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It's cool for cats

Sir Ranulph Fiennes’ latest expedition is stretching demand on machines ro the limit, as Adrian Greeman reports.

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At ease: Finning’s Richmond Dykes (left) and Spencer Smirl show off one of the specially modified bulldozer tractors

The centre of Antarctica is more like another planet than the rest of Earth. Its ice-covered environment is life-free, always frozen, and in winter sees temperatures dropping as low as -800C.

Such extremes are beyond the experience of most cold weather specialists and engineers, and try materials and equipment to the limit. It has certainly been a major challenge for Caterpillar dealer and supplier Finning UK, which last month delivered two specially modified bulldozer tractors for a new expedition to the region by veteran explorer Sir Ranulph Fiennes.

Fiennes is to spend eight months crossing the 3,200km width of the continent in midwinter for climate research, polar investigation and probably the sheer hell of doing something for the first time. A five man back-up team is going with him, bringing supplies in a train of wagons, fuel container cells - holding 40,000l of fuel at the start of the journey - and the “cabooses” that will be the team’s living accommodation during the trip.

Two powerful Caterpillar D6N dozers were selected to haul these loads, the biggest that could be handled by the 25t capacity loading crane on the expedition ship SA Agulhas.

Not surprisingly, the machines delivered to the expedition team at the end of November are just a little out of the ordinary. “In fact, they have undergone a two year programme of modifications and customisation,” Finning sales manager Lea Andrews told a public unveiling just before the units were dispatched. The £150,000 base cost of each machine has risen to around £1M in the process.

“The sledge will allow the machine to support itself across small crevasses and ice holes”

Andy Thomas, Finning

The most obvious of over 100 major modifications, and many more smaller ones, is a range of outside additions and add-ons, particularly on the forward blade, which now features a projecting wishbone-shaped steel arm ending in a small sledge unit, additional hydraulic rams supporting a transverse mast bar, another roller support bar and a haulage link.

“The sledge will allow the machine to support itself across small crevasses and ice holes,” explains Finning technical services application engineer Andy Thomas. It can also act as a crane unit at the front.

But the sledge will not work for large cavities and cracks, one of the great dangers on ice. The other blade additions will therefore help carry a ground radar system that will have a video display permanently on in the driver’s cab of the leading tractor. “Crevasses show up as a V shape,” explains Thomas.

The detector for the radar will be hauled on a sledge by Sir Ranulph, walking ahead.

To reduce the cable weight he has to pull, a steel mast is fixed to the top of the blade, projecting forwards across the roller unit for 9m to carry part of the cable load. The mast can also be raised with the rams for communications use.

Further back on the machines the steel tracks have been modified with extended grouser bars with a castellated edge for additional grip, and screw-in points for special ice spikes. These will be attached for crossing the eerily blue solid ice found mostly in glaciers, which is glassily smooth and gives no grip at all.

Rather than use tailor made ice-pick heads from the automotive industry, the Finning team has adapted the tungsten tipped teeth used in road planers “which are both more robust and cheaper”, says Thomas. Within the tracks there are now also lifting attachment points welded on for the crane lifts. A 360o pintle hook has also been added to the rear drawbar.

Also at the back of each unit is a 40t winch, both for hauling loads and for rescue work if anything - or anyone - falls into a cavern or crevasse.

A diesel powered pump is also mounted here that will maintain a flow of heated oil around the machine when the main engine is switched off, part of an elaborate system of warming and insulation designed to keep the machine from freezing solid and to aid start-up in the morning.

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Hidden dangers: The modified blade carries a ground radar system that will have a video display permanently on in the driver’s cab of the leading tractor

Keeping everything at least partially warm is a major function of many other modifications. The driver’s cab, of course, is extensively insulated and will be able to sustain a temperature differential between the interior and exterior of around 40oC. Various panels and covers are lined with silvered insulation materials.

There are extra access steps, and the cab has also been fitted with a roof hatch to allow the driver to escape if the machine should fall in a crevasse, or in case of cracking when it is on sea ice. This will be an early danger when it is offloaded from the supply vessel.

The most obvious addition here is a frame with a tent-like canopy on the roof of the cab. This will be unfolded and draped around the machine at night and, with insulation in the roof, will provide a first line of defence against the cold.

Batteries, inside an insulated compartment, have electrically heated jackets around them, and the transmission, hydraulic and engine sump oil tanks also have electrical heater pads. Another electrical heater warms the engine compartment.

But these are secondary systems. At night the main heating will be supplied by a boiler unit fixed near the engine, from which warm oil will circulate to various heat exchangers in the battery compartment, hydraulic tank and fuel tanks. A small Perkins engine powers the pump for this, mounted on the back, where there is also a hydraulically powered generator set capable of a 20kV output.

“The machine can either provide electricity or take power from the caboose units,” says Thomas.

Working out the machine design was done in the first 12 months after they were ordered three years ago in conjunction with Finning Canada chief engineer Spencer Smart and with Fiennes.

But a lot of other changes, mostly hidden, were also needed. “The standard machines are designed for conditions down to -40oC, which is ‘normal’,” says Thomas. But another -40oC beyond that can have a major impact on materials and their behaviour, including even on steel.

Finning has some experience from D5 machines supplied to the British Antarctic Survey, but these are used at the coastal stations where the most extreme conditions are not experienced.

“We started with special reengineering that Caterpillar did on the supplied undercarriage to allow operations down to -550C,” says Thomas. Rollers, idlers and final drive seals were re-designed with low ambient temperature components.

Other changes were made and then the modified machines were taken to a site in northern Sweden where many of the car manufacturers test their latest models, trialling them for four months. “This resulted in further changes and modifications,” according to Thomas. “It was a particularly cold winter which usefully gave us a minus forty environment.”

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Charles Brennel CAT engines

“We started with special re-engineering that Caterpillar did on the supplied undercarriage to allow operations down to -550C”

Andy Thomas, Finning

Tests in cold rooms and labs were also important for seals and other items made with plastics and rubbers, which are brittle or otherwise have changed properties at low temperatures.

Modifications were needed for the Cat engine to handle the aviation fuel being used on the trip, which does not freeze like diesel. The fuel has to be dosed with lubricant to ensure the engine injectors work properly.

Third party suppliers have also had to make tests or modify their components. Spillard Safety Systems, which installs rear view and other video cameras, had to change its cabling to cope with low temperatures; Arctic Fox from Holland, which supplies fuel and oil heaters, also went to Sweden; and Snap-on Industrial, which is helping sponsor the expedition, developed and donated a mobile fully enclosed workshop with toolkits for the tractor and equipment maintenance.

Last but not least there have had to be tests on people too, to see how well they can stand up to the severe conditions, both physically and psychologically,followed by special training that included the winter in Sweden.

Finning is sending two of its best driver engineers with the team, Spencer Smerl from Canada and Richmond Dykes from Northern Ireland, both selected by Fiennes from a shortlist of half a dozen.

The two will operate and maintain the D6N tractors. Among their tasks is the morning warm-up for the equipment, which has to be done slowly and methodically over a two to three hour period to prevent thermal shock as hydraulic fluids and oils circulate.

But even that will not fill all the time. They will need a lot of books for the dark evenings and long 10 month wait for the supply
ship when the trip is done.

  • To follow the expedition’s progress go to www.thecoldestjourney.org

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