FIELD: hydraulic tools for tightening threaded joints. SUBSTANCE: device includes unit forming main and additional chambers where piston and hollow piston move. Piston is provided with connector for connection with end part of bolt which is located inside hollow piston. Hollow piston partially extends to main chamber. Connected with additional chamber is device for feeding liquid for forcing liquid out of main chamber by hollow piston under action of pressure of liquid contained in additional chamber. EFFECT: extended operational capabilities due to reduced height. 6 cl, 1 dwg
