DE4039830C1 - Variable transmission with V-belt - incorporates hydraulic system for controlling setting of conical pulleys - Google Patents

Abstract

The cone pulley transmission applies axial force to an interposed belt etc. via hydraulic tensioners which are mounted on shafts to act on the axially adjusting pulleys. The tensioners are loaded via line-fed pressure medium by a pump from tank through a control valve. A torque sensor in the valve return chokes this to set the basic system pressure. A speed sensor on the drive shaft upstream of the transmission feeds medium as a function of speed onto a control element which together with a transmission power adjuster acts on the valve. An electrical switch valve (54) in the medium line (18,19) between valve (12) and drive-side tensioners (9,11) blocks off flow to this drive side tensioners when flow switches and connects the drive-side tensioners to offtake (26). The switch valve can only be switched provided that three in-series switches (58-60) are closed. The first switch (58) closes at minimum drive torque, the second (59) closes when the transmission is at a running radius on the drive side higher than the minimum running radius of the belt (8). The third switch (60) closes when the driving speed on the transmission side falls below a minimum value. USE/ADVANTAGE - Motor vehicles. Transmission can be switched over for starting from any position using control valve and series switches.

Description

The invention relates to a bevel gear with stu The translation can be adjusted and adjusted without gung axial pressure forces of the conical pulleys on a zwi these revolving traction means via hydraulic Has clamping device arranged on the gear shafts are net and axially to one on the respective gear bevel movable conical pulley, what the Clamping devices accordingly via a control valve as well adjoining pressure medium lines with pressure medium are acted upon by a pump from a Pressure medium collecting container is conveyable, wherein in the Return flow of the control valve there is a torque sensor the torque flow on the drive shaft of the gearbox is arranged and by the torque-dependent relative movement of two valve parts to each other depending on the load Backflow of the control valve throttles and thus the base System pressure determined, and being the gear upstream on its drive shaft a speed sensor is located, the pressure medium on depending on the speed Control there, which in connection with an on actuator for the drive power to the gearbox setting via the control valve.

Such a transmission is through DE-PS 39 00 204 be knows. It serves with its adjusting devices at the An  use in motor vehicles to translate between Automatically control drive and output, so that the Driver is exempt from this activity.

Here, on the part of the power lever, the so-called accelerator pedal both the filling of the combustion engine tors determined as well as the control for setting the Gear ratio given a signal that a target value for the engine speed. filling and engine speed are usually assigned in this way net that the respective engine power at as low as possible is applied according to fuel consumption. Because of the Engine map shows that filling and rotation number must run in the same direction.

For a carburetor engine, this means that when actuated or depression of the accelerator pedal the opening angle of the Throttle valve in the carburetor of the engine as well as the setpoint be increased for the engine speed. Corresponding both values are reduced when the accelerator pedal is released nert.

Exists between the actual value and the specified setpoint Engine speed a difference, so the control unit gives an adjustment command to the gearbox. This leads to a spreading of the drive-side conical washers and thus reducing the drive-side run radius of the traction device if the actual value is less than Setpoint is. On the other hand, the adjustment command leads to an increase in the drive radius of the Traction device if the actual value is greater than the setpoint.  

The one assigned to the position of the unactuated accelerator pedal lowest setpoint for the engine speed is clearly about the engine idling speed. This will make him is enough that a Ver. before stopping the vehicle command to reduce the barrel given radius of the traction device on the drive pulley set as soon as the engine speed falls below the setpoint tet. This serves the goal of preparing the gearbox the later starting process to the greatest possible over setting.

They are available under normal driving conditions standing time and the gelie by the pressure medium pump ejected the amount of pressure medium to the gearbox in the ge described to transfer start-up translation. Becomes critical the situation, however, in the event of an emergency stop, because then it can happen that the available pressure medium quantity in the shortage of time still available sufficient to move the gearbox to the starting ratio adjust, especially by blocking the drive for example, bikes on a slippery road surface are premature Transmission may come to a standstill.

