DE19601291A1 - Transmission for vehicle - Google Patents

Abstract

The transmission has a number of mechanical gear ratios controlled by a control unit which drives hydraulic servos. The control unit can operate in either a fully automatic mode or in a manual selection mode to give the driver more flexibility. The control unit is connected to sensors which monitor the vehicle speed, the engine speed, the gear ratio engaged as well as other parameters. The hydraulic servos operate directly on the gearchange sleeves or on the gearchange rods. The transmission control monitors the manual gear changes and can block those gearchange movements which would operate the transmission outside preset limits, e.g. for fuel economy and engine limits.

Description

The invention relates to a mechanical shift transmission be for motor vehicles according to the preamble of the An Proverb 1 and a method for electronic or manual switching of such, the driving state dependent or manually operable. Here will a conventionally designed step gear under Using gear pairs using conventional shift sleeves engage with each other brought or the intervention are separated can, used.

So far it has been with step gears, where gear there are pairs for the different gears, not possible an electronically controlled circuit make and ent the driver of a motor vehicle  to relieve speaking. Especially in situations very quickly in traffic where it matters to accelerate the motor vehicle, there are problems as for triggering the switching processes with the in conventionally used shift linkage and Shift levers for design-related time delays gen occur and therefore not the complete Traction ability of the motor vehicle exploited who that can.

Another disadvantage of the known manual transmission is that the driver's influence for optimal economical operation is not excluded sen or can be reduced. So it happens that the internal combustion engine by wrong choice of a posed Ganges, the internal combustion engine in operation points is operated which is uneconomical and with a relatively high fuel consumption are.

In addition, the driver of the motor vehicle in be agreed to confusing critical traffic situations tion by then required switching operations be steered, and dangerous situations can arise be conjured up.

Solutions are known in which that for gat appropriately trained manual gearbox required Disengaging automatically, i.e. independently of the driver, is feasible, such a modification can However, only partially eliminate the disadvantages mentioned or restrict. An influence on an optimal one Operation of the motor vehicle in relation to the force However, material consumption is also not possible with this.  

It is therefore an object of the invention to provide one possibility to create mechanical gearboxes in this regard to upgrade that they are driving-dependent and manual are switchable in different switching stages.

According to the invention, this task is characterized by the drawing part of claim 1 for the mechanical Manual transmission and those in the characterizing part of the Claim 21 for the method of electronic or manual switching of such a transmission ent characteristics kept resolved. Advantageous design tion forms and developments of the invention itself when applying the in the subordinate claims Chen mentioned features.

A mechanical gearbox designed according to the invention, in which gear pairs can be brought into engagement with one another by the targeted shifting of shift sleeves or the engagement can be released, has control electronics which have inputs for the measured engine speed n _m , the vehicle speed v, the Position of the mechanical clutch, the detection of the engaged gear and for manually operated switches for shifting into a higher, a lower and the reverse gear and outputs for the controls of a clutch release cylinder and shift actuating cylinder is provided.

The switching can be carried out both manually and electronically. The result of an actual / setpoint comparison of the engine speed n _m and the vehicle speed v that can be carried out in the control electronics is carried out with stored limit values. With the help of this actual / setpoint comparison, who can prevent a shift from being triggered by actuating a switch for upshifting or downshifting the transmission when the corresponding operating conditions are not present, ie vehicle speed and engine speed values are sufficient in which the corresponding torque and the required power can not be provided by the internal combustion engine with its characteristics or only with increased fuel consumption. In addition, the engine can be prevented from over-revving without a speed limit.

Another advantage of a training according to the invention Deten manual transmission is that this, whether probably constructed differently from a conventional automa can be operated, but the known converter losses do not occur.

Both the actuation of the disengageable friction clutch as well as the actuation of the shift actuating cylinders is preferably carried out hydraulically and can ent speaking about the outputs of the control electronics be influenced.

