Abstract: A hydraulic control device for controlling a belt-and-pulley type continuously variable transmission for an automotive vehicle which includes an input and an output shaft, a pair of variable-diameter pulleys provided on the input and output shafts, respectively, a transmission belt connecting the pair of pulleys, and a pair of hydraulic actuators for changing effective diameters of the variable-diameter pulleys. The hydraulic control device further includes a shift control valve device for controlling pressures applied to the hydraulic actuators, to change the speed ratio of the continuously variable transmission over a mechanically defined range, and a controller for applying a drive signal to the shift control valve device. The controller includes a device for limiting a value of the drive signal, so as to prevent the actual speed ratio of the transmission from reaching upper and lower limits of the mechanically defined range.

Abstract: A hydraulic control system for a continuously variable transmission for an automotive vehicle, the transmission having a first and a second variable-diameter pulley provided on respective first and second shafts, a belt connecting the first and second pulleys, and a first and a second hydraulic cylinder for changing effective diameters of the first and second pulleys.

Abstract: Infinitely variable transmission comprising a primary pulley fitted on a drive-shaft and a secondary pulley fitted on a driven shaft, both pulleys consisting of two conical opposed discs of which one is movable along the shaft on which it is fitted, a V-belt being looped over both pulleys, wherein the center lines of the pulleys are offset when the transmission is in its medium position and are in line when the transmission is the lower ratio range.

Abstract: A control device of non-stage transmission for vehicles comprising a V-belt and pulleys, and which serves as an electronic control unit by receiving engine control information and drive control information to generate a duty control signal according to a referece pressure of hydraulic control of the non-stage transmission, and electrically controlling transmission gear ratio in a form of electronic control device, whereby accuracy and life of the control device as well as fuel consumption and driving performance of vehicle is improved.

Abstract: A control for a continuously variable transmission provides an improved transient performance by restraining proportional and integral terms when an error exceeds a predetermined value range. This is effective in suppressing an overshoot in driver pulley revolution speed in approaching to its target speed. This control is provided with a safeguard against break down of a vehicle speed sensor such that the above mentioned restrain is removed when the vehicle speed indicative signal should drop to zero during running of the vehicle.

Abstract: A motor vehicle transmission has a pulley system comprising a variable diameter drive pulley and a variable diameter driven pulley, with an endless belt extending around the pulleys to impart the rotation of a drive shaft to a driven shaft at a speed ratio determined by the relative effective diameters of the two pulleys. A substantially tubular shell has an enlarged end secured to the movable cone of the driven pulley and a constricted end loosely fitted over the driven shaft. Rigidly mounted on the driven shaft, a partition divides the interior of the shell into an actuating fluid chamber, to be supplied with pressurized fluid for controllably moving the movable cone towards and away from the fixed cone, and a counterbalance chamber.

Abstract: A continuously variable transmission has a drive pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, a driven pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, and a belt engaged with both pulleys. The system has a hydraulic circuit having a pump for supplying oil to both the hydraulic cylinders and a drain passage for draining oil in the hydraulic cylinder of the drive pulley, and a transmission ratio control valve having a spool for controlling the oil supplied to the cylinder of the drive pulley and the oil drained from the cylinder to change the transmission ratio. A cam is provided for shifting the spool of the transmission ratio control valve in accordance with depression of an accelerator pedal of a vehicle, and a variable orifice is provided in the drain passage for controlling flow rate of drain oil from the cylinder of the drive pulley.

Abstract: A continuously variable transmission has a selector device having a planetary gear device for selecting forward and reverse drives. The planetary gear device has a forward hydraulic chamber and a reverse hydraulic chamber for selectively providing a forward gear train and a reverse gear train. A high pressure oil pump is provided for supplying a transmission actuating oil having a high line pressure, and a low pressure oil pump is provided for supplying an actuating oil having a low actuating pressure. A selector valve is provided for selectively applying the low actuating pressure to the forward or reverse hydraulic chambers. A pressure increasing valve is provided for applying a higher actuating pressure to the reverse hydraulic chamber than the forward hydraulic chamber.

