Abstract:
Quick-change device ( 12 ) comprising a quick coupler ( 16 ) fastened on the driven-machine side, an adapter ( 16 ) which can be locked with the quick coupler ( 16 ) and is connected to a tool ( 14 ), and a hydraulic coupling ( 20 ) for producing a hydraulic connection between the hydraulic system on the driven machine and the hydraulics of the tool ( 14 ), wherein the hydraulic coupling ( 20 ) includes a first coupling part ( 20   a ) and a second coupling part ( 20   b ) and the two coupling parts ( 20   a,    20   b ) are held relative to one another in an operating position, wherein the first coupling part ( 20   a ) and the second coupling part ( 20   b ) interact with at least mechanical retaining means ( 68,78,80 ) which are formed separately from the locking means of the quick-change device ( 12 ). The invention is distinguished by the fact that the coupling parts ( 20   a,    20   b ) are held frictionally in the operating position by the mechanical retaining means ( 67,78, 80 ).

Description:
Applicant claims priority to German patent application DE 10 2006 023 420.0 filed May 17, 2006. 
   FIELD OF THE INVENTION 
   The present invention pertains to a quick-change device. 
   BACKGROUND OF THE INVENTION 
   Many different embodiments of this type of quick-change device have become known. 
   A first embodiment of a quick-change device is known from, for example, EP 0 483 232 B1 and consists of a quick changer, comprising a pivoting and locking device, and an adapter. The quick changer is assigned to the arm of the excavator, and the opposing adapter, which is to be connected to the quick changer, is mounted on an exchangeable tool such as a sorting bucket. 
   The pivoting and locking device described in the publication cited above locks the adapter and the quick changer together, but it also brings the hydraulic couplings for the hydraulic fluid together. To bring these hydraulic couplings together, they must be pivoted over a relatively long distance. As a result of the spreading forces which occur during operation, the hydraulic couplings can leak and ultimately fail. This can also lead to considerable environmental damage. 
   A quick-change device is also known from WO 2005/093172 A1, which executes a pivoting movement to connect the quick changer to the adapter and also to connect the two coupling blocks together. The coupling blocks are mounted on the free end opposite the pivot axis, and one of the coupling blocks is supported in a floating manner. To counteract the spreading forces, a device is provided which generates hydraulic pressure on the hydraulic coupling in such a way that the coupling can resist the spreading forces. The force acts essentially in a direction perpendicular to the contact surfaces between the coupling blocks. Relative movements based on the elasticity of the selected material or on the basis of the floating support are thus avoided. In addition, a reliable hydraulic connection is guaranteed during operation. 
   The problem with this design, however, is that, in certain types of applications, the hydraulic pressures are very high, and these therefore cause very high spreading forces. Considerable effort is therefore required to counteract these spreading forces by means of a hydraulically produced pressure. 
   A quick-change device of the general type in question is also known from DE 101 59 417 A1. Here the coupling blocks of the hydraulic coupling are held positively in position by hooks, which are supported on one of the coupling blocks and which engage with a pin on the other coupling block when in the operating position. 
   It has been found, however, that, when the spreading forces are very high, either the mechanical means undergo fatigue and break or the material creeps, which causes the mechanical means to jam. As a result, the hydraulic coupling can no longer be disconnected, and, depending on the embodiment, the quick changer is also blocked. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the invention, therefore, the invention is based on the task of elaborating a quick-change device in such a way that, while avoiding the disadvantages cited above, it is possible with simple means to counteract the spreading forces which occur during the coupling process and during operation, so that it is guaranteed that the hydraulic coupling can be disconnected when needed regardless of the circumstances. 
   The invention is based on the realization that, by the use of nonpositively connected retaining means, which go into action when the hydraulic coupling is connected, it is possible for most of the spreading forces to be absorbed, while at the same time it is also remains possible, if necessary, to disconnect the mechanical means by separating the nonpositive connection. Even if the material creeps under the high mechanical forces which occur during operation, it is still possible to disconnect the retaining means by separating the nonpositive connection. This can be optimized even more by certain design measures. 
