Abstract: A hydraulic control system for a continuously variable transmission which has an input and an output variable-diameter pulley, a belt connecting the input and output pulleys, and a pair of cylinders for changing effective diameters of the pulleys. The control system includes a hydraulic source to supply a pressurized fluid for applying first and second line pressure to one and the other of the cylinders via a first and a second line, respectively.

Abstract: A reduction ratio controlling mechanism provided within the hydraulic control system of a continuously variable automatic transmission of a vehicle including a V-belt type continuously variable transmission which comprises an input pulley and an output pulley, the effective diameter of each of said pulleys being variable by means of a corresponding hydraulic servomechanism, and a V-belt extending between said input and said output pulleys, for changing the reduction ratio of said continuously variable transmission by supplying a hydraulic fluid to and by draining same from the hydraulic servomechanism of said input pulley.

Abstract: A control valve system for a continuously variable belt transmission for an internal combustion engine comprising a main control valve acted upon by a force related to the transmission ratio and the rotational speed of the primary shaft, a transmission ratio control valve acted upon by a force related to the desired calibrated rotational speed of the engine and of the primary shaft, and an auxiliary valve connected mechanically to the transmission ratio control valve, the auxiliary valve (15) being acted upon by means of an electromagnetic pressure regulator (21) as a function of a selected characteristic relationship of desired rotational speeds for different operating conditions in an electronic control unit.

Abstract: A control system for a continuously variable transmission has a line pressure control valve having ports and a spool for controlling the line pressure of oil supplied to a cylinder of a pulley device to change the transmission ratio. The line pressure control valve has chambers. When the transmission ratio reaches a maximum value after disengagement of a clutch, a line pressure reducing signal generates. The signal is applied to the line pressure control valve to shift the spool thereof, so that the line pressure is reduced to a minimum value. By controlling the pressure of oil supplied to the chambers in accordance with a desired line pressure, the spool is shifted, so that the line pressure is controlled.

Abstract: A hydraulic control apparatus for controlling a line pressure utilized in a continuously variable transmission. The apparatus controls the amount of line pressure supplied to be as small as possible without resulting in any slippage between a belt member which spans the pulleys. The apparatus monitors torque on the input shaft and output shaft to determine if any slippage is occurring.

Abstract: A belt type steplessly variable transmission includes a belt-pulley device of variable speed ratio and a fluid pressure operated actuator for changing the speed ratio of the belt-pulley device. A fluid control valve is provided for controlling a supply of fluid pressure to the actuator to thereby determine the speed ratio of the belt-pulley device. The fluid control valve is associated including with a manually operable member movable between a first position in which it does not affect operation of the fluid control valve and a second position in which the supply of fluid pressure is changed so that a change in the speed ratio does not take place until input speed to the belt-pulley device exceeds a predetermined value. A manually operable valve is provided for changing the supply of fluid pressure so that the speed ratio of the belt-pulley means is increased.

Abstract: A control system for a continuously variable transmission wherein when a difference between an actual value and a target value is greater than a predetermined value, a feed-forward control is used, whereas when the difference is smaller than the predetermined value, a feed-back control is used.

Abstract: Method and apparatus for controlling a continuously variable transmission operatively connecting an engine and drive wheels of a vehicle, wherein a speed ratio of the transmission is controlled such that an actual engine speed coincides with a target engine speed.

Abstract: Method and apparatus for controlling a continuously variable transmission operatively connecting an engine and drive wheels of a vehicle, wherein a speed ratio of the transmission is controlled such that an actual engine speed coincides with a target engine speed. The method and apparatus comprise steps or devices for: determining a normal target speed and a variation-restraint trigger speed based at least on a currently required output of the engine, the normal target speed being higher than the trigger speed and normally used as the target engine speed; restraining a rate of variation in the speed ratio while the actual engine speed is raised from the trigger speed to the normal target speed during acceleration of the vehicle; and selecting the trigger speed as a special target speed when the actual engine speed has been raised to the normal target speed. After the special target speed has been selected, the transmission is controlled such that the engine speed is lowered to the special target speed, i.e.

Abstract: A continuously variable transmission (CVT) is controlled such that an actual engine speed becomes equal to a desired engine speed. The desired engine speed is set to a value not less than a minimum engine speed for fuel cut so that fuel is to be cut when an intake throttle valve is at a position below a predetermined position during the deceleration of a vehicle. When the position of the throttle valve exceeds the predetermined one, the desired engine speed is set during a predetermined period to a value different from a usual value which is defined as a function of parameters of the vehicle.

