Show S palling signalling Sign alling mine hoists x from moving cages BY C A AUEN ALLEN the problem of signalling sign alling to the hoisting engineer from a moving cage in the shaft has been considered by many mine operators for a number of years there are several methods in use in different mining districts and so far as the writer is aware they have been further developed in utah than in any other state the latest installations stal lations are of interest because they use a very low voltage circuit for the shaft wires and also because the wiring can be so arranged that the hoist can be stopped from the cage if so desired the first installation in utah was in the shaft of the centennial eureka mine under the management of C E allen alien it was placed in operation in the summer of 1899 and has been in continuous and satisfactory operation for twenty one years the arrangement ran consists of two bare wires down the shaft carrying a current at 60 volts potential with a device on the cage for making connection between the two wires this device is simply a short piece of wire which is thoroughly insulated from the cage and is operated by a short lever whenever the cage rider wishes to signal the engineer lie he pulls down the lever forcing the short wire out against the two bare wires thus making a circuit which rings the hell bell in the hoist room A similar device was placed in the grand central shaft at 11 mammoth amMoth utah but was later abandoned the caulp cause of failure was reported to be that the shaft was very wet how system works at eagle blue bell at a later date a system having the same general arrangement as that used in the centennial eureka mine was placed in the shaft of the eagle and blue bell mine at eureka utah but dry batteries were substituted reducing the voltage to about 10 volts this shaft is wet in places but no trouble has been experienced the eagle and al blue bell mine is under the management of imer pett of salt lake city and several everal improvements on the method have been een made by the mine electrician james strang rang in consultation with leonard wilo 0 of salt lake in order to give a better idea of the pos bili ties and application of the system it should be stated that the hoist is a double teel reel modern electric hoist with oil operated etches clutches and brakes the clutch and brake for r each reel are actuated by different movements ove ments of the same control lever the hoist olst has s the usual safety devices such as 11 switches in the head position ile metai mining engineer bureau of mines ort of investigation switches for each reel and ball governor control these safety devices are operated by what may he be termed the control wiring which is in series with a no voltage release on the switchboard should the circuit in the control wires be broken the no voltage release acts which cuts off the power and automatically applies the brakes for example if the cage should be pulled up to the limit switches the circuit would be broken automatically stopping the hoist this arrangement of wiring for the safety devices is not materially different from that used on other electric hoists and is mentioned here solely to show that opening the control circuit is all that is needed to stop the hoist in the eagle blue bell shaft there are two no 4 bare copper wires one on each side of the shaft guides one of these wires is used for signalling sign alling from the levels the second wire forming the return the second wire is also used to make the circuit for ringing the bell from a moving cage signalling Sign alling from the cage As regards signalling sign alling from the cage it may be assumed that there is only one bare wire in the shaft this wire extending into the hoist room and through an ordinary western union relay switch to the ground on the cage is a battery of six dry cells in a piece of iron pipe for protection one terminal of the battery is connected to the hoisting cable and is thus grounded through the hoist the other terminal is connected with an ordinary pushbutton switch and a piece of curved copper plate which by means of a small lever can be pushed out against the bare wire the pushbutton push button Is on the same level when the cage rider pulls the lever at the same time pressing the button current flows from the dry cells through the bare wire through the relay into the ground thence through the hoist cable back to the cells the current flowing through the relay closes a separate electrical circuit which rings the signal bell the current for the bell circuit is supplied by 30 dry cells in the hoist room but connection could be made with a direct power or lighting circuit the important feature of this arrangement is that the dry cells placed on the cage give a low voltage current only 10 or 12 volts eliminating all possibility of danger such as would be present were higher voltage used also if the contact lever should be accidentally struck and contact made with the bare wire the circuit would not be completed because in order to close it the button must bo be pushed at the same time the lever is thrown the use of the relay in the hoist room is also important because it permits the use of a low voltage current in the shaft and a higher voltage to ring the bell in order to stop the hoist from the cage by the same wiring system it is only necessary to place in the control circuit of the hoist another relay so arranged that when the circuit is completed in the shaft this relay will open the hoist control circuit As soo soon as this circuit is open the no voltage release on the hoist switchboard will be operated cutting off the power and automatically mati cally stopping the hoist modified plan at park city 0 N friendly general superintendent of the judge mining alining smelting smelling Sm elting company is installing a modification of the eagle blue bell system for use in the daly west shaft at park city it is planned to do all the signalling sign alling from the cage and have no signal arrangement on the levels except the flash or buzzer system for calling the cage A number 0 bare wire will be suspended in the shaft with insulators every four feet instead of a hand lever to make contact against the wire there will be a continuous contact with the wire as between an electric motor and trolley wire six dry cells will be placed on the cage as at the eagle blue bell shaft and the relays and bell circuits on the surface will also be the same push buttons will be used to close the circuit double deck cages are in use and to make it possible for a cage tender to give signals from the cage while standing on the station at either side of the shaft four pushbuttons push buttons will be used two on each side of each deck by this method there is no possibility of anyone signalling sign alling the hoisting engineer except from the cage it not infrequently happens that careless or ignorant employees signal the engineer when they do not know where the cage is causing the engineer to move the cage when it should not be moved |