Abstract: An active torque management clutch system that includes an ATM clutch, a clutch actuator, and a controller is provided. The ATM clutch is positioned between a driven sheave of a CVT and an axle. The clutch actuator is used to control the ATM clutch. The controller is in communication with at least one vehicle sensor and the clutch actuator. The controller is configured to open the ATM clutch when sensor information indicates a shift is about to occur and close the ATM clutch when the sensor information indicates engine torque is required in a driveline.

Abstract: A vehicular drive unit for a battery electric vehicle (BEV) includes an electric motor, for propelling the BEV, having an output shaft; a planetary gearbox, having an input and an output; a sprocket coupled to an output of the electric motor or an input of the planetary gearbox; and an endless loop rotatably coupled with the sprocket and the input of the planetary gearbox thereby configured to transmit rotational movement of the output shaft of the electric motor to a drive shaft of the BEV, wherein an axis of rotation of the drive shaft of the BEV is offset from an axis of rotation of the output shaft of the electric motor.

Abstract: A drive system includes an electric machine that generates a torque. An output shaft rotates bi-directionally and receives the torque. A coupling is disposed between the electric machine and the output shaft. The coupling includes a torque converter that multiplies the torque. One clutch transfers the torque from the electric machine to the torque converter, when the electric machine operates in a first rotational direction. Another clutch transfers the torque from the electric machine to the torque converter, when the electric machine operates in a second rotational direction that is opposite to the first rotational direction. A gearset includes a number of meshing gears and is disposed between the electric machine and the output shaft to transfer the torque to the output shaft.

Abstract: A hydrostatic assembly includes a pressure medium with a variable viscosity and a control device through which at least one process variable or state variable of the hydrostatic assembly is open-loop or closed-loop controlled as a function of the viscosity. The hydrostatic assembly further includes a temperature sensing device configured to sense a temperature of the pressure medium.

Abstract: A recreational vehicle is provided including a power source, such as an engine or an electric motor, and a transmission having a variable gear ratio. A sub-transmission coupled to an output of the transmission includes a plurality of selectable gear configurations including park gear and at least one of a forward gear, a neutral gear and a reverse gear. An electronic controller is operative to electronically control the gear configuration of the sub-transmission in response to a set of conditions.

Abstract: A recreational vehicle is provided including a power source, such as an engine or an electric motor, and a transmission having a variable gear ratio. A sub-transmission coupled to an output of the transmission includes a plurality of selectable gear configurations including park gear and at least one of a forward gear, a neutral gear and a reverse gear. An electronic controller is operative to electronically control the gear configuration of the sub-transmission in response to a set of conditions.

Abstract: A method of decoupling output torque from input torque during engine speed control of a hybrid powertrain for a vehicle comprises determining, via a controller, a virtual output torque required on an output member of a multi-mode transmission given a virtual input torque commanded on an input member of the multi-mode transmission for engine speed control in a selected mode of the multi-mode transmission such that rotational speed of the output member is unchanged to prevent undesired torque variation at the output member. The controller determines the virtual output torque via a first stored transfer function relating virtual output torque to virtual input torque based on modeled physical dynamics of the vehicle driveline for the selected mode of the multi-mode transmission. A hybrid powertrain includes an engine and a hybrid transmission, and a controller that controls the hybrid transmission according to the method.

Abstract: An upshift target turbine rotational speed and a target primary rotational speed are calculated based on a target input shaft rotational speed restricted in a range of an upper limit guard value to a lower limit guard value. Thus, the difference between the upshift target turbine rotational speed and the target primary rotational speed is suitably decreased. When a torque transmission path is switched from a second transmission path to a first transmission path, the difference between an actual turbine rotational speed at a switching start time point and the actual turbine rotational speed at a switching completion time point is reduced.

Abstract: In a controller for an automatic transmission, when a jump gear shift via a plurality of intermediate shift stages is executed, a first and a second target intermediate shift stages are extracted, and a target input shaft rotation speed change rate is calculated from a difference in synchronous rotation speed between a shift stage before a current gear shift and the second target intermediate shift stage as a target shift stage of a gear shift which is executed after the current gear shift. Accordingly, it is possible to avoid a situation in which a shifting time in the gear shift control of the step before the second target intermediate shift stage becomes very short and thus packing of a clutch pack is not executed in a timely manner.

