National Mine Service Company

Joachim N Blutreich

A battery for a combination battery-trolley wire powered mine locomotive is connected at its positive terminal by a conductor to an energized trolley wire that extends through the mine haulageway. A charging contactor having normally open contacts connected to the positive terminal of the battery is connected by a conductor to the negative terminal of the battery. Current from the trolley wire energizes the contactor to close the contacts and supply current to the battery for charging the battery to a preselected voltage level. A voltage sensing apparatus monitors the voltage appearing across the charging contactor. If the voltage exceeds a preselected level for safe charging, one or more Zener diodes is switched to a conductive state to energize a relay coil that actuates a normally closed relay to deenergize the contactor and open the contacts to terminate current flow to the positive terminal of the battery. When the voltage of the battery drops below the maximum safe voltage level, the Zener diode of the voltage sensing apparatus switches to a nonconductive state. The relay coil is deenergized and the relay contact is closed so that current flow from the trolley wire energizes the contactor and current flows through the closed contacts to the battery. An ampere-hour meter monitors the voltage level of the battery and when the battery is charged to full capacity, the ampere-hour meter actuates a normally closed contact associated therewith in the circuit to open the contact and terminate charging of the battery.

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Ashland, KY, United States of America

Joachim N Blutreich