AERIAL ROPEWAY FOR COAL

Press, Volume LXXXIX, Issue 27036, 11 May 1953, Page 8

AERIAL ROPEWAY FOR COAL

Work At Stockton Tested OPERATION NEXT MONTH (From Our Own Reporter) _ WESTPORT, May 9. The most modern system of haulage on any coalfield in New Zealand —an aerial ropeway which eventually will be five and a third miles long—will be brought into operation on June 4 between the Stockton open-cast and underground fields and the bins at Ngakawau. In the drop of 2560 feet from the rich fields to the bins on the railway ropeway, travelling at a speed of 420 ft a minute at top speed, can transport 2000 tons of coal every eight hours. The maximum haulage by the old system was 1432 tons, in two shifts. Designed and built in England, the ropeway has been assembled by New Zealand workers, employees of the Ministry of Works. Every part was fabricated in England for the designers, the British Ropeway Engineering Company, a firm which has built ropeways from Spitsbergen to India and the Gold Coast. Working on profile plans of the route survey, the engineers in England prepared between iOO and 800 plans, with the most minute details. Nothing was left to calculation in New Zealand. The result is a precise engineering job. Every part arrived in New Zealand simply marked in serial numbers, with distinguishing colour marks for the various stations, and they fitted like sets of meccano toys. The Stockton aerial ropeway is among the largest in the world, and trial runs, with the buckets empty, this week produced only minor faults for adjustment before the system hauls loaded buckets. The ropeway has cost about £700,000. "Although wages are high in New Zealand, the ropeway has been installed .as cheaply as it could have been done anywhere else in the world,” said Mr E. A. Ashenden, the Pacific area representative of BRECO, who has been at Stockton supervising the erection, in paying a tribute to the workmen, with Mr J. McNeight as their foreman. The only great technical difficulty was the engineering to carry the ropeway across the 500 ft deep Mine Creek gorge, immediately behind the coastal lulls before the ropeway runs down into the Ngakawau bins. The maximum sag in the one-third of a mile across the ravine is 100 ft. On this ®tr*tch, 18 tons of coal will pass down at the one time. The engineering problem for this .span was to avoid the use of high trestles at either side of the gorge. The ropes are thicker across the gorge. They are anchored by concrete blocks in cages below the surface of the uphill trestle. The down rope has a counter-weight of 35 tons, and the return rope is held by 144 tons of concrete blocks. Because of the danger of vehicles being struck by passing buckets up the hill, few persons are likely to see the ropeway in action across the gorge, the most spectacular sight. Steep, winding access roads had to be cut on both approaches to the edges of the gorge to allow the gear to be brought lu’ l nd . a swa th was hacked out of J“ e . down the precipitous sides so that the rope ooula be handled across the gorge.

Costly Flume Experiment , si * n ,s e 4? 28 j h J? n the flume hunt by the Westport-Stockton Coal Company at a cost of £75,000 proved a failure, concern had been felt over the haulage of coal from the Stockton mines to the bins at Ngakawau. The steep corners and grades on the route caused large quantities of the coal to be lost. On one trial, 500 tons were tipped into the flume and only 135 tons reached Ngakawau, the rest being spilled into the gullies. So the electric-locomotive and rope systems came back into their own. The line from the fields to Millerton was the first electrical line in New Zealand. It was unique in use over such country, the grades being as high as one in -eight. But even years ago the haulage system was uneconomic and the company decided that aerial haulage was the only method of dealing with the coal transport problem. In 1939, Mr W. Hardy, the managingdirector •of the Westport-Stockton company, visited Britain and negotiated for the erection of an aerial ropeway. The war began and the erection was deferred. When the mines were bought by the Government after the war, Mr T. H. McGhie, now Buller district superintendent of State Mines, and others associated with him at Stockton, emphasised to the Government that it « as urgent to install the aerial form of transport. Besides its capacity to transport with infinitesimal loss 2000 tons of coal a day from Stockton to the railway, the ropeway has two extremely important,economic factors. Whereas 65 men have been used up to the present to operate the electric-loco-motive and rope road haulage systems, only 10 will be required to work the aerial ropeway. The second is the tremendous saving in power. Power From Brakes The ropeway, indeed, generates power. The five 86 horsepower driving motors at the five stations on the route have installed in them motors to absorb the heat and energy generated at the brake boxes. They will draw power from the Ngakawau generating station, with its capacity of 1500 k.w., to start the drive, but when the rope runs they become generators, pumping power back into the main lines. At full speed, 300 k.w. will be generated, against the use of 450 k.w. of Ngakawau power by the old haulage system.

