US2252818A
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Grinding machine
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US2209303A
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Method of heat-treating elongated objects
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US2242838A
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Inductive heat treating apparatus
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US2227866A
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Protected and insulated heat treatment coil
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US2229680A
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Polyphase high frequency heating device
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US2241431A
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Electric coil and core therefor
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US2214681A
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Apparatus for treating metals or metallic articles
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US2189819A
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Multiple transformer switching system
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US2208607A
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Apparatus for heat-treating gun bores
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US2238082A
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Cylinder treating machine
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US2223902A
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Transformer distributing system
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US2140337A
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Oven and system of ventilation therefor
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US2256873A
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Inside induction heater
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US2180126A
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Cleaning and degreasing system
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US2040884A
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Oven and system of ventilation therefor
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US2118480A
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Method of treating metals or metallic articles
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US1616067A
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Elongated electrically-heated oven
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US1712010A
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Unit electrical heater
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US1667747A
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Relay for electrical control apparatus
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CA400070A
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Transformer distributing system
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