Abstract: An automatic start controlling apparatus for automatically starting an internal combustion engine. A transmission is coupled to the engine. The transmission has a clutch, which is actuated by an oil pump other than the engine when the engine stops. The transmission has an input shaft and an output shaft. The input shaft is connected to the engine. The automatic start controlling apparatus has a controller. When the engine is automatically started, the controller detects whether the clutch is completely engaged. When the controller judges that the clutch is partially engaged, the controller reduces the output torque of the engine or limits an increase of the output torque.

Abstract: A method of regulating the position of a clutch actuator in a vehicle employs the concept of adapting the servo-loop parameters of a position controller of the clutch to different operating conditions of the vehicle, as well as the concept of applying and continuously adapting a bias current of the actuator motor in order to avoid or minimize the incidence of a hunting or after-regulation behavior of the control loop and to thereby minimize the energy consumption of the actuator motor.

Abstract: Within the scope of the method for motor reduction while closing the lock-up clutch for automatic transmission of a motor vehicle, the starting value of the motor reduction is brought up via an adjustable ramp within the time period elapsed while laying on the disks of the lock-up bridge clutch, the motor reduction being adjustable with reference to a characteristic field.

Abstract: A microcomputer-based electronic control system for a full time four wheel drive torque transfer case monitors the relative slip between the front and rear output shafts of the transfer case, and generates a signal to engage an electromagnetic clutch for a predetermined time period in the event a predetermined slip threshold is exceeded. The control system continuously interrogates two Hall effect sensors positioned over toothed wheels on the front and rear outputs of the transfer case. Tooth counts are stored in two numerical stacks (one for each sensor), the depth of which may be adapted to the requirements of the particular design. Upon detecting a tooth count, the system adds the count to the sensor's current stack register and pushes all of the registers of the other stack down one register. The last register is pushed out or deleted from the stack memory.

Abstract: At the time of the change-speed, by correcting the torque reducing portion of an output shaft during the change-speed, the revolution number of an input shaft is controlled on the basis of the corrected torque reduction correcting value. Also, the torque of said input shaft is adjusted at the end of the change-speed on the basis of said torque correcting value.

Abstract: Control of shiftable clutches by a clutch control signal that is a function of the difference between the actual and desired engine rotational speeds and of the gradient of the actual engine rotational speed and wherein the clutch control signal values are generated by the employment of a set of clutch engagement and disengagement speed curves.

Abstract: A control for a vehicle drive line system (10) including an automated vehicle dry master clutch (14) drivingly interposed in between a fuel-controlled engine (12) and the input shaft (20) of a mechanical transmission.

Abstract: A control device for controlling a clutch of a vehicle wherein an actuator is connected to and provides for operating the clutch, the work position of which is determined by a position sensor which supplies a measured position signal to a control device receiving an information signal and supplying a control signal for the actuator; the control device has a monitor circuit for determining malfunctioning of the position sensor and supplying a fault signal; and a virtual sensor device for estimating the work position of the clutch to supply the control device, in the presence of the fault signal, with a virtual position signal instead of the measured position signal.

Abstract: A lock-up control system for an automatic transmission including a torque converter and a lock-up clutch. The lock-up control system comprises an accelerator pedal depression amount sensor for detecting a depression amount of an accelerator pedal, and a controller. The controller includes an accelerator pedal movement speed calculating section for calculating a movement speed of the accelerator pedal. The controller includes a lock-up control section adapted to disengage the lock-up clutch in a condition in which a driving point of the vehicle is within a lock-up condition releasing region in a set lock-up schedule, and to engage the lock-up clutch in a condition in which the driving point is within a lock-up condition applying region.

Abstract: A method for operating a torque-converter lockup clutch (20) for a hydrodynamic converter (1), where the slip (s) of the torque converter (1) is adjusted using a setpoint value (sw), while the torque-converter lockup clutch (20) is being closed. The method is also designed with the intention of providing an especially high degree of ride comfort while the torque-converter lockup clutch (20) is being closed. In addition, the present invention provides for the setpoint value (sw) being continuously selected as a function of time, inside a closing interval, taking into consideration the input torque (E) currently being applied to the torque converter (1). A control device (24) particularly suitable for implementing the method includes a control unit (26), which selects a setpoint value (sw) for the slip (s) of the converter (1) as a function of time, and taking into consideration the input torque (E) currently being applied to the torque converter (1).