At standstill, however, a bevel gear can normal contact conditions practically not adjusted and thus also the existing adjustment command do not execute. The reason for this is that at Conical disk drives of the type in question Resistance to adjustment movements with decreasing um running speed of the traction device increases sharply, follow maximum reached when the gear unit is at a standstill. This can result, for example, after an emergency brake  result in situations in which the gearbox gears tongue is not traced back to the starting position where with it a restart for the driver of the vehicle connects with difficulties or becomes impossible.

The object of the invention is therefore a conical disk instincts of the type mentioned in the beginning that regardless of the driving conditions always a transfer of the gear ratio to the An driving position is ensured.

This object is achieved in that - To enable a drastic relief of the to spreading washer set - in the pressure medium line between control valve and drive-side clamping device an electrically operated changeover valve is used through which when the pressure medium is switched flow of this line to the drive-side clamping means lockable and the drive-side clamping device hydraulic is connectable to a pressure medium drain, and that Changeover valve only when three in the closed position arranged electrical switch in its Umstellstel is convertible, the first switch being in Closed position is when the drive torque is one Assumes minimum value, the second switch in the closing position is when the bevel gearbox on the drive side on a running radius above the smallest running radius the traction device is, and the third switch in closing position is when the transmission-side drive speed falls below a minimum value.

From DE-PS 22 00 555 it is known that still thereby adjusting the position of a bevel gear  make sure that the fluid pressure from the Spannmit is taken away. However, this for the clamping devices both on the drive side and on the output side by a in the pressure medium return flow of the control valve ordered relief valve, initially by one hand 've had to be pressed in order to shutdown position of the gearbox by actuating another, enable handle coupled to the control valve. The two existing in the known case ste are not connected to each other in terms of control technology, so that the known standstill adjustment is not both designed automatically acting as well in this way its function is time-consuming. In order to the known standstill adjustment is not suitable for rapid and automatic action on motor vehicles Conical disk gearboxes located on the machine.

In contrast, the measures according to the invention have the Effect that in one out of the driving condition itself automatically as soon as possible Standstill adjustment of the bevel gear on translation gear required for a new start only the drive side is relieved Clamping device from the pressure medium pressure above the control valve only in connection with the drive side Pressure relief means assigned to clamping devices. Since the located on the driven side of the bevel gear the clamping devices remain under pressure, they cause the drive side to be relieved of pressure medium Clamping devices quickly the required standstill ver position of the gearbox.  

Is between a drive motor and the cone pulley drive a mechanical clutch, the torque sensor and upstream of the speed sensor on the drive arranged shaft of the transmission, it is appropriate that the first switch is closed when the clutch is disengaged is, so be with the actuation of the clutch in turn is operable. This results in the disengagement of the mechani clutch before the subsequent starting process automatically the adjustment of the gear ratio in the starting position. Here it is advantageous that the Ab to release the flow from the drive-side clamping means send pressure fluid to the torque sensor.

On the other hand, there is a design in which between a drive motor and the bevel gear hydrodynamic clutch, the torque sensor and the Speed sensor upstream, on the drive shaft of the Gear is arranged, it is appropriate that the first switch with a lever for adjusting the lei Stung the drive motor is coupled and then closed is when the power lever is in its low position rigorous drive power assigned position.

So here is the first switch with the accelerator or its position in operative connection, since the hydro dynamic coupling does not derive an actuating movement leaves. The pressure medium outflow advantageously takes place here if necessary via a throttle in the pressure medium collection container because in the presence of a hydrodynamic Coupling the torque sensor with one if small remains applied to residual torque, thus a throttle maintains effect and consequently not for one  Sufficient dismantling of the tension on the drive side pending fluid pressure is suitable.

As for the second switch, this can by one to the axial position of one of the axially displaceable Cone pulley coupled lever can be operated. This of course within the scope of the invention in such a way that the second switch is only closed when the bevel gear in such a ratio position in which the traction mechanism is on the drive side a run above the minimum walking radius radius.

