only one u201c tip u201d point of the hypocycloid however because the forces acting on the power trowel are then no longer symmetrical due to the different frictional conditions the danger would arise that the power trowel would drift laterally which would be undesirable therefore it is advantageous if the movement of a blade on the opposite side relative to the drive shaft is counteracted by a counter movement of another blade in fig7 such a movement picture is shown the inner curve describes a possible connecting link curve that the outer contour effects if the blades are displaced purely radially during their rotational movement the outer contour in turn corresponds to the surface that is to be swept over by the blade in fig7 as well dotted lines indicate different blade positions this third specific embodiment of the present invention has the advantage that almost arbitrary corner angles can be realized an angle less than 90 u00b0 can be advantageous for the operator because with such an angle the operator can move even into very narrow comers in addition in this specific embodiment there is the possibility of compensating forces through different e g asymmetrical connecting link shapes in riding power trowels having two rotors fig1 it is easily possible to obtain the counterforce required for the radial deflection of a blade from the inclination of the counter axis in a fourth.