Fluid detector device in a drive motor for an underground mining machine

Apparatus for detecting penetration of fluid in combination with a drive motor for an extracting machine such as a drum-type coal cutting machine employed for underground mining operations, said drive motor including windings within a motor housing, a motor shaft extending through end plates at the ends of the motor housing, bearing means supporting the motor shaft for rotation within the housing, and annular seal means between the motor shaft and the housing to normally prevent the passage of fluid into the housing from at least one end thereof, the improvement comprising:

• capacitive means including at least one charged carrier probe spaced from said seal means along said motor shaft for ultimate support by the motor housing between the end plates in a manner such that fluid penetrating into the motor housing beyond said seal means contacts and reduces the capacitive charge of said capacitive means,
• detecting means coupled in an electric circuit which includes said capacitive means for producing an electrical signal corresponding to a decrease capacitance of said capacitive means to thereby indicate penetration of fluid into the motor housing, and
• means energized in response to said electrical signal.