   According to the invention, therefore, the hydraulic coupling parts, when in the operating position, are held together nonpositively by the mechanical retaining means. As a result, the above-described disadvantages are avoided, and additional design possibilities are obtained, as will be demonstrated in the following. 
   According to one embodiment of the invention, a drive unit is able to move at least parts of the mechanical retaining means from a change position to the operating position and/or from the operating position to the change position. This is advantageous especially from the standpoint of the ease of operation of the quick-change device. 
   The drive unit for moving the mechanical retaining means from the change position to the operating position and/or from the operating position to the change position is designed as a hydraulic, pneumatic, electrical, mechanical, and/or magnetic drive. As a result, a wide field of application is obtained for the quick-change device according to the invention. 
   The first coupling part can be designed as a coupling block connected to the quick changer, and the second coupling part can be designed as a coupling block connected to the adapter, where each of the coupling blocks comprises at least one part of a hydraulic coupling valve cooperating with the other part of the valve on the other block. The coupling blocks offer the advantage that the mechanical retaining means thus act simply on the coupling blocks and/or that these means can be integrated into the coupling blocks. 
   So that the hydraulic coupling can be kept operationally reliable even under very high spreading forces, it is advantageous, when the hydraulic coupling is in the operating position, for a mechanical drive to generate an opposing force acting on the coupling parts—see WO 2005/093172 A1—to provide additional opposition to the spreading forces and to relieve the load on the mechanical retaining means. Especially from the standpoint of saving space and simplifying the design, the mechanical drive which produces the opposing force is the same as the drive unit which moves the mechanical retaining means between the change position and the operating position. 
   Alternatively, the drive unit which moves the mechanical retaining means from the change position to the operating position can be the same, whereas the drive unit which moves the mechanical means from the operating position to the change position is formed by some other type of drive, in particular by a force-storing device such as a spring. 
   According to one embodiment of the invention, the drive unit which moves the mechanical retaining means from the change position to the operating position is designed as a fluidic, especially a hydraulic, drive with a single-acting piston. Alternatively, the drive unit which moves the mechanical retaining means from the change position to the operating position and from the operating position to the change position can be designed as a fluidic, especially a hydraulic, drive with a double-acting piston. The mechanical retaining means can in this case be easily moved by the hydraulic system already present on the working machine. This means that the lines can be easily connected, but it also makes it possible to retrofit existing working machines with a quick-change device according to the invention with little effort. 
   The mechanical retaining means comprise in particular a first part, which is connected to the quick changer, and a second part, which is connected to the adapter. The first part is preferably designed as a pin, and the second part is designed as a receptacle for the pin. The nonpositive connection is achieved primarily by the fact that the forward end of the bar tapers down in wedge-like fashion, and that the receptacle is given a corresponding shape. In addition, a force acting in the direction toward the operating position also acts on the pin. This force can be produced by the drive unit which moves the mechanical retaining means from the change position to the operating position and/or vice versa. Alternatively or in addition, this force can also be produced by a force-storing device, which could be activated under certain conditions. 
   To simplify the fabrication of the pin, it is designed as a cylindrical bolt with a conical shape in its forward area. 
   Jamming even at high pressures can be easily avoided by providing a bearing play S, which is present in the operating position underneath the locking pin and which extends as far as the inside surface of the receptacle. The bearing play S guarantees that the locking pins will always have a certain degree of freedom of movement in the downward direction and thus can also be disconnected even under difficult conditions. 
   According to one embodiment of the invention, allowance is made for manufacturing tolerances and wear by designing the lateral surface of the forward area of the locking pin and the associated surface of the receptacle as corresponding conical surfaces extending over a circumferential angle of up to 180°, where the steep circumferential surfaces of the receptacle which make up the rest of the circumference to 360° cooperate with the assigned circumferential surface areas of the forward area of the pin to enclose the predetermined bearing play S. Upon the occurrence of wear, the pressure-actuated locking pin will always be able to move farther forward, and reliable retention and surface-to-surface contact remain guaranteed. 