Abstract: Method and apparatus for controlling a continuously variable transmission operatively connecting an engine and drive wheels of a vehicle, wherein a speed ratio of the transmission is controlled such that an actual engine speed coincides with a target engine speed determined based on a currently required engine output and according to a predetermined relation between the target engine speed and the required engine output. The method and apparatus comprise a step or device for restraining a rate of variation in the speed ratio during a time span between the moment when the actual engine speed or output has exceeded a variation-restraint trigger speed or output of the engine, and the moment when the actual engine speed or output has reached the target speed or output. The trigger engine speed or output is determined based on a predetermined transmission efficiency of the transmission, and on the target engine speed or output, and is lower or smaller than the target engine speed or output.

Abstract: Method and apparatus for controlling a continuously variable transmission operatively connecting an engine and drive wheels of a vehicle, wherein a speed ratio of the transmission is controlled such that an actual engine speed coincides with a target engine speed determined based on a currently required engine output and according to a predetermined relation between the target engine speed and the required engine output. The method and apparatus comprise a step or device for restraining a rate of variation in the speed ratio during a time span between the moment when the actual engine speed has exceeded a variation-restraint trigger speed of the engine, and the moment when the actual engine speed has reached the target speed. The trigger engine speed is lower than the target engine speed, and determined based on a transmission efficiency of the transmission. The transmission efficiency is determined based on a detected changing rate of variation in the speed ratio of the transmission.

Abstract: Method and apparatus for controlling a continuously variable transmission for a vehicle for transmitting an output of an engine of the vehicle to its drive wheels, comprising a step or device for detecting an engine speed, a step or device for detecting a vehicle running speed, a step or device for sensing a vacuum pressure in an intake manifold connected to the engine, a step or device for determining an actual engine output based on the detected engine speed and the sensed intake vacuum pressure, a step or device for determining a target engine speed based on the detected vehicle running speed and the determined actual engine output, and according to a predetermined relation among the target engine speed, the vehicle running speed and the actual engine output, said relation being predetermined to attain a required output of the engine with a minimum specific fuel consumption, and further comprising a step or device for controlling the speed ratio such that the detected engine speed coincides with the target

Abstract: Method and apparatus for controlling a continuously variable transmission for a vehicle for transmitting an output of an engine of the vehicle to its drive wheels, comprising a step or device for detecting a running speed of the vehicle, a step or device for sensing a flow of an intake gas through an intake manifold toward the engine, a step or device for determining a target engine speed based on the detected running speed and the sensed intake gas flow, and according to a predetermined relation among the target engine speed, the running speed and the intake gas flow, which relation is predetermined to attain a required output of the engine with a minimum specific fuel consumption, and further comprising a step or device for controlling the speed ratio such that a speed of the engine coincides with the determined target engine speed.

Abstract: A system for controlling the transmission ratio of an infinitely variable belt drive transmission having a primary pulley, a secondary pulley, a belt engaged with both pulleys, a pressure oil circuit having a pump for supplying pressure oil, and a transmission ratio control valve responsive engine speed for controlling the pressure oil and for changing the transmission ratio. The system has an electronic control circuit responsive to ignition pulses of the engine for producing output pulses dependent on the engine speed, and an electromagnetic valve responsive to the output pulses for controlling the amount of pressure oil applied to the transmission ratio control valve, thereby controlling the transmission ratio in dependency on the engine speed.

Abstract: A hydraulic control apparatus for controlling a line pressure utilized in a continuously variable transmission. The apparatus controls the amount of line pressure supplied to be as small as possible without resulting in any slippage between a belt member which spans the pulleys. The apparatus monitors torque on the input shaft and output shaft to determine if any slippage is occurring.

Abstract: A control system for an infinitely variable belt-drive transmission which has a drive pulley having a hydraulically shiftable disc and a servo chamber for shifting the disc, a driven pulley having a hydraulically shiftable disc and a servo chamber for shifting the disc, and a belt engaged with both the pulleys. A hydraulic control circuit is provided for supplying oil to the servo chambers and for draining the servo chambers. A lubricating oil circuit is provided in the hydraulic control circuit for supplying lubricating oil to the drive pulley, and a passage is provided for supplying a part of the lubricating oil to the servo chamber of the drive pulley, thereby filling the servo chamber with the oil before the starting of transmission operation.

