By Spencer Smirl

During our initial 250hr service 200hrs ago we had discovered that Seeker was transferring oil from both final drives into the transmission. This is the result of a failed lip seal where the axle shaft runs between the two gear boxes. This can be a fairly common failure at low temperatures but very unlikely at such low operating hours. The failure of the seal is the result of one of two things: the rubber from which the seal is constructed becomes very hard in the cold temperatures and can no longer keep a positive seal against the axle shaft or during periods of downtime in extreme cold the seal can freeze to the shaft and then tear when the machine is moved again.

Finning had a cold weather consultant which had advised them of a remedy for this repeated failure. This consultant had a long running history of operating D5Ns in Antarctica, a slightly smaller Cat Track Type Tractor. He had advised that we should use D4H (another, smaller Cat bulldozer) axle seals to replace our D6N seals as they are a slightly tighter fit to the shaft and seemed to last longer on the D5N’s. Caterpillar helped by sourcing silicone seals from their supplier who made bespoke axle seals out of silicone based rubber. These would stay much softer in cold temperatures and also used a double lip design to double our sealing surfaces.

Before both Cats left Cannock in England they were each fitted with these replacement seals to test them against each other. Seeker had the D4H seals installed, while Rover got the experimental double lip seals.  Nothing against silicone seals from supplier, but most bets were on the D4H seal as it already had a proven history in Antarctica.

It was to everyone’s surprise when Seeker failed first, as it was Seeker who had the D4H seals. As the route from our service location back to Crown Bay was relatively flat, reducing the amount of oil that could be transferred, and our final drives were running very clean anyways. We decided we would leave the replacement of these seals till then. The little bit of oil that would be transferred would not do any harm. When we arrived back at Crown Bay, we were to have six days for any needed repairs and adjustments before the expo would start the afternoon of the 20th. If most of you remember, we had one day, then it stormed for seven, putting us way off schedule. I decided the replacement of the seals could wait until we were back at the base of the mountain pass, I didn’t want to hold up the start of our expedition more than it already had been.

We made it back to the base of the mountain climb, across the first crevasse field, in half the time it took us when we made our depot run. I had no guilt in calling a full day maintenance shut down now.  We managed to replace the leaking axle seals and had time to spare to adjust the Stowing of both tents atop the two bulldozers.

With 500hrs on the clocks, it is expected to have some needed repairs. We have been quite fortunate we have had to do so little to Seeker and Rover. The quality of Cat’s bulldozer line is a direct reason I had the confidence to accompany this expedition. I hope this trend continues and I return home with a lot of parts to credit.