   Alternatively, one part of the mechanical retaining means can be designed as a rocker with a locking claw, and the other part of the mechanical means can be designed as an abutment, both the claw and the abutment being wedge-shaped. 
   In particular, the movement of the mechanical retaining means from the change position to the pivoted position and vice versa is linear. This makes a simple design possible. 
   The quick changer can be designed to pivot around a pivot axis and can comprise at least one locking bar, the line of movement of which cooperates with the pivot axis to form a working plane. 
   The locking bar is then preferably able to move along a first straight line in a direction perpendicular to the pivot axis, and the coupling movement of the hydraulic coupling proceeds along a second straight line, essentially perpendicular to the first straight line. 
   To facilitate a compact design, the second line is perpendicular to the pivot axis. 
   According to one embodiment of the invention, the pin moves from the change position to the operating position along a third straight line. 
   The third straight line can lie in the working plane; in particular, it can be perpendicular to the first and second straight lines and especially it can be parallel to the pivot axis. 
   According to another aspect, the invention is based on the task of elaborating a quick-change device in such a way that, while avoiding by simple means the disadvantages cited above, a compact design is obtained and the spreading forces which occur during the coupling step and in operation are counteracted in a simple manner. 
   The invention is based on the realization that, by designing the mechanical means for securing the hydraulic coupling in such a way that their movements are linear, a compact but efficient device is made possible. 
   According to the invention, therefore, the movements of the mechanical means from the change position to the pivoted position and vice versa are linear, where in particular the mechanical means are held positively or nonpositively in the operating position. 
   Additional advantages and embodiments of the invention can be derived from the description of the inventive embodiments in conjunction with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a perspective view of a quick-change device with a quick changer and an adapter, where the quick changer is connected to an excavator arm and the adapter to a sorting bucket; 
       FIG. 2  shows a perspective view of the quick-change device of a first embodiment of the invention in the coupled state; 
       FIG. 3  shows an enlarged, partial, cross-sectional, perspective view of the embodiment of  FIG. 2 ; 
       FIG. 4  shows a perspective view of another embodiment of the invention; 
       FIG. 5  shows an enlarged, partial, cross-sectional, perspective view of part of  FIG. 4 ; 
       FIG. 6  shows a perspective diagram of another embodiment of the invention; 
       FIG. 7  shows an enlarged, partial, longitudinal cross section through  FIG. 6 ; 
       FIG. 8  shows a perspective diagram of another embodiment of the invention; and 
       FIG. 9  shows an enlarged, perspective view of  FIG. 8 . 
   

   DESCRIPTION OF THE INVENTION 
     FIG. 1  shows the arm  10  of a working machine, namely, an earth-moving machine, such as an excavator, in perspective. At the end of the arm  10  there is a quick-change device  12 , which is connected in turn to a conventional sorting bucket  14 . 
   The quick-change device  12  consists of a quick changer  16  connected to the arm  10  and an adapter  18 . The adapter  18  is permanently mounted on the bucket  14 . Through the use of the quick-change device  12 , the arm  10  can be connected to various tools such as the illustrated sorting bucket  14  by way of the adapter. Instead of the sorting bucket  14  mentioned above, it is also possible to use other tools, especially those which are hydraulically operated, such as hydraulic hammers, hydraulic shears, etc. 
   These tools are driven by a hydraulic drive, which is powered by the working machine. For this purpose, the quick-change device  12  has a hydraulic coupling  20 . The tool, in this case the bucket  14 , is connected to the hydraulic system of the earth-moving machine by way of the hydraulic coupling  20 . For certain applications, the bucket  14  is provided with a rear wall  22 , which can be opened hydraulically. The rear wall  22  is opened and closed by a hydraulic drive (not shown), integrated into the bucket  14 . The hydraulic drive is connected to the hydraulic system of the earth-moving machine by the hydraulic coupling  20 . 
