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Vibration dampener
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Slant drilling tools for oil wells
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Hardened inserts for drill bits
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GB1168521A
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Tunnelling Machine
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Oscillating tunneling machine
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Rotary tunneling machine having improved debris disposal means
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Telescopic joint having means for signalling when the joint is extended
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Raise driver
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Tunnel boring machine
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Protective overhead shield for tunneling machine and method
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Bearing seal
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Bucket head mining machine having roof engaging anchor and conveyor
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Jet bit
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Lubrication and sealing of well drilling bit
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Large diameter well-drilling bit
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Carburized drill bit bearing
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Flexible connection
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Well drilling apparatus
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Rotary axial impact type earth boring tool
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US3096835A
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Bearing seal for rotary rock bits
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