Abstract: A control system 32 and method for controlling neutral idle operation of a vehicle 10 is provided. The method includes measuring a brake pressure in a brake control line of vehicle 10. The control line communicates fluid to a brake 128 coupled to a wheel of vehicle 10. The method further includes determining an incline angle of vehicle 10. The method further includes determining a desired brake pressure based on the incline angle. The desired brake pressure is a pressure sufficient to allow the vehicle brakes to maintain vehicle 10 at a predetermined position. Finally, the method includes disengaging a transmission clutch 46 torsionally coupling a vehicle engine 12 to a wheel 24 when the measured brake pressure is greater than the desired brake pressure to initiate neutral idle operation.

Abstract: At the time of the change-speed, by correcting the torque reducing portion of an output shaft during the change-speed, the revolution number of an input shaft is controlled on the basis of the corrected torque reduction correcting value. Also, the torque of said input shaft is adjusted at the end of the change-speed on the basis of said torque correcting value.

Abstract: The proposal is for a process for controlling a CVT of the bevel-pulley-belt type in which, on the occurrence of a wheel-locking drive situation, a converter bridging clutch is disengaged and at the same time a forward or reverse drive clutch is disengaged. The pressure level of the secondary pulley (3) is hereby raised and the transmission ratio of the CVT is changed in accordance with a predeterminable transmission ratio change and a predeterminable gradient.

Abstract: A characteristics change of a control object is functionally represented by a parameter &thgr; which varies between values of 0 and 1 as the gain of the control object is surveyed. The frequency of the identification signal is set at a frequency where the difference in gains becomes large. The amplitude of the identification signal is set so that the variation width of the output of the control object is less than or equal to a predetermined value. Because the identification accuracy improves where the input/output characteristics with respect to the parameter are more sensitive, the identification signal set by such a setting apparatus imparts high identification accuracy. Moreover, because the amplitude of the identification signal is set based on the variation width of the output of the control object, identification can be performed without significantly affecting the output of the control object.

Abstract: A transfer case for a four-wheel drive motor vehicle includes an electronic control unit (ECU) and a synchronizer which facilitates shift on the fly operations such as, for example, a shift from two wheel high to four wheel high. A temperature sensor disposed either in the transfer case or elsewhere in the motor vehicle provides a temperature signal to the ECU which is utilized to adjust the on time of the synchronizer to compensate for the viscosity of the lubricating fluid within the transfer case or other temperature related variables which affect the time required to synchronize the drive line components prior to engagement. Such temperature compensation also facilitates fault detection and system oversight since the ECU can accurately anticipate the variability of the operating parameters based upon temperature and determinate malfunctions when operation occurs outside such temperature based parameters.

Abstract: A method for controlling an automatic transmission driven by an internal combustion engine is proposed in which a shift from a first to a second transmission ratio occurs as a pull upshift by a first clutch opening and a second clutch closing and electronic transmission control unit controls via electromagnetic valves the pressure curve of the first and of the second clutch during the shifting operation. The shifting operation is divided into different shifting phases, an engine intervention taking place within the gradient-adjustment (GE), the sliding (GL), the gradient-reduction (GA) and the closing (S) phases, an engine torque being reduced by an engine intervention factor (mdzegs) being transferred from the transmission control device to an engine control device of the internal combustion engine.

Abstract: In an automatic transmission having a torque converter interposed between an engine and a transmission mechanism, the torque converter includes a lock-up clutch capable of directly coupling an output shaft of the engine and an input shaft of the transmission mechanism. A speed difference detector is provided for detecting a difference between engine rotational speed and input shaft rotational speed. An engine speed controller means is also provided for controlling the engine speed to cause the speed difference to converge within a predetermined range. By detecting the speed difference, it is possible to precisely detect the actual vehicle state, and to reliably and smoothly engage the lock-up clutch without generating shift shock in any vehicle state. With this structure, the lock-up clutch can be reliably engaged and the engine brake can be secured.

Abstract: A method is provided for determining an acceptable torque level to be applied to at least one clutch pack (of an automobile) which includes the requirement of internal slip to transmit torque. The automobile includes a plurality of wheels. A velocity is sensed at each of the plurality of wheels of the automobile. A speed information value is calculated. The speed information value is a function of the sensed velocities at each of the plurality of wheels. The speed information value is then compared with a calibration table. Finally, the acceptable torque level is determined primarily from the calibration table based on the speed information value.