   The hydraulic coupling  20  has an upper coupling block  20   a  and a lower coupling block  20   b . The cooperating contact surfaces between the two coupling blocks  20   a ,  20   b  are flat. Hydraulic valves, centering pins  24  (see  FIGS. 3 and 4 ), and cleaning nozzles  26 , which are integrated into the centering pins to clean the hydraulic coupling, are introduced into these contact surfaces. 
   The adapter  18  of the quick-change device  12  comprises a base plate  28 , at one end of which a locking block  30  is provided, and at the end of the plate opposite the locking block  30 , there is a pivot axis  34 , which is held in place by means of fastening brackets  32 . The locking block  30  has a clamping surface  36  on the side facing the pivot axis  34 . This surface slants at an angle of 3-35°, preferably of 5-15°, to a surface perpendicular to the base surface of the adapter  18 . 
   The locking block  30  is also provided with two parallel conical openings  38 , which are arranged next to each other a certain distance apart and which are conical in longitudinal cross section. Each conical opening  38  is assigned to a locking bar  40  of the quick changer  16 , which can be pushed into the conical opening. 
   The forward end of the locking bar  40  is designed as a conical tip  40   a.    
   A suitable cone angle is chosen for the conical openings  38  bounded by the conical lateral surfaces. In the exemplary embodiment illustrated here, this angle is in the range of 5-15°. 
   The quick changer  16  has claws (not shown) on the side assigned to the pivot axis  34  of the adapter  18 . These claws grip the pivot axis  34 . 
   The end surface of the quick changer  16  assigned to the clamping surface  36  of the adapter has an abutment surface  42 , which slants at an angle of preferably 5-15° to the perpendicular—corresponding to the angle of the clamping surface  36 —and also has two openings, through each of which one of the locking bars  40 , which can be driven longitudinally through the quick changer  16 , can pass. 
   Centering elements are provided for the purpose of lateral centering—the first primary orientation—when the quick changer  16  is lowered onto the adapter  18 . The centering elements assigned to the quick changer  16  are designed as centering pins  44 , which are arranged laterally next to the abutment surface  42  of the quick changer  16 . The centering pins  44  cooperate with the lateral surfaces of the locking block  30  of the adapter  18 . 
   The adapter  18  also has centering elements which act in cooperation with the pivot axis  34  to center the quick changer  16  and the adapter  18  with respect to each other in the longitudinal direction of the clamping surface  36 —the second primary orientation. When the quick changer  16  is lowered onto the adapter  18 , the clamping surface  36  and the abutment surface  42  ensure in cooperation with the pivot axis  34  that the quick changer  16  and thus the sliding locking bars  40  of the quick changer  16  are aligned with the conical openings  48  and thus centered. The process of engaging the locking bars  40  of the quick changer  16  in the conical openings  38  in the adapter can thus take place without difficulty. 
   For the rest of the details concerning the function of the quick-change device, reference is made to EP 0 0569 026 A1 of the same applicant, the entire disclosure of which is to be considered part of the content of the present invention, and which is incorporated herein by reference hereto. 
   At the free end of the adapter  18 , the lower coupling block  20   b  is rigidly connected to the locking block  30  by brackets. Hydraulic outlets  46  are provided underneath the free end of the lower coupling block  20   b . The locking block  30  is for this purpose offset in the inward direction with respect to the lower coupling block  20   b  and the hydraulic outlets  46 , so that the hydraulic outlets  46  can be easily connected to the hydraulic hoses/hydraulic lines  82 . 