Abstract: A hydraulic pressure control apparatus for a continuously variable transmission. A hydraulic pressure, which is supplied to a cylinder of an output disc, is controlled to be a minimum value while obtaining a necessary torque to transfer between a belt and discs.

Abstract: A system for an infinitely variable belt-drive transmission for an engine comprises a primary pulley having a hydraulically shiftable disc, a secondary pulley having a hydraulically shiftable disc, a belt engaged with both pulleys, and a hydraulic circuit having a pump for supplying oil. A transmission ratio control valve is responsive to engine speed for controlling the oil and for shifting the disc of the primary pulley to change the transmission ratio, and a pressure regulator valve is responsive to the transmission ratio for increasing line pressure in the hydraulic circuit with an increase of the transmission ratio. A sensor is engaged with the disc of the primary pulley to be moved together with the disc so as to move a spool of the pressure regulator valve to increase the line pressure with an increase of engine speed.

Abstract: The reduction ratio of a continuously variable transmission is controlled by a stepper motor. The stepper motor is controlled such that each of rotary positions thereof corresponds uniquely to a desired optimum reduction ratio indicative signal indicative of a desired optimum reduction ratio. The desired optimum reduction ratio indicative signal is generated for operating condition of an automotive vehicle.

Abstract: A method and an apparatus for controlling the reduction ratio of a continuously variable transmission are disclosed wherein normally the reduction ratio is controlled in response to a desired optimum reduction ratio indicative signal obtained by retrieving the data stored in a memory versus engine load and vehicle speed, but when more vehicle acceleration is needed, the reduction ratio is controlled by a corrected desired optimum reduction ratio indicative signal to increase the reduction ratio.

Abstract: A control system for a continuously variable V-belt transmission is disclosed wherein for the purpose of preventing an undesirable rapid drop in pressure in a cylinder chamber of a drive pulley a flow restrictor is provided to restrict the flow of oil discharged from the cylinder chamber upon rapid change in reduction ratio of the continuously variable V-belt transmission.

Abstract: A hydraulic apparatus for a continuously variable transmission, through which the RPM ratios of a driving pulley to a driven pulley is consecutively varied. Such RPM ratios are varied by electrically controlling the volume of hydraulic fluid supplied to or drained from a cylinder of a driving pulley.

Abstract: Revolution speed of a drive pulley and a parameter indicative of an output of the engine are detected. A desired value in the engine revolution speed is obtained using a predetermined function for any value in the parameter indicative of the engine output. The reduction ratio is controlled in such a manner as to maintain the revolution speed of the drive pulley in a predetermined relationship with the desired value in the engine revolution speed.

Abstract: The reduction ratio of a continuously variable transmission is controlled by a shift motor. The shift motor is controlled such that each of rotary positions thereof corresponds uniquely to a desired optimum reduction ratio. Upon detecting a state wherein a rapid shifting is needed, the shift motor is rotated at an increased revolution speed as compared to a normal revolution speed.

Abstract: An automatic transmission provided with a combination of a belt drive continuously-variable speed transmission mechanism and a hydraulic control circuit. The belt drive continuously-variable speed transmission mechanism has an input variable-pitch pulley assembly and an output variable-pitch pulley assembly. The hydraulic control circuit includes a regulator valve, a throttle pressure valve, a reduction ratio detecting valve, a reduction ratio control valve and a reduction ratio control mechanism. The reduction ratio control valve has an axially slidable spool and two pressure chambers formed in the valve body thereof at both axial ends of the spool respectively. The reduction ratio control mechanism includes conduits for conducting the working fluid of a throttle pressure to the pressure chambers of the reduction ratio control valve and two solenoid valves adapted to drain the corresponding pressure chambers, respectively, when actuated.

Abstract: A hydraulic control system comprises a line pressure regulator valve which uses a spring has non-uniform spring rate. A spring is compressed between a pressure regulating element and a member movable responsive to a reduction ratio between drive and driven pulleys. A length of the spring is varied by the member with variation in the reduction ratio. The line pressure regulator valve generates a line pressure having non-linear characteristic with respect to the variation in the reduction ratio.

