Patent Publication Number: US-2004040400-A1

Title: Driving school vehicle, double pedal device, pedal box, adjuster and driving instructor post for use in the driving school vehicle

Description:
[0001] The present invention relates to a driving school vehicle, a double pedal device having hydraulic coupling, a pedal unit, actuators, and a driving instructor post for use in a driving school vehicle.  
       [0002] In the WO 85/03369 a relevant pedal set assembly for a driving school vehicle is described. The known assembly has a first set of pedals having a brake pedal and a clutch pedal which are located on the driver&#39;s side in a vehicle and which are operated by the learner or driver during the driving lessons, and a second set of pedals again comprising a brake pedal and a clutch pedal which are located on the passenger&#39;s side and which are operated by the driving instructor during the driving lessons. The brake pedal on the instructor&#39;s side is coupled to the brake pedal on the driver&#39;s side via hydraulic means. In addition, the clutch pedal on the passenger&#39;s side is coupled to the clutch pedal on the driver&#39;s side via coupling means in the driving school vehicle. When the instructor operates the brake pedal or the clutch pedal, this operation or movement of the pedals is transferred to the corresponding pedals on the driver&#39;s side by the hydraulic means.  
       [0003] The driving instructor operates his pedals generally then if a dangerous situation or an emergency occurs, for instance, if the driver has overseen a necessary operation of the brake or in order to show the driver the appropriate operation of the pedals due to the cooperative operation of the instructor&#39;s pedals in an exemplified manner.  
       [0004] Each of the known hydraulic coupling means comprises a driving pressure cylinder having a piston rod that is mounted on the respective pedal on the instructor&#39;s side, a driven pressure cylinder having a piston rod as pressure cylinder means being connected to the corresponding pedal on the driver&#39;s side, and a fixed pressure line between both pressure cylinders.  
       [0005] Since the operation of a pedal on the instructor&#39;s side transfers the power or force of operating the pedal directly via the related piston rod to the column of liquid in the hydraulic coupling system, a buckling, bending or warping of the piston rod can occur which results in the piston rod and the associated pressure piston in the related pressure cylinder to become stuck, and, further, in consequence, results in degradation of the function of the hydraulic pedal coupling. This often insidiously or slowly advancing malfunction may lead in case of emergency, e.g. an emergency stop that has to be initiated by the driving instructor, to an accident.  
       [0006] It is, therefore, an object of the present invention to create a double pedal device of a driving school vehicle, which securely avoids a malfunction due to bending or warping of the piston rod of the hydraulic coupling means.  
       [0007] This object is solved by the driving school vehicle according to claim 116 and claim 117, and particularly by the double pedal device according to claim 1 or claim 49, by the pedal unit according to claim 27 or by the actuators according to claim 40 or claim 43 for use in the double pedal device.  
       [0008] Correspondingly, the double pedal device of the invention to be used in a driving school vehicle has at least one pedal on the driver&#39;s side, at least one pedal on the passenger&#39;s side, and hydraulic means coupling the pedal on the driver&#39;s side to the pedal on the passenger&#39;s side so that on operating the pedal on the passenger&#39;s side the pedal on the driver&#39;s side is operated, too, wherein the hydraulic means comprises at least a pressure cylinder means being coupled to the pedal on the passenger&#39;s side, at least one pressure cylinder means on the passenger&#39;s side being coupled to the pedal on the passenger&#39;s side and being symmetrical to an axis of symmetry, and at least one pressure pipe, line or conduit that couples the pressure cylinder means on the driver&#39;s side to the pressure cylinder means on the passenger&#39;s side hydraulically, wherein sliding means that are coupled mechanically to the pedal and the pressure cylinder means on the passenger&#39;s side for transferring power or force between pedal and the pressure cylinder means or mater cylinder means on the passenger&#39;s side, and guiding means on which the sliding means are supported preferably moveably such that only a force or force component acts in the direction of the axis of symmetry of the pressure cylinder means during the transfer of force from the pedal on the passenger&#39;s side to the pressure cylinder means.  
       [0009] The present invention has the decisive advantage that only horizontal forces, i.e. only forces in the direction of the axis of symmetry of the pressure cylinder means act, can act on the pressure cylinder means, and thus a bending or warping of the piston rod of the pressure cylinder means is avoided. Thus, the problems of the state of the art explained above are eliminated by the invention.  
       [0010] A pedal unit for use in a double pedal device, particularly on the passenger&#39;s side of a driving school vehicle, has at least one pedal and at least one pressure cylinder means being mechanically coupled to the pedal and being symmetrical to an axis of symmetry, wherein sliding means or a slider being mechanically coupled to the pedal and the pressure cylinder means for transferring power or force between the pedal and the pressure cylinder means, and guiding means are provided on which the sliding means is supported moveably or slideably such that only a force or a force component acts in the direction of the axis of symmetry of the pressure cylinder means during the transfer of force from the pedal to the pressure cylinder means.  
       [0011] Preferably, the guiding device comprises a guiding rod on which the slider or sliding means are supported moveably or slidably wherein the sliding means is supported on the guiding rod by a linear bearing or support. The use of linear bearing or support facilitates that the sliding means transfers only the linear horizontal component of the force onto the pressure cylinder device.  
       [0012] Preferably, the pedal unit on the passenger&#39;s side comprises at least two identical pressure cylinder means, the axes of symmetry thereof are arranged in parallel to each other and with distance to each other in the same plane. This so-called tandem cylinder facilitates the implementation of a big stroke of the pedal on the driver&#39;s side, wherein the pedal unit on the passenger&#39;s side has a small and compact size.  
       [0013] Preferably, the sliding means is made of plastic or synthetic resin, particularly polyethylene in order to provide a sufficient elasticity of the sliding means in the case of fluctuations of the temperature.  
       [0014] An actuator for use in the double pedal device of the invention and for engagement in a pedal on the driver&#39;s side of the driving school vehicle comprises a hydraulic pressure cylinder means and a moveable catch means that is moved by the pressure cylinder means of the actuator and is in engagement with the pedal on the driver&#39;s side.  
       [0015] The catch means has preferably a catch or carrier, which is covered at least partly by nylon or a similar material with low friction in order to avoid tilting or abrasion of the pedal lever at the catch.  
       [0016] A further actuator for use in the double pedal device of the invention and for engagement into a pedal on the driver&#39;s side of a driving school vehicle comprises a hydraulic pressure cylinder and a gear or gearing that converts a movement of the pressure cylinder of the actuator into a movement of the pedal being engaged in the actuator on the driver&#39;s side. A relatively small stroke or operation of the pressure cylinder on the driver&#39;s side can be converted by the gear into a big adjustment or movement of the pedal being coupled.  
       [0017] The present invention relates also to a double pedal device for use in a driving school vehicle, particularly with an automatic transmission.  
       [0018] When a driving school vehicle has an automatic transmission, then the set of pedals on the driver&#39;s side comprises an accelerator pedal and a brake pedal. A clutch pedal is omitted in a vehicle with automatic transmission. When the driver or learner operates the accelerator pedal wrongly, e.g. too strong operation of the accelerator in a curve etc., a dangerous situation may occur during a driving lesson. A double pedal device for a driving school vehicle should therefore allow the correction of a wrong operation of the accelerator pedal caused by the learner.  
       [0019] A double pedal device of the invention, which allows this correction, is mentioned in claim 49. Correspondingly, the double pedal device of the invention, which particularly may be used in a driving school vehicle having automatic transmission, has a driver&#39;s side accelerator pedal on the side of the learner, a passenger&#39;s side accelerator pedal on the side of the instructor, and coupling means that couple the driver&#39;s side accelerator pedal to the accelerator pedal on the passenger&#39;s side so that in the case of operation of the passenger&#39;s side accelerator pedal also the driver&#39;s side accelerator pedal is operated with increasing gas or acceleration, wherein, on the side of the instructor, an anti accelerator pedal or an anti gas pedal is provided in addition, and wherein the coupling means couple the accelerator pedal or gas pedal on the driver&#39;s side to the anti gas pedal on the passenger&#39;s side so that in the case of operation of the passenger&#39;s side anti gas pedal the driver&#39;s side accelerator pedal is operated with decreasing gas.  
       [0020] Thus, the double pedal device of the invention having anti gas has the remarkable advantage, that the instructor can perform a taking back of the gas by operating the anti gas pedal, and thus he can cancel or take back an inadequate operation of the gas pedal by the learner, whereby dangerous situations also during driving the driving school vehicle can be eliminated.  
       [0021] The coupling means of the invention may be, for instance, pure mechanical coupling means that, for instance, uses ropes or tackle lines. However, hydraulic means are preferred as coupling means which comprise accelerator pedal hydraulic means being engaged in the accelerator pedal on the driver&#39;s side, accelerator pedal hydraulic means on the passenger&#39;s side which are coupled to the accelerator pedal on the passenger&#39;s side, and anti gas pedal hydraulic means being coupled to the anti gas pedal on the passenger&#39;s side, and pressure pipe means connecting the gas pedal hydraulic means on the driver&#39;s side to the gas pedal hydraulic means on the passenger&#39;s side and to the anti gas pedal hydraulic means on the passenger&#39;s side hydraulically.  
       [0022] Preferably, the accelerator pedal hydraulic means on the driver&#39;s side, the accelerator pedal hydraulic means on the passenger&#39;s side and the anti gas pedal hydraulic means on the passenger&#39;s side each have at least one pressure cylinder means.  
       [0023] The anti gas pedal hydraulic means may have sliding means being mechanically coupled to the anti gas pedal on the passenger&#39;s side and to the associated pressure cylinder means for power transfer between the anti gas pedal and the pressure cylinder means, and guiding means on which the sliding means are supported in a sliding or movable manner.  
       [0024] In this case it would be preferred that only a force or a force component towards an axis of symmetry of the pressure cylinder means acts onto the associated pressure cylinder means in the case of transferring the force from the anti gas pedal to the associated pressure cylinder means. Hereby a sticking or a tilting of a pressure cylinder rod is prevented.  
       [0025] The anti gas pedal hydraulic means of the passenger&#39;s side preferably comprise two pressure cylinder means, the axes of symmetry thereof are arranged in parallel and in distance to each other in the same plane. This so-called tandem cylinder has the advantage that it facilitates converting a stroke of the anti gas pedal into a twice as big stroke of an anti gas actuator of the driver&#39;s side even in the case of very compact and small construction of the anti gas pedal hydraulic means.  
       [0026] Preferably, the accelerator pedal hydraulic means of the driver&#39;s side comprises actuator means on the driver&#39;s side of the vehicle, which engage in the driver&#39;s side accelerator pedal, and has at least one pressure cylinder means.  
       [0027] The actuating means may have a gas or accelerator actuator for increasing gas and an anti gas or anti accelerator actuator for taking back of gas.  
       [0028] Further, the accelerator pedal of the driver&#39;s side can be adjusted between a position of zero gas in which the gas or accelerator pedal is not operated, and a position of maximum gas in which maximum or full gas is adjusted. In this process, the anti gas actuator moves the driver&#39;s side accelerator pedal in the direction from the maximum gas position to the zero gas position if the passenger&#39;s side anti gas pedal is operated, and, in this case, the gas actuator moves the driver&#39;s side gas pedal in the direction from the zero gas position to the maximum gas position if the passenger&#39;s side gas pedal is operated.  
       [0029] The present invention relates also to an instructor&#39;s post or stand for use in a driving school vehicle, particularly a truck or a bus, comprising an instructor&#39;s seat, i.e. a seat of the vehicle to be used by the instructor, in the cap or cell of the driving school vehicle.  
       [0030] Known instructor&#39;s posts, particularly in trucks or busses, which are also used for sake of driving school, generally use the passenger&#39;s seat in the cap of the vehicle. The passenger&#39;s seat is designed in most cases, particularly in busses, only as auxiliary seat that provides only insufficient ergonomic conditions for the instructor. Further, the passenger&#39;s seat is distant from the seat on the driver&#39;s side so far that the instructor can control the learner during a driving lesson only with difficulty which can lead to dangerous situations during the driving school lessons. Thus, an instructor&#39;s post is desired which improves the ergonomic conditions of the driving instructor.  