   The upper coupling block  20   a  is connected to the quick changer  16  by a yoke with two arms  48 . Damping elements  50  are inserted between the upper coupling block  20   a  and the arms  48 , so that the upper coupling block  20   a  is supported in a floating fashion. Alternatively, the lower coupling block  20   b  can be supported in floating fashion by way of damping elements, and the upper coupling block  20   a  can be mounted directly on the yoke, i.e., on the arms  48 . In the embodiments shown in the figures, however, only the upper coupling block  20   a  is supported in floating fashion, because the alternative embodiment could be easily reproduced by any man of the art. 
   The floating support makes it easy to compensate for manufacturing tolerances. In addition, the upper coupling block  20   a  can, as a result, be easily centered on the lower coupling block  20   b  and properly aligned. The centering pin  24  with the cleaning nozzle  26  is used for this purpose. 
     FIGS. 2-5  show an embodiment of the invention. In the upper coupling block  20   a , an actuating pin  68  is supported in a sleeve  70 . The actuating pin  68  is hydraulically driven, is cylindrical in design, and is wedge-shaped at its forward end  72 . 
   The lower coupling block  20   b  is screwed laterally to the bracket  78 , which is rigidly connected to the adapter  18 . The bracket  78  has an opening  80  for the wedge  72  of the actuating pin  68 . On the side facing the wedge  72 , the opening  80  in the bracket  78  is adapted to the shape of the wedge  72  and is therefore also wedge-shaped, widening in the direction toward the coupling block  20   a . A bracket  78  is mounted on each side of the lower coupling block  20   b , and an actuating pin  68  is provided on each side of the upper coupling block  20   a  to engage in the associated bracket. The centering pins  24  with the cleaning nozzles  26  can be seen in the partial cross section. 
     FIGS. 2-5  also show that the hydraulic couplings  46  are connected to hydraulic lines  82 , which are routed in turn through the adapter  18  to the tool (not shown), such as the sorting bucket  14 . 
   The wedge-shaped opening  80  in the bracket  78  is designed as a through-opening for the actuating pin  68 . After the actuating pin  68  has moved into the wedge-shaped opening  80 , the actuating pin  68  has play S in the downward direction, which prevents the actuating pin  68  from jamming in the wedge-shaped opening no matter what the circumstances, especially after the occurrence of wear. 
     FIGS. 2-5  show an embodiment with a double-acting actuating piston  68 , that is, an actuating piston  68  which moves hydraulically from the change position, in which the quick-change device  12 , consisting of the quick-changer  16  mounted on the excavator arm  10  and one of the various possible adapters  18  connected to the tool  14 , is used to change from one tool to another, to the operating position, in which the quick changer  16  is rigidly connected to an adapter  18  and the hydraulic coupling  20  is coupled. The movement in the opposite direction also takes place hydraulically by application of an appropriate pressure on the piston from the other side. 
   Alternatively, a single-acting hydraulic piston (not shown) can be provided, in which the actuating piston  68  is moved by the application of an appropriate hydraulic pressure on only one side of the actuating piston  68 . To move the piston in the opposite direction, a spring is used, which is pretensioned when in the operating position and which, upon deactivation of the hydraulic force acting on the actuating piston  68 , pushes the piston back into the change position. These types of designs are known, and therefore there is no need for a detailed description. 
   The actuating piston  68 , in cooperation with the opening  80  in the bracket  78 , holds the coupling blocks  20   a ,  20   b  tightly together during operation. The hydraulic coupling  20  is connected and also disconnected almost at the same time that the quick changer  16  is connected to and disconnected from the adapter  18 . When the quick changer  16  is locked to the adapter, the actuating pin  68  travels simultaneously into the opening  80 . Unlocking takes place in an analogous manner. So that the locking bar  40  and the actuating pin  68  move almost simultaneously, they have a common drive unit. 
   The locking bar  40  and the actuating pin  68 , furthermore, travel in a common plane, which also includes the pivot axis  34 . As a result, the quick-change device acquires a compact design very advantageous for operation. 
