A hydraulic torque converter comprises vaned members, viz. an impeller, a turbine, and a stator designed to take up reactive torque. Each vaned member consists of a casing and an inner ring to which are fixed vanes which form a closed fluid circuit enclosed on the outside by the vaned-member casings which jointly form an outer toroidal surface, the inside enclosure being made up of the inner rings which jointly form an inner toroidal surface. The vanes of at least one of the vaned members are secured to the casing and inner ring by means of tongues fitted into slots provided in said casing and inner ring. Said vanes have a hydrodynamic profile of varying thickness and the body of each vane contains a plate whose projecting elements form said tongues. The torque converter constituting the present invention, when used in a passenger car, increases the efficiency of the transmission by 1-3 percent.

A coreless torque converter includes a pump impeller provided with coreless blades each having a first leading edge directed forward; a turbine runner provided with coreless blades each having a second leading edge directed rearward; and a stator provided with coreless blades each having front and rear edges which face the second and first leading edges respectively. Each of the first and second leading edges extends generally straight connecting radially outward and inward terminal ends thereof.

A hydrodynamic torque converter for relatively large power outputs which includes a centrifugally transversed pump wheel and a centripetally traversed turbine wheel, both equipped with blades having a single curvature and flat and/or conical wheel side walls, a turbine wheel outlet diameter approximately equal to the inlet diameter of the pump wheel and a guide wheel arranged directly upstream of the pump wheel and a further guide wheel arranged directly downstream of the turbine wheel; the radial length of the turbine blading is larger than 15 percent of the middle diameter of the turbine blading while the blade spacing of the turbine wheel at the middle diameter of the turbine blading amounts to about 30 to 50 percent of the radial length of the turbine blades and the interior width of each blade flow channel at the outlet of the turbine wheel is smaller than 35 percent of the blade spacing.

A flat-type torque converter wherein a toroid is formed of a turbine having a plate-worked turbine blade, a pump having a plate-worked pump blade and a stotor having a cast-iron stator blade, and a ratio L.sub.1 /(r.sub.2 --r.sub.1) of a toroid axial dimension L.sub.1 to its radial dimension (r.sub.2 --r.sub.1) lines between 0.67 and 0.87, a ratio r.sub.1 /r.sub.2 of a toroid internal radius r.sub.1 to its external radius r.sub.2 lies between 0.39 and 0.46, and the converter has a small axial thickness; characterized by that a wall thickness of the stator blade is made small so that an effective passage cross section inside the stator blade can be secured, a flow-in side tip edge of the stator blade is formed into a flat-shape, a core-side and a shell-side of the stator blade are formed by being twisted, and a core-side length of the stator blade is fabricated as long as possible.

A blade of an impeller for a hydrodynamic torque converter wherein the central flow thread at the point of the leading edge is displaced with respect to a central flow thread at a point of the trailing edge along a smaller wheel diameter as well as by an angle of rotation leading in a direction of rotation of the impeller. The trailing edge is disposed in a radial plane at least approximately perpendicular to an axis of rotation of the impeller. The leading edge of the point of the central flow thread has a leading angle of about 30.degree. to 40.degree. and the trailing edge is inclined in such a way that its corner point at an inner torus, delimiting an inner side of the impeller, is displaced by an angle of rotation in the direction of rotation toward the front with respect to its corner point at the outer torus which delimits the outer portion of the impeller.