A rotational speed control device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor may be movable axially on the shaft depending on the rotating speed of the shaft. The rotor is biased in a low torque direction. A braking torque between the rotor and the housing and/or between the rotor and a drive control ring is varied according to an axial position of the rotor on the shaft. The device may incorporate bypass channels to control a circulating pressure of the viscous fluid.

A braking arrangement for drive heads or pump heads, to be preferably used in a progressing cavity pump (PCP) system in oilfields, consisting of at least one disk moving inside a viscous fluid and facing a static disk, in which mechanical energy is transformed into heat. The viscous brake is a device acting as a function of the rotation speed, in which a higher speed generates a higher braking power caused by the increase of friction among the disks and the fluid. The arrangement may comprise more than one mobile and static disk assemblies, as well as a hollow axis instead of a solid one, to allow housing the pumping rod inside the axis, and may also comprise an anti-reverse bearing.

A braking arrangement for drive heads or pump heads, to be preferably used in a progressing cavity pump (PCP) system in oilfields, consisting of at least one disk moving inside a viscous fluid and facing a static disk, in which mechanical energy is transformed into heat. The viscous brake is a device acting as a function of the rotation speed, in which a higher speed generates a higher braking power caused by the increase of friction among the disks and the fluid. The arrangement may comprise more than one mobile and static disk assemblies, as well as a hollow axis instead of a solid one, to allow housing the pumping rod inside the axis, and may also comprise an anti-reverse bearing.

A hydrodynamic machine for producing a braking torque, the hydrodynamic machine comprising: a toroidal working chamber including a first bladed wheel and a second bladed wheel arranged concentrically with the first bladed wheel; and a hydraulic system including an open loop and closed loop control unit, a working medium accumulator, a line system, a pump operable to produce a volume flow circulation of a working medium through the line system and the toroidal working chamber, a heat exchanger, and a pressure control valve operable to control or adjust the baking performance or the braking torque.

A hydrodynamic machine for producing a braking torque, the hydrodynamic machine comprising: a toroidal working chamber including a first bladed wheel and a second bladed wheel arranged concentrically with the first bladed wheel; and a hydraulic system including an open loop and closed loop control unit, a working medium accumulator, a line system, a pump operable to produce a volume flow circulation of a working medium through the line system and the toroidal working chamber, a heat exchanger, and a pressure control valve operable to control or adjust the baking performance or the braking torque.

A rotational speed control device maintains a shaft rotation speed. The device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor is coupled with the shaft for rotation in the viscous fluid. The rotor is axially displaceable along the shaft between a low-shear position and a high-shear position. A spring mechanism is disposed in the housing and biases the rotor toward the low-shear position. The rotor may be designed to cooperate with the housing or other nonrotating features within the housing to vary a shear gap according to the axial position of the rotor. The rotor, housing and spring mechanism can be designed to cooperate to create large changes in braking torque in response to small changes in shaft rotational speed. This allows the rotation speed to be controlled within a relatively narrow range.

A rotational speed control device maintains a shaft rotation speed. The device includes a housing containing a viscous fluid and a shaft disposed in the housing and rotatable relative to the housing. A rotor is coupled with the shaft for rotation in the viscous fluid. The rotor is axially displaceable along the shaft between a low-shear position and a high-shear position. A spring mechanism is disposed in the housing and biases the rotor toward the low-shear position. The rotor may be designed to cooperate with the housing or other nonrotating features within the housing to vary a shear gap according to the axial position of the rotor. The rotor, housing and spring mechanism can be designed to cooperate to create large changes in braking torque in response to small changes in shaft rotational speed. This allows the rotation speed to be controlled within a relatively narrow range.

A method for controlling a hydrodynamic retarder in a motor vehicle that can be mechanically disengaged via a disconnect clutch, comprising a drive motor whose power output is controlled via an actuator such as a foot pedal or a lever; whereby in an overrun operation the acceleration of the motor vehicle is collected or detected and compared with a pre-specified acceleration value; and whereby in the non-braking mode the disconnect clutch is engaged, regardless of an initiation of a braking mode by an operator of the motor vehicle or a driver assist system and the working chamber is maintained drained when the acceleration exceeds an acceleration limit.

A method for controlling a hydrodynamic retarder in a motor vehicle that can be mechanically disengaged via a disconnect clutch, comprising a drive motor whose power output is controlled via an actuator such as a foot pedal or a lever; whereby in an overrun operation the acceleration of the motor vehicle is collected or detected and compared with a pre-specified acceleration value; and whereby in the non-braking mode the disconnect clutch is engaged, regardless of an initiation of a braking mode by an operator of the motor vehicle or a driver assist system and the working chamber is maintained drained when the acceleration exceeds an acceleration limit.

A device having a magnetorheological brake device and a method for braking relative movements with at least two brake components. A receiving space with a brake gap is formed between the brake components and contains a magnetorheological medium which can be influenced by a magnetic field and which includes magnetically polarizable particles. The device has at least one electrical coil unit to generate a controllable magnetic field in the brake gap. At least some of the magnetically polarizable particles are designed to form an engagement structure under the influence of the magnetic field and to group together in a controlled manner due to the magnetic field.