   According to this embodiment, the quick changer  16  can pivot around the pivot axis  34 . When the locking bar  40  of the quick changer is moving to lock the quick-change device  12  in position, it moves in a first direction perpendicular to the pivot axis  34 . The coupling movement—the second direction—of the hydraulic coupling  20  takes place essentially perpendicular to the first direction and in this case also perpendicular to the pivot axis  34 . The movement of the pin  60  from the change position to the operating position takes place in linear fashion in a third direction, which is perpendicular to the first and second directions. This third direction is parallel to the pivot axis  34 . 
     FIGS. 6 and 7  show another embodiment. Each centering pin  24  is provided with a conical receptacle  52  facing the quick changer  16 . The receptacle cooperates with the conical tip of a clamping pin  54  supported with freedom to slide back and forth in the lower coupling block  20   b.    
   The clamping pin  54  is provided with a rear stop stud  54   a , which cooperates with a plunger  56  inside the locking bar  40  of the quick changer  16 . The plunger  56  cooperates with a spring  58  in such a way that, when the plunger  56  is pushed in, the spring  58  is put under tension. 
   When the claws of the quick changer  16  are placed on the adapter  18  and the quick changer is pivoted around the pivot axis  34 , it centers itself as described above, so that the locking bars  40  are aligned with the conical openings  38 . In this position, the upper coupling block  20   a  lies on the lower coupling block  20   b . The locking bars  40  now move into the conical openings  38  and clamp the quick changer  16  to the adapter  18  and clamp the coupling blocks  20   a ,  20   b  to each other. As a result of this clamping operation, the coupling blocks  20   a ,  20   b  are coupled to each other. 
   When the locking bar  40  travels inward, the plunger  56  inside the locking bar  40  strikes the stop stud  54   a  of the clamping pin  54  and moves this pin away from the locking bar  40  against the force of the spring  58  and toward the conical receptacle  52  in the centering pin  24 . In analogy to the way in which the quick-changer  16  is clamped to the adapter  18  by the cooperation between the conical ends  40   a  of the locking bars  40  and the conical openings  38  in the adapter  18 , now the upper coupling block  20   a  is also clamped to the lower coupling block  20   b , where the conical end  54   b  of the clamping pin  54  has traveled into the conical receptacle  52 . 
   The spring  58  serves to compensate for the overstroke which the locking bar  40  makes versus the clamping pin  54 . The spring  58  is not compressed until the conical end  54   b  of the clamping pin  54  is resting completely inside the conical receptacle  52  and is thus holding the two coupling blocks/valve blocks  20   a ,  20   b  together. As a result, the coupling blocks  20   a ,  20   b  are protected even at this early point from spreading forces. The locking bars  40  are still not in contact with the walls of the conical openings  38  at this point but continue to move until they are fully engaged in the openings. This results in the previously mentioned overstroke, and the spring  58  is now put under tension. This guarantees that, after the quick changer  16  has become worn and thus rotates farther around the pivot axis  34  and thus the locking bars  40  gain the ability to seat themselves more deeply in the conical openings  38 , the coupling blocks  20   a ,  20   b  will always be reliably clamped together even before the locking bars are fully engaged. The clamping pins, which are, after all, already resting in the conical receptacles  52 , do not interfere in any way with the movement of the locking bars  40 . 
   After the conical end  54   b  of the clamping pin  54  enters the conical receptacle  52 , the conical end  54   b  of the clamping pin  54  rests flat on the walls of the conical receptacle  52  over a circumferential angle of up to a maximum of 180°. The partial surfaces of the clamping pin  54  making up the rest of the circumference to 360° create a bearing play S, which prevents the clamping pin  54  from jamming in the conical receptacle  52  under any circumstances, not even after the occurrence of wear. 