The advantageous as three-position switching actuation Less trained switching for the individual Nine gear steps can be done directly on the gearshift sleeves or the shift rods, which are already on conventional ones Manual transmissions are available, arranged attacking be. It is possible with such three-position cylinders Lich to operate two gears with one cylinder or, if necessary, make a separation. The use of such three-position cylinders has the  Advantage that the effort for the control of the Hy draulic circuit and the required space ver is wrestled.

For the measurement of the engine speed you can anyway on the rotation required for the motor control number sensors used and the measured values parallel to Motor control via an input to the control electronics nik of the gearbox are given. For the Mes solution to the speed of the vehicle existing speed sensors used on the wheels be the anyway with a lot of vehicles are already used for the anti-lock braking systems. The control electronics should be advantageous Speed signal of at least one wheel of a driven planes and a wheel of a non-driven axle are fed to any slip that may occur to be considered and an electronically controlled automatic shifting to a higher gear Prevent spinning of the driven wheels.

Manual shifting of the gearbox can be done with Betä activation of switches. For this are at least three switches or one switch with ent speaking number of switch positions required, which are preferably designed as push buttons. There at a switch is used to trigger a switch went into a higher one, a switch for the trigger solution of a switching process in a lower and another switch for switching in the back downward gear required. It is convenient to have a fourth To use switches with which the first gear depending on the other switches. This enables favorable operating conditions achieve that the arrangement of these switches directly on  Steering wheel of the motor vehicle or at least in it in the immediate vicinity.

In addition to the possibility of Er already described There is also a version of the vehicle speed Possibility on the output shaft of the gearbox to arrange a speed sensor with which under Be taking into account the gear engaged Vehicle speed can be determined. Of the set gear can be with sensors in the gearbox can be summarized, for example the position of Monitor gears or shift sleeves. For this you can sensors that measure inductively. But there is also the option of the control elec to use tronics and store them in which Gear is switched, and the corresponding memory value for determining the vehicle speed to use.

The one with the speed sensor on the output shaft the transmission is arranged, measured signal can in addition to the speed measurement also for the front gear of disengaging and engaging the mechanical friction Coupling can be used if it automatically should follow. For this are in another store corresponding control maps filed for the measured speed and the respectively inserted the clutch release cylinder control accordingly depending on time, so that the off return in the required direction traveled faster or shorter, d. H. the dome execution process faster or slower becomes.

Because both the operation of the circuit and that  Disengagement of the friction clutch is done hydraulically it makes sense in the hydraulic circuit, which is preferably central is trained and fulfills all tasks occur hydraulically in the motor vehicle, a pressure Arrange sensor whose signal at in hydraulics built up pressure the operational readiness of the Hydraulic system reports to the control electronics or a warning system in the event of a hydraulic system failure generated.

An input on the control electronics should also be preferred tronics be present, which with the braking system of the Motor vehicle is connected and reports a signal that says that the vehicle's brake is applied is so that the control electronics in the position can be seen that when using the wheel rotation number for vehicle speed measurement speed does not correspond to the value given by the measured speed of the wheels is specified and therefore no corresponding switching operations to be triggered.

It is advantageous if an output of the control electronics tronik with the electronic engine control of the Ver Internal combustion engine is connected and this before and during rend influenced by a switching process. It can once the fuel supply is at least throttled or the ignition timing is shifted for gasoline engines.

Is the transmission designed according to the invention like used an automatic transmission, d. H. the switching operations are exclusively via the control electronics triggered, it is favorable that the driver ent is informed or warned accordingly. For this should display means or warning devices  that visually indicate that the Control electronics a switching process in a low or higher gear. In addition, buzzer can also be provided a corresponding switch with different tones let the process be recognized.