A total of 112 pylons or trestles, of steel, varying in height from 17ft to 100 ft, carry the ropeway from Stockton down to the coast. Except for one turn of 40 degrees, the route is straight. The whole structure weighs 1831 tons. The steelwork weighs 970 tons, the ropes 216 tons, the mechanical parts 235 tons, the buckets and hangers 265 tons, the electric motors and control gear 25 tons and the spare parts 120 tons. Each rope driving wheel weighs about one ton and a half.

The track ropes, carrying the fourwheel bogies of the bucket hangers, are stationary, the hauling rope moving the loads along the lines. Except for the gorge span, the outgoing rope is 6in in circumference, consisting of 41 wires, with a breaking strain of 70 tons to the square inch. The return rope has the same breaking strain, but is only 3fin in circumference. For the gorge span of 600 yards, the wires have a circumference of 6Jin, with a breaking strain of between 115 and 125 tons to the square inch. On the down rope and the return rope, 370 buckets run. On the down trip, each bucket carries one ton and a half of coal. The spacing between them on the rope is 50 yards and when the ropeway is working at full speed they pass a given point at the rate of three a minute. •

Although the drops on the five sections vary—the first section drops 655 ft and the last into the Ngakawau bins 404 ft—all sections of the ropeway run at the same speed, regardless of the loads. Three Running Speeds When the ropeway .is set in action from the control station, it runs at the determined speed until it is stopped and another speed set. Speed cannot be changed, as by running through the gears on a motor-car. The ropeway has three speeds—full, threequarters and half. However, the ropeway can be stopped instantly over its whole length if a fault develops anywhere along the route. The stopping is done by pressing a button. The location of the stoppage is automatically recorded at the control station. The ropeway can be set in motion again only from the place where it is stopped. The action button is in a padlocked box at each station, and only those operators with keys will have access to it The bucket hangers are so designed that in the highest gales the buckets swing only slightly, even across the gorge span and down the dip. But to ensure that no damage is done to men or vehicles by falling coal as the

ropeway passes at five places over the winding JStockton hillside roads, protection bridges have been constructed. They are steel nets suspended from the pylons. The original plans were that the section of the ropeway from what is technically known as the No. 3 loop loading station down to Ngakawau was to be running by the end of 1951 and the top sections to the open-cast mines and the Webb mine (which in future will also be worked by opencast methods), six months later. The rearmaments rush in Britain and the 1951 strike in New Zealand held up deliveries of materials, and the operation of the No. 3 loop—Ngakawau section—is beginning 18 months after schedule. The top section of a mile and a half is expected to be working in a year; all the trestles are erected. The preseht production of the Stockton mines means that the ropeway will run far below its maximum capacity, and may be idle for days. But with the opening up of the vast open-cast fields it is expected to be a highly profitable investment. Even with the quantity now being handled big savings will be made in haulage costs.

June 4 will be a proud day for Mr McGhie and officers of the Mines Department when the Minister of Defence (Mr T. L. Macdonald) presses the button to start the ropeway officially into operation. The Denniston aerial ropeway from the plateau to the bins at the incline is far advanced and is expected to be in operation by the end of this year. This ropeway will have a capacity of 100 tons an hour.