Bed frame comprising at least: - a lower structure comprising two parallel bars (1, 2) connected by a crossbar, and the two connected parallel bars (1, 2) as well as the crossbar are disposed on the floor, - an upper structure comprising two bars (4, 5) parallel to the bars (1, 2) of the lower structure, - four arms (6, 7, 8 and 9), two left lateral arms (6, 7) and two right lateral arms (8, 9), mounted so as to be pivotable about the lower structure allowing the upper structure to be rendered translationally movable in planes parallel to the floor relative to the lower structure, between a plane situated at a minimum height relative to the floor, defining a bottom position, and a plane situated at a maximum height relative to the floor, defining a top position, - a brake cylinder fixed between the crossbar of the lower structure and a crossbar connecting the right lateral arms (8, 9) in order to draw the movements of the two deformable parallelograms upwards, allowing the upper structure to be raised when the cylinder is extended, characterised in that it comprises: - an actuating means connected to said cylinder making it possible to act mechanically on the opening of a valve of said cylinder connecting the two chambers of the piston when the user presses on the actuating means, which controls passage of the working fluid from one chamber to the other of said piston upon upward actuation of the frame, cessation of pressing on the actuating means stops the movement of said piston of the cylinder and locks said frame in a position determined by the user between the bottom position and the top position. - a lower structure comprising two parallel bars (1, 2) connected by a crossbar, and the two connected parallel bars (1, 2) as well as the crossbar are disposed on the floor, - an upper structure comprising two bars (4, 5) parallel to the bars (1, 2) of the lower structure, - four arms (6, 7, 8 and 9), two left lateral arms (6, 7) and two right lateral arms (8, 9), mounted so as to be pivotable about the lower structure allowing the upper structure to be rendered translationally movable in planes parallel to the floor relative to the lower structure, between a plane situated at a minimum height relative to the floor, defining a bottom position, and a plane situated at a maximum height relative to the floor, defining a top position, - a brake cylinder fixed between the crossbar of the lower structure and a crossbar connecting the right lateral arms (8, 9) in order to draw the movements of the two deformable parallelograms upwards, allowing the upper structure to be raised when the cylinder is extended, characterised in that it comprises: - an actuating means connected to said cylinder making it possible to act mechanically on the opening of a valve of said cylinder connecting the two chambers of the piston when the user presses on the actuating means, which controls passage of the working fluid from one chamber to the other of said piston upon upward actuation of the frame, cessation of pressing on the actuating means stops the movement of said piston of the cylinder and locks said frame in a position determined by the user between the bottom position and the top position. - an actuating means connected to said cylinder making it possible to act mechanically on the opening of a valve of said cylinder connecting the two chambers of the piston when the user presses on the actuating means, which controls passage of the working fluid from one chamber to the other of said piston upon upward actuation of the frame, cessation of pressing on the actuating means stops the movement of said piston of the cylinder and locks said frame in a position determined by the user between the bottom position and the top position.