FIELD: mining.;SUBSTANCE: present invention pertains to drilling techniques and can be used in drilling oil and gas wells using downhole drilling motors. The device has a hallow case with side openings, a bushing fitted inside the case, with a seat, radial overflow valves, a centre channel, facing a slide valve, spring loaded against the stop, fitted with provision for axial displacement and with a cowling, packing rings for covering the centre channel and a nut, limiting movement of the slide valve, and a bushing. The device has an upper adapter and a rubber seal, on whose outer surface there is a groove in which a baffle plate is fit. At one end of the seal, there is conical ring-shaped ledge, which, together with the baffle plate, is pressed to the slide valve and the hollow housing by an adjustment ring and a bearing disc, with the help of the threaded joint of the upper adapter with the hollow case. The other end of the seal freely lies inside the bushing with an annular gap in the zone of radial overflow channels and the seat of the bushing. The slide valve is fitted inside the bushing, in the bottom part, which is lower than the step made on its outer surface. There are overflow channels coming out to the annular gap, formed by the bushing, fitted on the outer step of the bush sleeve, and the bottom part of the bush sleeve.;EFFECT: reduced hydraulic resistance to the flow of drilling fluid, elimination of intense abrasion and fast wearing of components, increased air-tightness of the valve device, provision for long storage periods in working condition and increased reliability, durability and cost effectiveness of the device.;4 cl, 2 dwg
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