A memory unit is integrated in or connected to the control electronics for the actual / setpoint value comparison already described. In the memory unit are at least one upper limit speed n _o , one upper limit speed v _o and one maximum speed n _max for shifting into a higher gear as well as at least one lower limit speed n _U , a lower limit speed v _U and for each gear of the transmission stored a minimum speed n _min for shifting into a lower gear. The values mentioned can also be entered for various desired driving styles, such as sporty, quiet or fuel-saving, which, depending on the temperature and situation, can be used by the driver after corresponding entry in the control electronics for the actual / setpoint comparison.

In addition, rotation can also be done in the storage unit numerical values are included, one for each course Activation of the display means already mentioned and Generate warning devices if the result of the Compare an almost identity with the corresponding one value, measured and stored value.

Another input of the control electronics can with be connected to a sensor whose signal the Stel throttle valve, a control rod or one Control slide corresponds and this signal then  also in the control electronics, in the control of the transmission can be taken into account.

In terms of circuitry, the starter or the ignition system of the internal combustion engine switched so that the Position of the friction clutch is taken into account and a Only then can the internal combustion engine be started when the clutch is disconnected. For this can the signal indicating the position of the clutch release cylinder Linders represents via the control electronics be used.

It is with the transmission designed according to the invention possible, depending on the driver or driving condition gig to shift the individual gears, in the conventional way the clutch via pedals or in the case of an electronic, i.e. driver depending on triggered switching process without actuation the clutch pedal the clutch before changing gear separated and then coupled again becomes. During the switching process, the electroni cal engine control by the control electronics of the Transmission affects and at least the engine speed lowered to the extent necessary.

For switching the reverse gear there is an additional one Licher push button switch or a switch position such. The first course can be over another Key switch or by pressing the switch for engaging a lower gear so far, until the first gear has been reached. The Control electronics can be designed so that in any case when the engine is switched off the first gear is engaged.  

As already described, then the internal combustion engine can only be started when the clutch is disconnected. With A hydraulic pump is used in the hydraulic system a pressure builds up and when the required Chen operating pressure this state of a pressure sensor reported to the control electronics.

From this point in time, in the event that he gear has already been selected or after one corresponding actuation of the necessary Switch by appropriate influence on the dome by the driver the connection between Internal combustion engine and transmission manufactured and that Vehicle is set in motion. That turn in a higher gear can then be activated once of the corresponding key switch can be reached where by the tax on the clutch release cylinder electronics and the hydraulic system without another Activity of the driver, the clutch disengages and is engaged again when changing gear follows. When pressing the push button for Shifting into a higher gear becomes taxable an actual / setpoint comparison is carried out electronically, to determine that speed and vehicle speed required for the desired gear change have reached values.

A similar procedure is followed when by the driver switching by actuating another switch in a lower gear is desired. Here it is checked whether the engine speed and vehicle speed have reached lower limit values.

Constant pressure on the switches for the high or shifting a lower gear causes one  corresponding switching process whenever the corresponding upper or lower limits for Engine speed and vehicle speed reached are.

Switching operations always take place regardless of the driver, if maxi determined for the gear selected Mal or minimum speeds reached or exceeded be. The hydraulic system from the Control electronics influenced so that the clutch off back cylinder and the corresponding Schaltbe actuating cylinder in the appropriate position be is moved. Are automatic switching operations without that the driver has an appropriate switch actuated, triggered, is by the control electronics of the gearbox the electronic engine control affects that the engine speed during the shift process is reduced. The Mo The amount of fuel supplied is reduced accordingly and the ignition timing accordingly for gasoline engines be relocated.

The control electronics ask of the corresponding Sensors constantly the speed, the speed and the gear engaged and uses this measurement values in corresponding actual / setpoint comparison routine to decide whether a shift that manually triggered is prevented or enabled or triggered a shift without driver influence becomes.

Are the switches for switching to a low and move into a higher gear at the same time the control electronics evaluates this state than no actuation of a switch and the Automa  Tik operation of the transmission is still active and can, if an appropriate driving state is reached, accordingly a higher or lower gear switch.

