EP3399106B1 - Quick swap coupling for fixing an attachment - Google Patents

Description

Field of the Invention

The invention relates to a quick-change coupling for attaching an attachment to an excavator arm according to the preamble of claim 1 and a method for pretensioning and releasing a closing element of a quick-change coupling according to the preamble of claim 15.

State of the art

Quick-change couplings are known from the prior art, which enable fast attachment, detachment and changing of an attachment on an arm of an excavator. For example, an excavator bucket with a certain width can be quickly exchanged for another excavator bucket with a larger or smaller width on the excavator arm.

All existing quick-change couplings have a sliding locking hook or a sliding locking element. In a closed position, the locking hook includes one of the two retaining bolts of the attachment when the attachment is coupled to the excavator arm. If the attachment is to be uncoupled, the locking hook is moved to an open position.

In the case of fully automatic quick-change couplings, the locking hook is driven by an actuator. The actuator can be operated pneumatically, hydraulically or electrically. As a result, the attachment can be coupled and uncoupled to the excavator arm without the operator having to get out of the cab. The actuator can be controlled via a control provided in the driver's cab. These fully automatic quick-change couplings are characterized by a high level of operating convenience, but are relatively expensive to purchase.

Mechanical quick-change couplings must be operated directly manually. For coupling and uncoupling, the operating personnel must therefore move the locking hook manually into the open position or into the locking position and lock the locking hook in the locking position. The mechanical quick-change couplings are cheaper to buy than those described in the last paragraph Quick-change couplings. In addition, the maintenance and installation effort is lower. However, attaching and detaching an attachment is tedious and, accordingly, time-consuming.

In the EP 2 055 842 A2 describes a semi-automatic clutch for an excavator bucket on an excavator arm. A hole with 5 shoulders is provided on a rotating body. A sled can be moved by springs. Two coupling pins and one pin are moved together with the carriage. The pin can lock in the 5 paragraphs and thereby secure the coupling pins in different extended positions. The rotating body is prestressed by a spring means and firmly connected to a cam. If the excavator shovel is hooked into the claw with the bolt, a holding means of the excavator shovel presses on a release pin. The release pin releases the rotating body from the preloaded position, which releases the slide and the coupling pins fix the excavator bucket to the coupling. A pivot pin is rotated with a removable tool, which is firmly connected to the cam and the rotating body. By turning the rotating body, the bolt is moved linearly and preloaded in the open position of the coupling. A dosed relaxation of the slide when no excavator bucket is coupled to the coupling is not possible or only with great effort and risk.

In the GB 2 412 361 A a semi-automatic clutch is also described, in which a closure element is biased with a spring. A holding element with a release element holds the closure element in the open, pretensioned position. A retaining pin of an excavator shovel presses the release element and the release element is released and closes the coupling without securing against unintentional opening. The clutch is tensioned with a manually operated lever.

The WO 94/25689 describes a coupling for attaching an attachment to an excavator arm, which can be operated hydraulically or manually. A base joint links a locking part, through which locking part the clutch can be opened and closed. The base joint includes an intermediate arm, a projecting arm and an activation arm. The intermediate arm, which is articulated to the other arms and the closure part, is designed as a pressure cylinder. The pressure cylinder comprises a cylinder rod and a compression spring. In the Locking position, the locking part is biased by the pressure cylinder and the base joint is in a dead center position in which it cannot be pressed open. A handle is arranged on the projecting arm, by means of which the base joint can be rotated about an axis of rotation and, as a result, the closure part can be moved manually between the closed position and the open position. A hydraulic activation cylinder is articulated on the activation arm, through which the base joint can also be rotated and the closure part can be opened and closed from the driver's cabin.

Object of the invention

The disadvantages of the prior art described result in the object initiating the present invention of further developing a generic mechanical quick-change coupling by simplifying the coupling of an attachment and at the same time improving the operating safety.

description

According to the prior art, a quick-change coupling for fastening an attachment to an excavator arm comprises a receiving and fastening device and a fixed first insertion opening, which is formed or fastened to a first end of the receiving and fastening device. Furthermore, the quick-change coupling comprises a movable locking element arranged on the receiving and fastening device with a second insertion opening, which can be moved from an open position in which an attachment can be coupled or uncoupled to a closed position in which the retaining bolts of the attachment can be moved through the insertion openings are engaged and clamped.