The third switch is advantageously at the position position of the control coupled, which, as already said is acted upon by the speed sensor. These Position indicates the actual speed of the drive shaft again. The third switch is closed when the Actual speed falls below a certain limit.

Regarding the third switch, there can now be one Design with a mechanically disengageable clutch between the drive and the conical gearbox should be appropriate, that the third switch already at such a position position of the control element is closed, the one drive speed on the speed sensor with a Value below 1500 / min. corresponds. So here is done the standstill adjustment of the transmission, if on the part of the driver before starting off with the engine running Clutch is disengaged and the transmission is not yet in the over desired for the next start settlement position. However, the driver would choose  arbitrarily actuate the clutch while driving, see above the third switch would remain open and thus the switch valve not actuated when the actual drive speed of the gearbox is above the stated value. Here is the danger of overdriving the drive motor encountered.

With a design that includes a hydrodynamic coupling the drive connection between the engine and gearbox, it is appropriate, however, that the third switch at closed such a position of the control element sen is that of a drive-side speed at the speed sensor of zero or close to zero. These abs The switching threshold on the third switch is set cher that not at a return of the accelerator in the zero position while driving a pressure reduction at the drive-side clamping means can take place, whereby the There would be a risk of a lack of pressure on the gearbox.

With all the designs described above, it is advisable that in the pressure medium reflux in generally known Way a preload valve to the torque sensor tet, the throttle position depending on the Transmission position of the transmission by means of the Stellhe bels is adjustable so that with the smallest barrel radius of the traction device on the drive side of the gearbox Throttling effect is greatest.

Furthermore, it is in itself by DE-PS 28 28 347 known training of the torque sensor such that due to the torque-dependent relative movement of the valve parts of the torque sensor in the event of torque surges  Lich a certain volume of the pressure medium in the System and thus pumped into the hydraulic clamping devices is appropriate to provide according to DE-PS 38 17 532 that between the supply side of the pressure medium for rotation torque sensor and the hydraulic clamping devices leading fluid lines further fluid lines with opening in the pumping direction of the torque sensor Check valves are arranged.

Further characteristics and details emerge itself from the following description of execution shapes that are shown on the drawing. In the Show drawing:

Fig. 1 is a cone pulley drive for a motor vehicle with mechanical clutch in the Antriebsverbin extension between the drive motor and conical pulley gear and

Fig. 2 shows a transmission of the type shown in Fig. 1, but with a hydrodynamic coupling in the drive connection.

Fig. 1 shows a drive unit 1 in the form of an internal combustion engine, from which a drive shaft 2 extends. The drive shaft 2 is connected to the drive-side disk set 3 , 4 of a conical disk transmission, which on the other hand has an output-side disk set 5 , 6 , which rotates on an output shaft 7 , to which the drive wheels of a motor vehicle are connected in a manner not shown. The two sets of disks 3 , 4 and 5 , 6 are connected to each other by a traction device 8 rotating about them. On each shaft 2 , 7 is one of the conical disks, namely the conical disk 3 or 5 to adjust the gear ratio axially ver, for which purpose it is known in a known manner as Zylin dermantel 9 , 10 of a hydraulic pressure cylinder, the piston 11 is shaft-proof is arranged.

Thus, a hydraulic clamping means is formed on the axially displaceable conical disks 3 , 5 , the pressure medium is allocated via a four-way control valve 12 . For this purpose, there is a Druckmit telpump 13 on the drive shaft 2 , which sucks pressure medium from a reservoir 14 and via a flow control valve 15 and a line device 16 , 17 to the control valve 12 , from where it then corresponds to the switching position of the control valve via lines 18 , 19 and 20 the hydraulic clamping means is allocated on the two transmission sides.

The pressure medium flowing out of the control valve 12 is guided via a line 21 to a preload valve 22 . The throttle setting this bias valve takes place by means of an angle lever 23 which is Gert gela at 24 stationary and the pivot position is determined by the drive side, axially movable conical disk 3, by setting the angle lever engages in a circumferential groove 25 of the cylinder jacket 9 23rd

From the preload valve 22 , the pressure medium flowing away from the control valve 12 passes via a line 26 to a torque sensor 27 , which is connected upstream of the conical disk transmission on the drive shaft 2 . Behind the torque sensor 27 , the pressure medium exits the reservoir 14 without pressure.

