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BREAKWATER CONSTRUCTION.
157
the material« can be incorpor-
ated and discharged intoshoots
conveying it to its destined
situation, or mixing may take
place in the yard ashore, and
the concrete be conveyed in
skips to its appointed place.
The former method has the
advantage of greater conveni-
ence of output, the concrete
machines being allocable in
various parts, so as to com-
mand an extensive range, and
there being no tendency to
block the service-lines.
The End-on System.—
The low-level system practised
with a single powerful crane
running upon a track laid over
the finished portion of the work
isopen to the objection, already
stated, of limited scope. The
work proceeds outward from
the land, and it cannot be at-
tacked from several points as
in the case of staging. Yet the
method is one which has been
adopted in a very great number
of modern instances. Astrong
point in its favour, particularly
when dealing with huge blocks
of 30 to 50 tons and more,
is the greater stability of the
working base. On the other
hand, there are many occasions
when its full lifting power is
not in request, and when a
much less powerful machine
could do the work required at
the moment.
The machine employed in
connection witli this system
of construction goes by the
generic name of a “ Titan”
(fig. 129). In principle it con-
Back Elevation
'—-2 4-0 Centres of fails
56ô? to Cenfot Ballast ->
----42'0 fait -
---75'0“ Radius (Maximum)--4
SSO Hange of load-\l70'M'us ^'mJ!l^^
'97949///ey uaaM/ag q/.q?"
2
68 feet
fange of Lift
/9A3/ lieg SAOqe
jgßiaq anuj/xey
'i^ti's ß^ --^
Ground wheets
30'Dia
Fig. 129. —Titan.