Abstract:
The life of a clutch is prolonged via bypassing a clutch of a gearbox and engaging a machine braking system. A change in speed or direction of a gearbox output shaft is accomplished by a management controller sending a signal through a signal transmission system to bypass the clutch and engage the machine braking system. The method includes the steps of generating a signal; processing the signal by the management controller, sending a signal to bypass the clutch; and sending a signal to engage the vehicle braking system to change the speed or direction of rotation of the gearbox. Because changes of speed and/or direction of rotation of the output shaft are assisted by the machine braking system and the clutch is at least partially bypassed, it is ensured that the braking function of the starting clutch is considerably reduced or even eliminated. This leads to a considerable reduction in wear on the clutch, so that its service life can be greatly increased.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to German Application DE 101 48 696.0 filed on Oct. 2, 2001 and DE 102 23 296.2 filed on May 24, 2002. 
     1. Technical Field of the Invention 
     The invention relates generally to self-propelled machines and, more particularly, to a method and apparatus for prolonging the life of a clutch on such machines, especially agricultural or utility machine. 
     2. Description of the Related Art 
     EP 0 728 962 and its counterpart, U.S. Pat. No. 5,695,422, describe, inter alia, a hydrostatic-mechanical torque-divided transmission for agricultural machines, and other utility machines. To change direction of the machine the rotation of the input shaft is reduced to zero. Typically this is accomplished, at least in part, by reducing fuel feed and allowing the engine to gradually slow the rotation of the input shaft. Torque is transferred via a clutch inside the transmission. In the case of high torque transfer, this leads to both considerable heat generation in the clutch and to premature wear. To reduce heat generation and wear-related drawbacks, it is known that several clutches or braking elements can be integrated in the respective drive train. But this still leads to elevated heat generation in the drive train and has the disadvantage that a considerable number of additional assemblies are required. 
     The present invention is directed to overcoming one or more of the problems set forth above. 
     SUMMARY OF THE INVENTION 
     An aspect of the invention is to provide a method and an apparatus for the control of a self-propelled machine which, with little structural expenditure, minimizes wear of the drive train, reduces heat generation in the drive train, reduces the high power idle that occurs with ordinary methods for changing the direction of the machine, and/or lowers overall fuel consumption of the self-propelled machine. 
     Another aspect of the present invention is to control a self-propelled machine which includes a gearbox with an output shaft, a clutch, and a braking system. When a change of speed and/or direction of rotation of the output shaft is required, a management controller effects the change by at least partially bypassing the clutch and engaging the machine braking system. 
     When changes of speed and/or direction of rotation of the gearbox output shaft are assisted by the machine braking system, the braking function of the clutch is considerably reduced or completely excluded. This leads to a considerable reduction in wear of the clutch, so that its service life can be greatly increased, compared with known designs in the art. Also, apart from reducing the load on the clutch, a considerable reduction of engine idle power generated during deceleration is accomplished, so that the machine needs considerably less fuel, particularly in the case of changes in the direction of travel. 
     To not impair driving stability, it is of further advantage if associated with each land wheel or each axle of the machine are wheel brakes which are operated during changes of speed and/or direction of rotation of the gearbox output shaft. 
     A particularly advantageous embodiment arises if the self-propelled machine includes a traction machine and towed equipment. In this embodiment, the land wheels and/or axles of both the traction machine and the towed equipment are wheel brakes. For changes of speed and/or direction of rotation of the output shaft, the wheel brakes of both the traction machine and the towed equipment are operated. In this way, even with tractor/trailer combinations, it is ensured that, in addition to the wear-minimization of the clutch of the traction machine, high driving stability of the combination is accomplished. 
     To obtain high flexibility of the machine braking system in the case of changes of speed and/or direction, an advantageous embodiment includes a machine brake management system. 
     To obtain high driving stability independently of the driver&#39;s wish to decelerate, machine-generated input signals delivered to the management controller can be used to monitor the driving stability and achieve the inputted wish to decelerate. 
     In accordance with the present invention there is provided an apparatus for prolonging the life of a clutch of a self-propelled machine having a drive train including an engine, a gearbox with an output shaft, and a machine braking system; means for generating an input signal relating to a function of the drive train; a management controller for receiving the input signal, analyzing the input signal for its effect on the drive train, and generating a plurality of output signals; and means for transmitting one of the output signals to the machine braking system and another of the output signals to the clutch, and for automatically and cooperatively engaging the machine braking system and disengaging the clutch to assist a change in the speed or direction of rotation of the output shaft. 