Abstract: A power split transmission which has a first part (2) and a second part (22). The first part (2) includes a variator (10), a summing gearset (6) and a shiftable transmission gear assembly (18). A standard transmission can be used as the multispeed transmission (23).

Abstract: An infinitely-variable transmission system is disclosed. The system comprises an input shaft (10) and an output shaft (14). The transmission is operative to transmit rotational drive between the input shaft (10) and the output shaft (14). The transmission includes a variator (20) that can transmit drive at a continuously variable ratio between a minimum variator ratio and a maximum variator ratio. The transmission can operate a low-speed regime and in a high-speed regime.

Abstract: A value correlated with a basic required driving force to be required at re-acceleration is estimated from the deceleration of a decelerating vehicle. A target gear ratio of a CVT is determined from a value obtained by correcting the value correlated with the basic required driving force based on a maximum amount of vehicle speed change at the current time point and an amount of vehicle speed change from the start of a gear ratio control up to the current time point.

Abstract: A two mode continuously variable transmission (CVT) for a motor vehicle includes an optional speed change device connected to a pulley and a belt assembly or other continuously variable unit. The pulley and belt assembly is also connected to a gear box having a planetary gear assembly. The gear box has two brakes and a clutch. The gear set arrangement is connected to a final drive unit. Selective engagement of the clutch and brakes provides two modes of operation to the CVT.

Abstract: A speed ratio control device for an automatic transmission of a vehicle calculate a minimum engine rotation speed based on a travel load, and sets a target speed ratio such that the engine rotation speed does not fall below the minimum engine rotation speed. If the travel load of the vehicle is equal to or greater than a predetermined value, a higher value is used for the minimum engine rotation speed compared to a case when the travel load of the vehicle is smaller than the predetermined value. Re-acceleration performance of the vehicle under a high travel load as in a case when the vehicle travels uphill while towing another vehicle is thereby improved.

Abstract: The present invention provides an information management system suitable for a construction machine, which drives a solenoid valve separately from normal control to thereby make it possible to perform failure diagnosis for the solenoid valve and each sensor easily and with satisfactory accuracy. A controller has a failure diagnosis mode selected by a control panel of a display device. When the failure diagnosis mode is selected by the control panel and instructions for failure diagnosis related to a specific solenoid valve of a plurality of solenoid valves are given, the controller outputs a failure diagnosis drive signal to the specific solenoid valve, inputs an output value from a sensor related to the specific solenoid valve among a plurality of sensors, and displays, based on the output value from the specific sensor, information as to whether the specific solenoid valve and the specific sensor are normal on a display device.

Abstract: An exemplary infinitely variable transmission includes a planetary gear set situated in a drive train of an automotive vehicle and interfaced with a worm gear driven by an electrical motor continuously controlled by an electronic control unit in response to a torque demand. Another aspect may be selection of the worm gear helix angle to effect a balance between worm gear teeth friction and load placed on the worm gear by the planetary gear set, such that power required to drive the worm gear is minimized for all input load conditions.

Abstract: A control device continuously variable transmission for vehicle according to the present invention includes a continuously variable transmission mechanism capable of continuously changing a speed ratio, a sub-transmission mechanism provided in series with the continuously variable transmission mechanism, including a first gear position and a second gear position having a smaller speed ratio than the first gear position as forward gear positions and adapted to switch between the first gear position and the second gear position by selectively engaging or releasing a plurality of frictional engagement elements, and a transmission control unit wherein a vehicle is stopped with the gear position of the sub-transmission mechanism kept in the second gear position when being stopped in a state where the gear position of the sub-transmission mechanism is in the second gear position.

Abstract: A method of operating a vehicle drive-train during a starting process. The drive-train has a drive mechanism which can couple a continuously-variable power-branched transmission in which a plurality of transmission ratios can be engaged. The transmission ratios can be varied continuously by adjusting a variator, the transmission driving a drive output. A force flow between the drive mechanism and the drive output can be produced by a frictional shifting element by appropriately adjusting the transmission capacity of the shifting element. When a start command is issued, a starting transmission ratio is engaged in the area of the transmission device. During the engagement of the starting transmission ratio the transmission capacity of the frictional shifting element is adjusted to values greater than zero.