Abstract: A continuously variable transmission has a torque converter with a lockup clutch. A high pressure oil pump is provided adjacent the transmission and a low pressure oil pump is provided adjacent the torque converter. A line pressure control valve is provided for controlling the pressure of oil supplied from the high pressure oil pump to produce a line pressure for operating the transmission. A lockup control valve operated by low pressure oil supplied from the low pressure oil pump is provided for controlling the lockup clutch, and a solenoid operated valve is provided to generate a converter condition pressure for operating the lockup control valve, for operating the lockup clutch. The converter condition pressure is applied to the line pressure control valve so as to increase the line pressure.

Abstract: A pulley type speed-shifting device is provided with a driving pulley and driven pulley mounted on each transmission shaft which are parallel, and a belt member is trained between both pulleys. A moving member is connected for movement in the axial direction with one sideplate of the driving pulley and is axially moved on the movable sideplate through screw motion caused by relative rotation around the transmission shaft. A speed-shifting pulley mechanism is provided for rotating the moving member relatively around the transmission shaft to change the transmission ratio between the transmission shafts in accordance with a required mode change.

Abstract: A control valve has ports and a spool which has lands and an annular groove between the lands. The land has a plurality of hollow portions at a circumferential edge portion adjacent the annular groove so as to gradually increase the opening area of one of the ports.

Abstract: A hydraulic control apparatus is employed in a stepless transmission in which an endless belt is stretched between and wrapped around a pair of pulleys and the velocity ratio between input and output shafts is changed by varying the width of a groove defined in each of the pulleys. Hydraulic pressure supplied from a hydraulic pressure supply source is reduced to necessary levels by first and second adjusting apparatus, respectively, and then sent ot respective cylinder chambers of the pulleys. A controller controls the hydraulic pressure supply source on the basis of either one of the hydraulic pressures respectively reduced by the first and second adjusting apparatus which is higher than the other so that the supply source generates a hydraulic pressure which is sufficiently high to supply the higher hydraulic pressure, thus reducing loss of power in the hydraulic pressure supply source.

Abstract: A hydraulic control system for a stepless belt and pulley transmission in which the sides of the pulleys are movable by hydraulic pressure to vary the position of the belt and thereby the transmission ratio and belt tension. The control system comprises control valves including servo mechanisms for controlling the supply of operating fluid to the pulleys during various phases of system operation.

Abstract: A continuously variable transmission has a drive pulley, an annular groove formed on a side of the drive pulley, and a pitot tube provided in the annular groove. The pitot tube has an elliptic section, and the major axis of the ellipse is arranged in a tangential direction of an annular flow of oil in the groove. An open end of the pitot tube faces to said flow of oil.

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 driven pulley. The pressure of the oil supplied to control the spool is controlled by an on-off control valve in accordance with engine operating conditions to control the line pressure. The duty ratio of pulses for operating the on-off control valve is obtained by positioning a desired line pressure between the lowest line pressure and the highest line pressure corresponding to duty ratios of 100% and 0%, respectively.

Abstract: A hydraulic control system for a continuously variable transmission for an automotive vehicle, the transmission having a first and a second variable-diameter pulley provided on respective first and second shafts, a belt connecting the first and second pulleys, and a first and a second hydraulic cylinder for changing effective diameters of the first and second pulleys.

Abstract: A belt driven automatic transmission for producing a continuous range of drive ratios includes an input pully rotatably mounted on the axis of an engine crankshaft and an output pulley rotatably supported on the axis of the transmission output shaft. The pulleys are driveably connected by an endless drive belt, whose radial position on the pulleys varies in accordance with the position of axially displaceable sheaves that move in accordance with the magnitudes of pressure in actuating cylinders. The pulley system is driveably connected to the impeller of a hydrokinetic torque converter whose turbine is driven from the impeller. The turbine is continously connected to the output shaft. A forward and reverse planetary gearset is driven from the transmission selectively in accordance with the position of synchronizer sleeve.

