Volume Eleven - Pre-Victorian to the Present Day - some more aspects - The Steam Navvy and the Dock Extension of 1883 . . .

The main lifting chain passes from the winding drum, through the tower and over the pulleys on the top, through the bucket arm, over a sheave on the end of the jib, round a snatch block on the handle of the bucket, up to another sheave on the jib, and down again to the snatch block, obtaining therefore a treble purchase.

The bucket is shown in detail in Figs.4 and 5. Its mouth is semi-elliptical ; its cutting edge is of steel, and is protected by four strong picks or teeth, which are made so as to be easily renewed when worn, being fixed to the lip of the bucket by countersunk bolts and nuts, as shown. These picks or teeth are of different strengths according to the stuff to be excavated ; the chisel-shaped head of one of the stronger kind is shown in Fig.3, and is suitable for the hardest boulder clay.