(57) A transportable apparatus comprising a framework (1) supporting by means of hydraulic
jacks (7) a pipe telescopic system, to be moved up or down, in its collapsed condition.
The telescopic system (3) comprises telescopically connected coaxial pipes (3a, 3b,...)
defining in combination, a duct (30) open at its ends for casting concrete, in a bore
hole (2). Each of the pipes, the last excepted, is formed by two coaxial walls (15,
15'; 14, 14',...) and by an upper sidely extending outwards head (28b, 28c,...) forming
annular chamber upstream the head (28, 28c,...) and pairs of annular chambers (29a,
29a; 29b', 29b';...) downstream of the respective head. Said chambers are open at
their opposite end and respectively house the head of the subsequent pipe and at least
a variable portion of this latter, means are provided for feeding a pressurized fluid
into the chambers (11. 28b, 28c....) or alternatively in the chambers (29a, 29a; 29b',
29b';...), which act together with the heads (28b, 28c,...) as double acting annular
cylinders and pistons, for performing the elongation or collapse of the pipe telescopic
system.
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