Abstract: A hydraulic control system for a continuously variable transmission for an automotive vehicle, the transmission having a first and a second variable-diameter pulley provided on respective first and second shafts, a belt connecting the first and second pulleys, and a first and a second hydraulic cylinder for changing effective diameters of the first and second pulleys. The control system includes a shift-control valve receiving a first line pressure from said pressure source to one of the cylinders, while simultaneously permitting a flow of the fluid from the other cylinder. A second pressure line is connected to the shift-control valve to receive therefrom a pressure of the fluid flowing from above-indicated other cylinder. A pressure regulating valve regulates the pressure in the second pressure line, as a second line pressure lower than said first line pressure.

Abstract: An infinitely variable belt drive having a pair of belt clamping servos and a ratio control servo, a high pressure source connected to a common high pressure feed circuit for the clamping servos, a ratio control servo, a low pressure source that is independent of the high pressure source, and a high pressure accumulator and pressure amplifier system that is adapted to supply the clamping servos with a high pressure with minimal high pressure fluid flow.

Abstract: A control system for a continuously variable transmission has a transmission ratio control valve having a spool for controlling oil supplied to a cylinder of a drive pulley to change the transmission ratio. The control system operates to control the transmission ratio in accordance with a desired ratio including a desired overdrive ratio for providing an overdrive transmission ratio. In a low vehicle speed range, the overdrive transmission ratio is controlled to a value slightly larger than the overdrive transmission ratio.

Abstract: A control system for a motor vehicle provided with a continuously variable transmission. The transmission has a drive pulley, a driven pulley, a transmission ratio control valve having ports and a spool, and a hydraulic circuit for supplying oil to the transmission ratio control valve so as to control the transmission ratio. When a speed sensor of one of the pulleys fails to properly sense the speed of the pulley, the transmission ratio control valve is operated by fail-safe operation so as to maintain the ratio transmission to a proper value.

Abstract: A control system has a transmission ratio control valve having a spool for controlling oil supplied to a cylinder of a drive pulley to change the transmission ratio. The transmission ratio control valve has chambers at both ends of the spool. By controlling the amount of oil supplied to the chambers in accordance with the difference between desired transmission ratio and actual transmission ratio, the spool is shifted, so that the transmission ratio changing speed is controlled. The desired transmission ratio is determined by a desired speed of input of the transmission.

Abstract: A hydraulic control system for a belt drive continuously-variable speed transmission comprising a continuously-variable speed transmission means including a primary variable-pitch pulley having a fixed pulley flange fixed to an input shaft and a movable pulley flange adapted to be axially slidable on said input shaft, a secondary variable-pitch pulley having a fixed pulley flange fixed to an output shaft and a movable pulley flange adapted to be axially slidable on said output shaft, and an endless belt interconnecting said primary and said secondary variable-pitch pulleys; and a hydraulic control circuit including hydraulic servomechanisms hydraulically interconnected with the respective movable pulley flanges of said primary and said secondary variable-pitch pulleys for pressing the corresponding movable pulley flanges toward the corresponding fixed pulley flanges, a regulator valve for supplying the pressurized working fluid of a controlled pressure to said hydraulic servomechanisms, and a control valve ca

Abstract: A control system for an infinitely variable transmission has a transmission ratio control valve having a spool for controlling oil supplied to a cylinder of a drive pulley to change the transmission ratio. The transmission ratio control valve has chambers at both ends of the spool. By controlling the pressure of oil supplied to the chambers in accordance with engine operating conditions, the spool is shifted, so that the speed of changing the transmission ratio is controlled.

Abstract: The device enables the control of a gearbox comprising a continuous variator with two hydraulically-controlled pulleys, primary and secondary, of expanding type. The device comprises a hydraulic control unit with a supply inlet for connection to a source of hydraulic fluid, and first and second control outlets for connection to the primary and secondary pulleys of the variator. The hydraulic unit includes a manually-operated control member. In dependence on the position of the control member, the hydraulic unit supplies varying amounts of pressurized hydraulic fluid to the primary and secondary pulleys of the variator, producing a different transmission ratio.

