The Machinery that makes Better Roads

Dominion, Volume 19, Issue 48, 20 November 1925, Page 5

The Machinery that makes Better Roads

• Achievements of New Zealand Engineers Slthouch .u .< p.v iM u. many modern improvements in the plant nece V ary -* duced into the country, the necessary plant had to be imported from « q « iT en.. .1 ■.=.«!. ae. f n B with * The portable plant has been specially work, or disconnected and made ready for transport m a few hours. A stretches of roads. The plant can be fully assembled ready tor worn, feature that is of great value in a young country. , ... ... b : tum i no us concrete plant at Rongotai, which is now working The Wellington City Council has recently lnB '?” ed \>£ ably tbe most modern of its kind, is designed on what is to capacity, and giving excellent results. This machine ? r ti y and enables the work of surfacing to be carried on without any the continuous system, which supplies the material m a munm m t temperatures are a'big factor in securing the best results, delays. A feature of the utmost importance, where high andl uni P ingredients, sand and shingle, are dumped into a pit, froin y In preparing the material, necessary for the process of surf^ng^the ,g of the famous Niven drier used which a chain-and-bucket elevator conveys them to the dn . ■ . cylindrical steel shell, having mounted on one end in nearly all our freezing works, abattoirs, and fertiliser plan , P _ ? ro ]j erB below, at the other end it is carried on a heavy accurately machined roller path on which it revolves. Supported by are provided for the drying of the ”TS7rSF e °cX B led with fire-brick slab.

materials treated. A turnace is provmeu — —— securely bolted in position. \ rejects passing out through a special chute at the end of the sere n. Hopper,.—The ‘J™' Sd' ” kv m rniick-actinsz valve with which each tiopp T J* i_„ the different grades of aggregates into their pre determine p This mechanism is entirely manufactured m New Zealand. The Mixer. —From the weighing hopper, the hot materials are deposited quick-acting valve mixA wh.ch » steam jackeUed so as to minimise radiation losses during the mixing p „„r r< .etlv L„„ d..; Bn.a«, 8 n.a«, J.J .a “’j: :L‘Vd""X ? m which is naturally subjected to severe wear, lining plates have been fitted throughout, which can be removed and replaced in a few minutes, no dismantling of the mixer itself being necessary. Now that the heated materials have been accurately weighed and mixed the molten bitumen, which has also been scientifically weighed, is introdued into the mixer. When the mixing process has been completed, the operation of a specially designed quick-acting door ensures the rapid and complete discharge of the mixer’s contents. This mixer has a capacity of 6001 b. in 30 seconds.. _i As has been previously mentioned, if the mixture is to be delivered to the scene of paving operations at the proper heat-for the best results, quick dispatch is essential, and it is in this regard that the Niven plant is su P® r ‘° r to all other makes. For that reason, the mixer does its job with remarkable speed, and in very large quantities. Other Features.—Two fire-heated bitumen kettles are provided, each .fitted with improved furnaces having a fire-brick arch over the fire to ensure the more ev”P distribution of heat. The capacity of each » 1000 gallons and provision is made for drawing off the molten bitumen from either ke t at wdl. To ensure that correct temperatures are maintained throughout the whole process, special dial pyrometers are fitted to each kettle. There is also a special flexible tube pyrometer to reg.ster the temperature of the hot material passing from the heater to the eleyaor. The Patent Storage and Loading Device. —As quick dispatch means increased economy in paving cost, Messrs. Niven and Co. applied themselves to the problem of cutting out the stand-by losses, which are a serious drawback to ever)/ other type of plant m use in New Zealand to-day. This important problem has been solved in a highly satisfactory manner. W the imported plants in use in New Zealand to-day, it is necessary for the mixer plant to “mark time” if road transport is not available—and the road transport in turn has to remain idle until the full load is mixed for it, Niven and Co. have designed a storage and loading device for which they have made application for a patent, and this equipment is now m use in conjunction with their new plant, which has been installed at Rongotai. IB is a wonderfully efficient plant, embodying many unique automatic features, which enable it to be operated without additional labour or power. A steam jacketted storage hopper is provided, mounted on a truck running on an inclined ramp (see illustration). This hopper is of sufficient capacity to take a full load for a motor lorry, and consequently the mixer can go on working independent of road transport. As soon as the lorry puts in an appearance, and whilst it is manoeuvring into position, the man operating the mixer merely engages a lever which puts the operating mechanism into action, and the hopper, with its load of hot mix travels - UP the inclined ramp. When it reaches the correct position, the hopper is automatically tipped, the load being deposited into the lorry, which is then ready to depart instantly with its full load, only having been standing a few seconds. The hopper then automatically returns to the filling position and again returns to its loading base by gravity. Another batch is always ready for the moving unit immediately it returns to its base, the whole operation requiring only 60 seconds. .... . , , ,j In the event of any hitch with transport, the hot can her! indefinitely. This equipment, which works with clock-like enables the plant to go on “delivering the goods,” and ensures the dispatch of a load when required. Fewer wagons are required than in the case of an American installation, as every wagon is on the road al( tho time, instead of having to wait ton or fifteen minutes every trip, —