A coupling system

Abstract

A coupling system (1) for coupling a tool, such as a shovel, to an arm, such as an excavator arm, said coupling system comprising: a tool-coupling (2) comprising a first coupling part (4) and a second coupling part (6). The system further comprises an arm-coupling (1) which comprises: a first coupling mount (3) for receiving the first coupling part (4); a second coupling mount (5) for receiving the second coupling part (6); a moveable securing element (7, 7´´) comprising a first end having a first catching part (8) for catching and securing the second coupling part (6) when placed in the second coupling mount (5). An actuator adapted for moving of said securing element (7) such that said first catching part (8) is catching or releasing said second coupling part (6) when placed in said second coupling mount (5). The systems securing element comprising a second end having a second catching part (9) for catching and securing the first coupling part (4) in the first coupling mount (3).

Description

[0001] A COUPLING SYSTEM

[0002] The present invention relates to a coupling system for coupling a tool, such as a shovel, to an arm, such as an excavator arm, said coupling system comprising: a tool-coupling comprising: first hydraulic connectors, a first coupling part and a second coupling part and an arm-coupling which comprises: a first coupling mount for receiving the first coupling part, a second coupling mount for receiving the second coupling part, a moveable securing element comprising: a first end having a first catching part for catching and securing the second coupling part when placed in the second coupling mount, an actuator adapted for moving of said securing element such that said first catching part is catching or releasing said second coupling part when placed in said second coupling mount and second hydraulic connectors being complementary to said first hydraulic connector.

[0003] DESCRIPTION OF RELATED ART

[0004] The expression construction machine denotes any machine, of the self-propelled vehicle type or a stationary machine, positioned on land, on a vessel, on a pontoon or on a railway vehicle, equipped with at least one arm, at the end of which a tool is detachably mounted, with said tool being of the shovel, bucket, gripper, chisel, hammer, basket, lifting hook type or any other tool used within the context of heavy on-site, civil engineering, transport, agricultural, mining and quarrying or handling work.

[0005] The arms of a constructions machine are most often made such that they can accommodate various tools, both by their function and by their size, in order to undertake different jobs. These tools can move along one or more axes relative to the end of the arm of the vehicle. A tool is coupled on the end of a working arm by using a coupling system which comprises a plurality of parts and is known as a quick coupler assembly, more easily denoted using the expression "quick coupler,".

[0006] Quick couplers are frequently used with construction machines such as hydraulic excavators for coupling different tools such as shovels onto an excavator arm or similar tool operators such as articulated arm booms in order to be able to use different tools without long changeover times. Such quick couplers often comprise two coupling parts, one of them being situated on the tool and the other being situated on the working arm. The coupling part situated on the tool normally comprises two spaced apart locking axles as locking elements, whereas the other coupling part, in particular the coupling part at the excavator arm side, have a preferably v-shaped coupling mount for hooking on at a first one of the two locking axles and a locking mount for locking at the second locking axle. After hooking the first locking axle in the coupling mount, the two coupling parts can be pivoted with respect to one another, wherein the locking axle seated in the coupling mount forms the pivot axle so that the second locking axle moves or is pivoted into the locking mount where the second locking axle may then be locked by a locking element such as an extendable wedge so that it is no longer possible to move the first locking axle out of the coupling mount.

[0007] The movement of the wedge may be controlled by an actuator actuated by outside energy and the actuator may, for example, comprises a hydraulic cylinder.

[0008] The tool that is connected to the arm may be a hydraulic tool that is moved / activated by means of a hydraulic motor located in the tool that can utilize energy generated by a flowing fluid that flows between an inlet and an outlet in the tool, each of which are connected to complementary inlets and outlets in the arm.

[0009] When a tool with a built-in hydraulic motor is to be connected to an arm, the inlet and outlet in the tool must be connected with the complementary inlet and outlet in the arm.

[0010] These are permanently mounted, and the driver of construction machines as excavators must today manually connect and disconnect the hydraulic connections which therefore requires him to leave his seat in the cabin when this is to be used.

[0011] It is an object of the invention to provide a system which enables the driver of the excavator to connect and disconnect hydraulic tools without having to leave the machine's cabin to connect and disconnect the hydraulic connections.