       [0031] This object is solved by the driving school vehicle according to claim 116 or claim 117, and particularly by the driving instructor&#39;s post according to claim 72, claim 88, claim 94, claim 95, claim 101, or claim 114. Accordingly, the instructor&#39;s post of the invention for the driving school vehicle, particularly for use in a truck or a bus, has an instructor&#39;s seat, i.e. a seat in the vehicle for use by the instructor, in the cap of the driving school vehicle, and instructor&#39;s side pedal means in a double pedal device for operation by the instructor wherein the instructor&#39;s side pedal means are coupled to driver&#39;s side pedal means for controlling the driver&#39;s side pedal means of the double pedal device, and wherein a distance between the vehicle seat and the instructor&#39;s side pedal means can be adjusted. The instructor&#39;s post can be adapted to the dimensions or measures of the respective instructor by means of adjustment ability of the distance between the instructor&#39;s seat and the pedal means. Thereby, the instructor has a more relaxed and more convenient position of the body during the driving lesson, which contributes to an improved power of concentration of the instructor.  
       [0032] The vehicle seat of the instructor and/or the pedal means of the instructor&#39;s post can be arranged in longitudinal direction of the driving school vehicle in the cap of the driving school vehicle in a shiftable or moveable manner for changing the distance between the vehicle seat and the instructor&#39;s side pedal means.  
       [0033] The instructor&#39;s seat may be arranged preferably on or in rails or grooves in the floor pan of the vehicle, which extend in parallel to each other and then the instructor&#39;s seat can be shifted thereon. The instructor&#39;s side pedal group can be fixed to the base or floor pan of the vehicle or the pedal means can be formed shiftably or in an easily moveable manner.  
       [0034] For instance, the pedal means may be mounted on the floor pan of the vehicle by means of an easily releasable Velcro fastener. If the distance between the pedal means and the seat should be changed, the Velcro fastener may easily released and the pedal means can be arranged in the new position with changed distance as desired. The surface of the Velcro fastener on the floor pan of the vehicle is formed to be bigger with regard to the surface than the adhering surface of the Velcro fastener on the pedal means in order to allow a corresponding adjustment of the distance between seat and pedal group.  
       [0035] Preferably, the instructor&#39;s seat has a seat surface that is arranged more higher than the seat surface of the driver&#39;s seat in order to facilitate a better view of the learner&#39;s driving action and driving operation by the instructor.  
       [0036] The instructor&#39;s seat has preferably a seat portion or member and pneumatic spring action means supporting the seat portion. The pneumatic spring or air suspension allows a convenient and comfortable sitting of the instructor and, in addition, adjusting the height of the seat by a height adjusting means for adjusting the height of the instructor&#39;s seat above the driving school vehicle floor pan.  
       [0037] The instructor&#39;s seat may also comprise a backrest member and a pivoting arrangement for adjusting the inclination of the backrest member relative to the seat surface of the seat portion whereby an additional adjusting possibility and, thus, a even more comfortable or yet more ergonomic sitting position of the instructor can be attained.  
       [0038] The instructor&#39;s side pedal means are preferably coupled to the driver&#39;s side pedal means via hydraulic means. Further, the hydraulic means may have a flexible pressure line, pipe or conduit for transferring an actuating pressure to the driver&#39;s side pedal. The use of flexible pressure lines in the hydraulic means has the advantage that the instructor&#39;s side pedal means may be easily shifted or displaced for adapting to the instructor&#39;s seat without requiring mounting efforts for the rearrangement of coupling lines between the pedal groups.  
       [0039] The instructor&#39;s seat has preferably a rack or support on which the instructor&#39;s side pedal means is mounted. This has the advantage that the instructor&#39;s post having a seat and pedal means is formed in unit that can be mounted in one step of work into the driving school vehicle and it can be also demounted easily again if required. Then a position of the pedal means relative to the seat on the rack, which has been adjusted once, can be maintained. The same instructor then must not readjust the instructor&#39;s post each time when the instructor&#39;s post is mounted in the vehicle. Here it is also preferred that the rack comprises means for adjusting the distance between the instructor&#39;s seat and the instructor&#39;s side pedal means or that the rack can be adjusted easily.  
       [0040] The instructor&#39;s side pedal means may be shiftably mounted on the rack for adjusting the distance between the instructor&#39;s seat and the instructor&#39;s pedal means.  
       [0041] The rack for the instructor&#39;s side pedal means is preferably mounted on the seat portion of the instructor&#39;s seat. This facilitates that the pedal means always maintain the adjusted position relative to the seat surface even when the seat itself should be readjusted in height.  
       [0042] The rack may have a guide in which the instructor&#39;s side pedal means can be moved or locked. In addition, the instructor&#39;s side pedal means can be inserted into the guide or it can be removed there from.  
       [0043] The present invention relates also to an instructor&#39;s post or stand for a driving school vehicle, particularly a truck or a bus, having a vehicle seat for the instructor in the driver&#39;s cap of the driving school vehicle and pedal means for operation by the instructor wherein the instructor&#39;s side pedal means are coupled to driver&#39;s side pedal means for controlling the driver&#39;s side pedal means and wherein display means, particularly an electronic display, is provided which shows to the instructor at least a view of the surroundings of the driving school vehicle.  
       [0044] The display means has the remarkable advantage that the instructor may catch the current driving situation completely even when his angle of view to the exterior mirror is different to the learner&#39;s angle of view or even only restricted. The instructor can observe, for instance, the blind angle by using the display device. Thus, this contributes remarkably in making the driving schoolwork more safely.  
       [0045] The display may have several display fields each of which can show a different view of the surroundings of the driving school vehicle. For instance, a left side, right side view of the surroundings, a rear view an/or a front view of the driving school vehicle and of its surroundings may be shown whereby the instructor&#39;s possibilities for observing can be improved.  
       [0046] The instructor&#39;s post has preferably coupling means, for instance, an easily pluggable connection or connector having corresponding plugs and cables, which connect or couple the display means to a video camera or to several video cameras mounted on the driving school vehicle which catch the view(s) of surroundings of the driving school vehicle for displaying the views of surroundings on the display means.  
       [0047] The display means are preferably fixed to the instructor&#39;s seat in order to attain an instructor&#39;s post in one unit. The support for the display means may be mounted on the seat member of the instructor&#39;s seat.  
       [0048] The present invention also relates to an instructor&#39;s post or an instructor&#39;s seat device for use in a driving school vehicle, particularly a truck or a bus, having a vehicle seat for the instructor in the cap of the vehicle wherein the instructor&#39;s seat is arranged or mounted in a middle area between a driver&#39;s seat and a passenger&#39;s seat on the floor pan or chassis base group of the driving school vehicle.  
       [0049] Known instructor&#39;s posts, particularly in trucks or busses, which also are used for the purposes of driving schools, use generally the passenger&#39;s seat in the driver&#39;s cap of the vehicle. The passenger&#39;s seat is in most cases only formed as auxiliary seat, particularly in busses, which only offers insufficient ergonomic conditions for the instructor. Further, the passenger&#39;s seat is distant to the seat on the driver&#39;s side such far that the instructor can control the learner during a driving lesson only with difficulties, which may lead to dangerous situations during the driving lessons. Therefore, an instructor&#39;s post is desired which improves the ergonomic conditions of the instructor and, therefore, enhances the security during the driving lessons.  
       [0050] This object is solved by the instructor&#39;s post according to claim 94, claim 95, claim 101 or claim 114. Correspondingly the instructor&#39;s post of the invention to be used in a driving school vehicle, particularly in a truck or in a bus, has an instructor&#39;s side pedal device to be operated by the instructor wherein the pedal means is coupled to driver&#39;s side pedal means for controlling the driver&#39;s side pedal means which together form a double pedal device, and it has at least one pedal, and a footrest for the instructor which is arranged in a region above the pedal.  
       [0051] The instructor&#39;s post of the invention for a driving school vehicle, particularly a truck or a bus, has an instructor&#39;s side controlling unit, which is coupled to an electrical arrangement or device of the driving school vehicle for controlling the driving operation.  
       [0052] The instructor&#39;s post or the double pedal device of the invention for a driving school vehicle particularly a truck or a bus has instructor&#39;s side pedal means for operation by the instructor, wherein the pedal means are coupled to a driver&#39;s side pedal means for controlling the driver&#39;s side pedal means and wherein a pedal linkage of the pedal means is surrounded by a folded and flexible sleeve or cover.  
       [0053] Further advantageous embodiments of the present invention are mentioned in the dependent claims. 
     
    
    
     [0054] Further advantages, advantageous embodiments and uses of the present invention result from the following description of preferred and exemplified embodiments of the invention in connection with the enclosed drawings, which show:  
     [0055]FIG. 1 a schematic perspective view of a preferred pedal unit in the double pedal device of FIGS. 4 and 5 according to a preferred embodiment of the invention;  
     [0056]FIG. 2 a perspective, partly cut away and separated view of a preferred actuator on the driver&#39;s side for use in the double pedal device of FIGS. 4 and 5 according to a preferred embodiment of the invention;  
     [0057]FIG. 3 a separated, partly sectional perspective view of a further preferred actuator on the driver&#39;s side of the vehicle for use in the double pedal device of FIGS. 4 and 5 according to a preferred embodiment of the invention;  
     [0058]FIG. 4 a perspective view of the driver&#39;s side pedal means of a preferred embodiment of the double pedal device of the invention, which may be used in the instructor&#39;s post of FIGS. 11 and 12 and also in the instructor&#39;s post of FIGS. 13, 14 and  15 , inclusively the components of FIGS. 1, 2 and  3 ;  
     [0059]FIG. 5 a perspective view of the passenger&#39;s side pedal means of a preferred embodiment of the double pedal device of the invention wherein both pedal means of FIGS. 4 and 5 are connected to each other at the interfaces A, B and C and wherein the passenger&#39;s side pedal means and the instructor&#39;s side pedal means may be used in the instructor&#39;s post of FIGS. 11 and 12 and also in the instructor&#39;s post of FIGS. 13, 14 and  15 , inclusively the components of FIGS. 1, 2 and  3 ;  
     [0060]FIG. 6 a schematic perspective view of a preferred pedal unit to be used in the double pedal device with anti gas of FIGS. 9 and 10 according to a further preferred embodiment of the invention;  
     [0061]FIG. 7 a perspective partly cut off and separated view of an actuator on the driver&#39;s side for use in the double pedal device of FIGS. 9 and 10 according to a preferred embodiment of the invention;  
     [0062]FIG. 8 a separated partly cut off perspective view of a further actuator on the driver&#39;s side of the vehicle for use in the double pedal device of FIGS. 9 and 10 according to a preferred embodiment of the invention;  
     [0063]FIG. 9 a perspective view of the driver&#39;s side pedal means of a further preferred embodiment of the double pedal device of the invention which may be used in the instructor&#39;s post of FIGS. 11 and 12 and also in the instructor&#39;s post of FIGS. 13, 14 and  15 , inclusively the components of FIGS. 6, 7 and  8 ;  
     [0064]FIG. 10 a perspective view of the passenger&#39;s side pedal means of the further preferred embodiment of the double pedal device of the invention with anti gas pedal wherein both parts according to FIGS. 9 and 10 are connected to each other at the interfaces A 2 , B 2  and C 2  and wherein the passenger&#39;s side pedal of FIG. 9 may also be used in the instructor&#39;s post of FIGS. 11 and 12 and also in the instructor&#39;s post of FIGS. 13, 14 and  15 , inclusively the components of FIGS. 6, 7 and  8 ;  
     [0065]FIG. 11 a schematic lateral view of the driver&#39;s cap of a driving school vehicle with a mounted instructor&#39;s post according to a preferred embodiment of the invention, to be seen in the direction of the arrow I of FIG. 12;  
     [0066]FIG. 12 a schematic plane view of the separated instructor&#39;s post of FIG. 11, to be seen in the direction of the arrow II of FIG. 11;  
     [0067]FIG. 13 a perspective plane view of an instructor&#39;s post according to a preferred embodiment of the invention comprising an instructor&#39;s seat, a controlling unit and a rack for an instructor&#39;s side pedal means wherein the instructor&#39;s post is mounted in a cap of a driving school vehicle;  
     [0068]FIG. 14 a perspective view of the instructor&#39;s post of the embodiment of the invention of FIG. 13 being seen from the passenger&#39;s side of the driving school vehicle; and  
     [0069]FIG. 15 a perspective detailed view of the embodiment of FIGS. 13 and 14 wherein the rack for the instructor&#39;s side pedal means is shown in more detail. 