The closing element is pretensioned and lockable in the open position. The closing element does not have to be transferred manually from the open position to the closing position, but rather moves automatically into the closing position by releasing the pretension as soon as the closing element is unlocked. The present quick-change coupling is therefore semi-automatic, which makes operation easier and a quick coupling process of an attachment leads. Furthermore, the quick-change coupling is free of hydraulic or pneumatic actuators, which makes the quick-change coupling particularly reliable and low-maintenance.

The problem is solved with a quick-change coupling in that an operating lever is movably arranged on the receiving and fastening device, which has a first hand attachment, whereby it can be operated with the first hand of the user of the coupling and which operating lever is the closing element in the Opened and locked in the closed position and unlocked and that the clutch comprises a clamping lever with a second hand attachment, whereby the clamping lever with the second hand of the user can be operated simultaneously with the operating lever for pretensioning and for relaxing the closing element. Since the user of the clutch has to use both hands to move and pretension the locking element into the open position, the clutch is particularly safe and injuries when operating the clutch, in particular hand injuries, are excluded. Since both hands are inevitably used in safe places on the coupling, neither hand can be in a place where it could be injured.

In the context of this patent application, a hand attachment is to be understood as an area on the operating lever and the tensioning lever which enables the operating lever and the tensioning lever to be operated with one of the user's hands or one or more fingers. Such a handle can therefore be a handle or a hook. It is also conceivable for the hand attachment to be an extension of the lever or for the lever to have an area which can be attacked by the user in such a way that the operating lever or the tensioning lever can be moved in an intended direction.

The operating lever enables the locking element to be secured in the open and in the closed position. This reliably protects the quick-change coupling from malfunctions, which in the worst case can lead to accidents. The locking element is unlocked by manual intervention or by further displacement from the open position using the second retaining bolt or a tensioning lever. Since other forms of unlocking are not possible, the quick-change coupling works particularly easily and safely.

In a particularly preferred embodiment of the invention, the operating lever is between a first position in which the operating lever locks the closing element in the closing position, a second position in which the closing element is movable between the closing position and the oven position and a third position in which the operating lever locks the closing element locked in the open position, movable. The locking element can only be moved to the open position when the operating lever is in the second position. The pivoting into the second position can only be done by deliberate manual intervention. In addition, a spring element presses the closing element into the closing position. The closing element is therefore doubly secured against accidental opening in a surprisingly simple manner. Unintentional loosening of the attachment from the quick-change coupling is reliably excluded.

It has proven to be expedient if the operating lever is arranged between the receiving and fastening device and the closing element and is rotatably articulated on the receiving and fastening device. The operating lever is accordingly well protected against dirt and mechanical damage. The turning of the control lever up to a stop can be implemented intuitively. The operation of the control lever is correspondingly simple and prone to errors.

In a further particularly preferred embodiment of the invention, a link guide is provided on the operating lever, which cooperates with a guide element arranged on the closing element, which engages in the link guide. Both the operating lever and the closing element are positively guided and the mobility of the operating lever and the closing element are dependent on one another. As a result, the closing element can only be transferred from the closing position into the open position if the operating personnel moves the operating lever and the clamping lever one after the other and coordinated with one another. The quick-change coupling is secured several times against malfunction by simple mechanical means.

The guide element can expediently be locked in the link guide when the operating lever is in the third position. The closing element, which is pretensioned in the open position, cannot push the operating lever from the third position into the second position, since the guide element, preferably a pin, is pressed into a recess in the link guide by the pretension. The locking can only be done cancel when a certain operating step takes place. The unlocking of the operating lever is preferably canceled in the third position when the closing element is displaced beyond the open position against the closing position direction. This shift can be done by the second retaining bolt or the tensioning lever. Accidental opening of the closing element can be reliably prevented in a surprisingly simple manner by providing the specially shaped link guide.

