Rope-dog tower ready for dog ropes

The Yates Shaft is a step closer to becoming the primary entryway to the underground laboratory, with the completion last week of the rope-dog tower. Contractor Heavy Constructors, of Rapid City, S.D., which built the tower, is moving out this week, and Sanford Lab personnel are staging materials in preparation for the second big step: lowering two 5,200-foot steel-wire ropes down the shaft.

For those who haven?t been following this project in Deep Thoughts, ?rope dogs? are part of a safety system that will stop the Yates Shaft conveyance in the unlikely event of a hoist-rope failure.  (In the 73-year history of the Yates Shaft, there has never been a hoist-rope failure.) ?Dogs? are clamps that travel with the conveyance up and down the shaft. The wire ropes run through the dogs, on either side of the conveyance. If the hoist rope goes slack, the dogs automatically clamp the ropes. The dog ropes, in turn, are suspended from the new rope-dog tower, a structure 100 feet tall that has been constructed inside the Yates Headframe building. (See the photo.)

Sanford Lab personnel will use a winch, now installed in the Yates Shaft yard, to lower each of the 35,000-pound dog ropes down the shaft and into position. For about two weeks, beginning next Monday (April 9), the Yates Shaft conveyance will be out of service during that project.

Until this month, the Ross Shaft has been the main entryway to the underground lab. That meant visitors to the Davis Campus on the 4850 Level had to walk or ride a train for about a kilometer to reach their destination. In two or three weeks, the Yates Shaft will deliver scientists, technicians and visitors almost to doorstep of the Davis Campus.

With the Yates Shaft in full service, replacement of steel in the Ross Shaft will begin. (The Ross Shaft  will remain available for secondary egress.)