In its inflow, namely the line 26 , the torque sensor 27 maintains a torque-dependent pressure and, together with the preload valve 22, determines the base pressure of the hydraulic system controlling the bevel-disk gear so that a perfect power transmission is ensured on the bevel-disk gear.

The torque sensor 27 is designed in a manner known per se so that it can pump a certain amount of pressure medium back into the line 26 when torque surges occur, in order in this way to respond to the sudden pressure requirement for supporting the torque shock on the drive and output axially adjustable conical disks of the conical disk gear. So that this amount of pressure medium is available as quickly as possible on the axially displaceable conical pulleys, there are between the line 26 and the lines 19 and 20 line connections 28 , 29 with Rückschlagventi len 30 , 31 , via which the pressure medium quantity delivered by the torque sensor 27 when it occurs can flow from torque surges.

Connected to the pressure medium supply via line 16 is a pressure relief valve 32 which serves as a safety valve and does not normally speak to.

Furthermore, there is a differential pressure valve 33 between the inflow line 17 and the back flow line 21 of the control valve 12 , through which the available differential pressure when adjusting the bevel-disk gearbox is limited in order to avoid sudden changes in the transmission ratio of the bevel-disk gearbox in the event of sudden changes in the power of the drive unit 1 . See in detail DE-PS 39 00 204.

The setting of the translation of the conical disk gear bes depending on the power of the drive unit 1 and of the driving resistance is carried out with the aid of a speed sensor 34 connected upstream of the gearbox on the drive shaft 2 , which has a branch 35 from the line which strikes the drive side of the gearbox with pressure medium 19 is supplied and from which a speed-dependent pressure on a spring-loaded control element 37 in the form of a cylinder-piston unit is guided via a line 36 , so that the axial position of the piston 38 reflects the drive speed. The piston 38 is connected via its piston rod 39 in an articulated manner to one end of a lever 40 , the other end of which is articulated to an angle lever 41 , which is fixed to the housing at 42 and, with its other end 43, scans a control cam 44 which, at 45, is stationary gela gert, sits at the end of a linkage 46 , 47 , which is actuated by a power lever 49 , which is mounted in a fixed position at 48 , a so-called accelerator pedal, with the free end 50 of the accelerator pedal and a connection 51 being a power setting (not shown in detail) of the drive unit 1 takes place, for example influencing the throttle valve of an internal combustion engine.

The center of the lever 40 is abge via a pin 52 by the control valve 12 against the action of the spring 53 . A change in the position of the accelerator pedal 49 be a deflection of the lower end of the lever 40 and thus the control valve 12th The resultant Ver adjustment process on the bevel disc gearbox comes to an end when the drive speed has changed so much that the deflection of the control valve 12 is canceled again via the speed sensor 34 and the resulting position of the piston 38 at the upper end of the lever 40 .

Each setting of the accelerator pedal 49 thus corresponds to a specific drive speed. The two variables are assigned by the design of the control curve 44 .

If the power lever 49 or the accelerator pedal is moved into the idle position for the drive unit 1 , the lowest target speed is thus specified, which, as already mentioned, is clearly above the idle speed of the drive unit 1 . Now drops the actual speed below this setpoint, this causes the adjustment of the translation of the bevel gear in the starting position, in which the traction means 8 at the antriebsseiti gene cone disks 3 , 4 takes the smallest running radius. Here, due to the diminishing effect of the speed sensor 34, the piston 38 of the control valve 37 moves to the left, so that the control valve 12 can direct the pressure medium flow coming via the line 17 on the way via the line 20 to the clamping means 10 of the output-side disc set 5 , 6 , with which the traction device takes on the largest running radius.

However, if there is not enough time for this adjustment process due to special situations, for example in connection with emergency braking, the translation of the conical disk gear remains in a position deviating from the starting ratio, since the traction means 8 is particularly due to the existing frictional forces Can no longer change the radius between the conical pulleys of the gearbox.