    
    
     [0070]FIG. 2 shows an actuator  10  in a separated perspective and partly cut off view. The actuator  10  comprises a cylindrical hollow actuator casing  14  being opened at its end, a pressure cylinder  11  that extends at least partly within the cavity of the actuator casing  14  and concentrically to an axis of the actuator casing  14 , a piston rod  18  which is coupled to the pressure cylinder  11  within the cavity of the actuator casing  14  by means of a pressure cylinder piston not shown in the drawing and which is connected to a catch cylinder  17  at its other end in a fixedly manner, which is fitted in the actuator casing  14  in a slideable or moveable manner and which can be moved back and forth along the axis of the actuator casing  14  within the cavity, and a spring  16  extending between the other end of the actuator casing  14  concentrically to the axis of the actuator casing  14 , i.e. in more detail between the catch cylinder  17  and an actuator support  19  made of synthetic resin, which terminates the other end of the actuator casing  14 .  
     [0071] The pressure cylinder  11  is made of stainless steel or aluminium and it is hydraulically coupled to an associated pressure pipe or pressure line of the hydraulic coupling means by means of a hollow screw  13  being fixed at the end of the pressure cylinder  11  and having a screwable thread socket. The pressure cylinder  11  is arranged concentrically to the axis of the actuator casing  14  within the cavity or hollow space of the actuator casing  14 . The pressure cylinder  11  has grooves  12  extending radially and annularly on the exterior surface of the pressure cylinder  11  and at its end towards the hollow screw  13 . Pins  20  engage in the grooves  12 , which pass through corresponding holes in the wall of the actuator casing  14  in order to fix the pressure cylinder  11  on the actuator casing  14 .  
     [0072] According to FIG. 2, the pressure cylinder  11  has five of these radial grooves  12  on the whole wherein two neighbouring grooves cannot be seen in FIG. 2 since they are covered by the whole of the actuator casing  14 , but they are engaged in both fixing pins  20  shown.  
     [0073] During establishing the actuator  10 , one can determine by means of the radial grooves  12  and the pins  20  cooperating with the grooves how far the pressure cylinder  11  extends into the actuator casing  14  or projects from the end of the actuator casing whereby the position of the catch  15  along the actuator casing  14  in its initial position can be adjusted in which no pressure acts on the pressure cylinder  11 , and therefore the maximum stroke of the catch  15  of the actuator  10  in adaptation to the respectively given construction of the associated pedal can be adjusted. Thus, the actuator  10  can be adapted to the pedals of different types of vehicles and to vehicles having different stroke of pedal.  
     [0074] Within the pressure cylinder  11 , there is located a pressure piston (not shown) on which the hydraulic pressure existing in the pressure cylinder acts. The pressure piston is sealingly and moveably supported within the pressure cylinder  11  so that hydraulic liquid cannot escape from the pressure cylinder  11 . The pressure piston is connected to a piston rod  18  within the pressure cylinder  11  which projects from the pressure cylinder  11  within the actuator casing  14  and which extends concentrically to the axis of the cylindrical actuator casing  14 .  
     [0075] At the other end of the piston rod  18 , the catch cylinder  17  is accommodated which is moveable back and forth within the actuator casing  14  along the axis of the actuator casing  14  and which moves depending on the pressure of the hydraulic pressure cylinder  11 . The catch cylinder  17  can be made of stainless steel, aluminium, or a synthetic resin and is formed preferably in a solid manner.  
     [0076] The catch  15  is fixed to the external surface of the catch cylinder  17  and it has a hooked contour if seen in the front elevation wherein the opening of the hooked catch  15  points to the end of the actuator casing  14  with the actuator support  19 . The catch  15  has a catch leg extending in parallel to the axis of the actuator casing  14 , and a catch basis mounted on the catch cylinder  17 . The catch may be provided with a synthetic resin, particularly nylon, on its surface.  
     [0077] The opening of the catch, i.e. the region between the external wall of the actuator casing  14  and the surfaces of the catch  15  which are adjacent to the opening of the catch, is formed so that the pedal lever, to which the actuator  10  is coupled, fits into the catch opening of the catch  15  in order to assure a secure operation of the associated pedal or pedal lever.  
     [0078] The spring  16  is accommodated in the cavity of the actuator casing  14  between the actuator support  19  and the catch cylinder  17 , which is formed as a compression spring and which pushes the moveable catch cylinder in the cavity of the actuator casing  14  towards the pressure cylinder  11 .  
     [0079] The actuator support  19  is fitted into the cavity of the actuator casing  14  at the corresponding end of the actuator casing  14  and it terminates the corresponding end of the actuator casing  14 . The actuator support  19  serves as an opposing or counter support of the spring  16  and for mounting or fixing the actuator  10  on the chassis of the vehicle on the driver&#39;s side in the region of the pedal or on a basic plate  96  separately provided which is mounted or accommodated in the area of the pedal of the vehicle on the driver&#39;s side. The actuator support  19  can also be formed as articulation or joint in order to mount the actuator  10  on the chassis or the basic plate  96  in the region of the pedal on the driver&#39;s side in a jointed or articulate manner.  
     [0080] A slot  21  is formed in the wall of the actuator casing  14  which extends in parallel and along the axis of the actuator casing  14  and through which the catch  15  of the catch cylinder  17  projects from the actuator casing  14 . The free width of the slot  21  or of the recess is adapted to the thickness or dimension of the catch  15  so that the catch  15  is able to move freely back and forth. The length of the slot  21  corresponds at least to the maximum allowable stroke of the catch  15 . The slot  21  may be formed with regard to its dimension so that a guiding of the catch  15  is carried out by the walls of the slot.  
     [0081] When the pressure cylinder  11  of the actuator  10  is provided with pressure by operation of the associated pedal on the passenger&#39;s side, i.e. by the driving school instructor, the piston rod  18  and thus the catch cylinder  17  and the catch  15  are shifted towards the actuator support  19  against the compression force of the spring  16  whereby the pedal being engaged is operated on the driver&#39;s side. When subsequently the operation of the pedal on the passenger&#39;s side is taken back, also the hydraulic pressure in the pressure cylinder  11  decreases and the catch cylinder  17  together with the catch  15  is shifted or moved in the opposite direction, i.e. towards the pressure cylinder  11 , by the spring  16  until a balance between the pressure force of the pressure cylinder  11  and the compression force of the spring  16  is provided. When the instructor takes back the pedal pressure or the pedal action yet further until a pedal operation on the passenger&#39;s side does not longer exist, the spring  16  shifts or pushes the catch cylinder  17  along with the catch  15  more and more into the direction the pressure cylinder  11  until the catch  15  reaches its starting or initial position, in which there isn&#39;t any pressure action by the pressure cylinder  11 , but only a pressure is given by action of the spring  16 .  
     [0082]FIG. 3 shows an actuator  30  in a view corresponding to FIG. 2. The actuator  30  has an actuator casing  34  having a pressure cylinder  31  with grooves  32  extending radially on the surface, and a terminating hollow screw  33 , a catch  35  or support which projects from the actuator casing  34 , a spring  36 , which is formed as a compression spring, and a moveable cylinder  37  in the interior of the actuator casing  34  which is connected to a piston rod (not shown in FIG. 3) on one of its ends, wherein the piston rod extends into the pressure cylinder  31  and is connected to a pressure piston in the interior of the pressure cylinder  31 . The pressure cylinder  31  can be adjusted and fixed on the actuator casing  34  by the grooves  32 , and the fixing pins  40 .  
     [0083] The configuration and the function of the elements  31 ,  32 ,  33 ,  34 ,  36  and  39  of a actuator support and of a slot  51  are identical to the configuration and function of the corresponding elements of the actuator  10  which is shown in FIG. 2. Concerning a detailed description of the configuration and the function of these elements, it is referred to the explanations mentioned above with regard to FIG. 2. In contrast to actuator  10  in FIG. 2, the actuator  30  in FIG. 3 does, however, have not any catch, but it is connected to an associated pedal lever or driver&#39;s side pedal by a chain  41  or linkage. The configuration or construction of the actuator  30  having a chain  41  will be described in detail in the following.  
     [0084] A chain support  42  is set on or pushed on the cylindrical actuator casing  34  of the actuator  30 , which is formed as a rectangular cuboid. The chain support  42  is clamped fixedly on the actuator casing  34  of the actuator  30  by means of a clamping screw  43 . In FIG. 8, a small gap  52  can be seen within the lower area of the chain support  42 , which enables clamping by the clamping screw  43  on the circumference of the actuator casing  34 . Before clamping of the chain support  42 , the chain support  42  may be shifted on the circumference of the cylindrical actuator casing  34  and, thus, it can be adjusted in its final position. By clamping, the chain support  42  is fixed in its position on the actuator casing  34  and along the length of the actuator casing  34 . In the upper portion of the rectangular chain support  42  a compartment  44  is provided which is opened to the outside and accessible from the outside at the shown corner of the chain support  42 . In the compartment a first gear wheel  45  or pinion gear or toothed wheel is arranged on a shaft  46  or arranged rotateably together with the shaft  46 . The chain  41  is held on the chain support  42  with a chain mount  47  at one of its ends.  
     [0085] A support  35  is connected to the cylinder  37 , which projects out of the actuator casing  34  through the slot  51 . As support  35  the hooked catch  15  in FIG. 7 is used in FIG. 3. A cylindrical gear wheel casing  48  is mounted on the support  35 , in which a further gear wheel  49  is rotateably arranged and supported. In the wall of the gear wheel casing  48 , two slots  48 . 1  are formed which are distant to each other and through which the chain  41  passes.  
     [0086] The chain  41  extends starting from the chain mount  47  on the chain support  42  towards the gear wheel casing  48  that is connected to the support  35 . The chain  41  is put around the gear wheel  49  and extends through one of the slots  48 . 1  into the gear wheel casing  48  and through the other of the slots  48 . 1  to the outside of the gear wheel casing  48  and, therefore, it is redirected or deflected by 180° by the gear wheel  49 . The chain  41  extends from the gear wheel casing  48  towards the chain support  42  and it entries into the compartment  44 , it passes the gear wheel  45  that engages in the chain members of the chain  41 , and it exits the compartment  44  after being deflected by 90°. After the compartment  44 , the chain extends to the associated pedal or pedal lever, on which the chain is mounted by, for instance, a clamp or a bracket with its final chain member.  
     [0087] If the pressure cylinder  31  is subjected to pressure force against the force of the spring  36 , the cylinder  37  is moved towards the actuator support  39 . Along the cylinder  37 , then also the support  35  with the gear wheel casing  48  is moved, whereby the chain  41  is pulled from the chain support  42  towards the actuator support  39 . This movement is transferred from the gear wheel  49  to the mount of the chain  41  on the pedal, whereby the pedal is operated by the tension or pull of the chain.  
     [0088] If the pressure within the pressure cylinder  31  is decreased, the cylinder  37  along with the support  35  and the gear wheel casing  48  are shifted or moved back by the spring  36  towards the chain support  42 , whereby the length of the chain between the chain support  42  and the gear wheel  49  or the gear wheel casing  48  is shortened and, thus, the operation of the coupled pedals is taken back.  
     [0089] A stroke of the pressure cylinder  31  or a stroke of the cylinder  37  in the actuator casing  34  and of the support  35  having the chain casing  48  is converted into a double as big stroke of the portion of the chain  41  between the chain support  42  and the pedal by the 180° redirection of the chain  41  via the gear wheel  49 , whereby big strokes of the pedal can be performed by the actuator  30 .  
     [0090] In FIG. 1, a pedal unit  80  that is arranged on the passenger&#39;s side is shown in accordance to a preferred embodiment of the present invention. The pedal unit  80  comprises to hydraulic cylinders  69 ,  68 , which have identical construction and are arranged with distance to each other and in parallel to each other, pressure piston rods  70  and  71  of identical configuration, guiding rods  66  and  65  of identical configuration, a hydraulic block  64 , a slider  63  or a carriage, which is supported on the guiding rods  66  and  65  moveably to and fro, which is clearly shown in FIG. 1 by the double arrow being shown, an end block  62 , in which the pedal lever  60  is supported pivotably and jointly or articulately, and a supporting lever  61 , which is jointly supported on the pedal lever  60  and also on the slider  63  and which, therefore, couples the slider  63  to the pedal lever  60  in order to transfer a movement of a pedal lever  60  to the slider  63  by means of the supporting lever  61 .  