     FIGS. 8 and 9  show another embodiment of the invention. The upper coupling block  20   a  is provided with a hydraulically actuated actuating bar  60 , which is capable of traveling laterally outward and thus against the force of a spring (not shown). A rocker  62 , which is supported more-or-less at its midpoint on the upper coupling block  20   a  so that it is free to rock back and forth, cooperates with the actuating bar  60 . At one end, the rocker  62  has a projection  62   a , which cooperates with the actuating bar  60 , and at the other end it has a claw  62   b , which grips the lower coupling block  20   b . The claw  62   b  is beveled to match the associated lower abutment surface of the lower coupling block  20   b . Jamming is prevented by the cooperation between these two slanted surfaces, and the pressure exerted by way of the actuating bar  60  on the rocker  62  makes it possible to hold the coupling blocks  20   a ,  20   b  nonpositively together. The rocker  62  is supported rotatably on a pivot pin  64  and is pretensioned by a torsion spring (not shown) in such a way that the rocker  62  releases the lower coupling block  20   b  when the actuating bolt  60  travels inward. 
   The pivot pin  64  is connected to the upper coupling block  20   a  and thus to the quick changer  16  by a retaining arm  66 . In this way the coupling blocks  20   a ,  20   b  are held together during operation, that is, in the coupled state, by the rocker  62 , the pivot pin  64 , the retaining arm  66 , and the claw  62   b  in cooperation with the beveled abutment surface of the lower coupling block  20   b  under the hydrostatic force acting on the actuating bar  60 . The design just described is provided on both sides of the coupling blocks  20   a ,  20   b.    
   The spreading forces which occur can thus be transmitted between the upper and lower coupling blocks  20   a ,  20   b  via the rocker  62  on each side. The hydrostatic force being applied holds the actuating bar  60  in question in the retaining position. When the hydrostatic force is deactivated, the spring in the upper coupling block  20   a  assigned to the actuating bar  60  in question moves the bar inward, so that the corresponding rocker  62  can pivot under the action of the torsion spring (not shown) connected to the pivot pin  64  far enough to release the lower coupling block  20   b  and thus to allow the quick-change device  12  to be opened. 
   All of the previously described embodiments of the invention are symmetric to the longitudinal center axis of the quick changer  16 , so that, for example, two sets of the mechanical retaining means for holding the coupling blocks  20   a ,  20   b  together are provided, one on each side. Alternatively, the mechanical retaining means can be arranged differently, or all of them can be arranged at the front of the quick-change device. 
   The embodiments shown in the drawing comprise a quick-change system according to the quick-change device disclosed in WO 2005/093172 A1. 
   The invention is characterized by the simplicity with which the spreading forces can be counteracted by mechanical means. Additional forces/pressures, however, are also required to actuate and to hold the mechanical means, such as the bars, in position. When the hydraulic pressure is turned off, the upper and lower coupling blocks  20   a ,  20   b  are released, and the quick changer  12  can be opened. 
   Because the bars travel in straight lines and are arranged essentially on the same plane as that which also holds the pivot axis, a compact design is achieved. 
   LIST OF REFERENCE NUMBERS 
   
       
         10  arm 
         12  quick-change device 
         14  bucket 
         16  quick changer 
         18  adapter 
         20  hydraulic coupling 
         20   a  upper coupling block 
         20   b  lower coupling block 
         22  rear wall 
         24  centering pins 
         26  cleaning nozzle 
         28  base plate of the adapter 
         30  locking block 
         32  fastening bracket 
         34  pivot axis 
         36  clamping surface 
         38  conical opening 
         40  locking bar 
         40   a  conical end 
         42  abutment surface 
         44  pins 
         46  hydraulic connections 
         48  arm/yoke 
         50  damping element 
         52  conical receptacle 
         54  clamping bar 
         54   a  stop stud 
         54   b  conical end 
         56  plunger 
         58  spring 
         60  actuating bar 
         62  rocker 
         62   a  projection 
         62   b  claw 
         64  pivot pin 
         66  retaining arm 
         68  actuating pin 
         70  sleeve 
         72  forward end of the actuating pin/wedge 
         74  piston rod 
         76  hydraulic piston 
         78  bracket 
         80  opening 
         82  hydraulic line