Abstract: A control device for controlling a clutch of a vehicle wherein an actuator is connected to and provides for operating the clutch, the work position of which is determined by a position sensor which supplies a measured position signal to a control device receiving an information signal and supplying a control signal for the actuator; the control device has a monitor circuit for determining malfunctioning of the position sensor and supplying a fault signal; and a virtual sensor device for estimating the work position of the clutch to supply the control device, in the presence of the fault signal, with a virtual position signal instead of the measured position signal.

Abstract: An infinite speed ratio continuously variable transmission is provided with a continuously variable transmission (2), fixed speed ratio transmission (3), planetary gear set (5), power recirculation clutch (9) and direct clutch (10). A target speed ratio of the infinite speed ratio continuously variable transmission is set based on a vehicle speed and an accelerator pedal depression amount. When the target speed ratio varies beyond a rotation synchronous point, a control unit (80) assigns an order of priority to control of the power recirculation clutch (9) and direct clutch (10), and control of the speed ratio of the continuously variable transmission (2), and thereby causes a real speed ratio of the infinite speed ratio continuously variable transmission to vary in the same direction until it reaches the target speed ratio (S21, S22, S31, S32, S121, S122).

Abstract: An apparatus and method of operating an adaptive drive system of a motor vehicle which reduces drive line wear, improves safety margins and permits weight reduction in drive line components activates a clutch between a primary and secondary drive line when the vehicle is determined to be heavily loaded. The method steps include sensing the position of a throttle position sensor, sensing the instantaneous speed of a motor vehicle and computing instantaneous acceleration, determining whether the ratio of vehicle acceleration to throttle position is less than predetermined threshold value and engaging a transfer case clutch to transfer drive torque from a primary drive line to a secondary drive line. Operation of this method is transparent to the driver inasmuch as the clutch is activated when the vehicle is heavily loaded as determined by the throttle position to acceleration ratio.

Abstract: A correction coefficient setting unit calculates as a difference in an actual revolution speed the difference between the actual revolution speed of a front driving axle and the actual revolution speed of a rear driving axle. Moreover, the correction coefficient setting unit calculates the ideal reference revolution speed of the front driving axle and the ideal reference revolution speed of the rear driving axle in consideration of a difference in a radius of gyration between the driving axles. The correction coefficient setting unit also calculates as a difference in a reference revolution speed the difference between the ideal reference revolution speed of the front driving axle and the ideal reference revolution speed of the rear driving axle.

Abstract: A determination method and apparatus for permitting deceleration regeneration or charge of a hybrid vehicle, by which erroneous determination relating to the clutch operation can be prevented. The method includes a first determination step of detecting clutch operation performed by a driver and determining a connection state of the clutch; a second determination step of determining a connection state of the clutch based on a correspondence relationship between vehicle speed and engine speed; and a permission determining step of permitting the deceleration regeneration or charge by the motor when it is determined that the clutch is connected both in the first and second determination steps.

Abstract: A control for a vehicle drive line system (10) including an automated vehicle dry master clutch (14) drivingly interposed in between a fuel-controlled engine (12) and the input shaft (20) of a mechanical transmission.

Abstract: A control apparatus for an automatic transmission capable of sufficiently producing the effect of neutral control by reducing a period of time from stop of a vehicle to the release of an input clutch. Vehicle stop prediction means for predicting immediate stop of the vehicle from a vehicle speed detected by a vehicle speed sensor is provided. Input clutch control means for reducing a hydraulic pressure in a hydraulic servo of the input clutch from a hydraulic pressure in a normal engagement state to a waiting pressure capable of maintaining an engagement state of the clutch based on the prediction of the stop of the vehicle by the vehicle stop prediction means is provided. The operation of releasing the input clutch concurrent with the neutral control is started from a state of the waiting pressure, so that the input clutch is released in a short period of time.

Abstract: In an infinite speed ratio transmission comprising a continuously variable transmission (2), reduction gear unit (3) and planetary gear set (5), the speed ratio of the continuously variable transmission (2) is controlled by a step motor (36). A range selected by a selector lever (86) is detected by a sensor (84). When the selected range has changed from a stationary range to one of a forward motion range and a reverse motion range, a microprocessor (80) first drives the step motor (36) to a predetermined position (S48, S54).