[0012] Another object is to provide an alternative solution. This is achieved by the system further comprising an extender mechanism being capable of extending or retracting said second hydraulic connectors or a part thereof and thereby engage or disengage said second hydraulic connectors with or from the first hydraulic connectors, said extender mechanism being directly or indirectly connected to said securing element such that the extender mechanism is extending or retracting said second hydraulic connectors when said actuator moves said securing element for catching or releasing said second coupling part (6) when placed in said second coupling mount.

[0013] Embodiments of the invention are recited in the dependent claims.

[0014] An embodiment of the invention will now be explained with reference to the figures wherein:

[0015] Fig. 1 shows part of an arm provided with an arm-coupling; fig. 2 show a tool coupling; fig. 3 shows in greater details an arm-coupling; fig 4 shows the arm-coupling in engagement with the tool coupling; fig. 5 show a system comprising hydraulic couplings fig. 6 shows the cross-section B-B indicated in figure 5; fig. 7 shows, a cross section of a hydraulic cylinder; fig. 8 shows a hydraulic couplings provided with an extender mechanism.

[0016] In figure 1 is show an arm-coupling 1 and in figure 2 is shown tool coupling, the tool coupling 2 and the arm coupling 1 are parts of a coupling system for a construction machine.

[0017] The arms of a constructions machine are most often made such that they can accommodate various tools, both by their function and by their size, in order to undertake different jobs. These tools can move along one or more axes relative to the end of the arm of the vehicle. A tool is coupled on the end of a working arm by using a coupling system which comprises a plurality of parts and is known as a quick coupler assembly, more easily denoted using the expression "quick coupler,".

[0018] Quick couplers are frequently used with construction machines such as hydraulic excavators for coupling different tools such as shovels onto an excavator arm, or similar tool operators such as articulated arm booms, in order to be able to use different tools without long changeover times.

[0019] Such quick couplers comprise two coupling parts, one of them 2 being situated on the tool and the other 1 being situated on the working arm 12.

[0020] The coupling part situated on the tool shown in figure 2 comprises: two hydraulic couplings 11 and two spaced apart locking axles 6, 4 as locking elements.

[0021] The other coupling part situated on the arm, comprises: two hydraulic couplings 10 that are complementary to the hydraulic couplings 11 on the tool, a v-shaped first coupling mount 3 for mounting the first one 4 of the two locking axles and a second coupling mount 5 for mounting the second locking axle 6.

[0022] After hooking the first locking axle 4 in the first coupling mount 3, the two coupling parts can be pivoted with respect to one another, wherein the locking axle 4 now seated in the coupling mount 3 forms the pivot axle so that the second locking axle 6 moves or is pivoted into the coupling mount 5 where the second locking axle is then locked / catched by an extendable wedge 8, so that it is no longer possible to move the first or the second locking axle out of the coupling mounts.

[0023] The movement of the catching part / wedge 8 may be controlled by an actuator actuated by outside energy and the actuator may, for example, comprises a hydraulic cylinder.

[0024] The wedge 8 shown in figure 1 is situated at the first end of a moveable securing element 7 (best seen in figure 3). The wedge 8 functions as a first catching part 8 for catching and securing the second coupling part 6, when placed in the second coupling mount 5. The second and first coupling parts 4,6 are in the shown embodiments made as axles, however these coupling parts may be made with other shapes / differently by a person having ordinary skill in the art. A disadvantage of prior art systems is that dangerous situations may occur when only the first axle 4 - which forms the pivot point - gets hold of the coupling part of the arm and the wedge 8 does not lock the second axle. In these situations, the improperly attached tools may even be lifted from the ground by the arm and since no solutions in prior art are locking the first axle 4 to the coupling mount 3, construction machines may lift and unintentionally drop improperly attached tools.

[0025] According to the invention, this is prevented by designing the other end of the securing element 7 so that the securing element may catch the first coupling part 4 when placed in the first coupling mount 3.