     Other aspects, objects and advantages of the present invention can be obtained from a study of the drawings, the disclosure and the accompanying claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is now made to the drawings which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the views: 
     FIG. 1 is a schematic top view of a self-propelled machine with a management controller embodying the invention; 
     FIG. 2 is a detailed view of a transmission and clutch; 
     FIG. 3 is a side view of a self-propelled machine with the management controller according to the invention; 
     FIG. 4 is the management controller according to the invention in a block diagram; and 
     FIGS. 5A and 5B are graphic illustrations comparing energy use. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a schematic top view of a self-propelled machine  1  having a front and a rear. The self-propelled machine  1  has a direction of travel labeled FR. The self-propelled machine  1  has a frame  2 , shown only schematically, that receives a drive engine  3  which is operatively connected by energy transmitting means  4  to a gearbox  5  which will be described in more detail later, wherein the gearbox  5  receives a clutch  6 , which may be a starting clutch. In the preferred embodiment, the energy transmitting means  4  is an input shaft. A first output shaft  7  of the gearbox  5  is operatively connected to a transfer gearbox  8 . A first output member  9  operatively connects the transfer gearbox  8  to a first auxiliary gearbox  12 , and a second output member  10  operatively connects the transfer gearbox  8  to a second auxiliary gearbox  13 . In the preferred embodiment, the output members  9 , 10  may be intermediate shafts and the auxiliary gears  12 , 13  may be differential gears. While the second auxiliary gearbox  13  in front in the direction of travel FR drives a front axle  14 , the first auxiliary gearbox  12  at the rear in the direction of travel FR is connected in driving relationship to a rear axle  15 . Both the front axle  14  and the rear axle  15  in the embodiment shown receive at their free ends a land wheel  16  which can be braked by means of a wheel brake  17 . The axles  14 , 15  and the wheel brake  17  may instead be associated with an alternative running system, such as a crawler track assembly. In the preferred embodiment, there is a wheel brake operatively connected to each wheel  16 . The wheel brakes  17  can also be designed as a hydraulic motor  18 , so that driving and braking of the wheels  16  is effected by these hydraulic motors  18  alone. On the other hand, the wheel brakes  17  shown schematically can also be gearbox-brake combinations known in the art as wheel motors  19 . Also, one or more driven or freely rotatable axles  14 ,  15  are associated with the self-propelled machine  1 . The wheel brakes  17  are connected via a first signal transmission system  20  to each other and to a management controller  21  associated with the self-propelled machine  1 . The wheel brakes  17  can be associated with the land wheels  16  or only with axles  14 ,  15 . 
     Particularly easy control of the braking operation arises if the driver via suitable input means can trigger a braking signal, a steering signal, a signal for determining the direction of travel and the so-called “braking via the drive train.” In an operator&#39;s platform  22 , a steering wheel  24 , a brake pedal  25  and a ground speed control lever  26  are available to a driver  23  in a manner known in the art for control of the self-propelled machine  1 . The steering wheel  24  and the brake pedal  25  each include a sensor for providing a signal. Also, mounted in the operator&#39;s platform  22  is a control switch  39 , upon operation of which braking is initiated via the drive train by means of an engine brake or gearbox brake, also called a retarder, which is known in the art and therefore not described in more detail. 
     Referring now to FIG. 2, in its simplest form the gearbox  5  can be designed as a reversing gear  27 , wherein the energy transmitting means  4  is operatively connected to an intermediate shaft  28 . Associated with the intermediate shaft  28  are at least one first spur gear  29  and at least one second spur gear  30 , wherein both spur gears  29 ,  30  can be non-rotatably connected via the clutch  6  alternately to the intermediate shaft  28 . Likewise two spur gears, a third spur gear  31  and a fourth spur gear  32 , are associated with the output shaft  7  of the reversing gear  27 , which drives the wheels  16  via the transfer gearbox  8 , the output members  9 , 10 , and the axles  14 , 15 . The third spur gear  31  meshes directly with the first spur gear  29  of the intermediate shaft  28 , while the fourth spur gear  32  of the output shaft  7  is connected in driving relationship via an intermediate gear  33  for reversing the direction of rotation to the second spur gear  30  of the intermediate shaft  28 . The reversing gear  27  can, for example, form part of a gearbox  5  not shown in more detail and designed as a hydrostatically/mechanically torque-divided gearbox  34 . 
