Arctic Exposure

The Usibelli coal mine in Healy, Alaska, uses a variety of heavy equipment that is subjected to some of the harshest conditions on the planet.

Using synthetic fluids, Usibelli's O&K shovels have extended their low pressure hydraulic filter changes from 500 to 1000 hours, and their high-pressure changes from 1000 to 3000 hours.

Usibelli operates a highly utilized fleet of surface mining equipment including Caterpillar wheel loaders, track dozers and haul trucks, as well as two massive O&K shovels and a $12 million dragline that began operating in 1978 — and still is the largest piece of land equipment in Alaska.

In 1997, the mine began to search for a new lubricant for hydraulics and transmissions that would meet the challenges of operating mining equipment around-the-clock in temperatures ranging from summer highs of 70° F and above to frigid winter lows going down below –60° F. Technical engineers at ExxonMobil studied the problem, and determined that what Usibelli needed was a product not available commercially at that time. Usibelli needed a transmission/hydraulic oil for its equipment that would withstand temperature extremes and provide all-season wear protection.

The lubricant Usibelli wanted had to reduce wear during cold-temperature starts, while also shortening equipment warm-up time. It needed resistance to oxidation and thermal stability at high temperatures to protect against deposits and corrosion. And it should extend both oil and equipment service life in the harsh operating environment. Last but not least, the lubricant had to meet Caterpillar's TO-4 fluid specifications.

No such thing exists, but . . .
Mobil specially blended a synthetic lubricant, dubbed Mobiltrans SHC Arctic, for use by the Usibelli Coal Mine. After a short trial period, Usibelli began converting its entire fleet of heavy-duty equipment to using Mobiltrans SHC Arctic as its exclusive hydraulic and transmission lubricant.

"There is nothing like Mobiltrans SHC Arctic for cold weather off-highway operations," said Scott Killian, the mine's maintenance manager. "With this fluid, startup in cold temperatures is as easy as turning on the equipment and going to work. You don't have to wait to pre-heat your systems, regardless of how frigid it is outside. This is the most flexible lubricant we've ever worked with."

Killian noted that sudden wide shifts in temperature — called Chinook winds by locals — are particularly hard on equipment. "One day it can be -30° F and the next day it can be 40° F. Conventional hydraulic and transmission fluids simply can't handle such temperature extremes," he explained. "Even with the use of oil pan and engine block heaters, cold soaked equipment at -40° F would require labor, tarps, and generators during startup if we were using a mineral oil rather than Mobil's synthetic lubricant."

Usibelli has saved more than $31,000 in each of the last two years with this synthetic lubricant, rather than conventional mineral oil products. They have extended oil and filter change intervals, as well as reduced labor costs. These savings do not even take into account significantly reduced cold-start wear, shortened warm up time for the equipment on bitter cold mornings, greater equipment uptime, and higher productivity.

Through established maintenance practices, continued oil analysis trending, and the Mobil Planned Engineering Service Program, Usibelli Coal Mine has extended its oil drain intervals in transmissions to 3000 hours versus the industry average of 1000 hours. The company has also extended fluid-drain intervals in its hydraulic systems up to 8000 hours and more — compared to the industry average of 2000 hours.

Usibelli has also achieved significant extended filter-change savings in its larger O&K shovels. In the lower pressure hydraulic systems, filter changes have been extended from 500 to 1000 hours. In the highpressure hydraulics, filter changes have been extended from 1000 to 3000 hours. Lubrication contamination is generally introduced from the outside or generated by the lubricant as a product of oxidation, or both. Extending filter life as Usibelli is doing is an excellent example of both outside contaminant control and the oxidation stability of Mobiltrans SHC Arctic.