Abstract: A transmission arrangement for transmitting power from a power source to an electrical generator. The transmission arrangement comprises a continuously variable transmission (CVT) and an alternative transmission that is more efficient at transmitting power than the CVT. The transmission arrangement further comprises a power mixing mechanism for combining power from the CVT and the alternative transmission into a combined power output to be provided to the electrical generator. The percentage of CVT power within the combined power output decreases as the power supplied by the power source increases.

Abstract: When a through speed ratio, which is an overall speed ratio of a variator and a subtransmission mechanism, varies from a larger speed ratio than a mode switch speed ratio to a smaller speed ratio than the mode switch speed ratio, a gear position of the subtransmission mechanism is changed from a first gear position to a second gear position. The mode switch speed ratio is set at a through speed ratio obtained when the speed ratio of the variator is a Highest speed ratio and the gear position of the subtransmission mechanism is the first gear position.

Abstract: A system and method for shifting a hybrid vehicle is provided which utilizes one or more controllers to release one or more clutches and brakes when a transmission is shifted into neutral or park and then prevents a rotational element from being rotated by controlling an engine and a motor/generator when the transmission is in neutral or park. Accordingly, shift shock or slip is minimized when a transmission is shifted from a park or a neutral to a drive or a reverse, thus improving a shifting feeling and safety of the vehicle.

Abstract: In a multiple mode continuously variable transmission having a variator, a planetary gear assembly, a low mode brake that grounds a first component of the planetary gear assembly to provide lower operating speeds and a high mode brake that grounds a second component of the planetary gear assembly to provide higher operating speeds, the method of providing a mode upshift comprising the steps of adjusting the ratio of the variator from a low ratio to a high ratio, releasing the low mode brake while simultaneously engaging the high mode brake during a torque phase of the shift and reducing the variator ratio from a high ratio to a low ratio during the inertia phase of the shift, thereby eliminating torque interruption and providing a constant torque output.

Abstract: A control device for a vehicle continuously variable transmission comprises a shift control means for controlling either of or both the speed ratio at the continuously variable transmission mechanism and the gear position at the subtransmission mechanism so as to adjust an overall speed ratio to a final speed ratio and a torque capacity control means for controlling the torque capacity at a disengagement-side frictional engagement element in the subtransmission mechanism so as to sustain a torque capacity value substantially equal to zero in an inertia phase occurring during a process of adjusting the gear position at the subtransmission mechanism from the first gear position to the second gear position when a negative torque is input to the vehicle continuously variable transmission.

Abstract: In an automatic transmission with a speed changer having a plurality of engagement elements and configured to shift the speed changer into a selected one of a plurality of shift stages by switching engaged and disengaged states of the engagement elements, a first rotation sensor is provided for detecting input rotation of the speed changer and a second rotation sensor for detecting output rotation of the speed changer. Also provided is a transmission controller configured to determine whether a change in input torque inputted into the speed changer occurs. The transmission controller is further configured to determine that interlock has occurred in the speed changer, when there is no pulse signal output from the second rotation sensor though, during a vehicle stopped state, the input-torque change has occurred and the pulse signal from the first rotation sensor has been outputted.

Abstract: A control apparatus for an automatic transmission includes a stepwise variable transmission mechanism; a power ON/OFF state judging section; and a shift control section configured to control the stepwise variable transmission mechanism to a target rotational speed by disengaging the first engagement portion and engaging the second engagement portion in accordance with a torque inputted to the stepwise variable transmission mechanism, the shift control section being configured to engage one of the first engagement portion and the second engagement portion which has a function to suppress a variation of an input rotational speed of the stepwise variable transmission mechanism which is generated by a switching of the power ON/OFF state when the power ON/OFF state is switched at the shift control of the stepwise variable transmission mechanism, and to disengage the other of the first engagement portion and the second engagement portion.

Abstract: Systems and methods for operating a driveline system are disclosed and include a step-variable transmission. A continuously variable transmission (CVT) is coupled between an input source and the step-variable transmission. The CVT receives a first torque from the input source and outputs a second torque. The CVT has a plurality of planetary members in rolling contact with an inner race and an outer race. A radial distance between the planetary members and a drive-transmitting member corresponds to a transmission ratio of the CVT.

Abstract: The transmission controller changes the gear position of the subtransmission mechanism and varies the speed ratio of the variator in an opposite direction to a speed ratio variation direction of the subtransmission mechanism when the actual through speed ratio passes a predetermined mode switch line. When the improvement in the shift response of the continuously variable transmission is determined to be required and the actual through speed ratio passes the mode switch line from a Low side to the High side, the transmission controller increases a shift speed of the subtransmission mechanism compared with a normal coordinated shift.