     [0091] The pedal lever  60  engages in a recess of the end block  62  with one of its ends, in which a pin extends, around the longitudinal axis thereof the pedal lever  60  can be pivoted or rotated. The recess in the end block  62  has dimensions such that a sufficient freedom of movement of the end of the pedal lever  60 , which is supported in the end block  62 , is provided. A plane pedal disc is fixed to an opposite end of the pedal lever  60  that allows an operation by foot by the passenger or the driving school instructor.  
     [0092] The supporting lever  61  is jointly mounted on the pedal lever  60  so that a movement of the pedal lever  60  is transferred to the supporting lever  61 . The other end of the supporting lever  61  engages in a slotted recess  63 . 1  (refer to FIG. 5) of the slider  63  and it is supported within this recess rotateably or pivotably around a transverse pin wherein the transverse pin of the slider  63  is oriented for supporting the supporting lever  61  in parallel to the supporting pin in the end block  62  for supporting the pedal lever  60 . Further, the transverse pin for supporting the supporting lever  61  in the slider  63  and also the supporting pin for supporting the pedal lever  60  in the end block  62  are oriented perpendicularly to a direction of movement of the slider  63  on the guiding rods  65  and  66 .  
     [0093] The block shaped slider  63  is moveably supported or mounted with a linear support  72  on the guiding rod  66  and with a second linear support  74  on the guiding rod  65 . Both linear supports  72  and  74  or bearings are fitted or inserted in bores, holes or channels passing through and having a section of circular shape in the slider  63 , and are accommodated therein and allow a linear support of the slider  63  on the guiding rods  66  and  65 . The slider  63  consists of, for instance, polyethylene (type Simona PE-HWST according to ISO  10285 ). As linear support  72  or  74 , for instance, a linear ball bearing having running path plates (type SKF LBBR12-2LS) can be used.  
     [0094] Further, in the slider  63 , pressure piston rods  70  and  71 , which extend in parallel to each other, are fixed with their ends being not adjacent to the pressure piston. Thus, a movement or shifting of the slider  63  on the guiding rods  66  and  65  is transferred directly onto the pressure piston rods  70  and  71 .  
     [0095] The pressure piston rods  70  and  71  engage in the pressure cylinder  69  and  68  with the pressure piston rod  70  projecting into the pressure cylinder  69  and the pressure piston rod  71  projecting into the pressure cylinder  68 . Pressure pistons are arranged on the ends of the pressure piston rods  70  and  71  which are located within the pressure cylinders  69  and  68 , wherein the pressure pistons are moveably and sealingly supported in the corresponding pressure cylinders  69  and  68 , respectively. A movement of the pressure piston rods  70  or  71  is transferred to the corresponding pressure pistons and, therefore, it acts on the liquid column within the pressure cylinders.  
     [0096] Both pressure cylinders  69  and  68  extend in parallel to each other and are fixed in the hydraulic block  64 , for instance, by corresponding screw connections. The exits of both pressure cylinders  68  and  69  are united via a channel  64 . 1  in the hydraulic block  64  to an entrance of the hydraulic block  64  that is provided with a hollow screw  64 . 2  (refer to FIG. 5).  
     [0097] The guiding rods  66  and  65  extending in parallel to each other are fixedly connected at one end to the hydraulic block  64 , for instance, by means of corresponding screw connections. They extend further through the slider  63 , namely through the linear supports  72  and  74 , and to the end block  62  to which they are connected again, for instance by screw connections. A compression spring  68  is installed between the slider  63  and the hydraulic block  64 , the compression spring is wound around the guiding rod  66  in the shape of a helix. The compression spring  68  or helical spring is fixed or screwed with one end to the hydraulic block  64 , whereas the other end of the compression spring  68  is screwed on the slider. The compression force of the compression spring  68  moves the slider  63  away from the hydraulic block  64  towards the end block  62  if there is not any counter force by the pedal lever  60 . A further compression spring  67  or a coil spring is arranged on the guiding rod  65  between the slider  63  and the hydraulic block  64  and is fixed thereon like the compression spring  68 . The compression force of the compression spring  67  also tends to move the slider  63  away from the hydraulic block  64  towards the end block  62 .  
     [0098] A sleeve  73  is pushed onto the guiding rod  66  between the slider  63  and the end block  62 . An identical sleeve  73  is also pushed onto the guiding rod  65  between the slider  63  and the end block  62 . Both sleeves  73  are configured identically to each other and have the purpose to limit the movement of the slider  63  towards the end block  62 . I.e. the slider  63  touches the sleeves  73 , if only the compression forces of both springs  68  and  67  act without any counter force of a pedal operation. The slider  63  then is in the position shown in FIG. 1.  
     [0099] The fictitious symmetry axis F of the pressure cylinder  69  and the fictitious symmetry axis of the pressure piston rod  70  coincide. In addition, the fictitious axes of the pressure cylinder and of the pressure rod  71  coincide. The axes of both pressure cylinders  69  and  68  are oriented accurately in parallel to each other. Additionally, the axes of the guiding rods  66  and  65  are oriented in parallel to each other and extend along with the axes of the pressure cylinders  69  and  68  in a common plane. The supporting lever  61  is supported in the middle of the slider  63  so that forces occurring during operation of pedal are evenly distributed to both cylindrical pistons  70  and  71  via the slider  63 . In addition, the pedal lever  60  is supported in the middle between the guiding rods  66  and  65  on the end block  62 .  
     [0100] The pedal unit is preferably mounted on a plate  100  or basis, which lies on the passenger&#39;s side base of the vehicle and is fixed thereon preferably by a Velcro fastener. Thus, the pedal unit  80 , due to the circumstances that only a Velcro fastener is required, can easily be mounted and, if necessary, demounted, too. The pedal unit  80  or its mounting plate  100  may also be screwed on the base. The Velcro fastener is sufficient since the force acting during operation of pedal on the pedal lever  60  is transferred via the pedal lever  60  and the supporting lever  61  to the slider  63  so that only a linear force component is developed only in the direction of movement of the slider  63  and additionally a force component is developed which acts perpendicularly to the direction of movement of the slider  63 , i.e. towards the base of the vehicle, whereby the pedal unit  80  is pressed perpendicularly towards the base of the vehicle during operation of pedal and, therefore, tilting forces can not act on the pedal unit  80  during operation of pedal.  
     [0101] In FIGS. 4 and 5, a preferred embodiment of double pedal device of the invention for a driving school vehicle is shown as an example, wherein in FIG. 4 the pedal set or the pedal means  90 . 5  on the driver&#39;s side of the vehicle and in FIG. 5 the second pedal set or the second pedal means  80 . 5  on the passenger&#39;s side are shown, i.e. on the instructor&#39;s side.  
     [0102] The first pedal set  90 . 5  on the driver&#39;s side comprises as usually an accelerator pedal  95 , a brake pedal  94  and a clutch pedal  93 , an actuator  10  according to FIG. 2, the catch  15  thereof is engaged in a pedal lever  93 . 1  of the pedal  93 , an additional actuator  30  which is shown if FIG. 3 in more detail, a chain  41  thereof is on one of it ends fixed to a pedal lever  94 . 1  of the pedal  94 , for instance, using a clamp or a bracket, and an additional actuator  10 . 1  having the same configuration as the actuator  10  in FIG. 2 and having a catch  15 . 1  which is engaged in a pedal lever  95 . 1  of the pedal  95 . An actuator plate  96  is provided on which the actuator  10  together with the actuator support  19  is mounted, on which the actuator  30  together with its support  39  is fixed and on which in addition the actuator  10 . 1  together with its actuator support is fixed.  
     [0103] The pressure cylinder  11  of the actuator  10  is fluid coupled via the hollow screw  13  terminating the pressure cylinder  11  to the hydraulic pressure line  92 . The pressure cylinder  31  of the actuator  30  is fluid coupled via the hollow screw  33  to a pressure line  91 . The pressure cylinder  11 . 1  of the actuator  10 . 1  is fluid coupled to a pressure line  90 , too.  
     [0104] The second pedal set  80 . 5  on the passenger&#39;s side has a casing that is not shown and, according to FIG. 5, three pedals  97 ,  98 ,  99 , wherein the pedal  97  is the accelerator pedal, the pedal  98  is the brake pedal, and the pedal  99  is the clutch pedal. The second pedal set comprises a pedal unit  80  that is described in more detail in FIG. 1, a further pedal unit  80 . 1  that corresponds to the pedal unit  80  being described in FIG. 1, and a third pedal unit  81  that, in difference to the pedal units  80  and  80 . 1 , only comprises a single pressure cylinder having a pressure piston rod, a single guiding rod with compression spring, a slider correspondingly designed, a hydraulic block and a supporting lever connection to the pedal  97 .  
     [0105] The hydraulic block  64  of the pedal unit  80  is interconnected to the pressure line  92  via the hollow screw  64 . 2  that has a screwing bolt. The hydraulic block of the pedal unit  80 . 1  is coupled to the pressure line  91  via a hollow screw. The hydraulic block of the pedal unit  81  is also coupled to the pressure line  90  via hollow screw.  
     [0106] The used hydraulic means comprise, as shown in FIG. 5, the pressure cylinder means on the passenger&#39;s side each having a pressure cylinder with pressure piston rod, the pressure cylinder means of the actuators  10 ,  10 . 1  and  30  each having a pressure cylinder and an associated pressure piston rod, the flexible pressure lines  90 ,  91  and  92 , and the hydraulic blocks  64  on the passenger&#39;s side are filled with a hydraulic liquid. A hydraulic oil, gabel or fork oil, or white oil can be used as hydraulic liquid. Preferably, a hydraulic liquid having a viscosity number 1 is used in order to avoid delays in reaction of the hydraulic liquid column on fluctuations of the pressure. A white oil preferably used is a Renolin MRLVG5 type oil and has a viscosity number of 1. The pressure lines are, for instance, micro fluid flexible hose lines made of synthetic armid fibers (e.g. type EMMKT8 PN500 PB 800 DN 2).  
     [0107] In operating the pedal  99  on the instructor&#39;s side the slider  63  is shifted towards the hydraulic block  64  whereby the piston rods  70  and  71  exert pressure on the liquid column in the pressure cylinders  69  and  68 . This pressure is transferred within the liquid column from the hydraulic block  64  to the pressure line  92  and, finally, the pressure is coupled to the pressure cylinder  11  of the actuator  10  via the hollow screw  13 . The pressure piston rod  18  then shifts the cylinder  17  together with the catch  15 . Since the catch  15  is engaged in the pedal lever  93 . 1  of the pedal  93 , the pedal  93  is operated. If the pressure on the pedal  99  is decreased or removed, the spring  16  of the actuator  10  shifts back the cylinder having the catch  15  and, thus, also the pressure piston rod  18 . The slider  63  of the pedal unit  80  is shifted back in its initial position, i.e. the stop position at the sleeves  73 , by the spring force of both springs  67  and  68  and by the change or the suction pressure in the pressure cylinders.  
     [0108] If the pedal  98  is operated on the passenger&#39;s side, the pressure on the liquid column is transferred via both pressure cylinders and the hydraulic block of the pedal unit  80 . 1 , having the same construction as the pedal unit  80 , to the pressure line  91  and therefrom to the pressure cylinder  31  of the actuator  30 . Thus, the support  35  having the gear wheel casing  48  is shifted whereby the portion of the chain between the chain support  42  and the pedal lever  94 . 1  is shortened and the pedal  94  is operated. If thereafter the operation of the pedal  98  on the passenger&#39;s side is decreased or removed, the pedal  94  is shifted back into its resting position by its pedal reshifting spring (not shown) whereby tension is exerted on the chain  41  being connected to the pedal lever  94 . 1  of the pedal  94 , and thereby the support  35  together with the gear wheel casing  48  is now drawn back towards the chain support  42 . The pressure on the liquid column is directed back to the passenger&#39;s side, namely to the hydraulic block of the pedal unit  80 . 1 , via the pressure cylinder of the actuator  30  and the pressure line  91 , thereby the pressure cylinder of the pedal unit  80 . 1  together with the compression springs of the pedal unit  80 . 1  shift back the slider in its initial position. Similar processes also occur in operating the pedal  97  via the pedal unit  81 , the pressure line  90 , and actuator  10 . 1  that is coupled to the pedal lever  95 . 1 .  
     [0109] In the following, a further preferred embodiment of the double pedal device of the invention for a driving school vehicle with automatic transmission is explained using FIGS. 6, 7,  8 ,  9 , and  10 .  
