A self-liftiαg pontoon (4), having a number of columns, said columns are formed by a circular pipe or pile (1) to the outside of which at least one upstanding teeth rack (2) is fixed, which rack (2) is capable of cooperating with driving and locking pawl means (6, 13) each mounted in a yoke means (5, 12) for a slidable movement in transverse direction with respect to longitudinal extension of the relative column, the yoke means (5, 12) of the driving pawl means (6, 13) being fastened to spaced apart annular members (25) mounted about the relative column for an up and down sliding movement along said column by means of a piston-cylinder assembly (11), while the yoke means (5, 12) of the locking pawl means (6, 13) is fixed to said body.
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