Abstract: A continuously variable transmission includes a hydrodynamic device, such as a fluid coupling or a torque converter, having a lock-up clutch. The reduction ratio of the continuously variable transmission is controlled by a shift motor. The shift motor is controlled such that each of rotary positions thereof corresponds uniquely to a desired optimum reduction ratio. Upon detecting a state wherein a rapid down shift is needed, the lock-up clutch is temporarily disengaged to allow the hydrodynamic device to slip during the rapid down shift.

Abstract: The disclosed control system for a CVT controls the line pressure which is applied to the secondary pulley to maintain adequate belt tension, at a level significantly lower than previously was produced. An improved throttle valve is provided, and used in this throttle-sensitive regulation of line pressure. An improved ratio valve is provided, which combines spring and fluid forces in a manner to produce the ratio-indicating fluid signal, with negligible loading on the movable sheave where the ratio change is sensed. In the ratio-changing portion of the system, the combination of a timing valve and accumulator valve cooperate in demand type downshifts to provide adequate time for oil flow into the secondary pulley chamber as the primary pulley chamber is exhausted, to keep adequate belt tension during such a downshift.

Abstract: A hydraulic control system disclosed herein comprises a line pressure regulator valve which regulates the fluid supplied from a pump to provide a line pressure variable at least depending upon output torque of the engine. The line pressure is supplied to a shift control valve which regulates the fluid supply to and discharge from cylinder chambers of drive and driven pulleys.

Abstract: A method and a system for controlling a continuously variable transmission are disclosed wherein, upon varying fluid pressure within a cylinder chamber of a drive pulley, fluid pressure within a cylinder chamber of a driven pulley is kept constant, while, upon varying the fluid pressure within the cylinder chamber of the driven pulley, the fluid pressure within the drive pulley is kept constant.

Abstract: In a transmission mechanism having an actuator member which is movable to adjust the speed ratio of the transmission, the rate of movement of the actuator member is controlled to provide a desired overall response function. When the ratio error is less than a reference value, the actuator rate of movement is controlled as a function of speed ratio such that the overall rate of change of ratio produces stable response. When the ratio error is at or greater than the reference value, the actuator rate of movement is controlled as a function of ratio error such that the overall rate of change of ratio produces fast response consistant with driveability.

Abstract: A power transmission device for vehicles comprises: a housing rotatably supporting a crank shaft of an engine of the vehicle; a first shaft rotatably supported inside the housing to be coaxial with the crank shaft; a clutch unit having a drive member arranged inside the housing and coupled to the crank shaft, and a driven member fixed to the first shaft; a second shaft rotatably supported inside the housing to be parallel to the first shaft. The device has also infinite variable transmission including a drive pulley consisting of a fixed sheave and an axially movable sheave mounted on the first shaft, a driven pulley consisting of a fixed pulley and an axially movable sheave mounted on the second shaft, and a V belt which is placed the driving and driven pulleys through V grooves defined by the fixed and axially movable sheaves of the driving and driven pulleys.

Abstract: A continuously variable V-belt transmission comprises a V-belt running over drive and driven pulleys, each having an axially fixed conical disc, axially movable conical disc and a cylinder chamber for moving the axially movable conical disc. At least one of the pulleys has a compensation chamber which is separated from the cylinder chamber by a partition wall member. The compensation chamber is enclosed by the partition wall member, cylinder wall and trough including an annular disc like portion directed inwardly of the cylinder wall. The trough has a tubular portion directed axially from the disc like portion. A passage is formed and is so directed that flow of fluid from an outlet port of a torque converter is guided by the tubular portion toward the compensation chamber.

Abstract: Gear box, especially for motor vehicles, with a driving and a driven shaft, which carry pulleys, between which pulleys torque is transmitted by means of a V-belt or chain. The pulleys consist of discs movable towards and away from each other, to make variation possible of the speed ratio between the shafts. The movement of the discs and the clamping force against the V-belt is controlled with the aid of hydraulic cylinder devices. The hydraulic cylinder of the driving shaft is joined to a gear which is arranged concentrically with the cylinder and which engages a gear on the input shaft of the gear box.