[0026] In figure 3 is shown an arm- coupling system 1. In the left side of the figure, a first coupling mount 3 is seen, in which the first coupling part 4 of the tool must be brought into engagement. As can be seen in the figure, this part is v-shaped and it is in the inner part of the v that the first coupling part must lie when the tool is coupled to the system.

[0027] Most often, the first coupling mount 3 is designed so that it has a sloping v-like shape, this entails a quick connection as the gravity will force the first coupling part of the tool towards the innermost part (the narrowest part). This means that the tool's first coupling part can be retained loosely in the first coupling mount by gravity and therefore, dangerous situations can arise if a machine operator mistakenly believes that a “loose” tool is securely attached to the arm.

[0028] In the embodiment shown in Figure 3, the arm-coupling part comprises two movable securing elements 7. These two elements 7, are identical, so in the further explanation of the invention, reference will preferably be made with figure numbers that point to the securing element shown to the left in the figure. In the shown embodiment, the securing element comprises a first part 7 with a slot 20, in which there is a pin 21. This first part 7 is made as a cylinder, in which a second cylinder 7' is mounted, so that it can slide inside cylinder 7 in the longitudinal direction of the cylinders. An actuator 24 is connected to the first part 7 of the securing elements via a cross block 30 and when the actuators move the first part in the direction of arrow P, the locking part / wedge 8 (which is not seen in Figure 3) moves out into the position where it can lock a coupling part 6 in the coupling mount 5. In the embodiment shown, the cross block is provided with locking elements 22 that can also be activated hydraulically. These locking elements 22 can be displaced into locking holes 23. The actual movement of the locking elements 22 can be achieved with hydraulically driven actuators or with electrically driven actuators and these actuators can be operated via a system that can also control the other actuators described in this patent application. When the locking elements 22 are pushed out into one of the locking holes 23, both the cross block 30 and the first part 7 with the first catching part 8 / wedge are locked. This locking can be achieved both when the catching part 8 is retracted (as shown in Figure 3) and when the catching part / wedge 8 is pushed out into the position, where it can lock a coupling part.

[0029] When the first part 7 of the movable securing element is moved in the direction of the arrow p, the inner cylinder 7' will initially not be moved. It will, initially, maintain its position, as it is held in this position by compression springs 13 which are attached to the inner cylinder via a ring system 41 with a pinion screw 40 which is screwed firmly against the inner cylinder 7'. When the first part 7 has moved the distance - which the slot 20 is long - the pin 21 will hit the opposite side of the slot 20, and since the pin 20 is attached to the inner cylinder 7', the moveable securing element's inner cylinder will move in the direction of the arrow P. There has thus been a reduction in the movement, that the outer part 7 makes in relation to the inner part 7'.

[0030] Figure 4 shows an embodiment of the invention where the arm coupling engages with the two coupling parts 4 and 6. On the left side of the figure it can be seen that the inner cylinder 7' is provided with a catching part 9 comprising a constriction 9'. In the situation shown, the coupling parts 4 and 6 have engaged correctly with the two catching parts 7 and 8 and it can be seen in the figure how the first coupling part 4 is held in the first coupling mount 3 by the outer thicker part 51 on the inner cylinder 7'.

[0031] As can be seen in the figure, is the first coupling mount preferably 3 made inclined and v-shaped. In the shown embodiment is the upper surface 3' in the v- shaped coupling mount 3 inclined in relation to the upper surface 100 of the arm tool 1.

[0032] It is in the inner part of the v that the first coupling 4 part lies when the toolcoupling 2 is coupled to the arm coupling 1. When the first coupling part 4 is introduced into the v - as shown in the figure - it is retained here because the movable securing element 7, 7 is pulled towards the side shown on the right in the figure, whereby

[0033] • the outer thicker part 51 of the cylinder 7' and

[0034] • the upper inclined surface 3' in the first coupling mount 3 together forms a constriction which holds the first coupling part 4 in the first coupling mount 3.

[0035] In the embodiment shown, an additional safety feature has been added in that the length of the securing element 7. 7 is matched to the first 4 and the second coupling part 6 such that the thicker part 51 hits the first coupling part 4 if the second coupling part 6 has not been introduced / engaged in the second coupling mount 5. In the example shown I figure 4, the second coupling part 6 is correctly inserted into the second couplings mount 5 and thereby a small gap is created between the first coupling’s part 4 and the thicker part 51 on the narrowed / constricted part 9' of the catching part 9 as indicated by the two lines with the number 50 between them.