The invention is also preferably characterized in that the link guide is essentially a Z-shaped recess. The specially shaped recess enables the operating lever to strike the second position when it is pivoted manually from the first position. Only after the closing element has been moved into the open position can the operating lever be pivoted further into the third position. The inevitable step-by-step transfer of the closing element from the closing position into the open position can be achieved by simple mechanical means and at the same time leads to a particularly secure quick-change coupling.

In a further particularly preferred embodiment of the invention, the operating lever is biased in the third position. This makes it possible for the operating lever to be able to pivot automatically from the third position into the second and first position and to release the closing element after it has been unlocked in the third position. The closing element can therefore slide automatically from the open position into the closing position. Another advantage of the pretensioning of the operating lever is that manual operation of the operating lever must be done consciously against resistance.

The operating lever is expediently connected in an articulated manner to a first end of a rod and a second end of the rod is passed through a transverse web arranged on the receiving device. The rod fulfills two tasks in a surprisingly simple way. After it has been preloaded, it pushes the operating lever from the third position into the second and first position. In addition, it fulfills a control function because it visualizes the position of the locking element. If the closing element is in the open position, the second end of the rod protrudes from the crosspiece and is visible. In the closing position of the locking element, the second end of the rod is withdrawn and invisible. Carries the second end a signal color, so it can also be seen from the excavator's cab when it protrudes from the crossbar.

The first end of the rod is preferably circular in shape and is received in a joint socket formed on the operating lever. This form of articulation is particularly low. Additional holding means can be dispensed with, since the articulation is limited by a plate of the receiving device and the closing element. The distance between the plate and the closing element is predetermined by the height of the operating lever and is not increased by the articulated connection between the rod and the operating lever.

The pretensioning of the rod is preferably achieved in that a spring is attached to the rod, which spring can be compressed between a projection provided on the rod and the crossbar.

In a further preferred embodiment of the invention, the tensioning lever can be removed from the coupling and a through opening is provided on the receiving and fastening device, in which a tensioning lever for moving the closing element from the closing position into the open position can be suspended against the bias. The shorter end of the L-shaped clamping lever protrudes through the through opening and can move the closing element into the open position. Retaining grooves are preferably provided on the longitudinal sides of the through opening, which receive a transverse axis of the tensioning lever and on which the transverse axis can rotate and be supported.

In a further particularly preferred embodiment of the invention, the closing element can be moved beyond the open position against the direction of the closed position, as a result of which the operating lever can move automatically from the third position to the second position. This form of unlocking the locking element leads to a surprisingly simple possibility of automatically coupling an attachment to the quick-change coupling. If the excavator arm is positioned in such a way that the attachment rotates around the first retaining bolt in the direction of the quick-change coupling, the second retaining bolt presses the locking element in the direction described above. This unlocks the locking element. The operating lever is automatically pressed into the first position and the locking element automatically into the Closed position pressed because both the operating lever and the locking element are pre-tensioned. The locking element engages the second retaining bolt, as a result of which the attachment is coupled to the quick-change coupling.

A passage opening is expediently provided on the receiving and fastening device, through which the operating lever can be moved between the first, the second and the third position. The passage opening is preferably provided on a plate on which the operating lever is attached. The plate protrudes above the operating lever, which protects it, in particular from being bent or broken off.

It proves to be advantageous if the closing element is pretensioned with a spring element in the open position. The spring element automatically moves the closing element into the closing position when the closing element is released from the operating lever. In the closed position, the closing element is held by the spring element and is additionally locked in the first position by the operating lever. Several spring elements can also be provided. Coil springs, gas pressure springs or other elastic springs are suitable.

The spring element is expediently connected to the closing element and the crossbar. The crossbar offers enough space and stability so that the spring element can be supported.

Another aspect of the invention relates to a method for pretensioning and releasing a closing element of a quick-change coupling, as described above. A user of the clutch moves a clamping lever with his first hand, as a result of which the closing element is moved from a closing position into an open position, in which open position the closing element is pretensioned and locked.