Abstract: In a vehicle provided with a transmission that has a lock-up clutch that is directly couplable between drive sources and a drive shaft, the shock of switching between the drive sources is prevented from being transmitted. It is determined whether the drive source is to be switched, and when “YES” is determined, a lock-up clutch is disengaged or placed in a half-engaged state, and the shock due to switching of the drive source is prevented from being transmitted. Then, after it is confirmed that switching of the drive source is completed, the lock-up clutch is once again placed in the fully-engaged state.

Abstract: A lock-up control device is provided to control the engaging and release of a lock-up clutch, which is arranged in parallel with a torque converter to transmit driving force of an engine of a car. Herein, target driving force is calculated based on accelerator pedal opening and car velocity. A present shift position is detected using a shift map based on accelerator pedal opening, car velocity and engine speed. Target engine torque is calculated based on the target driving force and present shift position as well as a torque amplification ratio, which is detected when the torque converter is placed in a torque amplification state. A lock-up release instruction is issued under conditions that the torque converter is placed in the torque amplification state while the target engine torque is greater than a preset value, which is determined in advance based on a torque characteristic of the engine.

Abstract: A closed-throttle downshift control adjusts engine torque to raise the input speed of a transmission to the synchronous speed of the target speed ratio, and adaptively adjusts clutch control parameters to coordinate the off-going clutch release and the on-coming clutch apply, and to complete the shift with minimum driveline torque disturbance. A primary on-coming clutch control fills the on-coming clutch and then raises the on-coming pressure when the input speed reaches the synchronous speed of the target speed ratio. If input synchronization cannot be maintained, a contingent control increases the on-coming clutch pressure to gradually re-establish the input speed synchronization and thereupon engage the on-coming clutch to complete the shift. The fill time or the maintenance pressure of the on-coming clutch is adaptively decreased for reduced driveline disturbance in subsequent shifts of the same type if the output shaft jerk during the primary control exceeds a threshold.

Abstract: A multiple-ratio automatic transmission comprising a first multiple-ratio gear unit and a second simple planetary gear unit arranged in series in a torque flow path, each gear unit having a reaction brake that can be selectively activated and deactivated to effect a ratio change as the first gear unit is upshifted and the second gear unit is downshifted, ratio changes in each gear unit being effected by pressure-operated clutches and brakes, the brakes having opposed pressure-apply and pressure-release chambers. Separate exhaust flow paths are provided for a reaction brake release chamber and for a companion pressure-operated clutch. A pressure modifier valve circuit is provided for increasing the rate of response to a command for applying and releasing the clutch.

Abstract: An improved on-coming clutch fill control method in which a model of the transmission hydraulic system is used for control purposes to accurately predict the achievement of on-coming clutch torque capacity based on a comparison of the modeled volume of supplied fluid to a reference volume representing the actual volume of the on-coming clutch, and in which the reference volume for each type of shift is adaptively adjusted based on input speed aberrations observed during shifting. If input speed flaring occurs due to an underestimated reference volume, the reference volume is adaptively increased based on the volume of fluid supplied to the on-coming clutch between the initial detection of flaring and a detection of maximum flaring.

Abstract: An improved shift control for a hydraulic automatic transmission in which the apply chamber of an on-coming clutch is filled in the preparation phase of the shift using a hydraulic flow rate model to estimate the volume of hydraulic fluid supplied to the apply chamber. In an initial portion of the fill interval, fluid is supplied to the apply chamber at a first elevated pressure, while continuously updating the fluid volume estimate. When the remaining un-filled volume of the apply chamber reaches a reference volume, the supply pressure is reduced to a second pressure at which the next phase of the shift is to be carried out. When the chamber volume is filled, the torque capacity of the clutch rises to a level corresponding to the second pressure, and the next phase of the shift automatically ensues.

Abstract: A process and a device for determining the friction lining wear in a friction clutch with a clutch housing and a pressure plate, which is arranged axially movably therein and presses a clutch disk equipped with friction linings against a flywheel of an internal combustion engine. Three detecting elements are arranged at a defined axial distance to each other, and rotate with the friction clutch and a sensor is arranged outside of the clutch housing for finding the axial position of each detecting element, whereby at least one detecting element is connected to the clutch housing and the two other detecting elements are connected to the pressure plate.

Abstract: When a starter clutch slips, a wheel driving force is calculated based on a transmitting torque of the clutch obtained from not an engine torque but the clutch pressure (engagement force) of the starter clutch (S21-12), whereby a road gradient is calculated using the driving force so calculated and an acceleration of a vehicle.