[0036] This difference in the length of the movement the securing element - when the second coupling part 6 has engaged or has not engaged with the securing element 7,7' in the coupling mount 5 - is in an embodiment utilized as electronic sensors connected to the securing element monitors the position of the securing element. By monitoring the position of the securing element, the longer movement the securing element makes when the second coupling part 6 does not engage with the securing element 7 (or its wedge 8) can be used to trigger fault alarms.

[0037] The alarm may be in form of a sound but may - in other embodiments - be in form of light and / or wirelessly.

[0038] The electronic sensors can also be connected to the securing element 7, 7' so that a correct connection- with shorter movement of the securing element 7, 7' - correspondingly triggers an indication of a correct (safe) coupling between, the second coupling part 6 and the securing element 7,7 in the coupling mount 5 It is noted in this connection that although the word cylinder is used for this outermost part 7, it can have many other shapes, for example it can be designed as a long ring-shaped body.

[0039] With reference to Figure 5, which shows an embodiment of a unit for deploying hydraulic quick couplings 200, the functionality of the system that controls the hydraulics therefor will be explained in more detail.

[0040] Tool that is connected to a construction machine such as e.g., an excavator is often equipped with hydraulic tool units operated by an operator located in a cab on the construction machine. To supply the hydraulic tool units with hydraulic oil from the construction machine, the construction machine and tool include complementary hydraulic couplings that must be connected and / or disconnected when tools are mounted and / or removed from / on the machine arm.

[0041] In prior art technology, this is done by the operator of the machine manually disconnecting and connecting these hydraulic couplings. This is cumbersome and time-consuming, and furthermore it is necessary for the operator to leave the cabin of the construction machine.

[0042] When a tool is to be disconnected from the arm of a machine, this is done by pressurizing the chamber 106 with a pressure being higher than the pressure in the chamber 105. By doing this, the piston 102 will be forced to the left in the figure. Initially, this will happen synchronously with the piston, as the pressure spring 11 keeps the thickened part 112 of the valve body pressed against the piston 102. The synchronous movement will stop when the valve body head 103' is situated against the conical seat 104, after which only the piston and piston rod move to the left while the sliding part 113 slides on the valve body 103.

[0043] In the embodiments shown in the figures, the retraction of the hydraulic coupling parts takes place when the cross bar 30 or a part fixedly connected thereto hits a striker part 109 arranged on the hydraulic coupling parts 110. Since the cross bar 30, as explained earlier, is fastened to the locking mechanisms / wedges 8, which hold the tool firmly on the arm, uncoupling of these locking mechanisms / wedges will not be possible without the crossbar 30 or the part fixedly connected thereto is pulling the hydraulic couplings out of engagement. This prevents a tool from getting stuck in the hydraulic couplings 10 after the locking mechanism 8, 6, as explained with reference to figures 3 and 4, have been pulled out of engagement in order to release a tool.

[0044] The figure shows an embodiment of a system for placement on the arm of a construction machine, where connecting and disconnecting complementary hydraulic couplings in the respective tool and the construction machine happens automatically when a tool adapted in accordance with the invention is mounted / dismounted. The two identical coupling parts 10 shown in the figure can be pushed in and out.

[0045] In Figure 6, the section B-B (from Figure 5) is shown. In this section, internal parts of the actuator 24 can be seen, and these include a cylinder 110 with a side wall and two end walls. The cylinder is equipted with a piston 102 that divides the cylinder into two chambers 105, 106. The piston 102 is attached to a piston rod 101 which penetrates one of the cylinders end walls. The piston rod 101 is - outside the cylinder - attached to a cross block 30 (which is described in greater details above with reference to figure 3 and 4). The chamber 105 situated opposite the piston rod is provided with a conical opening 104 into a channel 107. The channel 107 is a hydraulic line / channel 107, which can supply a - in the hydraulic couplings - built-in extender mechanism with pressurized hydraulic oil such that they can extend and thereby go into connection with complementary hydraulic couplings placed in a tool that is being locked onto the construction machine's arm.