According to the invention, the user simultaneously operates with his second hand an operating lever arranged movably on the coupling, the operating lever releasing the movement of the closing element into the open position by means of its corresponding movement, and the closing element is locked in the open position by a further movement of the operating lever. This procedure ensures that the user of the clutch must put both hands in safe positions. It is therefore impossible for the user to injure his hands while operating the clutch.

In a further particularly preferred embodiment of the invention, the closing element is moved from the open position to the closing position on the one hand by an attachment that is coupled to the coupling opening the locking of the operating lever by moving the closing element and on the other hand the user of the coupling the clamping lever with its first Hand operated and the control lever operated simultaneously with his second hand, whereby the closing element is moved in a metered manner from the open position to the closed position.

The coupling enables the closing element to be relaxed if the coupling is not in operation for a long time. The manual relaxation sequence of the closing element can be done in a metered manner, since the user can counteract an abrupt relaxation after releasing the lock with the tensioning lever. The release of the locking of the closing element in the prestressed open position is released by turning the operating lever accordingly.

Figur 1:

eine Draufsicht auf eine halbautomatische Schnellwechselkupplung zum Befestigen eines Anbaugeräts an einem Baggerarm mit einem Schliesselement in einer Schliessposition und einem Bedienhebel in einer ersten Position;

Figur 2:

eine Seitenansicht der Schnellwechselkupplung aus Figur 1;

Figur 3:

eine axonometrische Ansicht der Schnellwechselkupplung aus Figur 1;

Figur 4:

eine Draufsicht auf die Schnellwechselkupplung mit dem Bedienhebel in einer zweiten Position;

Figur 5:

eine Draufsicht auf die Schnellwechselkupplung mit dem Bedienhebel in der zweiten Position und dem Schliesselement in einer Offenposition;

Figur 6:

eine Seitenansicht der Schnellwechselkupplung aus Figur 5

Figur 7:

eine Draufsicht auf die Schnellwechselkupplung mit dem Bedienhebel in einer dritten Position und dem Schliesselement in der Offenposition und

Figur 8:

eine axonometrische Ansicht der Schnellwechselkupplung aus Figur 6.

Further advantages and features result from the following description of an embodiment of the invention with reference to the schematic representations. In a representation that is not to scale:

Figure 1:

a plan view of a semi-automatic quick-change coupling for attaching an attachment to an excavator arm with a closing element in a closing position and an operating lever in a first position;

Figure 2:

a side view of the quick release coupling Figure 1 ;

Figure 3:

an axonometric view of the quick release coupling Figure 1 ;

Figure 4:

a plan view of the quick-change coupling with the operating lever in a second position;

Figure 5:

a plan view of the quick-change coupling with the operating lever in the second position and the closing element in an open position;

Figure 6:

a side view of the quick release coupling Figure 5

Figure 7:

a plan view of the quick-change coupling with the operating lever in a third position and the closing element in the open position and

Figure 8:

an axonometric view of the quick release coupling Figure 6 ,

In the Figures 1 to 8 a quick-change coupling is shown in different coupling positions, which is designated as a whole by reference number 11. The quick-change coupling 11 comprises a receiving and fastening device, only the receiving device 13 being shown in the figures. The fastening device serves for the articulated fastening of the quick-change coupling 11 on an excavator arm. The receiving device 13 comprises a first and second claw 15a, 15b in which a first retaining bolt of an attachment, for example an excavator shovel, can be received. The claws 15a, 15b form a first insertion opening 16, in which the first retaining bolt is held. The receiving device 13 also comprises a plate 17, on the longitudinal sides of which the claws 15a, 15b are fastened. For reasons of clarity, the plate 17 is shown transparently in the figures.

A closing element 19 is slidably arranged between the claws 15a, 15b. The closing element 19 is guided in mutually facing grooves 21a, 21b ( Figure 3 . 6 . 8th ). The closing element 19 is along the grooves 21a, 21b between an open position ( Figures 1 - 4 ) and a closing position ( Figures 5 - 8 ) movable. A second insertion opening 23 is provided on the closing element 19. In the open position, an attachment can be attached or detached. In the closed position, the second holding bolt of the attachment is also held on the holding device 13 by the holding bolts being engaged and clamped through the insertion openings 16, 23.

