Caterpillar D11T dozer

Date: 14.02.2011

At 100 tonnes the Caterpillar D11T track type tractor is one serious piece of equipment.

Caterpillar D11T enjoys a ripping good time. And at 100 tonnes noone's going to argue with it.

When it comes to shifting tonnes of rock and coal, bigger is usually better. And at over 100 tonnes they don't come much bigger than the Caterpillar D11T track type tractor that is now operating for the Stockton Alliance on the West Coast.

The D11T is the first of its kind to land in New Zealand and is one of the final units delivered as part of Goughs' contract to supply 95 pieces of Caterpillar machinery, worth $120 million, to Solid Energy's Stockton opencast coking coal mine north of Westport.

The Stockton operation features a number of other very large Caterpillar dozers including D8T and D10T units, which have operating weights of 38,000kg and 66,000kg respectively. However these are dwarfed by the D11T, which weighs in at over 100,000kg.

Engine and power

The D11T is powered by a Cat C32 ACERT technology engine, which optimises performance while meeting full emissions compliance. Performing at full rated net power of 634kW (850hp) at 1800rpm with a high torque rise of 21 percent, the large displacement and high torque allow the D11T to doze through tough material prevalent on the Stockton plateau. Goughs sales and marketing manager, Steve Templer, says that Cat mining tractors are built to move more. And they're built to move more for a long, long time.

"It's not unusual for a Cat track type tractor in a mining application to log more than 100,000 hours. Longevity is built in," he says.

He adds that Caterpillar has a 100-year legacy with designing the best track type tractors in the world, with each new series focusing on continuous improvement and introducing the latest technology. On the D11T he says,

"It's about providing a dozer that can provide the lowest cost per metre through outstanding production and reliability, in the toughest working conditions. And at Stockton the conditions don't come much tougher."

The D11T features a dual tilt SU blade that improves load control and allows the operator to optimise the blade pitch angle for each portion of the dozing cycle. A single shank ripper is attached to penetrate and rip the toughest of materials.

Stockton Alliance Training Superintendent Peter Currie details what the Cat D11T does on site.

"The D11T is used primarily for ripping hard rock and the bulk push of overburden at Stockton. In terms of material moved, the general rule of thumb is that if the machine weighs 100 tonnes it can push 100 tonnes of material, and this is certainly the case with the D11T. These duties are performed in areas to establish level drilling benches for drill rigs to gain access, and for ripping in and around underground voids. A GPS system fitted to the D11T, which is loaded with this void information, ensures the operator is aware of the proximity of these previously mined underground workings," Peter says.

The overburden at Stockton consists of abrasive sandstone and shale. When combined with the ever-present rainfall (around 6m per year), the mud from these materials acts like grinding paste and accelerates wear on the undercarriage and tracks of the D11T and other tracked machines on site.

Peter says the huge heavy duty off-highway transporter supplied by Jackson Enterprises and hauled by a modified Cat 777D will play a key role in reducing wear rates on tracked machines at Stockton. "The trailer has a 200-tonne capacity and provides the operation with the ability to move a unit such as the D11T around the mine site, reducing walking distances between jobs and for transporting heavy track equipment to workshops for scheduled servicing and maintenance."

Inside the cab

The Cat D11T operator environment is more than a cab; it's an integrated electronic platform designed to maximise productivity. Low-effort electronic steering, ripper and dozer controls are easily accessible and provide precise manoeuvring.

An interesting feature of the D11T is that ripping operations are performed by the dozer operator via the Work Area Vision System (WAVS) (two rearward facing cameras that link to an adjustable LCD colour monitor in the cab), as the operator is not actually able to see the ripping work site from high up in the operator station.

Power for the future

The Cat D11T combines power and efficiency with advanced technology to keep material moving at high volume with lower cost per metre. Rugged construction and state-of-the-art technology combine to ensure a 100-tonne dozer with long life and low operating costs, that is sure to continue the worldwide legacy of Caterpillar tractors for many years to come at Stockton Mine.

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