OCR

The conveyor system Is operated 24 hours per day, six (and sometimes seven) days per week. The operating and operating maintenance crew comprises 48 men. The conveyors are all started in. sequence from a single console with only one start button for the group of six conveyors . Also there is only one normal stop button and it closes a contact which stops the vibrating feeders only. Another contact in this circuit starts a timer and after 15 minutes all conveyors are stopped simultaneously. There is an emergency stop button which stops all conveyors immediately. The console also houses the rheostats for varying the feed rate coming from the vibrating feeders. There is an automatic weighing device on the tunnel conveyor and the indicating, totalizing and chart recording instrument is in full view of the conveyor operator. There are selective ringing-selective speaking, sound powered telephones in all strategic locations. Safety Features Got Unplanned "Test" There has always been much respect, and wide latitude, given to the possibility of a run-away conveyor or conveyors. There has seen one instance of the absolute necessity for the mechanical and electrical safe- guards to bring a loaded or overloaded conveyor to a stop. One evening, when control of feed was. temporarily lost for approximately three minutes, Flight No. 1 became fully loaded at a rate in excess of 1600 LTPH. This resulted in a motor overload, instantaneous overspeeding of the belt and large pieces of charred brake lining. All safety features performed at intended. On one occasion it was necessary to electrically disconnect one of the two drive motors and operate at reduced capacity with a single drive. Fortunately, electrical and operating personnel had anticipated this pos- sibility, which minimized the time required to resume operations at the reduced rate. There is a plan now under study, which would facilitate removing any one drive--or in the future two drives--from the circuits. Instead of making time consuming emergency connection, a set of wiring and controls would be installed, whereby a drive or drives could be switched out by simply closing a switch. Operating costs for the year 1963 through July 31 were $0.035 per long ton conveyed. In conclusion, the conveyors have functioned as a reliable and integrated haulage system since the completion of construction in late 1961. The steel cord belting, the largest single item of the project, is showing a minimum amount of wear and tear under punishing service. The power generated by the descending load has been an important asset to the conventional power generating facilities.