     [0110] In FIG. 7, an actuator  10 . 2  which is used in the same construction as an anti gas or anti accelerator actuator  10 . 12  and also as an accelerator or gas actuator  10 . 22  of actuator means  10 . 32  of a driver&#39;s side accelerator pedal hydraulic means (refer also to FIG. 9) is shown in a separated perspective and partly sectional view. The actuator  10 . 2  comprises a cylindrical hollow actuator casing  14 . 2  that is opened at the ends, a pressure cylinder  11 . 2  that extends at least in part in the hollow space of the actuator casing concentrically with the axis of the actuator casing, a piston rod  18 . 2  or piston bar that is coupled by pressure to the pressure cylinder  11 . 2  within the actuator casing  14 . 2  via a pressure cylinder piston not shown and that is fixedly coupled to a catch cylinder  17 . 2  on its other end, which shiftably fits into the cavity of the actuator casing  14 . 2  and can be moved to and fro therein along the axis of the actuator casing  14 . 2 ., and a spring  16 . 2  that extends concentrically with the axis of the actuator casing  14 . 2  between the other end of the actuator casing  14 . 2 , i.e. in more detail between the catch cylinder  17 . 2  and an actuator support  19 . 2  made of synthetic resin which terminates the other end of the actuator casing  14 . 2 .  
     [0111] The pressure cylinder  11 . 2  consists of a stainless steel or aluminium and is hydraulically coupled to an associated pressure line of the hydraulic coupling means via a hollow screw  13 . 2  being mounted to pressure cylinder  11 . 2  at the end and having, on one of its ends, a thread socket for screwing in. The pressure cylinder  11 . 2  is arranged concentrically with the axis of the actuator casing  14 . 2  in the cavity of the actuator casing  14 . 2 . On the end region towards the hollow screw  13 . 2 , the pressure cylinder  11 . 2  has grooves  12 . 2  extending radially and annularly on its outer surface in which pins  20 . 2  passing through corresponding holes in the wall of the actuator casing  14 . 2  are engaged in order to fix the pressure cylinder  11 . 2  on the actuator casing  14 . 2 .  
     [0112] In FIG. 7 the pressure cylinder  11 . 2  comprises five of these grooves  12 . 2  wherein two grooves being next to each other can not been seen in FIG. 7 since they are covered by the wall of the actuator casing  14 . 2 , but they are engaged in associated fixing pins  20 . 2  both being shown.  
     [0113] On establishing or adjusting of the actuator  10 . 2 , it can be determined by the radial grooves  12 . 2  and the pins  20 . 2  cooperating therewith how far the pressure cylinder  11 . 2  extends into the actuator casing  14 . 2  or how far it projects there from at its end, whereby the position of the catch  15 . 2  along the actuator casing  14 . 2  in its initial position can be adjusted in which there is not any pressure acting on the pressure cylinder  11 . 2 , and therefore also the maximum stroke of the catch  15 . 2  of the actuator  10 . 2  can be adjusted for adapting to the respective construction of the associated pedal. The actuator  10 . 2  can therefore be adapted to the pedals of different types of vehicles having different stroke of pedal.  
     [0114] A pressure piston not shown is located within the pressure cylinder  11 . 2  on which the hydraulic pressure acts, which is present in the pressure cylinder. The pressure piston is supported within the pressure cylinder  11 . 2  in a sealing and moveable manner such that hydraulic liquid cannot escape out of the pressure cylinder  11 . 2 . The pressure piston is connected to a piston rod  18 . 2  in the pressure cylinder  11 . 2  which projects from the pressure cylinder  11 . 2  in the interior of the actuator casing  14 . 2  and which extends concentrically to the axis of the cylindrical actuator casing  14 . 2 .  
     [0115] A catch cylinder  17 . 2  is accommodated at the other end of the piston rod  18 . 2  or the piston bar which can be moved to and fro in the interior of the actuator casing  14 . 2  along the axis of the actuator casing  14 . 2  and which moves depending on the pressure acting on the hydraulic pressure cylinder  11 . 2 . The catch cylinder  17 . 2  can be made of stainless steel, aluminium, or synthetic resin and is preferably designed in a solid manner.  
     [0116] The catch  15 . 2  is fixed on the outer surface of the catch cylinder  17 . 2  and comprises a hooked shape in the elevation view wherein the opening or aperture of the hooked catch  15 . 2  faces to the end of the actuator casing  14 . 2  having the actuator support  19 . 2 . The catch  15 . 2  comprises a catch leg extending in parallel to the axis of the actuator casing  14 . 2 , and a catch basis being attached to the catch cylinder  17 . 2 . The catch can be provided with synthetic resin, particularly Nylon, on its surface.  
     [0117] The opening of the catch that is the region between the outer wall of the actuator casing  14 . 2  and the face of the catch  15 . 2 , being adjacent to the opening of the catch, is constructed such the pedal lever, to which the actuator  10 . 2  is coupled, is fitted in the opening of the catch  15 . 2  in order to ensure a secure operation of the associated pedal or pedal lever.  
     [0118] A spring  16 . 2  being constructed as a compression spring is accommodated in the cavity of the actuator casing  14 . 2  between the actuator support  19 . 2  and the catch cylinder  17 . 2 , which pushes the moveable catch cylinder  17 . 2  towards the pressure cylinder  11 . 2  within the actuator casing  14 . 2 .  
     [0119] The actuator support  19 . 2  is fitted in the cavity of the actuator casing  14 . 2  on the corresponding end thereof and it closes or terminates also the corresponding end of the actuator casing  14 . 2 . The actuator support  19 . 2  serves as a stop of the spring  16 . 2  and for mounting the actuator  10 . 2  on the chassis of the vehicle on the driver&#39;s side within the region of the pedal or on a basic plate being separately provided and being installed or accommodated in the region or area of the pedal of the vehicle on the driver&#39;s side. The actuator support  19 . 2  can also be constructed as a joint or articulate in order to jointly attach the actuator  10 . 2  on the chassis of the basis plate in the area of the pedal of the driver&#39;s side.  
     [0120] A slot  21 . 2  is recessed in the wall of the actuator casing  14 . 2 , which extends in parallel and along the axis of the actuator casing  14 . 2  and through which the catch  15 . 2  is projected out of the actuator casing  14 . 2  from the catch cylinder  17 . 2 . The free width of the slot  21 . 2  or of the recess corresponds to the thickness or dimension of the catch  15 . 2  such that the catch  15 . 2  is able to move freely to and fro in the slot  21 . 2 . The length of the slot  21 . 2  corresponds at least to the stroke of the catch  15 . 2 , which is allowed in maximum. The slot  21 . 2  can be formed with regard to its dimensions such that the walls of the slot perform a guiding of the catch  15 . 2 .  
     [0121] If the pressure cylinder  11 . 2  of the actuator  10 . 2  is subjected to pressure by operation of the associated pedal on the passenger&#39;s side which means by the driving instructor, the piston rod  18 . 2  and thus also the catch cylinder  17 . 2  and the catch  15 . 2  are shifted towards the actuator support  19 . 2  against the pressure force of the spring  16 . 2  whereby the pedal being engaged, e.g. the driver&#39;s side accelerator pedal, is operated on the driver&#39;s side. If then the operation of the pedal is decreased on the passenger&#39;s side, also the hydraulic pressure decreases in the pressure cylinder  11 . 2  and the catch cylinder  17 . 2  together with the catch  15 . 2  are moved by the spring  16 . 2  in the opposite direction, i.e. towards the pressure cylinder  11 . 2 , until a balance between the pressure force of the pressure cylinder  11 . 2  and the pressure force of the spring  16 . 2  is present.  
     [0122] If the instructor decreases the pressure or force on the pedal or the pedal operation yet further until a pedal operation on the passenger&#39;s side is not present any more, the spring  16 . 2  pushes or shifts the catch cylinder  17 . 2  together with the catch  15 . 2  further and further towards the pressure cylinder  11 . 2  until the catch  15 . 2  reaches its initial position in which pressure does not act anymore by the pressure cylinder  11 . 2  but only pressure caused by the spring  16 . 2  is effective.  
     [0123] In FIG. 8 an actuator  30 . 2  is shown in a view corresponding to FIG. 7. The actuator  30 . 2  comprises an actuator casing  34 . 2  having a pressure cylinder  31 . 2  with grooves  32 . 2  extending radially on the surface and a terminating hollow screw  33 . 2 , a catch  35 . 2  or support that projects out of the actuator casing  34 . 2 , a spring  36 . 2  being constructed as a compression spring, and a moveable cylinder  37 . 2  in the interior of the actuator casing  34 . 2  which is connected to a piston rod  38 . 2  on one end which extends into the pressure cylinder  31 . 2  and which is connected to a pressure piston in the interior of the pressure cylinder  31 . 2 . The pressure cylinder  31 . 2  in turn can be adjusted and mounted by the grooves  32 . 2  and the fixing pins  40 . 2  on the actuator casing  34 . 2 .  
     [0124] The construction and function of the members  31 . 2 ,  32 . 2 ,  33 . 2 ,  34 . 2 ,  36 . 2 ,  39 . 2  and  51 . 2  are identical to the instruction and function of the corresponding members of the actuator  10 . 2  being shown in FIG. 7. Concerning a more detailed description of the construction and function of this members or parts thus it is referred to a description mentioned above with regard to FIG. 7.  
     [0125] In contrast to the actuator  10 . 2  in FIG. 7, however, the actuator  30 . 2  in FIG. 8 does not have any catch, but it is coupled via a chain  41 . 2  to an associated pedal lever or driver&#39;s side pedal, e.g. the driver&#39;s side brake pedal. The construction of the actuator  30 . 2  having the chain  41 . 2  is described in detail in the following.  
     [0126] A chain support  42 . 2  is set on or pushed on the cylindrical actuator casing  34 . 2  of the actuator  30 . 2 , which is formed as a cuboid block. The chain support  42 . 2  is clamped on the actuator casing  34 . 2  of the actuator  30 . 2  by means of a clamping or fixing screw  43 . 2 . In FIG. 8 a small gap  52 . 2  in the lower area of the chain support  52 . 2  can be seen which allows a clamping by the clamping screw  43 . 2  on the surface of the actuator casing  34 . 2 . Before clamping of the chain support  42 . 2 , the chain support  42 . 2  can be shifted on the periphery or circumference of the cylindrical actuator casing  34 . 2  and therefore its final position can be adjusted. By clamping, the chain support  42 . 2  is fixed on the actuator casing  34 . 2  in its position along the actuator casing  34 . 2 . In the upper portion of the block shaped or cuboid chain support  42 . 2 , a compartment  44 . 2  is provided which is opened via the shown corner of the chain support  42 . 2  to the outside or accessible from the outside. A first gear wheel  45 . 2  or pinion is located around a shaft  46 . 2  or rotateably there with. The chain  41 . 2  is held with one of its ends on the chain support  42 . 2  by means of a chain fastening  47 . 2 .  
     [0127] A support  35 . 2  is connected to the cylinder  37 . 2 , which projects out of the actuator casing  34 . 2  through a slot  51 . 2 . The hooked catch  15 . 2  of FIG. 7 is used as support  35 . 2  in FIG. 8. A cylindrical gear wheel casing  48 . 2  is fixed on the support  35 . 2 , in which a further gear wheel  49 . 2  is rotateably arranged or supported. In the wall of the gear wheel casing  48 . 2 , two slots  48 . 12  are recessed in distance to each other, through which the chain  41 . 2  extends.  
     [0128] The chain  41 . 2  extends from the chain fastening  47 . 2  on the chain support  42 . 2  towards the gear wheel casing  48 . 2  that is coupled to the support member  35 . 2 . The chain  41 . 2  is put around the gear wheel  49 . 2  and it extends through one of the slots  48 . 12  again out of the gear wheel casing  48 . 2  and, thus, it is deflected by 180° by the gear wheel  49 . 2 . The chain  41 . 2  extends from the gear wheel casing  48 . 2  towards the chain support  42 . 2  and enters the compartment  44 . 2 , passes the gear wheel  45 . 2 , which engages in the elements of the chain  41 . 2 , and leaves again the compartment  44 . 2  after being redirected or deflected by 90°. The chain extends from the compartment  44 . 2  to the associated pedal or pedal lever on which the chain is fixed with its end member, e.g. by means of a clamp or bracket.  