Abstract: An adaptive control system and method for direct clutch engagement control for an automatic transmission including a micro-controller that receives and stores input data from driveline sensors and executes transmission clutch control logic. The micro-controller develops output signals in real time and transfers the signals to a driver circuit that controls solenoids that enable clutch engagement. The signals for establishing clutch pressure buildup are delivered to a driver circuit that produces hydraulic pressure at the clutch to achieve a smooth torque and speed transition for the torque input elements of the transmission. Adaptive pressure values are stored in a keep-alive memory. The pressure values are adjusted values based on the result of previous engagements. This compensates for driveline variables such as changes in coefficients of friction, spring loads, clutch wear, etc.

Abstract: The proposal is for a process for controlling a CVT of the bevel-pulley-belt type in which, on the occurrence of a wheel-locking drive situation, a converter bridging clutch is disengaged and at the same time a forward or reverse drive clutch is disengaged. The pressure level of the secondary pulley (3) is hereby raised and the transmission ratio of the CVT is changed in accordance with a predeterminable transmission ratio change and a predeterminable gradient.

Abstract: An electronic control system for a transmission in a work vehicle such as an agricultural tractor is disclosed herein. The system includes sensors for detecting the output speed of the vehicle engine, the output speed of the transmission and the vehicle ground speed. Command devices are available to the vehicle operator for generating command signals, such as for commanding the direction of movement, as well as forward and reverse gear ratios. A controller receives signals from the sensors and command devices, and controls engagement and disengagement of combinations of fluid clutches in the transmission to obtain desired gear ratios between the transmission input and output shafts. The command devices include an input device for generating transmission command signals, and the controller responds by selectively engaging the clutches to shift the transmission at a predetermined shift rate. The controller determines a commanded gear ratio based at least in part on the transmission command signals.

Abstract: The control method comprises the stages of: generating a reference torque signal, the instantaneous value of which indicates the desired value of the torque transmitted through the clutch; generating a reaction signal correlated to the position of an actuating member of the clutch, the position of the actuating member being comprised between a first end-of-travel position in which the clutch is completely open and a second end-of-travel position in which the clutch is completely closed; generating an estimated torque signal, the instantaneous value of which indicates the estimated value of the torque transmitted through the clutch, on the basis of the reaction signal and a transmissibility function of the clutch; and generating a control signal for adjusting the position of the clutch as a function of the reference torque signal and the estimated torque signal.

Abstract: The present invention is an apparatus and method to control the steering of a tracked machine having a clutch/brake steering system. The tracked machine has a left drive and a right drive. The left drive has a clutch and brake and the right drive has a clutch and brake. The present invention includes a navigator to determine a desired trajectory, determine a desired left drive velocity and a desired right drive velocity, and generate desired left and right drive velocity signals. The present invention also includes a left speed sensor and a right speed sensor to determine actual left and right drive velocities, and generate actual left and right drive velocity signals. A clutch/brake controller is included to receive the desired left and right drive velocity signals and the actual left and right drive velocity signals, and control at least one of the left and right drive velocities.

Abstract: A gear shift failure of an automatic transmission to a wrong gear other than an indented gear is made by estimating slippage theoretically caused in a torque converter on the basis of an engine speed and a turbine speed theoretically determined for an intended gear according to the vehicle speed and comparing the estimating slippage with predetermined reference slippage. When the estimated slippage exceeds the predetermined threshold slippage, it is decided that there has occurred a wrong shift to a gear other than the intended gear.

Abstract: In one aspect of this invention, a fluid actuated clutch is disclosed. The fluid actuated clutch is operatively connected to a control valve that is actuated by an electronic controller that receives a signal from an input mechanism, including a value for speed of an engine drive and a value of output speed for a torque converter. The method includes detecting a torque converter ratio which is the output speed of the torque converter divided by the engine drive speed, and detecting if there is at least one torque converter decrease exceeding a predetermined level and preferably detecting if there are at least two consecutive decreases in the torque converter ratio with at least one of the torque converter decreases exceeding a predetermined minimum level. This condition represents the end-of-fill point for the fluid actuated clutch.

Abstract: A control device for an automatic motor vehicle transmission has electrohydraulically actuated gearshift elements which increase the smoothness of shifting during a shifting operation, especially a shifting operation in a traction mode, by varying hydraulic pressure for actuating the gearshift elements. In a first phase of the shifting operation, in which idle travels of the gearshift elements are overcome, the pressure is rapidly made to approach a desired value through the use of a control signal (open-loop control) with a high duty cycle. In a second phase of the shifting operation, in which a transmission input moment changes from the gearshift element of an old gear over to the gearshift element of a new gear, the hydraulic pressure is built up with a high duty cycle.