The invention is intended to be carried out in one embodiment example will be described in more detail.

Show:

Fig. 1 is a diagram of the electronic and elec trical components of the inventive solution,

Fig. 2 is a circuit diagram of the hydraulic system for controlling the transmission, and

Fig. 3 is a schematic representation of a three position switch actuating cylinder in three positions.

1, a circuit is shown schematically in FIG. Illustrated for the electronic and electrical components of the OF INVENTION to the invention solution. In this embodiment, the control electronics 27 have three inputs for speed sensors 1 arranged on wheels, an example of a motor vehicle driven only on one axis being described here. It is in this embodiment, the speed at both front wheels not driven separately and the speed measured on the driven rear axle and the control electronics 27 supplied. The control electronics 27 is also connected to a sensor 2 , which provides a signal when the braking system of the motor vehicle is actuated and in such a case, in the control of the transmission, which has not been taken into account in this figure dar, be observed is. Another sensor 3 is arranged on the clutch actuation and can be used to prevent starting of the internal combustion engine if the clutch has not been actuated at this time, ie has not been disengaged.

Another input of the control electronics 27 is connected to a lateral acceleration sensor 4 , the signal of which can also be taken into account in the control of a transmission designed according to the invention.

In this figure, pushbutton switches 5 can be seen , which are arranged directly on the steering wheel, or are integrated therein and deliver signals to the control electronics 27 by simple pressure during driving in order to achieve the engagement of a higher or lower gear.

In the driver's field of vision, a display 6 is arranged in the motor vehicle, with the aid of which the driver can recognize whether a gear change to a higher or lower gear is imminent or is currently being carried out. In addition, the gear engaged is shown on the display 6 .

The control electronics 27 also has an input at which the signal of a throttle valve position sensor 7 for a gasoline engine or accordingly on the control rod or a control slide of an injection pump for a diesel engine is arranged sensor.

The engine speed signal with a respective speed sensor 8 erelektronik given 27 to a further input of the CONT.

An output of the control electronics 27 is connected to a proportional valve 9 for actuating the mechanical friction clutch. With 11 a sensor is marked, which gives the position of the clutch or the clutch release cylinder to the control electronics 27 .

A pressure sensor 12 is received in the hydraulic system and delivers a corresponding signal to the control electronics 27 , which indicates whether a pressure is built up in the hydraulic system that is sufficient to ensure the operational readiness of the entire system.

Another speed sensor 13 is arranged on the output shaft of the transmission and the transmission speed measured with this is given to the control electronics 27 via a further input.

About outputs of the control electronics 27 are accordingly the number of possible switching stages to be switched with the mechanical transmission, existing magnetic valves 14 to 20 are connected. In this example, a gearbox with five forward and one reverse gear has been selected. The solenoid valves 14 to 20 influence the shift actuating cylinder depending on the signal from the control electronics 27 , whereby when a shift is triggered, a shift actuating cylinder is moved so that the gear pairing of the engaged gear is disengaged and, if applicable, a gear pair with a second actuating cylinder is the desired gear pair is brought into engagement with each other.

On the transmission there are further sensors 20 to 26 which provide the control electronics 27 with signals, with which it is possible to detect which gear is engaged at the respective time.

Next, the electronic unit 1 of an anti-lock braking system is shown in FIG. 28 included, whereby the signals of the wheel speed sensors 1 to the anti-lock brake system 28 and by this to the control electronics 27 of the Getrie bes can be added in parallel form.

In FIG. 2, the hydraulic system USAGE for an inventively designed gearbox is det may be represented. A central hydraulic pump 31 , which can also be used for other drives required in the vehicle, which have not been taken into account in this illustration, has a delivery capacity of 3 cm³ and is able to build up a pressure of up to approx. 110 bar . Following the hydraulic pump 31 , two 2/2 way valves 32 (unpressurized) are bypass-like in the line system below.

