Abstract: This hydrodynamic torque converter for the automatic transmission of motor vehicles which provide several gear ratios comprises means for bridging the input and output shafts of the converter. The hydraulic fluid supplied through the hollow transmission shaft penetrates into the converter inner space via a gaged orifice; the outlet of the control chamber of the converter is closed by a solenoid valve in one position thereof; the pressure in the converter inner space is the same as in the control chamber, and spring means are provided for urging the control piston to its release position when the assembly operates as a torque converter. In the other valve position the pressure prevailing in the converter inner space having its outlet closed is applied to the control piston against the force of the spring means. The pressure in the control chamber is low and thus the friction lining carried by the control piston produces the desired bridging action.

Abstract: The device consists of a comparison unit 35 comparing the respective speeds 31a and 32a of the input shaft 2 and the output shaft 7 of the converter with a pre-set value so as to supply a "bridging" control command to an electrohydraulic transducer 14; and a timing unit 34 eliminating the "bridging" by signal 34a during the changeover from one transmission ratio to another in accordance with the data supplied by the unit 20 and transmitting with a delay the changeover control command to the transmission control elements 13a and 13b.It is thus possible to "bridge" or lock out the converter for all the transmission ratios while eliminating the "bridging" when each ratio change is made.

Abstract: An electromagnetic coil 29 exerts an attractive force on a movable plate 30 of magnetic material, within which is mounted a ball 32 of non-magnetic material blocking the end of a passage 33 for the hydraulic fluid. The apparatus also comprises electronic means for supplying the coil 29 by means of a pulsed unidirectional current, the mark/space ratio and mean value of which are subject to control by an operating magnitude represented by an electric control signal. The apparatus can be utilized as a hydraulic potentiometer for the determination of a control pressure proportional to an electric control signal in a hydraulic control circuit of an automatic transmission of industrial vehicles.

Abstract: A first member of a magnetic housing has a core with a central passage and contains an electrical coil, and a second member of the housing has a ball cavity which receives and guides a magnetic ball. A central conduit and peripheral conduits enter the cavity of the second member. When the coil is activated, the magnetic field created thereby moves the ball into contact with the core to close the central passage in the first member, leaving the central and peripheral conduits in communication with each other. When the coil is deactivated, fluid pressure moves the ball to a position where it closes the central conduit so the central passage and the peripheral conduits will be in communication.

Abstract: An electromagnetically controlled hydraulic servo-control valve includes a hydraulic slide activated by an electromagnet with a plunger. The distributed pressure hydraulically pushes the slide and the plunger toward each other. Constrictions in the hydraulic conduits attenuate oscillations. The plunger and the slide have slightly different cross-sections to provide a control loop for the distributed pressure, affecting the position of the side. Use of a polarized electromagnetic supplied by a current that ranges from a negative value to a positive value doubles the regulating capacity. To prevent hysteresis of the pressure curves, as a function of the current, the electro-magnet can be supplied by a pulsed current or an alternating current with a continuous component. The servo-control valve might be used in connection with an automatic gear box control.