     [0129] If the pressure cylinder  31 . 2  is loaded by pressure against the force of the spring  36 . 2 , the cylinder  37 . 2  is moved towards the actuator support  39 . 2 . The support  35 . 2  with the gear wheel casing  48 . 2  moves together with the cylinder  37 . 2  whereby the chain  41 . 2  is pulled from the chain support  42 . 2  towards the actuator support  39 . 2 . This movement is transferred via the gear wheel  49 . 2  to the fastening of the chain  41 . 2  on the pedal whereby the pedal is operated by the tension of the chain.  
     [0130] If the pressure in the pressure cylinder decreases, the cylinder  37 . 2 , the support  35 . 2 , and the gear wheel casing  48 . 2  are shifted back towards the chain support  42 . 2  by the spring  36 . 2 , whereby the length of the chain between the chain support  42 . 2  and the gear wheel  49 . 2  or the gear wheel casing  48 . 2  is shortened and, therefore, the operation of the coupled pedal is lowered.  
     [0131] A stroke of the pressure cylinder  31 . 2  or the stroke of the cylinder  37 . 2  in the actuator casing  34 . 2  and the support  35 . 2  with the gear wheel casing  48 . 2  is converted into a twice as big stroke of the chain part of the chain  41 . 2  between the chain support  42 . 2  and the pedal whereby big strokes or movements of the pedal can be performed by the actuator  30 . 2 .  
     [0132] In FIG. 6 a pedal unit  80 . 2  according to a preferred embodiment of the invention and being arranged on the passenger&#39;s side is shown.  
     [0133] The pedal unit  80 . 2  has an anti gas or anti accelerator pedal  99 . 2  and anti accelerator pedal hydraulic means having two hydraulic cylinders  69 . 2 ,  68 . 2  arranged in parallel and apart to each other as pressure cylinder means having the same construction, compression springs  68 . 2  and  67 . 2  having the same construction, guiding rods  66 . 2  and  65 . 2  having the same construction, a hydraulic block  64 . 2 , a slider  63 . 2  or carriage being supported on the guiding rods  66 . 2  and  65 . 2  such that it can move to and fro which is explained by the double arrow shown in FIG. 6, an end block  62 . 2  in which a pedal lever  60 . 2  is supported jointly in a pivotal manner, and a support lever  61 . 2  being supported jointly on the pedal lever  60 . 2  and on the slider  63 . 2  and, thus, coupling the slider  63 . 2  to the pedal lever  60 . 2  in order to transfer a movement of the pedal lever  60 . 2  to the slider  63 . 2  via the support lever  61 . 2 .  
     [0134] The pedal lever  60 . 2  engages with one end in a recess of the end block  62 . 2  in which a pin extends, the pedal lever  60 . 2  being pivotably or rotateably around a longitudinal axis of the pin. The recess in the end block  62 . 2  is formed in dimensions such that a sufficient freedom of movement of the end of the pedal lever  60 . 2  being supported in the end block  62 . 2  is provided. A pedal disc of the anti gas pedal  99 . 2  is attached to the opposite end of the pedal lever  60 . 2  which allows to be operated by the passenger&#39;s or instructor&#39;s foot.  
     [0135] The support lever  61 . 2  is mounted on the pedal lever  60 . 2  jointly such that a movement of the pedal lever  60 . 2  is converted into a movement of the support lever  61 . 2 . The other end of the support lever  61 . 2  engages in a recess  63 . 12  having the form of a slot in the slider  63 . 2  and it is supported rotaetably or pivotably again around a transverse pin wherein the transverse pin of the slider  63 . 2  is oriented for supporting or mounting the support lever  61 . 2  in parallel to the support pin in the end block  62 . 2  for supporting the pedal lever  60 . 2 . Further, the transverse pin for supporting the support lever  61 . 2  in the slider  63 . 2  and also the mounting pin for supporting the pedal lever  60 . 2  in the end block  62 . 2  are oriented perpendicularly to a direction of movement of the slider  63 . 2  on the guiding rods  66 . 2  and  67 . 2 .  
     [0136] The rectangular slider  63 . 2  is supported by a linear bearing  72 . 2  on the guiding rod  66 . 2  and it is supported by a second linear bearing  74 . 2  on the guiding rod  65 . 2 . Both linear bearings  72 . 2  and  74 . 2  are fitted and accommodated in bores or channels extending through and having a circular section in the slider  63 . 2  and they allow a linear support of the slider  63 . 2  on the guiding rods  66 . 2  and  65 . 2 . The slider  63 . 2  consists, for instance, of polyethylene (type Simona PE-HWST according to ISO 10285). For instance, a linear ball bearing having running surface plates (type SKF LBBR12-2LS) can be used as linear bearing  72 . 2  or  74 . 2 .  
     [0137] Further, pressure piston rods  70 . 2  and  71 . 2  extending in parallel to each other are mounted with their ends being free from the pressure piston in the slider  63 . 2 . A movement or a shifting of the slider  63 . 2  on the guiding rods  66 . 2  and  65 . 2  is thus directly transferred to the pressure piston rods  70 . 2  and  71 . 2 .  
     [0138] The pressure piston rods  70 . 2  and  71 . 2  engage in the pressure cylinders  69 . 2  and  68 . 2  wherein the pressure piston rod  70 . 2  projects into the pressure cylinder  69 . 2  and wherein the pressure cylinder rod  71 . 2  projects into the pressure cylinder  68 . 2 . Pressure pistons being supported moveably and sealingly within the corresponding pressure cylinders  69 . 2  and  68 . 2 , respectively, are arranged on the ends of the pressure piston rods  70 . 2  and  71 . 2  that are located in the pressure cylinders  69 . 2  and  68 . 2 . A movement of the pressure cylinder rods  70 . 2  or  71 . 2  acts on the respective pressure pistons and, therefore, it acts on the liquid column in the pressure cylinders.  
     [0139] Both pressure cylinders  69 . 2  and  68 . 2  extend in parallel to each other and they are fixed in the hydraulic block  64 . 2 , for instance, by corresponding screwing means. The outlets of both pressure cylinders  68 . 2  and  69 . 2  are united to an inlet in the hydraulic block  64 . 2  by means of a channel  64 . 12  in the hydraulic block  64 . 2 .  
     [0140] The guiding rods  66 . 2  and  65 . 2  extending in parallel to each other are fixedly connected to the hydraulic block  64 . 2  at one end, for instance, by suitable screwing means, extend further through the slider  63 . 2 , namely through the linear bearings  72 . 2  and  74 . 2 , respectively, and extend further to the end block  62 . 2  with which they are fixedly connected again, for instance, by screws. A compression spring  68 . 2  wounding around the guiding rod helically is mounted between the slider  63 . 2  and the hydraulic block  64 . 2 . The compression spring or helical spring is fixed or screwed with one end on the hydraulic block  64 . 2  whereas the other end of the compression spring  68 . 2  is screwed on the slider. The compression force of the compression spring  86 . 2  shifts the slider  63 . 2  away from the hydraulic block  64 . 2  towards the end block  62 . 2  if a counter force of the pedal lever  60 . 2  does not exist. An additional compression spring  67 . 2  or helical spring is arranged on the guiding rod  65 . 2  between the slider  63 . 2  and the hydraulic block  64 . 2  and it is fixed thereto like the compression spring  68 . 2 . In addition, the compression force of the compression spring  67 . 2  tends to shift the slider  63 . 2  away from the hydraulic block  64 . 2  towards the end block  62 . 2 .  
     [0141] A stop sleeve  73 . 2  is shifted on the guiding rod  66 . 2  between the slider  63 . 2  and the end block  62 . 2 . An identical stop sleeve  73 . 2  is shifted on the guiding rod  65 . 2  between the slider  63 . 2  and the end block  62 . 2 . Both stop sleeves  73 . 2  are constructed identically to each other and have the purpose to limit the movement of the slider  63 . 2  towards the end block  62 . 2 , which means, that the slider  63 . 2  is stopped at the stop sleeves  73 . 2  if only the compression forces of both springs  68 . 2  and  67 . 2  act without any counter or opposite force by operating the pedal. Then, the slider  63 . 2  is in the position shown in FIG. 6.  
     [0142] The fictitious symmetry axes of the pressure cylinder  69 . 2  and of the pressure piston rod  70 . 2  coincide. The fictitious axes of the pressure cylinder and of the pressure rod  71 . 2  coincide. The axes of both pressure cylinders  69 . 2  and  68 . 2  extending accurately in parallel to each other. Further, the axes of the guiding rods  66 . 2  and  65 . 2  are oriented in parallel to each other and are arranged together with the axes of the pressure cylinders  69 . 2  and  68 . 2  in a common plane. The support lever  61 . 2  is supported in the middle of the slider  63 . 2  such that the forces occurring during operation of pedal are distributed uniformly via the slider  63 . 2  onto both cylinder pistons  70 . 2  and  71 . 2 . In addition, the pedal lever  60 . 2  is supported in the middle between the guiding rods  66 . 2  and  65 . 2  on the end block.  
     [0143] The pedal unit  80 . 2  is preferably attached to a plate  100 . 2  that is arranged on the base chassis on the passenger&#39;s side of the vehicle in the area of the passenger where it may be fixed to preferably by a Velcro fastener. Thus, the pedal unit  80 . 2  can easily be mounted and demounted since only the Velcro fastener has to be used. The pedal unit  80 . 2  or its mounting plate  100 . 2  can be secured by screws to the base. The Velcro fastener is sufficient as the force being present during pedal operation on the pedal lever  60 . 2  is transferred from the pedal lever  60 . 2  and the support lever  61 . 2  to the slider  63 . 2  such that a linear component of the force that arises in the moving direction of the slider  63 . 2  only, and a further component of force arises which acts perpendicularly to the moving direction of the slider  63 . 2 , i.e. towards the base of the vehicle. Due to these components of force, the pedal unit  80 . 2  is pressed in normal direction onto the base of the vehicle if the pedal is operated, and, therefore, no tilting forces can act on the pedal unit  80 . 2  during operation of pedal.  
     [0144] Referring to FIG. 9 and FIG. 10, a preferred embodiment of the double pedal device of the invention to be used in a driving school vehicle and having automatic transmission, wherein FIG. 9 shows the set of pedals  90 . 6  on the driver&#39;s side of the vehicle and FIG. 10 shows the second pedal set  80 . 6  on the passenger&#39;s side, i.e. on the instructor&#39;s side.  
     [0145] The first pedal set on the driver&#39;s side comprises an accelerator pedal  95 . 2 , a brake pedal  94 . 2 , an anti accelerator actuator  10 . 12  being shown in FIG. 7 and having a catch  15 . 12  that is engaged in a pedal lever  95 . 12  of the accelerator pedal  95 . 2 , a further actuator  30 . 2  being shown in more detail in FIG. 8 and having a chain  41 . 2 , an end thereof is attached or secured to a pedal lever  94 . 12  of the pedal  94 . 2  by means of, for instance, a clamp, and an accelerator actuator  10 . 22  having the same construction as the anti accelerator actuator  10 . 12 . A catch  15 . 22  of the accelerator actuator  10 . 22  is engaged in the pedal lever  95 . 12  of the accelerator pedal  95 . 2 .  
     [0146] A pressure cylinder  11 . 12  of the anti accelerator actuator  10 . 12  is coupled to a hydraulic pressure line  92 . 2  for passage of liquid or fluid via a hollow screw  13 . 12  that covers the pressure cylinder  11 . 12 . The pressure cylinder  31 . 2  of the actuator  30 . 2  is coupled to the pressure line  91 . 2  via the hollow screw  33 . 2 . A pressure cylinder  11 . 22  of the gas actuator  10 . 22  is coupled to a pressure line  90 . 2  or hydraulic line to allow passing of fluid.  
     [0147] The accelerator actuator  10 . 22  effects an increase of gas or acceleration and the anti accelerator actuator  10 . 12  effects a decrease of gas or acceleration. The gas pedal  95 . 2  is allowed to move between zero gas position in which no acceleration is present, and a full gas position in which full acceleration is present. The anti accelerator actuator  10 . 12  actuates the accelerator pedal  95 . 2  in the direction from the full acceleration position to the zero acceleration position if the anti accelerator pedal  99 . 2  on the passenger&#39;s side is operated. The accelerator actuator  10 . 22  actuates the accelerator pedal on the driver&#39;s side in the direction from the zero gas position to the full gas position if the accelerator pedal  97 . 2  on the instructor&#39;s side is operated.  