A filter 33 is flowed through by the pumped hydraulic fluid, and following the filter ter 33 , a check valve 34 is arranged in the line system for the hydraulic fluid.

Furthermore, the pressure sensor 12 already mentioned in the description of FIG. 1 is recorded at a suitable point in the hydraulic circuit.

The area of the hydraulic circuit which is used for the actuation of the friction clutch is identified by semicolons. In this case, a branch is connected to the central hydraulic line, to which a safety valve 35 and a further branch for a pressure accumulator 36 are connected. With the help of a proportional valve 37 connected to the circuit, the amount of hydraulic fluid that reaches the clutch release cylinder 42 and pressurizes it or removes the pressure and so the clutch is disconnected or recoupled is regulated. The proportional valve 37 is, as already described, influenced by the control electronics 27 accordingly. A return to the hydraulic tank 41 is located at the proportional valve 37 .

The central hydraulic line is then in turn guided to the transmission control part of the hydraulic system, likewise enclosed in semicolons. A pressure reducing valve 38 limits the pressure to 40 bar. The hydraulic fluid is guided by this to three 3/2 way valves 39 in this embodiment. From the pressure reducing valve 38 there is another return line to the central hydraulic tank 41 . The three 3/2 way valves 39 are connected to three three-position cylinders 40 , which are used as shift actuating cylinders. Depending on the position of the 3/2 Wegeven tile 39 , a three-position cylinder 40 is brought into a position which speaks the desired (by manual switching) or depending on the driving state and brings a gear pair into engagement with one another in order to switch on the corresponding gear in the transmission. It must be ensured that the other two three-position cylinders are sition in a butt 40 holding the other gears of the transmission in a position without an engagement of a further gear pair is carried out. 1 with the already mentioned in the description of FIG. 1 Gangsenso ren 20 to 26 that such a state he can be reached, the control unit 27 prevents the actuation of the other three-position cylinders 40 , so that damage to the transmission is excluded.

In Fig. 3 is a three-position cylinder 40 in the corresponding three positions A, B and C Darge provides. This three-position switching actuating cylinder 40 can be used with its simple structure in other areas of technology, where components or machine elements have to be moved or positioned relatively quickly and with little effort in various positions in a small system space.

In the advantageous shift actuating cylinder 40 , a piston 44 is kept floating in a longitudinal direction which is parallel to the working direction of an actuating piston 42 . For this purpose, 44 pressure spaces 45.1 and 46.2 are arranged on both sides of this piston, which are connected via lines to valves 39 or the hydraulic circuit.

In the upper diagram of Fig. 3, the position A, the pressure chamber is 46.2 shorted to the hydraulic circuit and the full pressure is applied in the pressure chamber 46.2. At the same time, the valve 39 is switched so that the pressure chamber 45.1 , which is arranged on the other side of the piston 44 , is connected to the return line to the tank for the hydraulic fluid 41 and by the movement of the piston 44 in the direction of the pressure chamber 45.1 the hydraulic fluid can escape from this pressure chamber 45.1 . The piston 44 is thus held in the position most viewed in the direction of the pressure chamber 45.1 .

In the representation of the position A, the two other pressure spaces 45.2 and 46.1 , which are arranged in the interior of the piston 44 , run with the hydraulic circuit for the pressure space 46.1 , and via a correspondingly switched valve 39, the pressure space 45.2 with the return line to the tank 41 connected. Due to the higher pressure in the pressure chamber 46.1, this acts on the corresponding surface of the actuating piston 42 and this is moved in the direction of the pressure chamber 45.2 zube. In such a selected position of the valves and switching of the connections to the hydraulic circuit, the piston 44 and the actuating piston 42 are each moved in the opposite direction.

