EP0975840B1 - Device for attaching interchangeable items of equipment rapidly, for an excavator - Google Patents

Abstract

The invention relates to a device for rapidly attaching interchangeable items of equipment to the boom of an excavator. The device has a latch mechanism (4) which in the locked position engages in a suitably shaped recess in the item of equipment being attached. A hydraulic cylinder (16) for operating the latch mechanism (4) is provided in the changing device (1), the piston rod of said cylinder being coupled to said latch mechanism (4). A safety bolt (15) is provided to prevent the latch mechanism from being moved back unintentionally. Said safety bolt rests against the rear side (14) of the latch mechanism (4) when in its operating position and prevents said latch mechanism from being pushed back into the rapid attachment device (1). A hydraulic cylinder (16) is provided for operating the safety bolt (15), the piston rod of said hydraulic cylinder (16) preferably forms the safety bolt (15) directly. The piston in the hydraulic cylinder (16) is spring-loaded, so that the safety bolt (15) is pushed into its operating position when there is no pressure in the cylinder (16). This ensures that the safety bolt (15) is always pushed into its operating position when there is a pressure drop in the hydraulic system.

Description

The invention relates to a quick-change device for excavators, with which an attachment (attachment tool) on an excavator boom, e.g. a shovel or the like can be attached with the features of the introductory part of claim 1.

Quick-change devices with hydraulic locking are known, in which a, for example conical, wedge of the quick-change device using a pressure medium cylinder, preferably a hydraulic cylinder, into a, possibly conical, Mount on the attachment, e.g. the spoon that is pushed.

They are also quick-change devices with manual locking known in which the latch of the quick-change device with A threaded spindle is pulled into the attachment on the attachment becomes.

To prevent the quick-change devices from accidentally moving open and the connection between excavator boom and attachment triggers, safety devices are known.

For example, on the quick-change devices with hydraulic Interlocking two three-way valves provided by which the hydraulics can be deactivated so that an accidental Do not operate the hydraulic control unit to an unintentional Guide open the lock of the quick-change device can.

In addition, there are mechanical fuses for quick-change devices known, which have the shape of a plate, which means a screw is attached to the bolt so that the quick-change device also in the event of a hydraulic defect (e.g. leaking hydraulic cylinder and thus a decrease in the locking force) cannot detach from the attachment.

For quick-change devices with manual locking are additional to prevent the threaded spindle from rotating and thus loosening the quick-change device that was previously mentioned fuses, consisting of a plate and screw intended.

A quick change device with a securing element is out the US 5 467 542 A known. In its operative position, this prevents known securing element moving the bolt from the Quick change device out. With the securing element is a Indicator pin connected to the position of the securing element (and not the latch) by pulling out of the quick-change device protrudes when the securing element is not in the active position is.

The aim of the invention is to provide a fuse for quick-change devices, which has a simple construction and which is easy to use.

According to the invention the object with the features of claim 1 solved.

Preferred and advantageous embodiments of the invention are Subject of subclaims 2 to 12.

The fact that in the quick-change device according to the invention as A retractable (retractable) bolt is provided for securing is in its active position next to that of the admission on Attachment (tool, e.g. spoon) engaging end of the latch opposite side is arranged, an unintentional pushing back of the bolt and thus an unintentional loosening of the Quick change device prevented.

There are several for the special design of the safety bolt Possibilities. So the safety bolt can be replaced by a spring-loaded pressure cylinder, preferably hydraulic cylinder, be operable. The fact that the hydraulic cylinder by a spring is acted upon, its piston rod holding the safety pin can form so loaded that the locking bolt even at one Hydraulic defect does not recede. So this is backup the locking of the quick-change device takes effect automatically.

In this embodiment, if the quick-change device The hydraulic circuit holding the locking cylinder can be opened again the quick-change device on the piston rod side acted to pull the bolt back, also used to act on the cylinder for the safety bolt in such a way that the safety bolt is pulled back, the (locking) Wedge backs away and the attachment (spoon) from the quick-change device can be uncoupled.

With a manually operated version of the safety bolt can be provided that the securing bolt, which is transverse to the bolt the quick-change device can be pushed back and forth, even with a failure of the locking force (e.g. break of the adjusting spindle for the bolt) cannot withdraw from its active position. For the concrete version with a manually adjustable safety bolt there are different options. So can be provided be that the securing bolt is provided with a tab on a locking pin held in position by means of a folding pin can be.

A semi-automatic embodiment of a manually adjustable Safety bolt can provide that the safety bolt by means of a compression spring to secure the bolt in its operative position is kept behind the bolt. Should in this embodiment Open quick-change device pulls an operator the safety bolt and pushes it in front of one, next to it the quick-change device arranged console on the attachment (e.g. spoon). In this position of the safety bolt (retracted, Quick-action device can be opened become. If it is decoupled from the implement, it pulls Spring the safety pin against the bolt, where it lies against the side. If in this embodiment the quick-change device again with an attachment. (Working tool, e.g. spoon) is locked, the bolt is pulled out of the quick-change device by means of the threaded spindle and the securing bolt is removed from the spring pulled into the securing position, in which it is behind the rear End of the bolt is arranged.

The invention is also based on the object, based on a quick-change device with the features of the introductory Parts of claims 13 or 14 to provide a quick-change device, which reliably indicates the position of the bolt.

According to the invention the task with the features of the independent Claim 13 or with the features of independent claim 14 solved.

