THE CALLIOPE DOCK.

New Zealand Herald, Volume L, Issue 15262, 28 March 1913, Page 4

THE CALLIOPE DOCK.

REPAIRS - AND. NEW ' PUMPSjf^ EXTENSIVE OPERATIONS.. IS®! "" ; ■ . v ■ Very extensive alterations and repairs '?■ being made by the Board at ' Calliope Dock. The dock was built about a quarter of a century ago, and during M that long period the old pumps have done ; ~ steady service until of late years they showed signs of serious failing. The bis * - caisson which closes the mouth of the ' r 4 dock has never, since it was put in, been - ' thoroughly overhauled. The Harbour Board decided some time ago to instal •' new pumps, and to carry out all possible 'If repairs to the caisson. ~

' The old pumps were large machines of. the reciprocating type, with large cylin- 4 deis placed in wells about 30ft deep. Tit a *,' pumps were operated by a large horizontal steam-engine. The pump cylinders situated low down and constantly wet' frv with sea-water, lasted wonderfully but the deterioration of cast-iron in such : \ conditions was inevitable apart from : M wear. . The new pumps are centrifugal, consisting of a set of vanes rotating rapidly in *y't : case, and having no valves other than a *?$ {>air of large cocks which close the de- / ' ivery pipes when the pumps are not run-'' V ning. The old wells have been used, and the pumps are placed at the bottom of H them, and are connected with intake and ' i delivery pipes 30in in diameter. Each : - •'$ pump is driven by a compound steam. A engine, working directly on a vertical •; - : V shaft. Added to the actual pumping ma- -*j : chinery is a full equipment of auxiliary' X] machinery. A large condenser is equipped 1 with its own engine and pumps; there isa vj feed-pump and feed-water filter, and an engine to open and close the big valves • i on the delivery pipes. ; . The inevitable slight leakages into » 1 large dock necessitate . small pomp, and 11 the old one is being retained. This is the only remnant of the old pumping plant v retained in the machine-room. At pre- : •»? > sent one of the main pumps has been practically finished, and the second is in : coarse of erection. The substitution of the new pumps for the old has necessi- ' : : tated some awkward work, for the pieces ''! of machinery which had to be lifted in- f eluded some very heavy lifts, and con- Jtl siderable alterations in the building ''iUittf&vf were necessary. The investigation of the big caisson.'., I showed that the iron plates of which it jj' ? built are in a remarkably good state 'of •••■$ E reservation even on the sea side, which HI j as now been sighted for the first time:" 7 ; 3 since the caisson was installed. A larri proportion •of the rivets, however, have 3'%? corroded very badly and are being renewed. A few plates have to be repto^; : l'/"8 In order to reach the underwater part of I the caisson, the ballast has been removed, V -3 so that the big tank floats very high; ani ' lil later on the structure will be turned ov«r'l'!i so that' the > bottom can .be repaired. -* M Alterations in the facings of the caisson'-' -'i will be made so that the caisson may be ; used with either side towards the dock,l ,and both sides can then be inspected and- -'1 repaired when necessary. v .- =#: The operations on the caisson are )$§ lengthy, and it will be some considerable '»> time before the dock can be made available 'for use again. '