     Previously, to change the direction of travel FR of the self-propelled machine  1  from forward to reverse travel and vice versa, the clutch  6  must first release the driving connection between the spur gear  29 ,  30  which is non-rotatably connected to the intermediate shaft  28  at the time. In addition to the internal friction-related resistances of the drive train  3 - 15  and the external friction resistances of the land wheels  16  on the ground, braking of the self-propelled machine  1  to the standstill required for a change of direction of travel is effected to a considerable extent via the clutch  6 . This leads, as known from the state of the art, to considerable wear on the clutch  6 . Using an embodiment of the present invention, the braking function of the clutch  6  which promotes this wear can be reduced or avoided if the change of speed or direction of rotation of the output shaft  7  is assisted by a machine braking system  53 . The embodiment described at least partially bypasses the clutch  6  of the gearbox  5 . This further has the advantage that the driver no longer has to actuate a braking member directly, but simply the input of a wish to change direction of travel leads to automatic response of the braking system  53  by the management controller  21 . 
     The preferred method can be employed particularly effectively with so-called off-highway machines, in particular agricultural and forestry machines which as a rule are used both for transport on the road and for use according to the intended purpose on uneven land such as fields or in the forest and are subjected to considerable changes of driving speed particularly on uneven land, depending on the load. Due to the fact that the management controller  21  can act both on the clutch and on the machine braking system associated with the respective self-propelled machine  1 , reduced-load operation of the clutch  6  is accomplished. 
     According to the preferred embodiment, this partial bypassing of the clutch  6  is controlled by the management controller  21 . This control process is shown schematically in FIGS. 3 and 4. According to FIG. 3, the control elements of steering wheel  24 , ground speed control lever  26  and brake pedal  25  already described, which are integrated in the operator&#39;s platform  22  and actuatable by the driver  23 , are correspondingly connected by a first, a second, and a third line system  35 - 37  to the management controller  21 . The control switch  39  which triggers the drive train braking operation is connected by a fourth line system  38  to the management controller  21 . At their simplest, the line systems  35 - 38  described can be designed as electrical wires that transmit to the management controller  21  electrical signals which are generated by the control elements of steering wheel  24 , brake pedal  25 , ground speed control lever  26 , and control switch  39 . This signal transmission can also be effected wirelessly, for example by radio, dispensing with the need for line systems  35 - 38 . 
     Particularly easy monitoring of the driving stability of the self-propelled machine  1  and of achieving the wish to decelerate input by the driver  23  is achieved if the machine-generated input signals for the management controller  21  are the input signals of speed of the machine (“speed over land”), the speed of one or more land wheels (“wheel speed”), the measured direction of travel of the machine (“direction of travel”), or the measured position of one or more land wheels of the machine (“wheel position”). In the embodiment shown, associated with the self-propelled machine  1  in its front region is a driving speed sensor  40  that, for example, in a manner known in the art, emits a plurality of sound waves  41 . The driving speed sensor  40  receives the sound waves  41  back according to the Doppler principle and determines the driving speed from the frequency variation and/or the variation in amplitude. Further, associated with at least one of the land wheels  16  and operatively connected thereto is a wheel speed sensor  42 . The wheel speed sensor  42 , as its name implies, determines the speed of rotation of the land wheel  16 . The wheel speed sensor  42  can be associated with each of the land wheels  16 . The signals generated in the driving speed sensor  40  and the wheel speed sensor  42  are transmitted to the management controller  21  via a fifth and a sixth line system  43 ,  44 . Here too signal transmission can be effected wirelessly by radio, so that the line systems  43 ,  44  could be omitted. The signals transmitted by the line systems  35 - 38 ,  43 , and  44  form the input signals E 1 -E 6  of the management controller  21 . The management controller  21  generates according to FIG. 3, from these input signals E 1 -E 6 , a first output signal A 1  which is delivered via the first signal transmission system  20  to the wheel brakes  17  already described. Via a second signal transmission system  45 , a second output signal A 2  generated by the management controller  21  is transmitted to clutch  6  for triggering a shift operation in the gearbox  5 . The management controller  21  can generate further output signals An, wherein the output signals A 1 -An can be, for example, electrical or hydraulic signals. The first signal transmission system  20 , the second signal transmission system  45 , and a third signal transmission system  46  required for transmission of the output signals A 1 -An are corresponding electrical or hydraulic signal transmission systems  20 ,  45 ,  46 . With respect to the transmission of electrical output signals A 1 -An, the signal transmission systems  20 ,  45 ,  46  shown can be dispensed with by wireless transmission thereof. 