Abstract: A fuzzy control method of a damper clutch and, more particularly, a fuzzy control method enhances engine brake effect by directly connecting a pump to a turbine by engaging the damper when a shift control unit identifies an engine brake state. The fuzzy control method of a damper clutch includes receiving or checking input signals relating to a damper clutch; controlling shift timing by a fuzzy control; determining if an engine brake should be used or not; checking an amount of driver's engine brake will if the engine brake should be used; determining if an emergency brake should be used or not; engaging the damper clutch when an emergency brake should be used; and controlling the damper clutch through a normal control when both the engine brake and emergency brake are not used.

Abstract: The present invention is a control device and a control method for a transmission with a clutch, by which the clutch is smoothly coupled without generation of shocks or the like in a vehicle.

Abstract: A process for tuning the switching state of a torque converter lock-up clutch (WK) in an automatic transmission to the output speed of rotation (n.sub.-- ab) of the transmission output shaft or the wheel speeds of rotation (n.sub.-- wheel) of driving wheels of a vehicle by means of an electronic transmission controller (EGS) with computer unit and an electronic pressure regulator (EDS) includes the following steps:a) from the wheel speeds of rotation (n.sub.-- wheel) measured by a measurement device (1) on the driving wheels, or the output speed of rotation (n.sub.-- ab) of the transmission output shaft, a time-related gradient of speed of rotation (dn/dt) is detected during activated state of the torque converter lock-up clutch by the computer unit in a processing function (S3);b) in a discriminating function (S4) is checked whether the amount of the gradient of speed of rotation (dn/dt) is higher than a threshold value (GW .sub.

Abstract: A method for reducing transmission clutch engagement pressure during conditions when clutch hydraulic fluid is relatively more viscous. A clutch engagement pressure control signal is shaped by a system that has an addition branch (42) for shaping the control signal as the control signal is rising, a subtraction branch (44) for shaping the control signal as the control signal is falling, and a summing junction (46) for algebraically summing the signal outputs of the addition and the subtraction branches.

Abstract: Slip across a torque converter of an automotive powertrain is estimated using powertrain operating parameters throughout a powertrain operating cycle for use in powertrain control and diagnostic operations. Slip across the torque converter is estimated and is periodically updated in accordance with an adaptive control procedure to maintain model accuracy over time. The slip is estimated for both torque converter coupling and torque multiplication scenarios, with the greater of the estimates identified as indicating current slip. Current slip is applied to generate actual transmission gear ratio which is compared to commanded gear ratio when a transmission shift maneuver is not in process to identify transmission solenoid fault conditions, and which is applied for precise transmission shift enhancement control during a transmission shift maneuver.

Abstract: A device for controlling a starting procedure of a motor vehicle for initiating a movement of the motor vehicle includes a controller which receives as input, signals generated by an engine shaft speed sensor, a driving speed sensor, a transmission shaft speed sensor, a transmission output shaft speed sensor, and an accelerator pedal position sensor. The controller is operatively connected to the engine for increasing the engine speed above a minimum threshold value when the driver signals his desire for a racing start. The controller is also operatively connected to a clutch activation device for deliberately producing a slip of the driving wheels and for controlling the slip of the driving wheels by controlling a slip of the clutch after a starting time point signaled by the driver.

Abstract: This invention relates to an automatically controlled clutch in a motor vehicle drive train. Rotational speed differences between the clutch input and the clutch output are determined by a computer from rotational speeds of the vehicle engine, on the one hand, and rotational speeds of the vehicle drive wheels, on the other hand. Variations of a frequency which is characteristic of resonant frequencies in the drive train when the clutch is closed are not taken into account.

Abstract: The invention provides a method for detecting the wheel rpm values of the nondriven and the driven wheels and for comparing them with one another in order to improve vehicle stability, for example when the driving torque of the engine is too high. A friction clutch located between the drive motor and the wheels in the drive train is disengaged when the rpm of the driven wheels is less than the rpm of the nondriven wheels and the difference between the two wheel rpm values exceeds a given limiting value. The friction clutch is re-engaged when the difference between the two wheel rpm values reaches or falls below a second limiting value.