To counter this, an electrically operable changeover valve 54 is provided in the pressure medium connection 18 , 19 leading to the drive pulley set. This is shown in Fig. 1 in the switch position, which corresponds to normal operation, that is, a smooth connection between the lines 18 and 19 .

In the event, however, that the gear ratio should be adjusted to the start-up ratio when the conical disk gear is at a standstill, that is, such a ratio in which the traction means 8 between the drive-side conical disks 3 , 4 assumes the smallest running radius can be switched by the switching valve 54 the line connection 18 , 19 interrupted and the line 19 connected to the line leading to the torque sensor 27 line 26 , in this way to release the pressure side pressure prevailing in the cylinder-piston unit 9 , 11 via the torque sensor 27 into the reservoir 14 .

So that the switching valve 54 takes on the described switching position against the action of a fixed spring 55 , in the switching valve 54 providing electrical circuit 56 , which can be supplied by an energy source 57 , three electrical switches 58 , 59 and 60 must be closed . In order to bring these three switches into the closed position, the following conditions must be met:

The switch 58 is coupled to the disengagement mechanism 61 of a mechanical clutch 62 , which is located on the drive shaft on the transmission between the drive unit 1 and the cone pulley. When clutch 62 is disengaged, switch 58 is closed. The clutch 62 is actuated or disengaged when the driver of the motor vehicle wants to start from a standstill position.

The switch 59 is coupled to the free end 63 of the Winkelhe lever 23 in such a way that it is in the closed position as long as the conical disk 3 does not take its axially most distant position from the conical disk 4 , which is the smallest running radius of the traction means 8 between the Conical pulleys 3 and 4 corresponds. This is the radial position of the traction means 8 between the conical disks ben 3 and 4 , which is necessary for the starting ratio.

The switch 60 is closed only when drive prevails side at the rotation speed sensor 34 such a low speed that the til 37 given by the sensor 34 on the Steuerven pressure takes such a small value that the piston with respect to FIG. 1 in a more left position.

If these three necessary conditions for a drastic reduction in pressure are met, then the changeover valve 54 is transferred to the changeover position by corresponding electrical application of its adjusting mechanism, in which the drive-side pressure medium from line 19 to torque sensor 27 and thus to the pressure medium return flow into the reservoir 14 is given. From the side of the conical disk 3 , therefore, no contact pressure is exerted on the traction means 8 , so that the conical disk 3 can move to the left in relation to FIG. 1 in order to allow the traction means 8 to take the smallest possible running radius. This adjustment is caused by the fact that on the output side of the bevel disk gear at the hydraulic tensioning means 10 there due to the setting of the control valve 12 that pressure fluid delivered by the pump 13 is present, which seeks to reduce the distance between the conical disks 5 and 6 and thus the displacement of the traction device 8 to the largest possible radius.

The above-described standstill adjustment of the gear ratio takes place when the driver disengages clutch 62 while the engine is running and the gear is not in the starting ratio in which the traction mechanism 8 occupies the smallest possible running radius between the conical disks 3 and 4 .

In the event that the driver arbitrarily disengages the clutch 62 during normal driving, there is no risk of resetting the transmission ratio to the transmission ratio as long as the drive speed on the shaft 2 is above a certain limit value. Because then the control valve 37 is still pressurized via the speed sensor 34 so far that the switch 60 is in the open state. This is the Ge danger of over-rotating the drive unit 1 to avoid.

The fact that the pressure from the line 19 via the switching valve 54 in the case of the standstill adjustment via the line 26 to the torque sensor 27 has the advantage that when the power transmission is started again, the required pressure medium pressure is immediate and without negative effects is rebuilt on the pulley sets on the input and output sides, since the torque sensor can pump a certain volume of pressure medium backwards into the clamping means of the pulley sets in a manner known per se. If the pressure medium outflow from the changeover valve 54 directly into the reservoir 14 , the torque sensor 27 could only exert the pump effect described when the changeover valve 54 is completely closed again, that is, the connection between the lines 18 and 19 has been established. This would be critical in the event that clutch 62 would suddenly engage again while the transmission was still adjusting the standstill.

