Keeping tracks and wheels turning at sub-zero temps

  • 19-Jun-2008 07:50 EDT
Antarctice 4.jpg
Allison 3000 Series transmission; no special design modifications are made to cope with the Antarctic environment.

The Antarctic is as off-highway as off-highway gets. In many respects it is the ultimate mobility proving ground, with an extraordinary span of winter and summer temperatures from -90 to +15°C (-130 to +59°F). The coldest, driest, and windiest continent on Earth, 98% of its area is covered in ice to an average thickness of 1.6 km (1 mi). Not surprisingly, such extreme conditions mean it has no permanent human residents.

But it does have temporary residents—and they need off-highway vehicles other than those pulled by dogs. The visitors are mainly scientific research teams from more than 30 countries, and among them is the British Antarctic Survey (BAS). Facing such extreme conditions, with the need to tackle both ice and thick snow, means that the performance and reliability of support vehicles is vital—not just for work but for survival.

The BAS, based in Cambridge, UK, has been undertaking the majority of Britain’s scientific research on and around the Antarctic continent for about 60 years, and currently supports five research stations at Rothera, Halley, Signy, Bird Island, and King Edward Point. Strengthened ships sustain the Antarctic operations, providing advanced facilities for oceanographic research together with logistic support.

The BAS uses a range of tracked and wheeled vehicles, including snowmobiles, Tucker Sno-Cats, and mobile cranes. Off-the-shelf and specialized vehicles are used at Rothera and Halley. At Halley the vehicles are all tracked, giving access around the Brunt ice shelf, while at Rothera there is a mix of wheeled and tracked vehicles to deal with the constantly changing summer conditions as the snow recedes to leave bare rock around the base location. All the heavy plant vehicles are powered by diesel engines, which require special pre-heating before they are started in low temperatures.

They also use alternative fuels. These include Jet-A1 aviation fuel to prevent waxing experienced with regular diesel fuels in such low temperatures. All the vehicles are fitted with automatic transmissions to ensure they are simple to operate and less prone to damage. A dozen Sno-Cats are used for transporting personnel and towing sledges of up to 8-t (8.8-ton) maximum weight, carrying loads that include supply deliveries from BAS’ main logistics support ship, RRS Ernest Shackleton.

Powered by Cummins 6BT and QSB 170-bhp (127-kW) engines or Detroit Diesel engines and driving four tracks through Allison automatic transmissions, the Sno-Cats are steered by turntables fitted to the axles.

BAS’ Technology and Engineering Division is responsible for managing all aspects of its vehicles in Antarctica, with vehicle managers often spending the winter operating season at Rothera or Halley.

Martin Bell, Deputy Project Manager for Logistics and formerly the vehicle manager responsible for vehicle purchasing and maintenance, has many years’ experience in Antarctica. He fully appreciates the problems that vehicles can experience.

“Day-to-day planning and preparations for Antarctic operations and operating in harsh conditions are a constant challenge,” he said. “Low temperatures, deep snow, wind, traction problems, steep gradients, ice, and long operating hours combine to create difficult operating conditions.” The pressure to maintain vehicle reliability is huge.

“On our relief runs, a vehicle can be working alone, so reliability is paramount; and in winter months when we operate some of the Sno-Cats, a breakdown can be a life-and-death situation,” said Bell. “We prepare for these occasions by having emergency equipment and vehicles on standby. In the 16 years I have worked there, we have never had a transmission failure.”

With limited maintenance facilities in Antarctica and the nearest workshop thousands of miles away, it is essential that maintenance requirements be kept to a minimum. “We run AT545, MT643, and MD3560 Allison transmissions,” said Bell. “No special design modifications are made to the transmissions for coping in the Antarctic environment and very little maintenance is required—only oil and filter changes every 500 operational hours. Though a small oil heater is installed in the vehicles, this is often not needed.”

In the Antarctic it is essential to prevent failures but also to ensure that vehicles and their components have as long a service life as possible. Typical operating life of BAS vehicles is 15 to 20 years. With finite funding and budgets, any money saved in logistics support for BAS activities in Antarctica can be used to fund other functions, so contributing to the overall effectiveness of the research program.

All Allison gearboxes incorporate a torque converter, optimizing use of engine power and multiplying torque by a factor of two, making steep, icy gradients easier to climb and traversing soft snow and rubble, which can appear in certain areas as snow thaws in summer, more efficient.

The transmission also offers lock-up on first gear, which provides direct drive from the engine, reducing heat buildup and contributing to drivetrain longevity. Integrated diagnostics in the transmission monitor and provide advance warning of possible transmission-related issues. This information is available to help reduce the risk of transmission failure, preventing the potentially dangerous situations that could occur on-site as a result. Even if a problem should manifest itself, Allison has incorporated a “limp-home” mode, allowing a vehicle to be moved to a location where a technician can safely work on fixing the problem.

Allison-equipped Foremost mobile cranes are also being used in the Antarctic for ongoing development (but not expansion) of the Rothera site. By replacing old structures and making best use of new technologies, such as improved insulation and energy production and management systems, BAS aims to further reduce the environmental footprint of the station.

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