On the underside of the plate 17, an operating lever 25 is rotatably arranged about a first joint 27. The operating lever 25 is arranged between the plate 17 and the closing elements 19.

The operating lever 25 has a first and a second end 29, 31. The first end is shaped as a first hand attachment in the form of a hook 33. This makes it easier to operate the operating lever 25, since the operating personnel can put a finger on the hook 33 and can turn the operating lever 25 counterclockwise.

At the second end 31, a link guide 35 is provided, which has the shape of a Z. The link guide thus has a first and a second cross bar 37, 39, which are mutually arranged at the ends of a longitudinal bar 41. The link guide 35 interacts with a guide element. The guide element is preferably a pin 43 which is fastened to the closing element 19 and projects into the link guide 35.

A rod 45 is articulated to the operating lever 35. The first end of the rod is designed as a second joint 47. The first end of the rod 45 is preferably circular in shape and is received in an articulated socket 46 formed on the operating lever. This form of articulation is particularly low. Additional holding means can be dispensed with, since the second joint 47 is delimited by the plate 17 and the closing element 19. The distance between the plate 17 and the closing element 19 is predetermined by the height of the operating lever 25 and is not increased by the second joint 47.

Following the first end, the rod 45 has a bend 48 which is adapted to the outer contour of the operating lever 25. As a result, the rod 45 can rest against the operating lever 25 when it is in the first position and is not in the way of changing the position of the operating lever 25.

The second end 51 of the rod 45 is guided on a crossbar 49 in that the rod 45 is inserted through a first through opening 53 of the crossbar 49.

The crosspiece 49 serves as support for two spring elements 55 which are arranged between the crosspiece 49 and the closing element 19. The ends of the spring elements 55 are fastened to the transverse web 49 or to the closing element 19. The spring elements 55 can be gas pressure springs, coil springs or other elastic elements with a sufficient restoring force.

A first projection 57 is formed on the rod 45. A spring 59 is fitted onto the rod 45 and can be compressed between the first projection 57 and the transverse web 49.

A second elongated through opening 61 is provided on the plate 17. Holding grooves 63a, 63b are formed on the longitudinal sides of the second through opening 61. An L-shaped clamping lever 60 can be inserted into the second through opening 61 insert a transverse axis 62 and a second handle 64 in the form of a handle. The transverse axis 62 can be received in the holding grooves 63a, 63b, as a result of which the tensioning lever can be rotated about the transverse axis. The shorter end of the tensioning lever projects through the second through opening 61.

A passage opening 65 is provided on the plate 17. The hook 33 of the operating lever 25 can be reached through the passage opening 65. The plate 17 projects beyond the hook 33, as a result of which the operating lever 25 is protected, in particular from being bent or broken off.

The functioning of the quick-change coupling 11 is described in the following paragraphs:
First of all, the quick-change coupling 11 must be pretensioned for coupling an attachment or for uncoupling the coupled attachment. For this purpose, the clamping lever is inserted into the second through opening 61. If the tensioning lever is pressed down, its shorter end presses the closing element 19 from the closing position into the open position against the spring pressure of the spring elements 55.

Due to the shape of the link guide 35 and its interaction with the pin 43, the operating lever 25 can be pivoted between a first, a second and a third position.

In the Figures 1 and 3 it is shown that the operating lever 25 is in the first position. In this position, the pin 43 is received in the first crossbar 37. Since the pin 43 is firmly connected to the locking element 19, the locking element 19 is locked in the first position of the operating lever 25 and cannot be moved from the locking position. This is important so that an attachment that is coupled to the quick-change coupling 11 cannot be accidentally uncoupled from the coupling 11.

With one hand, the operating personnel can pivot the operating lever 25 into the second position with the aid of the hook 33 and thereby unlock the locking element 19 ( Figure 4 ). The operating lever 25 is in the second position when the pin 43 is at the transition from the first cross bar 37 to the longitudinal bar 41. The control lever 25 can be turned counter-clockwise against the pressure of the spring 59. The spring pressure causes the operating lever 25 to automatically turn clockwise when the link guide 35 allows it.