Abstract: A continuously variable transmission 4 for a vehicle includes a variator 20 that modifies a speed ratio continuously and a subtransmission mechanism 30 that is connected in series to the variator 20 and applies a first speed and a second speed, which is higher than the first speed, selectively. When the vehicle is running under a low load/high speed upshift condition having a lower load or a higher speed than a normal upshift condition, the subtransmission mechanism 30 is upshifted from the first speed to the second speed at a lower vehicle speed than under the normal upshift condition, and as a result, both rotation variation in an internal combustion engine 1 accompanying upshifting of the subtransmission mechanism 30 and an increase in a fuel consumption amount of the internal combustion engine 1 due to the shift operation in the continuously variable transmission 4 are suppressed.

Abstract: A motor-generator system for a vehicle, in which power transmission between a crankshaft of an engine and a motor-generator is performed by a V-belt wound around pulleys thereof, includes a speed controller controlling the rotational speed of the V-belt within a predetermined range and provided on a crankshaft pulley mounted on the crankshaft. The motor-generator system, among others, can maintain the power transmission force of the V-belt at a high level.

Abstract: A control device continuously variable transmission for vehicle according to the present invention includes a continuously variable transmission mechanism capable of continuously changing a speed ratio, a sub-transmission mechanism provided in series with the continuously variable transmission mechanism, including a first gear position and a second gear position having a smaller speed ratio than the first gear position as forward gear positions and adapted to switch between the first gear position and the second gear position by selectively engaging or releasing a plurality of frictional engagement elements, and a transmission control unit wherein a vehicle is stopped with the gear position of the sub-transmission mechanism kept in the second gear position when being stopped in a state where the gear position of the sub-transmission mechanism is in the second gear position.

Abstract: A continuously variable transmission includes a variator capable of varying a speed ratio continuously, and a subtransmission mechanism provided in series with the variator. On the basis of an operating condition of a vehicle, a transmission controller sets a destination through speed ratio, which is an overall speed ratio of the variator and the subtransmission mechanism to be realized in accordance with the operating condition, and controls the variator and the subtransmission mechanism on the basis thereof. When shifts are prohibited in the subtransmission mechanism, the destination through speed ratio is limited to a speed ratio range that can be realized only by a shift in the variator.

Abstract: The transmission controller changes the gear position of the subtransmission mechanism and varies the speed ratio of the variator in an opposite direction to a speed ratio variation direction of the subtransmission mechanism when the actual through speed ratio passes a predetermined mode switch line. When the improvement in the shift response of the continuously variable transmission is determined to be required and the actual through speed ratio passes the mode switch line from a Low side to the High side, the transmission controller increases a shift speed of the subtransmission mechanism compared with a normal coordinated shift.

Abstract: The described system and method allow a controller to calibrate a transmission variator of a continuously variable transmission for torque control by obtaining static and dynamic qualities and parameters of the variator through an automated calibration procedure. The system and method employ a pair of transmission mode configurations and operational configurations in combination to obtain system-specific information. In this way, the system is able to calibrate out the system variations to provide effective feed forward torque control of the continuously variable transmission. In an embodiment, a first calibration operation is performed while the transmission is neutralized and a second calibration operation is performed while the transmission is engaged in a mode providing a fixed variator output speed.

Abstract: The transmission controller performs a non-coordinated shift, in which the gear position of the subtransmission mechanism is modified from the second gear position to the first gear position at a higher speed than when the gear position of the subtransmission mechanism is modified by a coordinated shift while permitting a deviation between the through speed ratio and the target through speed ratio, instead of the coordinated shift when it is determined that the second speed kick down shift is to be performed.

Abstract: Vehicular drive system which is small-sized and/or improved in its fuel economy. A power distributing mechanism 16, which is provided with a differential-state switching device in the form of a switching clutch C0 and a switching brake B0, is switchable by the switching device between a differential state (continuously-variable shifting state) in which the mechanism is operable as an electrically controlled continuously variable transmission, and a fixed-speed-ratio shifting state in which the mechanism is operable as a transmission having a fixed speed ratio or ratios. The power distributing mechanism 16 is placed in the fixed-speed-ratio shifting state during a high-speed running of the vehicle or a high-speed operation of engine 8, so that the output of the engine 8 is transmitted to drive wheels 38 primarily through a mechanical power transmitting path, whereby fuel economy of the vehicle is improved owing to reduction of a loss of conversion of a mechanical energy into an electric energy.

