DEVICE FOR REDUCING THE IDLING LOSSES IN HYDRODYNAMIC BRAKES

PCT No. PCT/EP90/01486 Sec. 371 Date Feb. 14, 1992 Sec. 102(e) Date Feb. 14, 1992 PCT Filed Sep. 5, 1990 PCT Pub. No. WO91/03661 PCT Pub. Date Mar. 21, 1991.In a hydrodynamic brake (1), in order to reduce the ventilation losses, adjustable baffles (2, 20) are situated between a rotor (3) and a stator (4). During idling, when oil has been evacuated from the brake (1), one or more baffles (2, 20) of angular cross section in the outer area of the toroidal chambers (31, 41) separate the chambers via a radially inward projecting annular leg (21), a leg cylindrically situated in an axial direction abutting against the inner wall (52) of a chamber (5). During operation of the brake, that is, when the hydrodynamic brake (1) is filled with oil, the radially inward projecting leg (21) is located with its front edge (29) behind the toroidal chambers (31, 41). When only one baffle (20) covering the entire periphery of the outer area of the toroidal chambers (31, 41) is installed, slits (23, 28) are disposed in the radially inward projecting annular leg (21) to obtain the adequate elasticity. The actuation in the radially outward and inward end positions is obtained via an actuation device (6, 60), a specially advantageous design being a piston-cylinder unit (60) having two pistons (61) and a driver device on the pistons and drivers on the baffle (20), the inner position being obtained via springs (62) and the outer position via the pressure of a pressurized fluid in a pressure chamber (63) located between both pistons (61).