[0046] A valve body 103 with head 103 is mounted so that it is axially displaceable in a bore in the piston 102 and the piston rod 101. In the embodiment shown, the head 103' of the valve body is constructed as a cone, which is complementary to the cone 104 made in the end wall of the cylinder. This entails a tight connection between the valve body head 103' and the end wall of the cylinder when the valve body head 103' is guided into the conical opening 104. To keep the valve body head 103' and cone 104 in tight contact, a compression spring 111 is arranged such that the spring presses the valve body head 103'against the conical opening 104.

[0047] When the tool is to be locked onto the arm of a construction machine - as explained with reference to Figures 1-4 - this involves that the actuator 24 is extending the piston rod 101 which is connected to the locking means. In practice, hydraulic oil is pumped into the chamber 105 creating a suitable pressure difference between the right and left sides of the piston. This pressure difference will force the piston and piston rod 101 to move towards the shown to the right in the figure. Hydraulic mechanisms for establishing pressure differences between chambers 106 and 105 are well known to persons skilled in the art and accordingly, such mechanisms will not be explained further.

[0048] Turning now to figure 7, it will be explained how internal parts of the actuator 24 work together. Figure 7 thus shows the situation where the piston 102 is shifted all the way to the right and it can be seen on the left side of the figure that the valve body's head 103' in that situation no longer rests against the conical valve seat 104 thus letting the pressurized hydraulic oil in the chamber 105 to flow into the channel / line 107 and thereby cause the built-in extender mechanism (shown in figure 8) to extend the hydraulic couplings 10.

[0049] To achieve this, the piston 102 is constructed with a sliding part 113 being mutually adapted to the valve body 103 such that the piston can / will slide - to the side shown to the right in figure 7 - on the valve body 103. However, the piston will only slide on the valve body 103 until a thickened part 112 - which cannot pass through the sliding part 113 - hits the piston. After this, the piston will force the valve body to travel along the piston 102 and thus the head 103'of the valve body 103 will be pulled out of contact with the conical seat 104 as shown in figure 7. To prevent unintentional opening of fluid flow from chamber 105 into channel 107, the valve body s head 103'is held against the conical seat 104 by a pressure spring 111 being placed in the bore 110 of the piston rod such that the pressure spring pushes the valve body out of the bore and thus forcing the valve body's thickened 112 part against the piston 102 or the valve body's head 103' against the thereto adapted conical seat 104.

[0050] When a tool is to be disconnected from a machine, this is done by pressurizing the chamber 106 with a suitable higher pressure than the pressure in the chamber 105. By doing so, the piston 102 will be forced to the left in the figure. Initially, this will happen synchronously with the piston, as the pressure spring 11 keeps the thickened part 112 of the valve body pressed against the piston 102. The synchronous movement will stop when the valve body tip 103 is placed against the conical seat 104, after which only the piston and piston rod move to the left while the sliding part 113 slides on the valve body 103 stopped by the valve seat.

[0051] In the embodiments shown in the figures, the retraction of the hydraulic coupling parts takes place when the cross bar 30 hits a striker part 109 arranged on the hydraulic coupling parts 110. Since the Cross bar 30, as explained earlier, is fastened to the coupling mechanisms / wedges 8, which hold the tool firmly on the arm, a withdrawal of these coupling mechanisms / wedges will not be possible without the crossbar 30 pulling the hydraulic couplings out of engagement.

[0052] This prevents a tool from getting stuck in the hydraulic couplings 10 after the locking coupling parts 8, 6, as explained with reference to figures 3 and 4, have been pulled out of engagement.

[0053] Figure 8 shows an embodiment of a hydraulic coupling provided with an extender mechanism. The extender mechanism comprises an extender piston 223 which is connected to a hydraulic coupling 10, a tool channel 220' and a supply channel 220. The supply channel 220 is in hydraulic communication with the construction machine's hydraulic system and the tool channel 220' is in communication with the tip of the hydraulic coupling 10 so that a a complementary hydraulic clutch connected to this will be in hydraulic communication with the construction machine's hydraulic system.