Abstract: With a two-shaft engine, the accessory drive gearbox (5) for the operation of a generator and other auxiliaries (6) is connected to the high-pressure shaft (1) via a high-pressure shaft gearbox (3), which is coupled to a low-pressure shaft gearbox (8) connecting to the low-pressure shaft (7), via an overrunning clutch (11), a conical-pulley variable transmission (10) settable on the basis of the shaft speed on both sides, and a first switchable clutch (9). Under certain operating conditions with low speed of the high-pressure shaft or in case of engine failure, the power of the low-pressure shaft, with the clutch (9) engaged, is transferred to the high-pressure shaft gearbox and hence to the accessory drive gearbox via the conical-pulley variable transmission, which compensates for shaft speed difference, and the overrunning clutch, in order to reliably further operate the generator and other accessories with low fuel consumption or by windmilling only.

Abstract: A continuously variable transmission mechanically coupled with an automated mechanical transmission is adjusted during a shifting process. At the completion of the shifting process, an engine mechanically coupled with the automated mechanical transmission is provided a fueling pulse. Additionally, the speed of an output shaft of the automated mechanical transmission is filtered by a second order variable time constant low pass filter.

Abstract: A method is disclosed for controlling overall transmission ratios in a vehicle powertrain with an engine, fixed multiple-ratio gearing and infinitely variable ratio components. For a given vehicle speed and for a given vehicle traction wheel horsepower, the fixed multiple-ratio gearing and the infinitely variable ratio components are controlled to operate with an overall ratio that will permit the engine to operate with optimum efficiency.

Abstract: A power train control system for a mobile machine is disclosed. The power train control system has a power source configured to produce a power output, a transmission device operatively connected to receive the power output and propel the mobile machine, and a control module. The control module is configured to receive an indication of a power demand, receive an indication of a current travel speed of the mobile machine, and reference the power demand and the current travel speed with a power train efficiency map to determine a desired power source speed. The power train control system is also configured to control operation of the transmission device to bring a speed of the power source within a predetermined amount of the desired power source speed.

Abstract: In a power transmission system for transmitting power of an engine to a load, a planetary gear mechanism provided in parallel to a speed variator combines torque conveyed from the engine with torque conveyed from a motor generator in a state such that their torque ratio equals a predetermined ratio, and transmits the combined torque to a driven wheel. When performing power transmission between the engine and the driven wheel via both the speed variator and the planetary gear mechanism, power distribution between the power conveyed to the speed variator and the power conveyed to the planetary gear mechanism can be actively controlled by adjusting the torque of the motor generator. As a result, the speed variator capacity can be reduced while enhancing power transmission efficiency.

Abstract: A method is disclosed for controlling engine braking horsepower for a power transmission mechanism in a vehicle powertrain. The transmission mechanism has multiple-ratio gearing and a continuously variable transmission unit arranged in parallel disposition. A target engine speed during an engine braking mode is maintained by controlling the ratio of the continuously variable transmission unit.

Abstract: The following steps are performed in the control method: determining a mode of operation from amongst a permanent mode and a transient mode, as a function of a set of variables comprising said estimated values; correcting the value of the speed of rotation of the outlet shaft in such a manner that: if the mode has been determined as being the permanent mode, then the moving average (L?) of the gear ratio (L) over a period (T) of a plurality of unit time intervals lies between a first threshold value (S1) that is negative and a second threshold value (S2) that is positive; and if the mode has been determined as being the transient mode, then said moving average (L?) of the gear ratio (L) lies outside the range of values defined by the first and second threshold value (S1, S2).

Abstract: A method is disclosed for controlling overall transmission ratios in a vehicle powertrain with an engine, fixed multiple-ratio gearing and infinitely variable ratio components. For a given vehicle speed and for a given vehicle traction wheel horsepower, the fixed multiple-ratio gearing and the infinitely variable ratio components are controlled to operate with an overall ratio that will permit the engine to operate with optimum efficiency.