     Further associated with the self-propelled machine  1  can be a single-axle or multiple-axle towed equipment  47  having a ground drive axle  48 , in a manner analogous to the self-propelled machine  1 , and land wheels  16  and wheel brakes  17  cooperating therewith. The wheel brakes  17  are connected by the first signal transmission system  20  already described to the management controller  21 . The wheel brakes  17  may be associated with either all the land wheels  16  or only the ground drive axle  48  and connected by the first signal transmission system  20  to the management controller  21 . Also, associated with one or more of the land wheels  16  of the towed equipment  47  can be the wheel speed sensors  42 , as described. 
     According to the flow chart in FIG. 4, the driver  23  can actuate the control elements of brake pedal  25 , steering wheel  24 , ground speed control lever  26  and control switch  39  integrated in the operator&#39;s platform, so that the input signals E 1 -E 4  generated by these control elements  24 - 26 ,  39  are driver-generated. At their simplest the input signals E 1 -E 4  can be electrical signals which are generated in a manner known in the art by distance or angle-of-rotation sensors as well as on/off switches. 
     In the embodiment shown, input signal E 1  embodies a braking signal (“brake”) generated by the brake pedal  25 , E 2  embodies a steering signal (“steering lock”) generated by the steering wheel  24 , E 3  embodies a signal (“direction of travel”) generated by the ground speed control lever  26  and determining the set direction of travel (forward, reverse), and E 4  embodies a signal (“brake via drive train”) generated by the control switch  39  for switching on or off the engine brake and/or at least one gearbox brake. 
     In addition to the driving speed sensor  40 , which generates a driving speed signal E 5  (“speed over land”), and the wheel speed sensors  42 , which generate a speed-of-rotation signal E 6  (“wheel speed”) for the respective land wheel  16 , a direction-of-travel sensor  49  known in the art can be associated with the self-propelled machine  1  and with the towed equipment  47 , and a wheel angle sensor  50  which are also known can be associated with each land wheel  16 . While the direction-of-travel sensors  49  at their simplest determine the direction of rotation of the front or rear axle  14 ,  15  as well as of the ground drive axle  48  of the towed equipment  47  and from this measured direction of rotation generate a direction-of-travel signal E 7  (“direction of travel”), the wheel angle sensors  50  determine the deflection of the land wheel  16  associated with the respective wheel angle sensor  50  and generate therefrom in each case a steering signal E 8  (“wheel position”). Via a fourth signal transmission system  51  and a fifth signal transmission system  52 , the direction-of-travel signal E 7  and the steering signals E 8  are also transmitted to the management controller  21 , so that the signals E 5 -E 8  form machine-generated input signals E 5 -E 8  of the management controller  21 . 
     As already described and shown in FIG. 3, the wheel brakes  17  of the land wheels  16  are connected by the first signal transmission system  20  to the management controller  21 , wherein the management controller  21  receives a plurality of input signals E 1 -E 8  and generates output signals A 1 -An which act on the one hand on the wheel brakes  17  via the first signal transmission system  20  and on the other hand on the clutch  6  via the second line system. According to FIG. 2, the wheel brakes  17 , which can also be designed as hydraulic motors  18  or wheel motors  19  known in the art, and the first signal transmission system  20  connecting them form the machine braking system  53 . 
     As shown in FIGS. 3 and 4, a brake management system  54  includes the machine braking system  53 , the elements  24 - 26 ,  39 ,  40 ,  42 ,  49 ,  50  which generate the input signals E 1 -E 8 , the management controller  21  and the elements  5 ,  6 ,  17 - 19 , with the towed equipment  47 , which are influenced by the output signals A 1 -An thereof as well as the associated signal transmission systems  20 ,  35 - 38 ,  43 - 46 ,  51 ,  52 . Such a network makes it possible in a very simple manner to allocate to the driver  23  a plurality of input elements via which he can trigger a braking operation. In such an embodiment, the choice of respective input means can be freely determined by the driver. This is particularly important with self-propelled machines in which a distinction is made between so-called road or transport driving and off-road or working driving. In each of these modes of operation, the driver sometimes actuates very different control elements and his preponderant attention to very different processes must apply, so that triggering of a braking or acceleration operation should also be adaptable to the handling of these different control elements. Such a network additionally allows the configuration of completely new control structures, so that even complex self-propelled machines with, for example, so-called single-lever control or single-pedal control can be represented. 