Abstract: A reduction ratio detecting mechanism for V-belt type continuously variable transmission of this invention comprising a spool disposed with one end thereof projecting from a valve body containing said oil-hydraulic controller of said V-belt type continuously variable transmission and with the axis thereof in parallel with the axis of either one of said input and output pulleys and capable of providing a reduction ratio pressure corresponding to the amount of displacement of said spool, said reduction ratio pressure being applied to said oil-hydraulic controller, wherein the movable flange of said input pulley or said output pulley and said reduction ratio valve are connected by a connecting lever which is engaged, at one end thereof, with said movable flange so as to allow the turning of said movable flange and, at the other end thereof, with the projecting part of said spool, is capable of directly and accurately detecting the reduction ratio between the input and output shafts.

Abstract: In a hydraulic regulator in a V-belt type continuously variable transmission for vehicles, a regulator valve supplied with input hydraulic pressure controls the line pressure as output hydraulic pressure depending on to the throttle opening, the reduction ratio between the input and output shafts of the V-belt type continuously variable transmission and the shift position of a manual valve. As the line pressure is close to the minimum value needed, power loss in the oil pump as well as fuel consumption are reduced.

Abstract: A continuously variable transmission of the expansible frusto-conical pulley type having fluid expansion chambers controlling expansion and contraction of the V-groove includes a fluid control circuit having a ratio control pressure regulator valve, a ratio relief valve connected across the ratio control regulator valve, providing for rapid down shift of the pulley combination while maintaining non-slip engagement between pulley discs and a flexible transmission band of trapezoidal cross section.

Abstract: A control system for continuously variable transmission for vehicles is provided with an electric circuit receiving input signals of vehicle running conditions and a hydraulic control circuit. The hydraulic control circuit comprises a reduction ratio control device controlled by the electric control circuit and regulating the hydraulic pressure supplied to the hydraulic servo system of the input pulley and changing the reduction ratio between the input and output shafts of a V-belt type continuously variable transmission, and a shift control mechanism controlled by the electric control circuit and regulating the rise time of hydraulic pressure supplied to the hydraulic servo system of friction engaging elements connected to a planetary gear set changing forward and reverse drives.

Abstract: In a belt type stepless shifter, movable flanges of pulleys are driven by hydraulic cylinders, and each of the cylinders is provided with a plurality of pressure carrying surfaces disposed in the axial direction, thereby a great amount of torque can be transmitted at low hydraulic pressure or at a small outer diameter. The belt type stepless shifter is adapted for use in a transmission apparatus of vehicles.

Abstract: To control transmission ratio of a continuously variable transmission connected to a combustion engine (e.g., for optimal fuel efficiency of a powered vehicle), effective diameter of pulleys is controlled in response to an electrical signal. A control signal suitable for comparison with hydrostatic pressure values is produced by a computing device based on input signals representing load, speed, and other operating conditions and based further on stored data representing engine characteristics. A control signal is conveniently used to control hydrostatic pressure by means of electromagnetically operated valves. Especially when pulsed valves controlled by digital electric signals are used, a reservoir is used to establish a steady hydrostatic pressure. Such control device is readily adapted to different engines by replacement of stored characteristic data.

Abstract: In a V-belt type continuously variable transmission for vehicles, the line pressure is supplied to a hydraulic servo system of the output pulley, while the pressure to a hydraulic servo system of the input pulley is regulated by a torque ratio control device. The torque ratio control device of the invention comprises an electric control circuit receiving input signals of the vehicle running conditions such as the throttle opening, the vehicle speed or the input pulley revolution speed and generating output signals to control the effective diameter of the input pulley, two electromagnetic solenoid valves controlled by the output signals of the electric control circuit, and a torque ratio control valve controlled by the two solenoid valves and regulating the hydraulic pressure supplied to the hydraulic servo system of the input pulley. The output hydraulic pressure of the torque ratio control device is supplied to the hydraulic servo system of the input pulley thereby continuously variable shifting is effected.

Abstract: A continuously variable transmission (CVT) with adjustable width pulleys has its belt tension and ratio controlled by an electronic-hydraulic system. The CVT also has a fluid-cooled clutch on the output pulley shaft. The engine speed, transmission output speed, throttle position, and gearshift position are sensed, and signals representing this information are passed to a computer. The computer provides set point signals denoting desired engine speed, line pressure, and clutch cooling condition to a control system. An electromechanical valve assembly regulates fluid flow to the CVT primary sheave, to control CVT ratio as a function of the computer provided set engine speed signal. A second electromechanical valve assembly controls the line pressure in the hydraulic system, which is applied to the secondary pulley to maintain belt tension, as a function of the set pressure signal provided by the computer.