With the other hand, the operating personnel can press the tensioning lever downwards, whereby the closing element 19 is pressed from the closed position into the open position. The pressure of the spring elements 55 must be overcome and these are compressed or preloaded in the open position. The pin 43 can slide during the transition from the closed position into the open position and vice versa along the longitudinal bar 41 of the link guide 35 ( Figure 5 ).

So that the closing element 19 remains in the pretensioned open position, it must be locked. For this purpose, the operating lever 25 must be turned further counterclockwise to the third position until the pin 43 strikes the end of the second crossbar 39 of the link guide 35.

If the operating lever 25 is relieved, the pin 43 is pressed into the end of the second crossbar 39 by the prestressing of the spring elements 55. As a result, the operating lever 25 locks the closing element 19 in the open position. At the transition between the longitudinal bar 41 and the second cross bar 39, a second projection 67 is formed, which holds the pin 43 reliably in the end of the second cross bar 39. This ensures that the pretensioning of the closing element prevents the pin 43 from being pressed into the longitudinal bar 41.

The bias of the operating lever 25 in the third position caused by the spring 59 enables the operating lever 25 to be automatically moved back into the first position when the closing element 19 is automatically closed.

In addition to resetting the operating lever 25, the rod 45 has another function. It fulfills a control function by indicating to the operating personnel whether the quick-change coupling is open or closed. If the second end 51 of the rod 45 protrudes from the crosspiece 49 and is visible, the closing element 19 is in the open position. If the second end 51 is not visible, the closing element 19 is in the closed position.

For the automatic coupling of an attachment, the first retaining bolt has to be received in the claws 15a, 15b. Then the excavator arm must be moved in such a way that the second retaining bolt pushes the closing element 19 somewhat from the open position backwards against the closed position. As a result, the pin 43 loses contact with the link guide and the operating lever snaps into the second position due to its pretension. As a result, the closing element is unlocked and is pressed into the closing position by the spring elements 55. In the closed position, the second retaining bolt is received in the second insertion opening 23. If the pin 43 is in the closed position, the rod 45 can press the operating lever 25 into the first position by the pretensioning of the spring 59. As a result, the closing element 19 is automatically locked in the closed position by the operating lever 25.

If the quick-change coupling 11 is not used for a longer period of time, the closing element 19 can be moved into the closing position with the help of the tensioning lever and can thus be relaxed without an attachment being coupled. For this purpose, the closing element 19 is to be pressed beyond the open position with the tensioning lever. As a result, the operating lever is released and can be rotated from the third position to the second position by its pretension. Then, with the help of the tensioning lever, the closing element 19 can be transferred into the closed position in a metered manner.

The invention discloses a semi-automatic quick-change coupling 11. The pretensioning or uncoupling of the attachment is carried out manually with the aid of a tensioning lever. The attachment is coupled automatically without the operator having to get out of the excavator cab. The snap-in of the second holding bolt of the attachment in the second insertion opening 23 is made possible by the pretensioning of the closing element 19 in the open position. The user of the coupling 11 must use both hands in order to be able to pretension the closing element 19 and to relax in a metered manner. The operation of the clutch 11 is therefore very safe and hand injuries are avoided.

Legend:

11

Quick-change coupling

13

cradle

15a, 15b

First and second claw

16

First insertion opening

17

plate

19

closing element

21a, 21b

groove

23

Second insertion opening

25

operating lever

27

First joint

29

First end of the control lever

31

Second end of the control lever

33

First hand approach, hook

35

link guide

37

First crossbar

39

Second crossbar

41

stringers

43

Pen, guide element

45

pole

47

Second joint, first end of the bar

48

bending

49

crosspiece

51

Second end of the bar

53

First passage opening

55

spring elements

57

First lead

59

feather

60

clamping lever

61

Second passage opening

62

transverse axis

63a, 63b

retaining

64

Second hand approach, handle

65

Through opening

67

Second lead

Claims (16)

1. Quick change coupling (11) for fixing a construction machine attachment, preferably on an excavator arm, with

   - a receiving and fixing device (13),

   - a fixed first insertion opening (16) that is molded or fixed at a first end of the receiving and fixing device (13),

