Environmental News

Wheel loader passes demanding Tweed test

The Tweed Shire Council covers 1303 square kilometres of the Northern Rivers district of New South Wales, and adjoins the Queensland border. With a growing population to serve, the Shire must plan for the future provision of services, including waste disposal.

An established quarry at Eviron was identified as a future landfill site, and the Shire took over operation of the quarry for future conversion to operation as a landfill for Tweed Shire Waste Management. This area alone will be inadequate for future needs, and applications are currently being processed to allow extraction on three adjoining sites that will eventually become part of the landfill.

While the Council was looking to purchase a larger loader to handle the increased volumes extracted from the quarry to meet target dates for operation as a landfill (it had a Doosan DL300 in its fleet), it was unwilling to purchase more capital equipment until the approvals were finalised.

As a result, it hired a range of loaders from hire companies and local quarries, and this gave it the benefit of an extended evaluation of the offerings of a number of manufacturers prior to committing to purchase.

The operation of the loaders was shared and input was sought from those operators, with two clear front-runners emerging: a Caterpillar 972H and a Doosan DL400. Others were marked down in areas such as ride quality, cabin comfort, reliability and productivity, while the front runners were at or near the top of all major evaluation criteria.

The extracted rock predominantly meets the demand for decorative aggregate (sometimes known as Tweed cream) for the landscaping industry, but also has application for CBR80 and CBR45 roadbase materials and cracker dust. Aggregate is produced in a range of sizes from dust (-7mm to 70mm+), and research was conducted with a view to blending the stone with recycled crushed concrete to produce a sub-base gravel.

With the need to have the landfill operating in the near future, the quarry increased its output and private sales account for 50 per cent or more of the output. Markets have been developed south to Ballina, north to Burpengary and west to Ipswich, with landscaping yards on the Gold Coast being big users. However, the quarry production manager believes that there is still considerable potential for further growth and is keen to develop new business.

While the attractiveness of the rock puts it in high demand for decorative purposes, it is a demanding product from an extraction point of view, with the high silica content causing high wear on cutting edges, screens and the like. Blasts are designed to achieve high rock fragmentation to reduce the crushing requirements and thus reduce crusher wear.

A further issue for the quarry was the need to stockpile blast material quickly after a blast, as the clay content meant that there was a high loss of material if there is heavy rain (a common occurrence in the Tweed Valley) while the shot material is still lying on the quarry floor. A fast and reliable loader is essential.

The Doosan DL400 has a number of attributes that suit this work. The comfort and ride quality allow the operator to have one hand on the steering wheel and the other on the joystick during operation. The ride quality is important when material is being shuttled from a stockpile to a crusher or screen, in allowing fast cycle times while minimising spillage. When building stockpiles, the Doosan has sufficient power and traction to allow the loader to climb the pile with a full bucket until the rear counterweight bottoms.

The Council’s DL300 had proven reliable in long-term use and both machines exhibited none of the problems that had affected some of the other brands trialled. Brake wear was good, and Doosan paid considerable attention to the location of the disc brakes, automatic maintenance of disc clearance and ready monitoring of disc wear without the need to disassemble the hub when designing the DL series.

The DL400 has since been superseded by the DL420 and is distributed in Australia by Clark Equipment. The DL420 is powered by a 209kW Cummins QSM 11 low-emission engine that provides 6.6 per cent better fuel efficiency. This drives through a fully automatic ZF electronic powershift transmission and limited slip differentials. The hydraulic system employs two load-sensing variable displacement axial piston pumps.

Doosan wheel loaders and hydraulic excavators are distributed by Clark Equipment through a national network of 20 branches and their dealers.

Source: Clark Equipment Sales Pty Ltd

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