HYDRAULIC JUNK RETRIEVER Russian patent published in 2006 - IPC E21B31/08 

FIELD: fishing for or freeing objects in boreholes or wells, particularly adapted for well bottom cleaning and foreign article removing.

SUBSTANCE: junk retriever comprises cylindrical body having upper part connected with sub. Piston, having inner channel to be closed with free-fall ball is arranged inside the body. Junk retriever also has teeth and bush. The body is provided with two draining orifices. Lower end body part is milled and shaped as guiding shoe. Piston is arranged under the sub and is located immediately adjacent the sub. The piston is connected to the body through shear rods. The bush is split and consists of two parts made of sheet material. The bush is provided with bent areas located along edges to be connected. The piston has grooves extending along lower outer side surface thereof and adapted to receive bent bush areas after closing of bush edges. Petal-like teeth are formed in lower part of shear bush. Lower end body part made as guiding shoe has inclined surface arranged from inner side thereof extending at an angle equal to teeth joining angle and facet formed from outer surface side. The facet is provided with hard-alloy polyhedral members. Upper bush part is tightly fitted in space between the body and the piston and connected to the piston by bolts.

EFFECT: simplified structure and manufacturability.

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