   - a movable closing element (19) placed on the receiving and fixing device (13) with a second insertion opening (23) that can be moved from an open position in which an attachment can be coupled or uncoupled to a closed position in which the retaining bolts of the attachment are engaged through the insertion openings and clamped, wherein the closing element (19) is pretensioned and lockable in the open position,
   characterized in that
   an operating lever (25) is placed movable on the receiving and fixing device (13), lever that has formed a first hand endpiece (33) so that it can be operated with the first hand of the user of the coupling (11) and which operating lever (25) locks and unlocks the closing element (19) in the open and in the closed position and
   that the coupling (11) comprises a tension lever (60) with a second endpiece (64) so that the tension lever (60) can be operated with the second hand of the user simultaneously with the operating lever (25) for pretensioning and releasing the closing element (19).
2. Coupling according to claim 1, characterized in that the operating lever (25) is movable between a first position, in which the operating lever (25) locks the closing element (19) in the closed position, a second position, in which the closing element (19) is movable between the closed position and the open position, and a third position in which the operating lever (25) locks the closing element in the open position.
3. Coupling according to claim 1 or 2, characterized in that the operating lever (25) is placed between the receiving and fixing device (13) and the closing element (19) and is rotatably hinged on the receiving and fixing device (13).
4. Coupling according to one of the preceding claims, characterized in that a slide guide (35) that cooperates with a guiding element (43) placed on the closing element (25) is provided on the operating lever (25), guiding element hat engages into the slide guide (35).
5. Coupling according to claim 4, characterized in that the guiding element (43) is latchable in the slide guide (35) when the operating lever (25) is in the third position.
6. Coupling according to claim 4 or 5, characterized in that the slide guide (35) is a substantially Z-shaped recess.
7. Coupling according to one of the claims 2 to 6, characterized in that the operating lever (25) is pretensioned in the third position.
8. Coupling according to one of the preceding claims, characterized in that the operating lever (25) is articulately connected with a first end (47) of a rod (45) and a second end (51) of the rod (45) is passed through a transverse web (49) placed on the receiving and fixing device (13).
9. Coupling according to claim 8, characterized in that a spring (59) that can be compressed between a projection (57) provided on the rod (45) and the transverse web (49) is mounted on the rod (45).
10. Coupling according to one of the preceding claims, characterized in that the clamping lever can be removed from the coupling (11) and a through opening (61) in which the clamping lever can be is provided on the receiving and fixing device (13), opening in which the clamping lever can be suspended to displace the closing element (19) from the open position to the open position against the pretensioning.
11. Coupling according to one of the claims 2 to 10, characterized in that the closing element (19) can be displaced beyond the open position against the direction of the closed position so that the operating lever (25) can automatically move from the third position to the second position.
12. Coupling according to one of the claims 2 to 11, characterized in that a passage opening (65) through which the operating lever (25) can be moved between the first, the second and the third position is provided on the receiving and fixing device (13).
13. Coupling according to one of the preceding claims, characterized in that the closing element (19) is pretensioned in the open position with a spring element (55).
14. Coupling according to claim 13, characterized in that the spring element (55) is connected with the closing element (19) and the transverse web (49).
15. Method for pretensioning and releasing a closing element (19) of a quick change coupling (11) according to one of the preceding claims, wherein a user of the coupling moves with his first hand a clamping lever (60) so that the closing element (19) is moved from a closed position into an open position in which the closing element (19) is pretensioned and locked,
    characterized in
    that the user operates simultaneously with his second hand an operating lever (25) placed movable on the coupling (11), wherein the operating lever (25) released with its corresponding motion the motion of the closing element (19) into the open position and the closing element (1) is locked in the open position with a further motion of the operating lever (25).
16. Method according to claim 15, characterized in that the closing element (19) is moved from the open position into the closed position, on the one hand wherein an attachment that is coupled to the coupling (11) opens the locking of the operating lever (25) by displacing the closing element (19) and on the other hand wherein the user of the coupling (11) operates the operating lever (25) simultaneously with his second hand so that the closing element is moved at a dosed rate from the open position to the closed position.

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