Abstract: A torque sensitive squeeze control for a variable ratio pulley drive system has a fluid translating unit, such as a pump, disposed in the input torque path. One member of the fluid translating unit is rotated by the input drive shaft while another member is fixed for rotation with an input pulley shaft. If a rotational difference between the input drive shaft and the pulley shaft is present, the fluid translating unit is effective to increase the pressure in the squeeze control piston of the input pulley thereby increasing the torque capacity of the pulley. A speed differential will occur when a torque difference between the two shafts if present. The hydraulic control for the output pulley is via a controlled servo valve mechanism which permits operator control of the drive ratio between the pulleys independently of the squeeze force on the input pulley.

Abstract: In a belt driven continually variable transmission, the drive ratio is changed by varying the radial position of the drive belt by moving displaceable sheaves of a pulley assembly. A system for actuating the displaceable sheaves includes a ratio control valve supplied with pressurized fluid and connected to a source of ratio control pressure produced by a solenoid actuated valve. An orifice located between the ratio control valve and the hydraulic cylinder in which the displaceable sheave is located has feedback lines located on opposite sides of the orifice. Pressure in the feedback lines produces a differential force on the ratio control valve tending to increase the flow rate to the cylinder when the pressure drop across the orifice decreases.

Abstract: A control system for an infinitely variable transmission has a transmission ratio control valve having a spool for controlling oil supplied to a cylinder of a drive pulley to change the transmission ratio. Acceleration of depression of an accelerator pedal is detected to produce an acceleration signal. By controlling the pressure of oil supplied to the transmission ratio control valve in accordance with engine operating conditions and the acceleration signal, the spool is shifted, so that the speed of changing the transmission ratio is controlled.

Abstract: A speed ratio control system for a continuously variable transmission is provided, wherein an oil flowrate to a hydraulic servo of an input or an output V-shaped pulley device is varied by a flow control valve, so that a speed ratio between the input and the output sides can be continuously changed. The system determines a deviation between a target value and a measured value and corrects the measured value in accordance with at least the characteristics of the flow control valve, so that the deviation and a rate of change per unit time of the speed ratio, or the deviation and a rate of change per unit time of a rotational speed of the input or output pulleys, will have a linear relationship over the entire area of control. This system avoids poor feedback gain because of the non-linearity of the characteristics of the flow control valve. Thus, the feedback gain is acceptable over the entire area of control of the continuously variable transmission.

Abstract: Infinitely variable transmission for a device with an internal combustion engine (67) is provided with an endless transmission member (14) which has been looped over two pulleys, each having a running groove situated between conical pulley halves (2,3 and 8,9 resp.), at least one conical half of each pulley being axially movable through an associated hydraulic cylinder (4,12), also provided with a first control valve (40) for regulation of the fluid pressure in the cylinder (12) of the driven pulley and in the supply line to a second control valve (20), which second valve is intended for the adjustment of the transmission ratio by regulation of the amount of fluid supplied to and discharged from the cylinder (4) of the driving pulley. Devices have been provided for the operation of the first control valve (40) which bring about an increase or a decrease of the fluid pressure in the cylinder (12) of the driven pulley, depending on the movements of the engine block.

Abstract: A control valve system for controlling the operation of a continuously variable belt-driven motor vehicle transmission includes a first hydraulic pump that supplies fluid to the displacement cylinders of the transmission through a main pressure regulating valve and a transmission ratio control valve as a function of the setting of the manual selector valve and as a function of the torque requirement and speed of the vehicle. The torque converter is supplied with hydraulic fluid by way of a relief valve which comes into operating in the event of failure of an electronic control unit and a decrease in the vehicle speed. A first emergency operation on/off valve transmits torque at converter discharge pressure, by way of a second emergency on/off valve, as emergency operation control pressure to a transmission ratio control valve.

Abstract: A control system for a motor vehicle provided with a continuously variable transmission. The 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. When torque of an engine is rapidly increased, the line pressure is increased so as to prevent a belt of the pulley device from slipping.

Abstract: A compact and rugged belt drive mechanism includes a hydraulically controlled actuator located generally between first and second variable pulley assemblies individually having a movable pulley disc and a fixed pulley disc in order to controllably position the movable pulley discs. A drive belt is entrained between the pulley assemblies, and a force-multiplying apparatus including a competitively profiled cam with oppositely inclined ramps and a plurality of roller members engaging the cam serves to automatically adjust tension on the drive belt. The force-multiplying apparatus and an associated plurality of compression springs for applying a preload against the drive belt are operatively associated with only one of the movable pulley discs for simplicity.