The avoidance of annoying loss times in the build-up of pressure also serves to guide the pressure medium flowing out of the differential pressure valve 33 via line 21 to the preload valve 22 . From the differential pressure valve 33 flows during the adjustment of the part of the delivery volume of the pump 13 , which, when the control valve 12 is fully deflected, extends beyond the part accommodated by the driven pulley set.

FIG. 2 shows a modification of the construction explained in detail with reference to FIG. 1. The components already described with reference to FIG. 1 are provided with the local terms in FIG. 2 without a further explanation.

The modification shown in Fig. 2 consists in wesentli that a hydrodynamic clutch 70 is used as a clutch in the drive shaft 2 . Such a clutch, which can also be expanded to a converter, does not have a disengaging mechanism that could be scanned in a manner comparable to the embodiment according to FIG. 1 by a switch in the electrical circuit of the changeover valve 54 . In addition, the clutch or converter transmits a low torque even when the drive unit 1 is idling. The resulting pressure in the inflow to the torque sensor 27 would prevent a standstill adjustment of the transmission when acting on the drive-side conical disk set 3 , 4 .

Therefore, the pressure medium coming in the switchover position of the Umschaltven valve 54 from the drive-side line 19 is returned via a throttle 71 and a line 72 to the reservoir 14 .

On the other hand, in the current path 73 to the switching valve 54, a switch 74 is used as a replacement for the switch 58 according to FIG. 1, which is in operative connection with the accelerator pedal 49 or its setting by the position of the lever 44 carrying the control cam via an extension approximately 75 samples.

In this case, the gear ratio is adjusted at a standstill in the direction of the starting ratio when the accelerator pedal 49 is not actuated, as a result of which the switch 74 is closed, the gear ratio does not correspond to the gear ratio desired for the starting process, and the switch 59 is closed, and the pending at the speed sensor 34 drive speed is equal to or close to zero, whereby the switch 60 is closed ge.

The mode of operation corresponds to that described with reference to FIG. 1. The only difference is that there is a lowering of the switching threshold at switch 60 . Since it is ensured that after a normal removal of the actuation of the throttle lever 49 while driving, a pressure reduction on the drive-side tensioning means 9 , 11 cannot take place. However, if all the conditions for changing the gear ratio of the conical disk gearbox are met at a standstill, and if the changeover valve 54 is brought into the changeover position, a pressure builds up on the throttle 71 only at the beginning of the pressure medium flow, which causes the adjustment of the gearbox translation hindered. The adjustment speed for the gear ratio reaches a limit value, the size of which depends on the cross section of the throttle 71 .

A coupling of the connection between the drive unit and the conical disk transmission while the adjustment of the conical disk transmission was at a standstill in the direction of the starting ratio is not as fast as in the embodiment described with reference to FIG. 1, since an increase in the application of the hydrodynamic clutch 70 drive-side torque is only possible by increasing the engine speed.

Therefore the time stands for the speed acceleration of the Motors also for renewed pressure build-up on the cone disc gearbox available.

The inventive device for the translation position of a bevel gear at standstill has been explained with reference to FIGS . 1 and 2 with reference to electrical switches. Of course, it is also possible to work in the same way with electronic switching means, so that the Ge subject of the invention should not be limited in this regard.

