Risk assessment of hoisting with and without a safety detaching hook.

Abstract

In the late 19th century steam winders with poor control led to literally many hundreds of overwinds per year. The current status on South African mines is that the frequency of overwinds is about five to ten per year, and these are nearly always slow speed overwinds in which no injuries or fatalities occur. Detaching hooks have two functions. Firstly to detach the rope from the cage in the event of a high speed overwind. This function minimizes the damage to infrastructure, but also releases the rope in overwinds at all speeds, including some low speed overwinds. This is not a safety function in that it does not prevent fatalities. The second function is to latch into the spectacle plate once the rope has detached, and provide a means of holding the cage from falling down the shaft. This is a safety function, in addition to the jack-catches, that helps prevent fatalities. Safety of persons always takes precedence over damage to infrastructure and loss of production, and this study only assesses the risk of serious injury and loss of life. Risk of damage to infrastructure and loss of production is not considered.