Abstract: A continuously variable belt drive comprising adjustable primary and secondary sheaves, a primary shaft connected drivably to an axially fixed cone sheave part and to a companion axially displaceable cone pulley part, an axially displaceable actuating servo cylinder connected to said axially displaceable cone pulley part, an actuating servo piston connected to said primary shaft including cam follower members connected respectively to said primary shaft and to a torque input clutch, one follower member defining in part a pressure regulating valve element that regulates the magnitude of the pressure in the actuating servo.

Abstract: A control arrangement for a continuously variable transmission includes an electronic control system and a hydraulic control system. In the hydraulic control system three separate electromechanical control assemblies are used to regulate the pressure in the secondary sheave chamber (to hold the belt tension), the fluid flow to and from the primary sheave chamber (to regulate the CVT ratio), and to control the pressure in the apply line for the clutch chamber. The pump assembly of the hydraulic control system has a first output connection for providing fluid at line (high) pressure in the main line, and a second, low pressure output connection for providing fluid at a low pressure to satisfy the clutch cooling requirements. The high pressure and low pressure systems are essentially independent of each other.

Abstract: An infinitely variable transmission in which the pitches of a driving pulley and a driven pulley are variable by means of hydraulic fluid pressure to vary the velocity ratio between the two pulleys. A lower pressure fluid and a higher pressure fluid are created from a hydraulic fluid from a hydraulic fluid supply source, with a constant pressure difference therebetween. The lower pressure fluid has its pressure value varied in response to the velocity ratio. The lower pressure fluid and the higher pressure fluid are selectively supplied to the movable pulley elements of the driving pulley and driven pulley. A hydraulic clutch and a pressure regulating valve are connected together by a hydraulic fluid supply passageway which is selectively closed and opened by a supply control valve. A drain passage is connected to the hydraulic fluid supply passageway to allow hydraulic fluid to escape from the hydraulic clutch when the passageway is closed by the supply control valve.

Abstract: A stepless belt transmission includes a working fluid control unit having a supply port for supplying working fluid to a hydraulic actuator, a discharge port for discharging the working fluid from the hydraulic actuator, a lead mechanism for changing the working fluid pressure internally of the hydraulic actuator by varying the opening degree of the supply port or discharge port in dependence upon vehicle running conditions, and a follow-up mechanism operatively associated with a movable flange displaced by the changed working fluid pressure to restore the port opening degree varied by the lead mechanism. It is possible to achieve highly sophisticated control of transmission ratio in dependence upon vehicle running conditions through a comparatively simple construction and on the basis of a simple control method in which the stroke of the lead mechanism is suitably regulated.

Abstract: A V belt stepless variable transmission provided with a driving pulley comprising a stationary conical disc fixed to a drive shaft and a movable conical disc axially movable with respect to the drive shaft, a driven pulley comprising a stationary conical disc fixed to a driven shaft and a movable conical disc axially movable with repsect to the driven shaft, and an endless V belt running across both the pulleys, so that an interval between each stationary conical disc and each movable conical disc is changed to thereby carry out stepless variable transmission, the driving pulley being provided with a tension adjusting means for mechanically giving to the movable conical disc thrust to meet input torque to thereby adjust tension on the V belt, and the driven pulley being provided with an hydraulic actuating cylinder for hydraulically driving the movable conical disc at the driven pulley, so that a fluid is supplied or discharged to or from the hydraulic actuating cylinder so as to actuate the movable conical d

Abstract: A belt driven automatic transmission for producing a continuous range of drive ratios includes an input pulley rotatably mounted on the axis of an engine crankshaft and an output pulley rotatably supported on the axis of the transmission output shaft. The pulleys are driveably connected by an endless drive belt, whose radial position on the pulleys varies in accordance with the position of axially displaceable sheaves that move in accordance with the magnitudes of pressure in actuating cylinders. The pulley system is driveably connected to the impeller of a hydrokinetic torque converter whose turbine is driven from the impeller. The turbine is continuously connected to the output shaft. A forward and reverse planetary gearset is driven from the transmission selectively in accordance with the position of synchronizer sleeve.

