FIELD: mining industry, particular, devices for raising pressure of drilling mud in well drilling. SUBSTANCE: drilling mud pressure transformer has body whose cavity is formed by cylindrical surfaces of different diameters, piston unit made in form of piston located in a part of body hollow and installed for reciprocation, with compression and back strokes, and with formation under the piston of rod chamber, and channel of high pressure. To raise the drilling mud pressure, piston unit in the pressure transformer is installed in the body with formation by the body lower wall and free end of rod of plunger chamber communicated by means of channel having check valve, with high-pressure channel and hollow of drill pipe. Rod chamber is communicated by means of channels with casing string-borehole annulus. Pressure transformer has control valve for control of stroke of piston unit. Control valve is installed at the inlet of hollow of piston chamber from the hollow of drill pipe. Pressure transformer also has drive for changing over of the control valve by the energy of flow of drilling mud. EFFECT: higher efficiency. 17 cl, 8 dwg
