Abstract: An infinitely variable compound transmission has a tripartite hydrodynamic torque converter having a pump, a turbine member and a guide member relatively rotatable about a common axis. An input pump shaft normally driven by an engine is connected to the pump, a guide shaft is connected to the guide member and coaxial with the pump shaft, and a turbine shaft coaxial with the guide and pump shafts is connected to the turbine member. A brake connected to the turbine shaft is energizable for immobilizing the turbine shaft against rotation. A coupling clutch connected between the turbine shaft and the guide shaft is actuatable for joint rotation of same about the axis. A bypass clutch is actuatable for connecting the pump shaft to one of the members. An infinitely variable belt transmission operatively connected to the guide shaft has an output shaft connectable to a load.

Abstract: A hydraulic control system of the type disclosed in U.S. Pat. No. 3,938,410 is improved by providing a 2-3 shift valve which connects a direct passage and a throttle-containing passage to the control valve for the second clutch or brake (second-friction device) while the pressure in the first clutch or brake (first friction device) is applied to one side of the second control valve, a restoring spring acting upon the opposite side of this second control valve. This valve establishes a threshold for the pressure in the first friction device such that the direct passage is connected to the second friction device below the threshold while the throttle-containing passage is connected to the second friction device at or above this threshold.

Abstract: To control the changeover between different speed ratios in an automotive transmission, with the aid of hydraulically actuatable clutches and brakes, a 1-2 shift valve (70) and a 2-3 shift valve (90) responsive to a speed-dependent fluid pressure are subjected to a countervailing load-dependent fluid pressure generated by a throttle valve (40), under the control of the vehicular accelerator, above a predetermined intermediate point of the load range. Fluid for the actuation of the clutches and brakes, under a pressure rising in the lower part of the load range and remaining constant in its upper part, is delivered by a modulating valve (340) in cascade with the throttle valve, provided with a limitedly displaceable slider, or by cascaded modulating and limiting valves (350, 357).

Abstract: A hydraulic speed-changing system for an automotive transmission includes a clutch K2 actuatable by a control valve with associated damper which delays full operation of the clutch to smooth the cut-in. The same clutch is used in third gear and in reverse, its actuation being accompanied in the latter instance by that of a brake B2. Fluid pressure used to control the operation of this brake is also utilized to exert upon the control valve of clutch K2 a supplemental force reducing the delay period of the damper.

Abstract: Two concurrently operated hydraulic brakes of an automotive transmission, actuated in an intermediate-speed ("second gear") position, are filled under the control of a slide valve whose slider in a normal position admits fluid at high rate to both brakes and thereafter assumes an unstable throttling position in which the fluid pressure gradually builds up in them to a value causing an associated plunger to return the slider to normal. One of the brakes, which is only unidirectionally effective, remains actuated also upon an upshift into a high-speed position ("third gear") whereas the other, bidirectionally effective brake is released upon such upshift under the control of a shift valve which cuts off the fluid flow to the latter brake and establishes a drainage path therefor by passing the slide valve.