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 drive pulley. A hydraulic circuit is provided for supplying oil to a port of the line pressure control valve so as to shift the spool. A pressure reducing valve is provided in the hydraulic circuit for keeping the pressure in the circuit constant and a control valve is provided in the hydraulic circuit so as to control the quantity of the constant pressure oil supplied to the end of the spool.

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 driven pulley to change the line pressure. The line pressure control valve has chambers at opposite sides of the spool. A spring is provided between one end of the spool and a spring retainer. By draining the oil supplied to the end of the spool in accordance with engine operating conditions, the line pressure is controlled. The line pressure is at a maximum value, when the quantity of the draining oil is at a minimum value.

Abstract: A control system for a continuously 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 supplementary oil circuit is provided in the hydraulic control circuit for supplying supplementary oil to the servo chamber of the drive pulley, thereby filling the servo chamber with the oil before the starting of transmission operation.

Abstract: In a device for performing the control during acceleration in a continuously variable transmission system for a vehicle, wherein a speed ratio e of the continuously variable transmission system is controlled such that an actual engine rotational speed Ne can be a target engine rotational speed Ne', a predetermined value Nb lower than Ne' and a predetermined vale N.times.3 slightly higher than Nb are set, the shift in the continuously variable transmission system is interrupted until Ne is increased to a predetermined value higher than Ne' when Ne enters a state of Nb<Ne.ltoreq.N.times.3, and the speed ratio e of the continuously variable transmission system is continuously raised until Ne is decreased to a state of Ne.ltoreq.N.times.3 when Ne is changed from a state of Ne>Ne' to a state of Ne<Ne', so that the device can maintain a satisfactory acceleration, suppress the decline of a transmission efficiency and reduce the noise level during acceleration.

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 ratio control system for a continuously variable transmission performs a feedback control wherein an integral control gain and a proportional control gain are varied depending upon the level of a line pressure that is used to actuate a pulley unit during shifting operation.

Abstract: In a control device in a continuously variable transmission system for a vehicle, wherein the continuously variable transmission system is provided on a power transmission route of an engine and a speed ratio thereof is controlled such that an engine rotational speed can be a target engine rotational speed, when a detected acceleration during acceleration is smaller in value than the reference acceleration or a detected deceleration during deceleration is smaller in value than the reference deceleration, the transient time target engine rotational speed is selected instead of the steady time target engine rotational speed, whereby a speed ratio of the continuously variable transmission system is made to be a small value during acceleration and deceleration.

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 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. A transmission ratio control valve having a spool is provided to be responsive to engine speed for controlling the oil and for shifting the disc of the primary pulley to change the transmission ratio. Pitot pressure dependent on the engine speed is applied to the spool to shift it against a spring, the force of which is determined by the depression of an accelerator pedal. An actuator is proviced to increase the load on the spring to downshift the transmission. A manual select device is provided to opeate the actuator for downshifting.

Abstract: A vehicular speed change gear wherein a stepless V-belt transmission and a stepped gear transmission are disposed in series in a power transmission system connecting an engine crankshaft and a driving wheel together. An automatic speed change actuator, which automatically actuates the speed change operation of the stepless transmission in association with an engine throttle valve opening and a vehicle speed is connected to the stepless transmission, and a manual speed change actuator is connected to the stepped transmission for manually actuating the speed change operation of the latter.

Abstract: A variable speed power transmission belt drive apparatus wherein a pair of asymmetric cross section drive belts are utilized in conjunction with complementary sheaves, including a pair of axially adjustably spaced outer sheaves and an intermediate sheave. The outwardly facing side faces of the intermediate sheave are substantially planar and substantially perpendicular to the axis of the shaft on which the pulley is mounted. The inwardly facing surfaces of the outer sheaves are conical and the side surfaces of the belts are complementary to the confronting faces of the sheaves. Fluid pressure structure is provided for applying substantially equal forces to the speed-adjusting sheaves in effecting the speed-adjusting operation. In the illustrated embodiment, the angled surfaces of the belts and outer sheaves extend at an angle in the range of approximately 5.degree. to 30.degree.