In the representation of the position B, the piston 44 is held in the pressure spaces 46.2 and 45.1 just as in the representation of the position A with the same valve positions and pressurization. In contrast, the 2/2-way valve 39 is switched differently, and the connection of the pressure chamber 45.2 is not to the return line to the tank 41 , but this is connected to the hydraulic circuit, and the entire pressure is present in the pressure chamber 45.2 . Since the effective piston area of the Actuate the supply piston 42 is opposite the pressure chamber 45.2 is greater than the effective piston area in the pressure chamber 46.1, although in two pressure chambers, an equal pressure is applied, reaches a movement toward the pressure chamber 46.1 of the actuating piston 42 and the betae actuating piston 42 be moved into an appropriate position.

In the representation of the position C, the pressure spaces 45.2 and 46.1 are connected by switching the 2- / 2-way valve 39 with the hydraulic circuit and the return to the tank 41 , as is the case in the representation of the position A.

The pressure chamber 46.2 is still directly connected to the hydraulic circuit, and the same pressure prevails in it. The pressure chamber 45.1 is also connected directly to the hydraulic circuit via the 2/2-way valve 39 and is also subjected to the same pressure. Since the surface of the pressure chamber 45.1 acting against the piston 44 is also larger than that of the pressure chamber 46.2 in this case, a corresponding force is exerted on the piston 44 and moves it in the direction of the pressure chamber 46.2 .

Each movement of the piston 44 inevitably causes the actuating piston 42 to be displaced in the same direction and by the same path. Thus, two working positions can already be realized simply by the movement of the piston 44 , and the third position required for the use of the shift actuating cylinder 40 in the manual transmission can be achieved by appropriate connection or separation of the pressure spaces 45.2 and 46.1 . With appropriate dimensioning of the individual parts and the pressure chambers there is even the possibility of guiding the actuating piston 42 in four positions and then holding it there.

In addition to the described possibility of influencing the movement of the pistons 44 and the actuating piston 42 with the 2/2-way valves 39 , the same effect can be achieved in a somewhat more complex form in that the pressure in the pressure chambers 45.1 and 46.2 and in the pressure chambers 45.2 and 46.1 differentiates and is controlled separately, for example by using proportional valves. In the event that this possibility is used, it is not necessary to dimension the effective surfaces of the pistons in the respective pressure chambers under differently, and the movement is controlled solely by the pressure in the different pressure chambers.

Claims (22)