Claims (11)

1.Tapered disk gear with continuously adjustable and adjustable translation, which has hydraulic tensioning means for generating axial contact forces of the tapered disks on a traction device rotating between them, which are arranged on the gearshafts and act axially on a respective tapered disk on the respective gearshaft, for which purpose the clamping means via a control valve and adjoining pressure medium lines can be acted upon with pressure medium, which can be promoted by a pump from a pressure medium collecting container, a torque sensor being located in the return flow of the control valve, which is arranged on the drive shaft of the transmission in the torque flow and by torque-dependent relative movement of two valve parts to each other, depending on the load, throttles the return flow of the control valve and thus determines the base pressure of the system, and with the transmission upstream on its drive shaft, a speed sensor be finds the pressure medium depending on the speed on a control element, which acts in conjunction with an adjusting element for the drive line on the gear ratio via the control valve, characterized in that in the pressure medium line ( 18 , 19 ) between the control valve ( 12 ) and the drive-side tensioning means ( 9 , 11 ) an electrically actuated changeover valve ( 54 ) is used, through which, when the pressure medium is switched, this flow to the drive-side tensioning means can be blocked and the drive-side tensioning means can be hydraulically connected to a pressure medium drain ( 26 , 72 ), and that the changeover valve can only be used for The closed position of three electrical switches ( 58 , 59 , 60 , 74 ) arranged in series can be converted into its switchover position, the first switch ( 58 , 74 ) being in the closed position when the drive torque assumes a minimum value, the second switch ( 59 ) in The closed position is when the Kegelsch is located on the drive side on a running radius above the smallest running radius of the traction means ( 8 ), and the third switch ( 60 ) is in the closed position when the gearbox drive speed falls below a minimum value. 2. Tapered disk transmission according to claim 1, wherein between a drive motor and the tapered disk transmission, a mechanical clutch, the torque sensor and the speed sensor connected upstream, is arranged on the drive shaft of the transmission Ge, characterized in that the first switch ( 58 ) with the clutch disengaged ( 62nd ) closed is. 3. Tapered disk gear according to claim 2, characterized in that the pressure medium drain ( 26 ) goes to the torque sensor ( 27 ). 4. tapered disk transmission according to claim 1, wherein between a drive motor and the tapered disk transmission, a hydrodynamic coupling, the torque sensor and the speed sensor upstream, is arranged on the drive shaft of the transmission, characterized in that the first switch ( 74 ) with a lever ( 49 ) for A position of the power of the drive motor ( 1 ) is coupled and is closed when the power lever is in its lowest drive power assigned position. 5. tapered disk gear according to claim 4, characterized in that the pressure medium drain ( 72 ) optionally via a throttle ( 71 ) in the pressure medium collecting container ( 14 ) it follows. 6. conical disk transmission according to one of the preceding claims, characterized in that the second switch ( 59 ) can be actuated by an actuating lever ( 23 ) coupled to the axial position of one of the axially displaceable conical disks ( 3 , 5 ). 7. conical disk transmission according to one of the preceding claims, characterized in that the third switch ( 60 ) is coupled to the position of the control element ( 37 ). 8. conical disk transmission according to claim 2 and 7, characterized in that the third switch ( 60 ) is closed at such a Stellposi tion of the control element ( 37 ), the drive-side speed on the speed sensor ( 34 ) with a value below 1500 / min. corresponds. 9. conical disk transmission according to claim 4 and 7, characterized in that the third switch ( 60 ) is closed at such a Stellposi tion of the control element ( 37 ) which corresponds to a drive-side speed on the speed sensor ( 34 ) of zero or near zero. 10. Tapered disk gear according to one of the preceding claims, characterized in that in the pressure medium return flow ( 21 ) the torque sensor ( 27 ) is connected upstream of a biasing valve ( 22 ), the Dros selstellung depending on the translation position of the transmission by means of the actuating lever ( 23 ) so adjustable is that with the smallest running radius of the traction means ( 8 ) on the drive side of the transmission, the Drosselwir effect is greatest. 11. Tapered disk gear according to one of the preceding claims, wherein a certain volume of the pressure medium is additionally pumped into the system and thus into the hydraulic clamping means by the torque-dependent relative movement of the valve parts of the torque sensor in the event of torque surges, characterized in that between the supply side ( 26 ) of the pressure medium to the torque sensor ( 27 ) and the pressure medium lines ( 19, 20 ) leading to the hydraulic tensioning means ( 9, 11, 10 ) , further pressure medium lines ( 28, 29 ) with blocking valves ( 30, 31 ) opening in the pumping direction of the torque sensor are arranged.