     The brake management system  54  may also ensure that the driver  23  can no longer directly influence the braking operation and hence deceleration of the self-propelled machine  1  with the towed equipment  47 . Due to the fact that deceleration is directly triggered by the management controller  21 , it can be ensured that the clutch  6  is relieved of energy load by applying one or more wheel brakes  17  and much less idle power is generated in the self-propelled machine  1  when reversing the direction of travel. 
     The simplest application arises if the driver  23  triggers a braking operation by actuation of the brake pedal  25  or presets a change of direction of travel by shifting the ground speed control lever  26 . From the input signals E 1 , E 3  delivered to the management controller  21 , the latter generates the first output signal A 1  (“brake”) which is delivered via the first signal transmission system  20  to one or more wheel brakes  17  of the land wheels  16 . In the embodiment shown as in FIG. 4, the wheel brake  17  is formed in a manner known in the art and therefore not shown in more detail by an adjustable brake valve  55  and a brake cylinder  57  operatively connected to this brake valve  55  by a hydraulic line system  56 . The output signal A 1  generated by the management controller  21  first causes displacement of the brake valve  55 , as a result of which the brake cylinder  57  brakes the land wheel  16  associated with it. Via at least one of the machine-generated input signals E 5  (“speed over land”), E 6  (“wheel speed”) or E 7  (“direction of travel”), the management controller  21  receives information on the instantaneous movement of the self-propelled machine, for example when the self-propelled machine is stationary in case of a desired change of direction of travel, its driving speed is zero. 
     Also, the management controller  21  generates the second output signal A 2  which is transmitted via the second signal transmission system  45  to the clutch  6  of the gearbox  5 . Depending on the braking characteristic defined by the management controller  21 , the output signal A 2  before or during output signal A 1  causes the braking operation in the gearbox  5  for opening the clutch  6 . At the moment of stopping, the management controller  21  generates a third output signal A 3  which is likewise transmitted via the second signal transmission system  45  to the clutch  6 . The third output signal A 3  triggers a further shift operation in the gearbox  5 , namely reengagement of the clutch  6 , wherein output signal A 1  releases the activated wheel brakes  17  again and the output shaft  7  of the gearbox  5  undergoes a reversal of the direction of rotation and hence the self-propelled machine  1  undergoes a change of direction of travel. Unlike the simplest application described, the clutch  6  of the gearbox  5 , in addition to the wheel brakes  17 , can likewise be involved in braking the self-propelled machine  1 . 
     To minimize wear on the brake linings, if the driver  23  wishes minimal deceleration, activation of the wheel brakes  17  can be prevented by the management controller  21  by the fact that, for example, the control switch  39  arranged in the operator&#39;s platform  22 , as already described, generates a signal to engage the engine brake or gearbox brake (“brake via drive train”). In this case the self-propelled machine  1  is decelerated in a manner known in the art and therefore not described in more detail via so-called engine or gearbox brakes. 
     Driving stability of the self-propelled machine  1  with the towed equipment  47  depends critically on the rideability of the ground over which the land wheels  16  are moving (road, ploughed land), the mass and mass distribution of the self-propelled machine  1  with the towed equipment  47 , the driving speed and radii of curvature to be driven through. The brake management system  54  can be used to improve the driving stability of the self-propelled machine  1  and associated towed equipment  47 . This is very important particularly for self-propelled and forestry machinery, as machines of this kind are frequently used on uneven land which is difficult to travel over and very slippery due to the action of rain and, depending on the crop being picked up, is subject to great fluctuations of weight. 
     Due to the fact that the self-propelled machine  1  with the towed equipment  47 , in addition to the driver-generated input signals E 1 -E 4 , also delivers machine-generated input signals E 5 -E 8  to the management controller  21 , the management controller  21  on the one hand is capable of comparing the signals “brake” E 1 , “steering lock” E 2 , “direction of travel” E 3 , “brake via drive train” E 4 , which are preset by the driver  23 , with the variations “speed over land” E 5 , “wheel speed” E 6 , “direction of travel” E 7 , “wheel position” E 8 , which occur at the self-propelled machine  1  and associated towed equipment  47 , and monitoring the attainment thereof. But on the other hand there is also the possibility of permanently programming into the management controller  21  limit values for any parameters in the form of characteristic curves  58  which must not be exceeded to ensure high driving stability. This concerns in particular the maintenance of maximum acceleration and deceleration as a function of the driving speed, the self-propelled machine mass and the radii of curvature to be driven through, wherein interactions between these parameters can also be taken into consideration. Also, by means of the management controller  21  it can be ensured that the deceleration preselected by the driver  23  is transmitted to all land wheels  16  with the towed equipment  47  in such a way that the self-propelled machine  1  and associated towed equipment  47  attains the preselected deceleration, wherein the deceleration of the individual land wheels  16  can differ from each other. This is particularly important if the self-propelled machine  1  is operated with a towed equipment  47  and it is to be ensured that during the braking operation a relative movement does not occur between self-propelled machine  1  and towed equipment  47 , or occurs only insignificantly. 