1. Mechanical gearbox for motor vehicles, which is switchable depending on the driving state or manually in different gear stages and a hydraulically disengageable friction clutch is arranged between an internal combustion engine and the gearbox, characterized in that control electronics ( 27 ) with inputs for the measured engine speed n _m , the Fahrzeugge speed v, the position of the mechanical clutch, the detection of the gear engaged, manually operated switch ( 5 ) for switching th in a higher, a lower and the reverse gear and
Outputs for the control of a clutch release cylinder ( 42 ) and switch actuation cylinder ( 40 ) is available;
wherein the shifting of the transmission is manually or electronically controlled depending on the result of an actual / target value comparison of the engine speed n _m and the vehicle speed v that can be carried out in the control electronics ( 27 ). 2. Manual transmission according to claim 1, characterized in that one of the control electronics ( 22 ) influenceable hydraulic circuit is present, in which three-position switching cylinder ( 40 ) for switching one or two gear stages are integrated for switching. 3. Manual transmission according to claim 1 or 2, characterized in that the shift actuating cylinder ( 40 ) are arranged directly attacking the shift sleeves or shift rods of the shift transmission. 4. Manual transmission according to one of claims 1 to 3, characterized in that speed sensors ( 1 ) on the wheels, the input signals for the motor vehicle speed and a signal for a possible slippage of the driven wheels, are connected to the control electronics ( 27 ). 5. Manual transmission according to claim 4, characterized in that the speed sensors ( 1 ) of the Antiblockiersy stem ( 28 ) of the motor vehicle with the control electronics ( 27 ) are connected. 6. Manual transmission according to one of claims 1 to 5, characterized in that an additional switch ( 5 ) for the first forward gear is connected to an input of the control electronics ( 27 ). 7. Manual transmission according to one of claims 1, 2, 3, 5 or 6, characterized in that a speed sensor ( 13 ) on the output shaft of the transmission, with which the vehicle speed can be determined in conjunction with the detection ( 20-26 ) of the gear engaged is arranged. 8. Manual transmission according to one of claims 1 to 7, characterized in that a pressure sensor ( 12 ) is inte grated in the hydraulic circuit. 9. Manual transmission according to one of claims 1 to 8, characterized in that the braking system ( 2 ) of the motor vehicle with an input of the control electronics ( 27 ) is the verbun. 10. Manual transmission according to one of claims 1 to 9, characterized in that an output of the control electronics ( 27 ) with the electronic engine control, this influencing before and during a switching operation, is connected. 11. Manual transmission according to one of claims 1 to 10, characterized, that the switches on the steering wheel of the motor vehicle are arranged.   12. Manual transmission according to one of claims 1 to 11, characterized in that display means ( 6 ) for performing a switching operation and for the selected gear are available. 13. Manual transmission according to one of claims 1 to 11, characterized in that in the control electronics ( 27 ) has a memory unit for each gear of the transmission at least an upper limit speed n _G0 , an upper limit speed v₀ and a maximum speed n _maxH for that Shifting into higher gear as well as at least a lower limit speed n _uR , a lower limit speed v _u and a minimum speed n _min for shifting into a lower gear for carrying out the target / actual value comparison with the measured values, integrated or connected to the control unit. 14. Manual transmission according to claim 13, characterized in that two speed _values n _wH and n _wR for the control of at least one display means ( 6 ) of a warning device and / or for information about the triggering of a switching operation are contained in the memory unit for each gear. 15. manual transmission according to claim 14, characterized, that the warning device at least one warning is light.   16. Manual transmission according to claim 14, characterized, that the device is a buzzer. 17. Manual transmission according to one of claims 1 to 16, characterized in that an input of the control electronics ( 27 ) with a sensor ( 7 ) for detecting the Drosselklap pen-, the control rod or Regelschieberstel development of the internal combustion engine is connected. 18. Manual transmission according to one of claims 1 to 17, characterized , that clutch and starter or ignition system like that are interconnected that a scarf only if the clutch is disconnected is possible. 19. Manual transmission according to claim 1 or 2, characterized in that the / the three-position switching actuating cylinder ( 40 ) in a housing ( 43 ) floating piston ( 44 ) in which two pressure chambers ( 45.2 ) and ( 46.1 ) bordered on opposite sides, by different pressurization in the pressure chambers ( 45.1 ) and ( 46.2 ), which keep the piston ( 44 ) floating, a longitudinally displaceable actuating piston ( 42 ) is received and guided in at least three positions. 20. The method according to claim 19, characterized in that the pressure spaces ( 45.1 , 45.2 , 46.1 , 46.2 ) are dimensioned so that the actuating piston ( 42 ) by opening and closing of the pressure spaces ( 45.1 , 45.2 , 46.1 , 46.2 ) connected Outputs of valves ( 39 ) a movement of the actuating piston ( 42 ) in one of three positions can be reached. 21. A method for the electronic or manual switching of a gearbox designed according to claim 1, characterized in that
that an actuation of a switch ( 5 ) for triggering a switching operation triggers such a when an upper limit speed n₀ and an upper limit speed v₀ of the vehicle for switching to a higher gear, a lower limit speed n _u for switching to a lower gear and a lower limit speed v _{u are} reached, and
a shift is triggered automatically when a maximum speed n _max or a minimum speed n _{min are reached} with an engaged gear. 22. Manual transmission according to claim 21, characterized, that when a speed difference between two between driven and non-driven wheels shifting into a higher gear is prevented.