     [0148] The second set of pedals  80 . 6  on the passenger&#39;s side has three pedals as shown in FIG. 10, the accelerator pedal  97 . 2 , the brake pedal  98 . 2  and the anti accelerator pedal  99 . 2 . The second pedal set comprises a pedal unit  80 . 2  having the anti gas pedal  99 . 2 , which is shown in more detail in FIG. 6, a further pedal unit  80 . 12  having the brake pedal  98 . 2  which corresponds to the pedal unit  80 . 2  being shown in FIG. 6, and a third pedal unit  81 . 2  having the accelerator pedal  97 . 2  which in contrast to the pedal units  80 . 2  and  80 . 12  comprises only one pressure cylinder with pressure piston rod, one guiding rod having compression spring, a slider, a hydraulic block and terminating block correspondingly adapted and being coupled to the accelerator pedal  97 . 2  via the supporting lever. Instead of the pedal unit  80 . 2 , one could also use an additional pedal unit  81 . 2  or vice versa, wherein however the amendment of the pedal function has to be taken into account.  
     [0149] The hydraulic block  64 . 2  of the pedal unit  80 . 2  is coupled for passage of a fluid via the hollow screw  64 . 22  that has a screwing bolt to the pressure line  92 . 2 . The hydraulic block of the pedal unit  80 . 12  is coupled to the pressure line  91 . 2  via its hollow screw. The hydraulic block of the pedal unit  81 . 2  is coupled to the pressure line  90 . 2  via its hollow screw.  
     [0150] The hydraulic means used which correspond to the passenger&#39;s side pressure cylinder means shown in FIG. 10 and each having a pressure cylinder with pressure piston rod, the pressure cylinder means of the actuators  10 . 12 ,  10 . 22  and  30 . 2  shown in FIG. 9 and each having a pressure cylinder and a relating pressure piston rod, the flexible pressure lines  90 . 2 ,  91 . 2  and  92 . 2  of a pressure line means, and the hydraulic blocks  64 . 2  are filled with a hydraulic liquid. A hydraulic oil, a fork oil, or a white oil may be used as hydraulic fluid. Preferably, a hydraulic liquid having a viscosity number of 1 is used in order to avoid delays in the response of the liquid column on alteration in pressure. White oil being preferably used is type Renolin MR1VG5 and has a viscosity number of 1. The pressure lines are, for instance, micro fluid tube or hose lines made of synthetic armid fibres (for instance, type EMMKT8 PN500 PB 800 DN 2).  
     [0151] If the anti accelerator pedal  99 . 2  on the instructor&#39;s side is operated, the slider  63 . 2  of the pedal unit  80 . 2  is shifted towards the hydraulic block  64 . 2  wherein the piston rods  70 . 2  and  71 . 2  provide pressure onto the liquid column within the pressure cylinders  69 . 2  and  68 . 2 . This pressure is transferred within the liquid column from the hydraulic block  64 . 2  to the pressure line  92 . 2  and, finally, it is coupled into the pressure cylinder  11 . 12  of the anti accelerator actuator  10 . 12  via the hollow screw  13 . 12 . The corresponding pressure piston rod then moves the cylinder along with the catch  15 . 12 . Since the catch  15 . 12  is engaged in the pedal lever  95 . 12  of the driver&#39;s side accelerator pedal  95 . 2  being operated, the accelerator pedal  95 . 2  is moved back to its zero gas position resulting in reducing of gas or acceleration. If the force or pressure onto the anti accelerator pedal  99 . 2  is reduced or cancelled, the spring  16 . 2  of the anti accelerator actuator  10 . 12  pushes back the cylinder and catch  15 . 12  and, thus, the pressure piston rod, too. The slider  63 . 2  of the pedal unit  80 . 2  is moved back to its initial position, i.e. the stop position at the sleeves  73 . 2 , by the alteration of the pressure or by the intake pressure within the pressure cylinders.  
     [0152] If the brake pedal  98 . 2  on the passenger&#39;s side is operated, the pressure on the liquid column propagates through both of the pressure cylinders and the hydraulic block of the pedal unit  81 . 12  to the pressure lines  91 . 2  and therefrom to the pressure cylinder  31 . 2  of the actuator  30 . 2 . Consequently, the support  35 . 2  together with the gear wheel casing  48 . 2  is offset whereby the chain portion between the chain support  42 . 2  and the pedal lever  94 . 12  is shortened and the pedal  94 . 2  is operated or moved. If afterwards the operation of the pedal  98 . 2  on the passenger&#39;s side is reduced or cancelled, the pedal  94 . 2  is brought back into its resting position by its pedal bring back spring (not shown) whereby tension acts on the chain  41 . 2  that is coupled to the pedal lever  94 . 12  of the brake pedal  94 . 2 , and thus the support  35 . 2  together with the gear wheel casing  48 . 2  is now pulled back towards the chain support  42 . 2 . The pressure arising in this situation on the liquid column is directed back to the passenger&#39;s side, i.e. to the hydraulic block of the pedal unit  80 . 12 , via the pressure cylinder of the actuator  30 . 2  and the pressure line  91 . 2  whereby the pressure cylinders of the pedal unit  80 . 12  together with the compression springs of the pedal unit  80 . 12  bring the slider back to its initial position.  
     [0153] By operating the passenger&#39;s side accelerator pedal  97 . 2  on the instructor&#39;s side, the slider of the pedal unit  81 . 2  is pushed towards the corresponding hydraulic block wherein the piston rod of the single pressure cylinder means of the pedal unit  81 . 2  provides pressure on the corresponding pressure cylinder  81 . 22 . This pressure is transferred within the liquid column from the hydraulic block  81 . 32  to the pressure line  90 . 2  and, finally, it is transferred via the hollow screw  13 . 22  to the pressure cylinder  11 . 22  of the accelerator actuator  10 . 22 . The pressure piston cylinder of the accelerator actuator  10 . 22  then operates the cylinder with catch  15 . 22 . Since the catch  15 . 22  is engaged in the pedal lever  95 . 12  of the driver&#39;s side pedal accelerator pedal  95 . 2 , the accelerator pedal  95 . 2  is moved towards its full gas position under increasing gas. Then, if the pressure on the passenger&#39;s side accelerator pedal  97 . 2  is reduced or cancelled, the spring of the accelerator actuator  10 . 22  pushes back again the cylinder together with the catch  15 . 22  and, thus, also the pressure piston rod. The slider of the pedal unit  81 . 2 , then, is moved back to its initial position by the force of the single spring of the pedal unit  81 . 2 , but in addition by the alternation of pressure or the intake pressure in the corresponding pressure cylinders of the pedal unit  81 . 2 .  
     [0154] Referring to the example of FIG. 11 and FIG. 12, a preferred embodiment of the driving school instructor&#39;s post of the invention to be used in a driving school vehicle is shown. The instructor&#39;s post comprises an instructor&#39;s seat  1 . 5 , the instructor&#39;s side pedal means  80 . 5  shown in FIG. 5 or the instructor&#39;s side pedal means  80 . 6  shown in FIG. 10, and display means  15 . 5 . An example of the instructor&#39;s post is installed in the cap or cell of the vehicle comprising an instrument panel  14 . 5  in a bus that is used as a driving school vehicle.  
     [0155] The instructor&#39;s seat  1 . 5  comprises a seat portion or member  31 . 5 , a backrest member  2 . 5 , a head support  6 . 5 , a pneumatic spring  5 . 5  or air suspension, one end thereof is coupled to the seat portion  31 . 5  and the other end thereof is coupled to the driving school vehicle floor pan  3 . 5  or base. The backrest member  2 . 5  is pivotable around an axis  8 . 5  to adjust the inclination of the backrest member  2 . 5  in relation to the seat surface  7 . 5  of the seat portion  31 . 5  for sitting on. By operating a valve of the pneumatic spring  5 . 5  by means of a lever  32 . 5 , the height of the level of the seat surface  7 . 5  above the floor pan  3 . 5  can be adjusted. The floor pan  3 . 5  is secured to a floor group  9 . 5  of the bus by screws  4 . 5 . Using a screw connection allows a quick installation of the instructor&#39;s seat  1 . 5  and, thus, of the whole instructor&#39;s post in the bus, and, further, a quick and easy demounting of the seat which allows a quick conversion of the vehicle to a driving school vehicle and vice versa, too. As illustrated in FIG. 11, the seat surface  7 . 5  is present at a higher level of height than the seat surface of a driver&#39;s seat  11 . 5  in comparison to a dashed driver&#39;s seat  11 . 5  shown schematically.  
     [0156] The driving school instructor&#39;s seat  1 . 5  and/or instructor&#39;s post may be located in the middle between the driver&#39;s seat  11 . 5  and passenger&#39;s seat not shown wherein this middle area may also extend towards the rear of the vehicle as shown in FIG. 11.  
     [0157] The instructor&#39;s side pedal means  80 . 5  (or  80 . 6 ) are attached to the seat portion  31 . 5  of the instructor&#39;s seat  1 . 5  by means of a holding device  12 . 5  or support. The holding device  12 . 5  comprises a seat plate  30 . 5 , an inclined member  33 . 5 , and a plate  34 . 5  that is oriented in parallel to the floor pan  3 . 5  or floor chassis group  9 . 5  of the vehicle. The seat plate  30 . 5  of the holding device  12 . 5  is fixed to the seat portion  31 . 5  by screws. The inclined member  33 . 5  extending downwards in an inclined manner couples the seat plate  30 . 5  to the plate  34 . 5  integrally. At the longitudinal edges of the plate  34 . 5 , two guiding means  17 . 5  and  18 . 5  extending in parallel to each other are attached which provide through receptacles in an area of the edge of the pedal means  80 . 5  (or  80 . 6 ) that can be inserted into the guiding means  17 . 5  and  18 . 5  in accordance to the direction of arrow  19 . 5 . On their topsides, the guiding means  17 . 5  and  18 . 5  have respective bores  38 . 5  being in series or corresponding longitudinal holes which help that the instructor&#39;s side pedal means  80 . 5  (or  80 . 6 ) can be locked in or fixed to the guiding means using screws or clamping. By offsetting or shifting the pedal means  80 . 5  (or  80 . 6 ) within the guiding means  17 . 5  and  18 . 5 , a distance A 5  between the instructor&#39;s seat  1 . 5  and the pedal means  80 . 5  (or  80 . 6 ) can be adjusted.  
     [0158] On the plate  34 . 5  of the holding device  12 . 5 , a display holder  16 . 5  is attached via an angle member, wherein display means  15 . 5  are attached to an end of the display holder. The display means  15 . 5  may be, for instance, a LCD or a monitor. The display means  15 . 5  is coupled electrically to a video camera  50 . 5  via coupling means and a connector  42 . 5  on the instrument panel  14 . 5 . The video camera  50 . 5  is attached to a left exterior rear view mirror  40 . 5  of the bus and, thus, it detects the surrounding area on the left side of the bus. The image or picture detected by the video camera  50 . 5  is indicated to the driving school instructor on the display means  15 . 5  whereby, for instance, a vehicle in the “blind angle” can be recognized by the instructor.  
     [0159] The instructor&#39;s side pedal means  80 . 5  in FIG. 5 comprises the pedal units  80 ,  80 . 1 , and  81  having the corresponding pedals  99 ,  98 , and  97 . The pedal means  80 . 5  are coupled to the supplementary driver&#39;s side pedal means  90 . 5  in FIG. 4 of the double pedal device for controlling the driver&#39;s pedal means  90 . 5  with priority via the pressure lines  90 ,  91 ,  92 .  
     [0160] Similarly, the instructor&#39;s side pedal means  80 . 6  in FIG. 10 comprises the pedal units  80 . 2 ,  80 . 12 , and  81 . 2  having the corresponding pedals  99 . 2 ,  98 . 2 , and  97 . 2 . The pedal means  80 . 6  are coupled to the supplementary driver&#39;s side pedal means  90 . 6  in FIG. 9 of the double pedal device having anti gas for controlling the driver&#39;s pedal means  90 . 6  with priority via the pressure lines  90 . 2 ,  91 . 2 ,  92 . 2 .  
