The Catarpiller D4 was the biggest bulldozer that we could safely transport across the sea ice. I am told that, as bulldozers go, this is not a very big one. It was great fun to drive around and very good for digging out vehicles & sledges that had been buried by the storms.
Early in September the D4 is being used to "raise" some German sledges. They got buried after a few blows and were stuck fast. Fortunately the shovels weren't required this time either as the D4 is powerful and yet gentle. The blade can be used to break the bonds of the ice on the skis, and then a gentle shove from behind gets 'em moving in the right direction. The D4 (with it's metal tracks) could operate in the coldest temperatures, when sno cats & ski doos were safely tucked up. This was vital as we had to move fuel for the generators about all year round. This is a sledge load of 45 gallon fuel drums.
Here is the D4 pulling a sledge of gas for our cooker in 1995.
We kept 2 D4s on base, but during the winter only one of them was in use. This one was placed on a 2 metre high mound at the start of the winter. By September the surface had covered the mound & a fair bit of the D4.
2 D4s were left on the base and a third is returned to the UK each year for a thorough overhaul. Any incoming mechanics learn the ropes with the one in the UK before coming down. This D4 is being winched of the low ice shelf at N9 during a summer in which there was no sea ice near the base.