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The closest most UK truck drivers come to extreme cold

20th December 2007
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Page 74, 20th December 2007 — The closest most UK truck drivers come to extreme cold
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is picking up a consignment of frozen produce — but for the British Antarctic Survey it's just part of a day's work. Dylan Gray looks at the most southerly fleet on the planet.

When a vehicle breaks down, more often than not its operator will be concerned about downtime .loads being stranded and the expense of having the vehicle fixed. But as anyone involved with the British Antarctic Survey (BAS) will tell you. vehicle reliability way down south can be a matter of life and death.

BAS, based in Cambridge, has been handling the majority of Britain's scientific research on and around the Antarctic continent for about 60 years and currently runs five research stations: at Rothera, Halley, Signy, Bird Island and King Edward Point.

Ice-strengthened ships sustain the Antarctic operations, providing advanced facilities for oceanographic research and logistics support, while a range of tracked and wheeled vehicles, including snowmobiles. Sno-Cats and mobile cranes, support day-to-day activities and ensure survival.

Various off-the-shelf and specialised vehicles are based at Rothera and Halley Antarctic stations. At Halley the vehicles are all tracked, giving year-round access around the Brunt ice shelf, while at Rothera there is a mix of wheeled and tracked vehicles to deal with the ever-changing summer conditions as the snow recedes to reveal bare rock.

All the heavy vehicles are powered by diesel engines, which require pre-heating before they can be started in the ultra-low temperatures. Specialist fuels such as let Al are used to avoid the waxing of conventional diesel fuels (see panel). All the vehicles are fitted with automatic transmissions to ensure they are simple to operate and less prone to damage.

Running at eight tonnes BAS currently runs a fleet of 12 Tucker Sno-Cats, which are used for transporting personnel and towing sledges up to eight tonnes GCW. These contain loads such as supplies from BAS's main logistics support ship, RRS Ernest Shackleton. Powered by Detroit Diesel or Cummins 613T and QSB engines of about 170hp, and driving through Allison automatic transmissions to four tracks, the Sno-Cats are steered by turntables fitted to the axles.

The cab simulates that of a standard pickup truck, including a steering wheel and pedals for the accelerator and brake. This is to allow a driver, who may be inexperienced with a tracked vehicle, to operate it with the minimum of instruction in case of an emergency— and it's essential that in this environment all drivers should be trained in the operation of ovcrsnow vehicles.

The Sno-Cat track system comprises four tracks that are independently sprung and pivoted at the drive axle.These tracks are capable of tilting up or down to provide a ramp for climbing over obstacles or spanning uneven terrain.The drive axle and spring system is trunnion-mounted to accommodate uneven terrain in the transverse plane.

The track suspension system has the added advantage of increasing vehicle traction due to the ability of each separately powered track to maintain ground contact over its full length at all times.This is particularly useful when cresting hills and operating on rugged terrain.

Some of the most important parts on these specialist vehicles are the rubber tracks. Unlike steel cleated tracks, rubber tracks can operate in most types of terrain without damage, including dry pavement, dirt roads, mud and deep powder snow.

The Sno-Cat is hydraulically steered by pivoting both the front and rear axles. This allows smooth movement over the terrain with minimum disturbance of ground cover. When turning there is no power loss or track slippage and turning involves minimum stress to track or carrier components.

The steering arrangement is particularly good while manoeuvring on hillsides.The front and rear tracks present a fan pattern on the terrain as the vehicle turns or moves sideways on a hillside; this is a major factor in preventing side-slip on ice or hard-faced slopes. As a further aid to traversing hillsides each individual track is provided with ice cleats, which reduce side slip and maximise traction.The fact that all tracks are powered at all times is a major advantage.

The four-track concept allows a variety of body styles— the engine can be mounted at the rear or centre of the vehicle and still maintain good weight distribution to the tracks.

Common components The use of standard automotive axles and common hydraulic and mechanical parts not only means that parts availability is good but ensures that no extraordinary mechanical skills are required for servicing.

An important safety feature is the Sno-Cat's rollover protective structure. All engine compartments are located outside the cab to cut engine and other mechanical noise, engine or transmission heat, and reduce the possibility of hazardous fumes from exhaust or fuel.

BAS's 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. The deputy project manager for logistics for the Halley VI build project, Martin Bell, formerly the vehicle IP manager responsible for vehicle purchasing and maintenance, has spent nine years in Antarctica on various contracts With his experience as vehicle manager for BAS, Bell understands better than anyone the challenges of operating a fleet in harsh environments — and they could hardly come much harsher than Antarctica.

-Day-to-day planning and preparation for Antarctic operations and operating in harsh conditions are a constant challenge," says Bell. -Low temperatures, deep snow, wind, traction, steep gradients, ice and long operating hours create difficult operating conditions, and 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-or-death situati on," Bell adds."We prepare for these occasions by having emergency equipment and vehicles on stand-by."

The Sno-Cat is equipped with an Allison sixspeed transmission, with ratios selected to maximise its performance in the snowy terrain. By reducing wear and tear on the driveline vehicle life is greatly extended and mainte mince costs are dramatically reduced.The typical operating life of BAS vehicles is 15-20 years. With finite funding, any money saved in logistics support for BAS activities in Antarctica can be spent on other functions, contributing to the success of research programmes which is their whole raison d'être.

All the gearboxes incorporate a torque converter, multiplying torque by a factor of two and making steep, icy gradients easier to climb.They also offer lock-up on first gear.This provides direct drive from the engine, reducing heat build-up and contributing to driveline longevity.

Integrated diagnostics in the transmission provide advance warning of possible transmission-related issues. This information reduces the risk of transmission failure, preventing many of the potentially dangerous situations that could occur as a result. And if a problem does arise, Allison has incorporated a limp-home' mode enabling a vehicle to be moved to a position where a technician can safely work on it.

The Allison controller also protects the engine and driveline from unnecessary damage by prohibiting the mis-selection of gears.lhe torque converter and planetary gearing also increase traction, improving the performance and control of vehicles operating on soft snow or loose rubble— both of which are conditions that can develop during snow thaws in the summer.

With limited maintenance facilities in Antarctica and the nearest workshop thousands of miles away, it is essential that maintenance requirements are kept to a minimum."We run AT545,MT643 and M03560 Allison transmissions," says 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 used. In the 16 years I've worked here we've never had a transmission failure."

If a vehicle does breakdown, depending on the problem it is either fixed on site. returned to the station's garage for repair or sent back to the UK. -It is very rare that we cannot fix things on site but if a serious problem occurred we would have to send the vehicle back to the UK to our workshops in Cambridge or back to the supplier," says Bell.

Losing vital vehicles would present serious problems and increase daily operational challenges even further so it is essential that vehicle productivity is kept high.

Survival skills

In an environment like Antarctica it is essential that everyone is given the necessary survival skills, and this includes operating support vehicles.

"We have a very comprehensive training period in the UK in September and then on site in Antarctica but quite a lot of our drivers are made up from general staff who have never driven an automatic transmission before.The transmission is easy to use and they like the simplicity," says Bell.

In very difficult driving conditions with poor visibility, storm-force winds and uneven ground, vehicle control can be very difficult for even the most experienced drivers.

The argument is that with an automatic transmission drivers are able to keep both hands on the steering wheel, allowing safer, easier operation.

The transmission also has a feature called Adaptive Controls:the gearbox learns drivers' behaviour and adjusts its shifts to suit.The Adaptive Controls will remember this optimum shift point over the vehicle's life.

Furthermore, reducing the driving skills required has the welcome effect of both simplifying the training required and reducing the time needed to deliver it. •


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