WAIPORI TRIPLICATION.

Evening Star, Issue 14629, 27 July 1911, Page 4

WAIPORI TRIPLICATION.

PELTON WHEEL CONSTRUCTION. A LOCAL JOB. When the Dunedin City Corporation decided on the triplication of the powergenerating units at Waipori Falls, having first satisfied themselves by inquiry that local engineering firms could manufacture ail hut the purely electrical machinery required, they calted for tenders locally as well as abroad. Messrs Cossens and Black, in competition with foreign manufacturers, secured tho contract for the tup ply of two pelton-wheel unite, of 1,003 kilowatts each Each unit- consists of a pair of pelton wheels, between which will be eitnated an electric generator, all revolving on the 0..10 shaft. The two genera tore are being imported from America, but all the reat of the work is being done locally. It involves the making ot four pelton wheels, with covers, valves, connections, etc. Some idea of the size of the job can be gathered from the fact that each • pelton wheel weighs about a ton. The. opouing of the, nozzles is sin in diameter, and with the 700 ft pressure head at Waipori the jet of water from the nozzle will strike the backets of the wheels with an impact of about 3 tons, go tho City Electrical Engineer states. Messrs Cossens and Black are now in the thick of their contract. An inspection ot their works tins morning, made in company with their works manager (Mr M'Lean) and the City Electrical Engineer (Mr Stark), revealed a job of some magnitude and of no little interest to engineers, and ni ,-haps the general public also. Tho r.itteiii making alone i.-- something of an eye opener. Huge- as some of these patterns arc, the deiieafo finish of the work in the-in suggests that these wooden prototypes of the meiai easting; must- alone have cost no small cum to construct. The linn have now been working three mouths on this contract, and they have very much more to show than the mere patterns. In fact-, Mr Stark ha,s exprctissd himself very pleased with the progress made, and with the quality of the wink as well. In the engineers' shop one is confronted with a host of castings in iron, etr.ei, and brass, all in various stage;; of progveso towards Hie finished article. They varv in size. For instance, there are the phiHiiner blocks which constitute ehe bearings for the main she ft (which is 9in in diameter). Each of these plummet blocks we Lib* over a ton. They are of a design eminently f-uiled for their important task, for the shaft that is to nestle in their cmbraee will be working under continuous, if. perhaps, varying, loading at high speed. The phmuner blocks are lifted with a special ring oil bearing, self adjusting, and containing oil wells and grilled water compartments, to keep the hearings at an even working temperature. The pelton wheels themselves are of cast steel, which has been made locally, and its quality is claimed to be quite equal to the imported article. Each bucket is being fitted to gauge, ami the buckets are being marie interchangeable. To illustrate the quality of the metal out of which these buckets are cast. Mr Stark took a hammer, and with a smart blow he took a piece clean out of one of the imported buckets that has been doing duty on one of the wheels out at the falls. A similar blow made no impression on one of the huekets recently cast in this eliop. The " needles." or eone-eha ped brass appliances working hi the orifice of the nozzle, by which the ie: is regulated in accordance with the "loan, were also seen in process of manufacture. Should the firm see their way to do so at a later stage, when the various pails are ready for " assembling, - ' an exhibition of this 'machinery might prove of no little educational value to the public.