the posts more on the side which was desired to move first.

The concrete in the walls, which was added as the caisson was being sunk, was kept at about the elevation of the ground.

Under these conditions, there was a continued but small leakage into the caisson of from 15,000 to 20,000 gal.

As soon as the cutting edge was cleared, bags of clay were placed under it in a well-tiered, solid pile, so that when the caisson was lowered the bags were cut through and most of the clay, bags and all, was squeezed back of the cutting edge between the rock and the caisson.