Abstract: A sleeve 28 making up a gear ratio control valve 21 is driven by not only a stepping motor 29 but also a secondary actuator 47. Pressure oil is made free to be introduced into the secondary actuator 47 through a manual oil pressure switching valve 37 which is switched over by a gearshift. Then, when the gearshift is operated from a non-running state to a running state, a gear ratio of a toroidal type continuously variable transmission is corrected by a predetermined amount by driving the sleeve 28 by the secondary actuator 47. As a result, while improving characteristic of a vehicle when starting from rest, the vehicle can be prevented from being reduced in speed unintentionally excessively even when the gearshift is operated while running.

Abstract: Hybrid controller 52 for a vehicular drive system is operable during a shifting control of step-variable transmission portion 20 for a stepping change of its speed ratio, for changing a speed ratio of continuously-variable transmission portion 11, such that total speed ratio ?T of transmission mechanism 10 defined by the speed ratio of the continuously-variable transmission portion 11 and the speed ratio of the step-variable transmission portion 20 is continuously changed, irrespective of the stepping change of the speed ratio of the step-variable transmission portion 20, so that an amount of stepping change of engine speed NE before and after a shifting action of the step-variable transmission portion 20 is reduced, and a shifting shock of the step-variable transmission portion 20 is reduced. The hybrid controller 52 permits the transmission mechanism 10 to function as a continuously variable transmission, thereby improving fuel economy of the vehicular drive system.

Abstract: A rotational speed of an input side disk is detected by an input side rotation sensor, and a rotational speed of an output side disk is detected by an output side rotation sensor, respectively. Based on detected values of the two sensors, a transmission ratio of a toroidal type continuously variable transmission is calculated. Further, a rotational speed of the output shaft is calculated from the transmission ratio and a gear ratio of a planetary gear type transmission. In a state in which the select lever selects no-running condition, the transmission ratio of the toroidal type continuously variable transmission is controlled such that the rotational speed of the output shaft becomes null or at an extremely low speed even when the running state is selected at the instance. Further, a position of a control valve apparatus under the state is stored to a controller.

Abstract: A continuously variable transmission has: an input shaft, an output shaft, a toroidal type continuously variable transmission, and a planetary gear mechanism including a sun gear, a ring gear and a planetary gear. The power transmitted to first and second power transmission systems is made to converge to two gears of the planetary gear mechanism, and a remaining gear is coupled with the output shaft. A mode changeover device effects a changeover between, during forward movement, a first mode for a low speed side, which utilizes the first power transmission system and a second mode for a high speed side, which utilizes the first and second power transmission systems. Such changeover is effected by the operation of connecting and disconnecting a first mode clutch and a second mode clutch. The operation of effecting the changeover between the first mode and the second mode is effected in 0.2 to 1 second.

Abstract: A transmission equipped with a continuously variable ratio-change mechanism CVT and a LOW rotational transmission mechanism GT, which are disposed parallel with each other, comprises a forward clutch 65 and a reverse brake 66, which are used to set a power transmission through the continuously variable ratio-change mechanism, a LOW clutch 46, which is used to set a power transmission through the LOW rotational transmission mechanism, and a control unit ECU and a hydraulic control valve HV, which control the engagement of the clutches and the brake. When the transmission is switched from its neutral mode to its in-gear mode, at first, the forward clutch 65 is brought gradually into engagement, and then it is released before the LOW clutch 46 is brought into engagement in a squat control.

Abstract: A control system and control method for an automotive vehicle having a multiple-ratio automatic transmission having two gearsets arranged in series relationship for delivering vehicle engine power to vehicle traction wheels, each gearset being controlled using friction elements that establish multiple torque flow paths, each gearset being characterized by at least two ratios, which define an overall transmission ratio, synchronous shifting of the gearsets effecting at least one swap-upshift and at least one swap-downshift in the overall transmission ratio, the control system compensating during a swap-shift progression for dynamic interaction between the gearsets.

Abstract: A continuously variable transmission apparatus has clutch device having a low speed clutch; a high speed clutch; and, a controller switching the transmission state into any one of a low speed mode and a high speed mode by connecting any one of the clutches, wherein timings for signaling by the controller for switching the connected and disconnected states of the clutches vary according to the switching directions of the low speed and high speed modes; and, a timing for signaling for connecting the low speed clutch with respect to the moment for signaling for cutting off the connection of the high speed clutch in order to switch the high speed mode over to the low speed mode is set earlier than a timing for signaling for connecting the high speed clutch with respect to the moment for signaling for cutting off the connection of the low speed clutch.