     [0161]FIGS. 13, 14 and  15  show another preferred embodiment of the instructor&#39;s post of the invention to be used in a driving school vehicle. The instructor&#39;s post comprises an instructor&#39;s seat  30 . 6 , a controlling unit  20 . 6 , instructor&#39;s side pedal means  80 . 5  on the passenger&#39;s side which is shown in FIG. 5 (or  80 . 6  in FIG. 10), and a holding device  1 . 6  or rack on which the pedal means  80 . 5  (or  80 . 6 ) are affixed. The instructor&#39;s post is installed, for instance, in the cap  40 . 6  or cell of the vehicle having an instrument panel  41 . 6  in a bus that is used as a driving school vehicle. The cap  40 . 6  of the vehicle has as usual a base  42 . 6  and a sheet like inner cover  43 . 6  extending normally to the base  42 . 6 .  
     [0162] The instructor&#39;s seat  30 . 6  comprises, inter alia, a seat member  33 . 6  having a seat surface, a backrest member  31 . 6 , and an armrest  32 . 6  on the right side and it is mounted on a base plate or base  42 . 6  of the driving school vehicle chassis. The instructor&#39;s seat  30 . 6  and/or the instructor&#39;s post can be located in a middle area between a driver&#39;s seat and a passenger&#39;s seat not shown.  
     [0163] The controlling unit  20 . 6  of the instructor&#39;s post of the invention is designed preferably in form of a control stick  20 . 16  or of a joystick and it has a handle  21 . 6 , an angle member  24 . 6 , a tubular fixing member  25 . 6 , a control knob  22 . 6 , and coupling means  23 . 6  for coupling of the control unit  20 . 6  to the electrical installations of the driving school vehicle.  
     [0164] The fixing member  25 . 6  is rigidly attached to the instructor&#39;s seat  30 . 6 . The angle member  24 . 6  of the control unit  20 . 6  has a tubular member  24 . 16  extending horizontally and a further tubular member  24 . 26  extending vertically and normally to the tubular member  24 . 16 . The tubular member  24 . 16  has a free end that is rotateably supported in the fixing member  25 . 6  around its axis and supported shiftably in and out of the fixing member  25 . 6 . The tubular or cylindrical handle  21 . 6  of the control stick  20 . 16  is supported rotateably around its axis in the tubular member  24 . 26  at one end and it carries the control knob  22 . 6  at the other end. The control knob  22 . 6  provides a plurality of switches  26 . 6  or electrical operation units, e.g. controllers, which are provided for electrical switching of functions of the electrical devices in the driving school vehicle. The functions to be switched by the switches  26 . 6  are, for instance, the functions of the signalling devices, e.g. blinker and horn, the wipe and wash devices, e.g. the windscreen wiper, and of the headlight devices, e.g. the dimmed headlight and upper beam headlights of the driving school vehicle. The teacher or instructor may even control also driving functions like braking, operating the clutch, acceleration and even steering or operating gear box if the electrical devices of the driving school vehicle comprise corresponding electrical actuators and features, e.g. control of the accelerator operation, the clutch, the braking operation etc. driven by electric motor. The switches  26 . 6  and electrical actuator means of the control unit  20 . 6  are coupled via the coupling means  23 . 6  to the electrical devices of the driving school vehicle. For instance, a cable may be used as it is shown in FIG. 15 which extends in the interior of the tubular members  25 . 6 ,  24 . 16 ,  24 . 26 ,  21 . 6  to the control knob  22 . 6  and which is there connected to the switches  26 . 6 , e.g. touch contact switches and rocker switches and actuators, either directly or via interface electronics. The cable is coupled, for instance, via a plug-type connection to a corresponding connector on the instrument panel  41 . 6  of the driving school vehicle. The connector of the instrument panel  41 . 6  or board is coupled electrically to the electrical devices of the driving school vehicle such that the function and features of the electrical system of the vehicle can be controlled by and from the control unit  20 . 6  as intended. But the coupling means  23 . 6  can be designed also as a telemetry arrangement comprising suitable transmitters and receivers for an electromagnetic, optical, e.g. infrared, or ultrasonic coupling of the control unit  20 . 6  to the electrical system of the driving school vehicle.  
     [0165] As generally preferred, the control unit  20 . 6  is attached to the instructor&#39;s seat  30 . 6  by, for instance, the mounting member  25 . 6 . Further, the control unit  20 . 6  is arranged in the instructor&#39;s post so that the instructor can operate it in a comfortable and ergonomic manner. In the embodiment presently shown, the control stick  20 . 16  of the control unit  20 . 6  is located near the free end of the right armrest  32 . 6  of the instructor&#39;s seat so that the instructor can easily embrace the handle  21 . 6  of the control stick  20 . 16  by hand and, particularly, he can easily reach the switches  26 . 6  by thumb on putting his right forearm on the armrest. Thus, the handle  21 . 6  has an approximate length that approximately corresponds to the width of a hand. The switches  26 . 6  on the control knob  22 . 6  are then approximately one length of thumb in maximum distant from the end of the handle  21 . 6  to allow a safe and comfortable operation of the switches  26 . 6 .  
     [0166] Display means (not shown) can be yet attached to the control unit  20 . 6 . For instance, a LCD may be used as display means. The display means are preferably coupled to, for instance, a video camera by additional coupling means in an electrical manner. The video camera can be attached to the left exterior rear view mirror of the bus and, thus, it detects the surrounding area on the left side of the bus. The image or picture detected by the video camera is indicated to the instructor on the display means whereby, for instance, a vehicle in the “blind angle” can be recognized by the instructor. The display means can be attached to the topside of the control knob  22 . 6  of the control stick  20 . 16  in the control unit  20 . 6 , for instance, by a flexible tube to adjust the position of the display means.  
     [0167] The pedal means on the instructor&#39;s side  80 . 5  (or  80 . 6 ) is attached to the vertical inner cover  43 . 6  or the vertical portion of the chassis of the driving school vehicle in the driver&#39;s cell  40 . 6 .  
     [0168] The holding device  1 . 6  has substantially a frame having two vertical bars  6 . 6  and  6 . 16  or rods, a base plate  2 . 6 , on which the vertical bars  6 . 6  and  6 . 16  stand perpendicularly, and an overhanging handle portion  12 . 6  projecting into the space of the driver&#39;s cell  40 . 6 . The vertical bars  6 . 6  and  6 . 16  extend between the bottom plate  2 . 6  and the handle portion  12 . 6 . Further, the holding device  1 . 6  has a footrest  7 . 6  and an attachment frame  10 . 6 ,  11 . 6  for attachment of the pedal means  80 . 5  (or  80 . 6 ) to the holding device  1 . 6 .  
     [0169] The holding device  1 . 6  is connected to the base plate  2 . 6  on the base  42 . 6  of the driving school vehicle by screws. A transverse member  4 . 6  extends between the vertical bars  6 . 6  and  6 . 16  horizontally, the transverse member  4 . 6  is attached to the inner cover  43 . 6  of the driving school vehicle by screws.  
     [0170] The handle portion  12 . 6  has a transverse bar  3 . 6 , a left side curved tube member  13 . 6  and a right side curved tube member  14 . 6  which connect the transverse bar  3 . 6  to the vertical bar  6 . 6  or the vertical bar  6 . 16  integrally. The curved tube members  13 . 6  and  14 . 6  project to the driver&#39;s side and passenger&#39;s door, respectively, in a curved and bellied manner oriented away from the vertical bars  6 . 6  and  6 . 16 , respectively.  
     [0171] The footrest  7 . 6  has a rest tube  7 . 16  extending horizontally and perpendicularly to the vertical bars  6 . 6  and  6 . 16  of equal length in a transverse manner, and two support tubes  8 . 6  and  9 . 6  having equal length and extending in parallel to each other. The support tube  8 . 6  connects the rest tube  7 . 16  to the vertical bar integrally while the support tube  9 . 6  connects the rest tube  7 . 16  to the other vertical bar  6 . 6  integrally.  
     [0172] The attachment frame  10 . 6 ,  11 . 6  has two side members extending in parallel to each other, one on the side of the vertical bar  6 . 16  and the other (not shown) on the side of the vertical bar  6 . 6 , the pedal means  80 . 5  (or  80 . 6 ) is attached, e.g. by screws, on and between them, and a transverse member  11 . 6  extending between the vertical bars  6 . 6  and  6 . 16  a little below the support tubes  8 . 6  and  9 . 6 . The shown side member  10 . 6  is inclined relative to the plane of the vertical bars  6 . 6  and  6 . 16  towards the instructor&#39;s seat  30 . 6  and it includes an angle to the vertical bar  6 . 16  that, for instance, may be  15  °. Consequently, also the side member not being shown is inclined relative to the plane of the vertical bars  6 . 6  and  6 . 16  towards the instructor&#39;s seat  30 . 6  and it includes the same angle to the vertical bar  6 . 6  which, for instance, may also have 15°. The angle point is located on the bottom plate  2 . 6  while the opening of the angle is at the level of the transverse member  11 . 6  on which the side members  12 . 6  are welded.  
     [0173] As shown in FIG. 15 in which the pedals of the pedal means  80 . 5  are depicted in a non operated condition, the pedals are located, if the pedal means  80 . 5  (or  80 . 6 ) are attached or secured to the side members  10 . 6 , in the space between the rest tube  7 . 16  of the footrest  7 . 6  and the base plate  2 . 6  of the holding device  1 . 6  or the base of the driver&#39;s cap or cell, or to say it in other words, the footrest  7 . 6  or its rest tube  7 . 16  is arranged in the space above the pedals. In more detail, the footrest and the transverse tube  7 . 16  extend in a plane being parallel to the plane of the vertical bars  6 . 6 ,  6 . 16 , and a fictitious axis through the pedals  99 ,  98  and  97  extends in a plane being parallel to the vertical plane of the rest tube  7 . 16 . The vertical plane of the rest tube  7 . 16  has a distance to the vertical parallel plane of the pedals. This horizontal distance is, for instance, 5 cm to 15 cm and it allows that the pedals can be reached without any obstacle. Thus, the footrest  7 . 6  extends in a displaced manner backwards within the area between the vertical bars  6 . 6 , and  6 . 16  and this vertical plane of pedals. If one puts a horizontal plane through the pedals  99 ,  98 , and  97  and a horizontal plane being parallel thereto through the rest tube  7 . 16 , both planes are perpendicular to the vertical plane of the vertical bars  6 . 6  and  6 . 16 , a vertical distance is present between both horizontal planes which may be, for instance, 5 cm to 20 cm. That means that the footrest  7 . 6  and the rest tube  7 . 16  are arranged in this distance in the area above the pedals.  
     [0174] It was found that the arrangement of the footrest  7 . 6  allows a very quick operation of the pedals by the instructor. The instructor, for instance, rests his left foot on the footrest  7 . 6 . Then, if the instructor has to intervene in the present driving in order to correct the student driver, the foot only needs to be moved downwards onto the pedals, e.g. the pedal  99 , to be able to provide a pedal operation. In this case, one can speak of “dropping” the foot that surprisingly leads to a very quick pedal operation reaction and, thus it leads to improved safety during driving school operation.  
     [0175] The instructor&#39;s side pedal means  80 . 5  of the instructor&#39;s post in FIGS. 13, 14 and  15  is shown in more detail in FIG. 5, which is composed of pedal units  80 ,  80 . 1  and  81  having the respective pedals  99 ,  98  and  97  for clutch, brake, and acceleration, respectively. The pedal means  80 . 5  is coupled to the supplementing driver&#39;s side pedal means  90 . 5  shown in FIG. 4 via the pressure lines  90 ,  91  and  92  for priority controlling of the driver&#39;s side pedal means  90 . 5 .  
     [0176] The pedal lever  60  and the support lever  61  of the pedal linkage are surrounded by a flexible frill or cover  601  being closed and folded (see FIG. 15), which consists of rubber, e.g. india-rubber. The cover  601  protects the pedal means  80 . 5  against pollution or dirtying, e.g. splash water. The pedal lever and the support lever of the pedal  98  also are provided with a corresponding folded and flexible protective cover  602 .  
     [0177] If the instructor&#39;s side pedal means  80 . 6  shown in FIG. 10 and having the pedal units  80 . 2 ,  80 . 12 , and  81 . 2  and the corresponding pedals  99 . 2 ,  98 . 2 , and  97 . 2  are used in the instructor&#39;s post according to FIGS. 13, 24, and  15 , the pedal means  80 . 6  are coupled to the supplementary driver&#39;s side pedal means  90 . 6  of the double pedal means  90 . 6  having anti gas for priority controlling of the driver&#39;s side pedal means  90 . 6  via the pressure lines  90 . 2 ,  91 . 2 ,  92 . 2 .