[0054] The extender piston 223 is housed in an extender cylinder 224 and these parts are via the channel 107' in direct hydraulic communication with the actuator's channel 107 (as seen in Figure 7) so that hydraulic oil from the channel 107 will flow into the channel 107' and further into the cylinder 224 on the left side of the coupling piston 223. Thereby, the extender piston 223 will be displaced to the right until the tool channel 220' hits the supply channel 220. Here the movement of the hydraulic coupling 10 will stop. As explained with reference to figure 7, the retraction of the hydraulic coupling 10 takes place by the cross bar (as seen in figure 7) hitting and pushing the striker part 109 on the quick coupling. Aspects

[0055] 1. A coupling system for coupling a tool, such as a shovel, to an arm, such as an excavator arm, said coupling system comprising:

[0056] • a tool-coupling (2) comprising a first coupling part (4) and a second coupling part (6) and

[0057] • an arm-coupling (1) which comprises:

[0058] • a first coupling mount (3) for receiving the first coupling part (4);

[0059] • a second coupling mount (5) for receiving the second coupling part (6);

[0060] • a moveable securing element (7, 7") comprising a first end having a first catching part (8) for catching and securing the second coupling part (6) when placed in the second coupling mount (5); an actuator adapted for moving of said securing element (7) such that said first catching part (8) is catching or releasing said second coupling part (6) when placed in said second coupling mount (5), said system being characterized by, said securing element comprising a second end having a second catching part (9) for catching and securing the first coupling part (4) in the first coupling mount (3).

[0061] 2. A coupling system according to aspect 1 , characterized by, said first end, and said second end of said securing element being connected by connecting means capable of transferring a linear motion from one of said first or said second end to the other of said first or said second end.

[0062] By making the securing element such that the first and second ends of this are connected via connecting means that transmit linear movement, a mechanical very strong and simple system is achieved, in its simplest form these connecting means can be a fixed connection between the two ends.

[0063] 3. A coupling system according to aspect 1 or 2, characterized by, said first end, and said second end of said securing element being connected by connecting means comprising a gear mechanism capable of changing the exchange of the linear motion transmitted between the first end and the second end. In this embodiment, said first end, and said second end of said securing element are such that they are connected by connecting means comprising a gear mechanism capable of changing the exchange of the linear motion transmitted between the first end and the second end. This is advantageous since said first coupling mounts and said second coupling mounts can have different sizes and even different shapes. When this is the case, the requirements for the shaping of the two catching parts at the two ends of the securing element will also vary and, in a completely similar way, the requirements for the length of the linear movement at the two ends - to achieve locking / release of the first coupling part and second coupling part - in respectively the first coupling mount and the second coupling mount also vary.

[0064] 4. A coupling system according to aspect 3, characterized in that, the gear exchange mechanism is reducing the linear motion when transferring motion from said second end to said first end.

[0065] Normally, in order to catch and secure the first coupling part, the first end doesn’t have to move as much as the second end.

[0066] 5. Coupling system according to any one of aspects 1-4, characterized in that, the first end of the securing element is adapted to the second coupling mount such that the securing element, upon activation, moves a certain specified distance when a second coupling part is present in the second coupling mount.

[0067] 6. A Coupling system according to aspect 5, characterized in that, the securing element, upon activation, moves a distance which is longer than the certain distance when a second coupling part isn’t present in the second coupling mount.

[0068] By making the coupling part mechanism such that a coupling part moves a given distance in case of a successful coupling and a different distance in case of malfunctions, the part can be monitored and thereby ascertain whether the coupling is a success. This monitoring can be both of a visual nature, but it can also be done electronically. 7. A coupling system according to any of the aspects 5 or 6, characterized in that, the securing element is mounted in the system in such a way that a part of the second end of the securing element is imbedded when the actuator has moved the securing element and thereby captured a second coupling part in the second coupling mount.

[0069] By performing the securing element so that a part of it moves into a position in which a part of it is unimbedded when coupling does not take place, it is particularly easy to visually ascertain whether the coupling is successful

[0070] 8. A coupling system according to any of the aspects 5 -7, characterized in that, the securing element is mounted in the system in such a way that the second end of the securing element is no longer embedded but protruding beyond a surface when the actuator upon activation has moved the securing element when a second coupling part isn’t present in the second coupling mount.