     Due to the fact that wheel angle sensors  50  and wheel speed sensors  42  for determining the land wheel speed are associated with the land wheels  16  and the associated towed equipment  47 , by means of the management controller  21  it can be ensured that the speed of each land wheel  16  is adapted to the steering lock of the respective land wheel  16 . In particular this improves the driving stability on bends and turns and leads to less wear on the wheels, because the wheel slip, which is considerable particularly on slippery ground, can easily be counteracted by individual braking of the land wheels  16 . 
     High driving stability and easy handling of the self-propelled machine  1 , for example when braking and accelerating, are achieved in particular if the management controller  21  also generates one or more output signals which are delivered to a machine management system  60  known in the art for ensuring stable driving behavior of the self-propelled machine  1  at all times as a function of loading states, driving speeds, the properties of the ground contacted by the land wheels and radii of curvature to be driven through. 
     It is of particular advantage if the output signals of the management controller  21  delivered to the machine management system  60  include the change of speed of the self-propelled machine  1  and the computer-measured energy of the self-propelled machine  1 . In this case, the measured change of speed can be monitored and influenced, for example by means of the machine management system  60 , to avoid accelerations or decelerations of the self-propelled machine  1  which might endanger the driving stability. The computer-measured kinetic energy of the self-propelled machine, on the other hand, can be further processed in the machine management system  60 , for example to the effect that, in the case of a self-propelled machine  1  on a slope, the brakes are not released until the energy provided by the drive system reliably prevents the self-propelled machine  1  from rolling back. 
     Also, the management controller  21  can be configured so as to be capable of determining the braking force required to brake the self-propelled machine  1  with the towed equipment  47  and calculating from this braking force the energy needed for subsequent starting. The starting energy determined in this way could be delivered by the management controller  21  as a further output signal A 4  by means of a sixth signal transmission system  59  to the machine management system  60  which is known in the art and therefore not described in more detail and in which, depending on at least this signal A 4 , a starting operation of the self-propelled machine  1  with the towed equipment  47  for stable driving can be ensured. 
     FIG. 5A shows the energy balance when reversing the direction of rotation by means of a reversing gear according to the state of the art. The self-propelled machine  1  travels at moment t 1  at a speed of −V 1  and brakes through the further time cycle t to a speed of v=0, in order then to be accelerated again, wherein the self-propelled machine  1  finally moves at a speed of V 2  at time t 2 . In simplified form it is assumed here that the engine speed n engine  is almost constant during this operation. The area “b” represents the energy quantity which is taken from the self-propelled machine  1  during braking and according to the state of the art occurs in the clutch  6 . The area “c” represents the energy quantity of the drive engine  3  which is converted in the clutch  6  by slipping of the clutch  6  during acceleration of the self-propelled machine  1  and cannot be used for machine acceleration. 
     Referring to FIG. 5B, the area “a” on the other hand embodies the so-called idle power that is introduced into the whole system of the self-propelled machine  1  by the drive engine  3  in the braking stage. Again, area “b” represents the energy quantity which is taken from the self-propelled machine  1  during braking and area “c” represents the energy quantity of the engine  3  which is converted in the clutch  6  by slipping of the clutch  6  during acceleration. The idle power occurs entirely in the clutch  6  and cannot be used for the self-propelled machine. According to the present embodiment, during braking of the self-propelled machine this idle power fraction “a” is decreased by bypassing the clutch  6 , and at best this fraction according to FIG. 5A equals zero. 
     In summary, the method for prolonging the life of a clutch of a self-propelled machine  1  includes the steps of: generating an input signal e.g. E 1 -E 6  relating to a function of the drive train  3 - 15 ; analyzing the input signal for its effect on the drive train; generating a plurality of output signals A 1 -An; transmitting one of the output signals A 1  to the machine braking system  53 ; transmitting another of the output signals A 2  to the clutch  6 ; and automatically cooperatively engaging the machine braking system  53  and disengaging the clutch  6  to assist a change in the speed or direction of rotation of the output shaft  7 . 
     The invention in its broader aspects is not limited to the specific steps and apparatus shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.