Abstract: An infinitely variable cone pulley transmission has a first and a second pulley mounted on driving and driven shafts and connected by an endless belt. Each pulley is formed of first and second pulley discs. A hydraulic device sets and maintains each first pulley by hydraulic pressure in an axial position corresponding to a desired transmission ratio between the driving and the driven shafts. A torque sensor is mounted adjacent a second pulley disc for receiving a torque. The torque sensor has a pressing device mounted for axial displacement as a function of the torque and a valve arranged for displacement by the pressing device for varying the hydraulic pressure on the first pulley discs. The pressing device has a first ring torque-transmittingly and axially immovably mounted in the vicinity of the second pulley disc, a second ring relatively rotatably and axially slidably mounted between the second pulley disc and the first ring and forming a movable part of the valve.

Abstract: In an infinitely variable cone pulley transmission having a driving shaft connected to a source of driving power, a driven shaft, a pair of conical discs nonrotatably mounted on each shaft with at least one disc of each pair being axially displaceable on its associated shaft, an endless transmission element adapted to run between the two pairs of discs for transmitting power between the shafts, a cylinder-piston unit associated with one axially displaceable disc on each pair for urging that disc toward the other disc of the same pair with a force proportional to the pressure of fluid in the unit, a distributing valve arranged to be arbitrarily adjusted to vary the speed ratio of the transmission, and connected to a pressure fluid source and to each unit for supplying pressure fluid thereto, and a normally-closed control valve connected in fluid flow communication with the distributing valve for controlling the fluid pressure in the unit associated with the driven shaft, the closing force presented by the cont

Abstract: A variable drive ratio pulley system has longitudinally adjustable pulley halves operated by fluid pressure which acts on piston and cylinder structures operatively connected with the adjustable pulley halves. The fluid pressure in one of the piston and cylinder structures is controlled by a valve spool responsive to an actuator on which a lever member is pivotally disposed and maintained in abutment with the drive surface on the adjustable pulley half. The lever member also abuts a control rod which is linearly movable in response to command signals. Linear movement of the control rod initiates pivoting of the lever member and enforces or permits resultant linear movement of the actuator so that the spool valve is operated to change the pressure level operating on the piston thereby permitting movement of the pulley half resulting in a change of the drive ratio.

Abstract: A method and apparatus for controlling the transmission ratio of a two-pulley type of infinitely variable V-belt transmission wherein the diameter of the driving pulley is adjusted in partial response to the fluid pressure in a hydraulic cylinder which controls the diameter of the driven pulley.

Abstract: To control transmission ratio of a continuously variable transmission connected to a combustion engine (e.g., for optimal fuel efficiency of a powered vehicle), effective diameter of pulleys is controlled in response to an electrical signal. A control signal suitable for comparison with hydrodynamic pressure values is produced by a computing device based on input signals representing load, speed, and other operating conditions and based further on stored data representing engine characteristics. A control signal is conveniently used to control hydrodynamic pressure by means of electromagnetically operated valves. Such control device is readily adapted to different engines by replacement of stored characteristic data.

Abstract: A variable speed belt drive in which the axially moveable sheave flange is connected to the drive shaft by a flexible element which performs the function of transmitting the torque from the shaft to the axially moveable flange, and which defines a fluid pressure chamber for applying a variable pressure to the moveable flange for moving the flange axially on the shaft as the pressure in the chamber is varied by the operation of a control device. The flexible element may be an annular member having a generally U-shaped configuration with inwardly extending side walls, one of the side walls being connected to the flange and the other side wall being connected to a flange-like member rigidly mounted on the shaft. Passages are provided through the shaft to connect the chamber with a source of controlled pressure.

Abstract: In apparatus for controlling the transmission ratio of an infinitely variable V-belt transmission having variable pitch input and output pulleys operable by hydraulic cylinders, each pulley being formed of a pair of conical discs, at least one of which is axially movable relative to the other disc of that pair and the input pulley being driven by a power source: a hydraulic control valve for operating the cylinders, the valve having an internal axially movable spool; a device responsive to the speed of the input pulley for urging the spool in one direction; a compression spring urging the spool in an opposite direction, the spring being loaded through an intermediate connecting assembly by an external loading device; and a regulating device connected to the intermediate connecting assembly, the regulating device being responsive to an operating variable of the transmission.