[0071] By performing the system with securing element in such a way that a part of the securing element is flush with a surface when successful coupling has taken place, but that the same part protrudes beyond the surface when malfunctions occur, a system has been achieved in which malfunctions can easily be detected electronically with sensors, but even also by human touch / feel with fingers or visual inspection.

[0072] 9. A Coupling system according to any one of aspects 1-8, characterized in that the securing element comprises a first end provided with a wedge-shaped gripping part being mutually adapted to the second coupling part and to the second coupling mount such that the wedge-shaped gripping part can slide over the second coupling part and thereby lock the second coupling part in the second coupling mount.

[0073] This entails a very strong connection.

[0074] All aspects of the invention can be combined with all embodiments recited in the claims.

Claims

CLAIMS1. A coupling system for coupling a tool, such as a shovel, to an arm, such as an excavator arm, said coupling system comprising:• a tool-coupling (2) comprising: first hydraulic connectors, a first coupling part (4) and a second coupling part (6) and• an arm-coupling (1) which comprises:• a first coupling mount (3) for receiving the first coupling part (4),• a second coupling mount (5) for receiving the second coupling part (6),• a moveable securing element (7, 7") comprising a first end having a first catching part (8) for catching and securing the second coupling part (6) when placed in the second coupling mount (5),• an actuator adapted for moving of said securing element (7) such that said first catching part (8) is catching or releasing said second coupling part (6) when placed in said second coupling mount (5) and• second hydraulic connectors being complementary to said first hydraulic connector,• said system being characterized by further comprising an extender mechanism being capable of extending or retracting said second hydraulic connectors or a part thereof and thereby engage or disengage said second hydraulic connectors with or from the first hydraulic connectors, said extender mechanism being directly or indirectly connected to said securing element such that the extender mechanism is extending or retracting said second hydraulic connectors when said actuator moves said securing element (7) for catching or releasing said second coupling part (6) when placed in said second coupling mount (5).

2. The coupling system according to claim 1, characterized in that, the actuator is a hydraulic actuator comprising a hydraulic cylinder having: a side surface and two end surfaces, a piston equipped with a piston rod that extends through one of the end surfaces such that the securing element is moveable by the piston rod.

3. The coupling system according to claim 1 or 2, characterized in that, the extender mechanism is connected to said securing element by means of a mechanical connection.

4. The coupling system according to any of the claims 1-3, characterized in that, the extender mechanism comprises a hydraulic mechanism.

5. The coupling system according to claim 3, characterized in that, the extender mechanism comprises a hydraulic mechanism which extends said second hydraulic connectors when said actuator moves said securing element (7) for catching said second coupling part (6) when placed in said second coupling mount (5).

6. The coupling system according to any of the claims 3-5, characterized by, the securing element or a part fixedly connected thereto comprises a strikerpart adapted such that it strikes the second hydraulic connectors or a part fixedly connected thereto and thereby moves the second hydraulic connectors out of engagement with the first hydraulic connectors when said securing element moves such that the second coupling part (6) is released from the second coupling mount (5).

7. The coupling system according to any of the claims 3-6, characterized in that, the cross bar comprises a bracket adapted such that it catches the striker-part when said securing element moves such that the second coupling part (6) is released from the second coupling mount (5).

8. The coupling system according to any of the claims 3-7, characterized in that, the bracket and the striker-part are mutually adapted such the striker part is released when said securing element moves such that said second coupling part (6) is caught in said second coupling mount (5).

9. A coupling system according to any of the claims 4-8, characterized by including a valve element that can open or close the supply of hydraulic oil from the actuators hydraulic cylinder to the extender mechanism, which valve element is located in the end face opposite the piston rod and is directly or indirectly connected to the piston / piston rod such:• that the valve element is open when the piston rod is in the position where said first catching part (8) has caught said second coupling part (6) and• that the valve element is closed when the piston rod is in the position where said first catching part (8) has released said second coupling part (6) .

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