AUTOMATIC PIPE WRENCH Russian patent published in 2008 - IPC E21B19/16 

FIELD: drilling equipment, particularly drilling devices for round-trip operation mechanization during assembling or disassembling of drilling strings, casing pipes and flow strings.

SUBSTANCE: automatic pipe wrench comprises upper and lower pipe clamping devices, intermediate reducer, transmission gear 4, drive motor 5 and manometer 6. Transmission gear 4 includes differential reduction means 10 and speed selector coaxially installed inside cylindrical body. Speed selector includes toothed high-speed 11 and low-speed 12 half-couplings linked to high speed 13 and low speed shafts of differential reduction means 10 correspondingly. Sliding toothed half-coupling 14 cooperates with high-speed 11 and low-speed 12 half-couplings. Speed selector also has power cylinder 15 with spring-loaded piston 16. The power cylinder 15 is coaxial to toothed half-coupling 14 and cooperates therewith.

EFFECT: simplified structure, increased wrench capacity and manometer operation accuracy, decreased weight and size.

4 cl, 3 dwg