Rope-dog tower footings mostly poured

Traffic has been heavy in the Yates Shaft yard recently, with deliveries of steel and concrete for a new “rope-dog” safety system. Rope dogs will protect the Yates Shaft service cage from failures—an important feature in any 5,000-foot shaft.

A “dog” is a device that prevents movement. In the Ross Shaft, for example, if the wire rope securing the service cage should go slack, “dogs” with gear-like teeth would automatically deploy to grip the shaft guides, preventing the cage from falling. Homestake Mining Co. installed that system.

The Yates Shaft, which in March will become the main access route to the underground, required a new system. If the Yates cage rope goes slack, the new dogs will automatically grip two wire ropes that will descend the north and south sides of the Yates Shaft. The wire ropes, each 5,200 feet long, will be suspended from a 110-foot steel tower that will be built inside the Yates Shaft headframe building. (The headframe is about 150 feet tall.) 

The rope-dog tower will be anchored in two large concrete footings inside the headframe, on the north and south sides of the shaft. The south footing required knocking out two floors to rooms below (including the old bit room), which have been filled with concrete. The footings will require a total 160 yards of concrete.

Wire ropes, by the way, are a kind of cable made of braided steel wires. Project Engineer Mike Johnson says the dog ropes are “torque-balanced, half-locked coils,” which means they are extremely strong.

Some concrete work remains to be done, but footings for the tower are mostly poured. The tower itself will be erected in February.  (Postscript: in the history of the Ross (1934) and Yates (1939) shafts, there has never been a rope failure.)