Preferred and advantageous embodiments of the invention are Subject of subclaims 15 to 22.

With the quick-change device according to the invention can at hydraulic and / or manual locking by visual inspection determine whether a correct interlock between the quick-change device and the attachment (attachment, e.g. Spoon) is given. This ensures that visual inspection is also possible from the cab of an excavator.

Fig. 1 eine hydraulische Schnellwechselvorrichtung mit einem Löffel als Anbaugerät, entriegelt,

Fig. 2 die hydraulische Schnellwechselvorrichtung mit Löffel, verriegelt,

Fig. 3 in Seitenansicht, teilweise geschnitten, die Schnellwechselvorrichtung von Fig. 1 und 2,

Fig. 4 eine Einzelheit zu Fig. 3 im Bereich der Sicherung,

Fig. 5 in Draufsicht, teilweise geschnitten eine hydraulische Schnelllwechselvorrichtung,

Fig. 6 in Draufsicht, teilweise geschnitten, eine hydraulische Schnellwechselvorrichtung mit einer anderen Ausführungsform der Sicherung, entriegelt,

Fig. 7 die Sicherungsvorrichtung aus Fig. 6, verriegelt,

Fig. 8 eine manuelle Schnellwechselvorrichtung mit Baggerlöffel, entriegelt,

Fig. 9 die Schnellwechselvorrichtung gemäß Fig. 8, verriegelt,

Fig. 10 die Schnellwechselvorrichtung von Fig. 8 und 9 in Seitenansicht, teilweise geschnitten,

Fig. 11 die Schnellwechselvorrichtung von Fig. 8 bis 10 in Draufsicht, teilweise geschnitten mit Sicherungsbolzen, in verriegelter Stellung,

Fig. 12 eine Einzelheit im Bereich des Sicherungsbolzens von Fig. 11,

Fig. 13 eine manuelle Schnellwechselvorrichtung mit einer anderen Ausführungsform des Sicherungsbolzens in Draufsicht, wobei der Sicherungsbolzen in entriegelter Stellung ist,

Fig. 13a die Vorrichtung von Fig. 13 mit vorgeschobenem Sicherungsbolzen,

Fig. 13b eine Einzelheit zu Fig. 13 und 13a,

Fig. 14a eine Seitenansicht der Schnellwechselvorrichtung von Fig. 13 und 13a mit einem Arbeitswerkzeug (Baggerlöffel) entriegelt,

Fig. 14b die Schnellwechselvorrichtung von Fig. 14a verriegelt,

Fig. 15 in Draufsicht, teilweise geschnitten, eine Schnellwechselvorrichtung mit Verriegelungskontrolle bei zurückgezogenem Riegel,

Fig. 16 die Schnellwechselvorrichtung von Fig. 15 bei ausgefahrenem Riegel und mit Verriegelungskontrolleinrichtung,

Fig. 17 eine Schnellwechselvorrichtung, ähnlich jener von Fig. 11 mit Verriegelungskontrolleinrichtung bei zurückgezogenem Riegel,

Fig. 18 die Verriegelungsvorrichtung von Fig. 17 bei vorgeschobenem Riegel und Verriegelungskontrolleinrichtung,

Fig. 19 ein Hydraulikschema einer Verriegelungsvorrichtung und

Fig. 20 eine andere Ausführungsform einer Verriegelungskontrolleinrichtung.

Further details and features of the invention will become apparent from the following description of exemplary embodiments of the invention, in which description reference is made to the attached drawings, in which examples of devices of the invention are shown. It shows:

1 is a hydraulic quick-change device with a spoon as an attachment, unlocked,

2 the hydraulic quick-change device with spoon, locked,

3 is a side view, partially in section, of the quick-change device of FIGS. 1 and 2,

4 shows a detail of FIG. 3 in the area of the fuse,

5 is a top view, partially in section, of a hydraulic quick-change device,

6 is a top view, partially in section, of a hydraulic quick-change device with another embodiment of the lock, unlocked,

7 the locking device from FIG. 6, locked,

8 shows a manual quick-change device with an excavator bucket, unlocked,

9, the quick-change device according to FIG. 8, locked,

10 is a side view, partially in section, of the quick-change device of FIGS. 8 and 9,

11 shows the quick-change device from FIGS. 8 to 10 in a top view, partially in section with securing bolts, in the locked position,

12 shows a detail in the area of the securing bolt of FIG. 11,

13 shows a manual quick-change device with another embodiment of the securing bolt in a top view, the securing bolt being in the unlocked position,

13a shows the device from FIG. 13 with the securing bolt advanced, FIG.

13b shows a detail of FIGS. 13 and 13a,

14a unlocked a side view of the quick-change device of FIGS. 13 and 13a with a working tool (excavator bucket),

14b locked the quick-change device of Fig. 14a,

15 is a top view, partially in section, of a quick-change device with locking control when the bolt is withdrawn,

16 shows the quick-change device from FIG. 15 with the bolt extended and with the locking control device,

17 shows a quick-change device, similar to that of FIG. 11, with a locking control device when the bolt is withdrawn,

18 shows the locking device from FIG. 17 with the bolt advanced and locking control device,

19 is a hydraulic diagram of a locking device and

20 shows another embodiment of a locking control device.

A quick-change device 1 shown in FIGS. 1 and 2, the od at the free end of an excavator boom (not shown). The like. Is arranged for fixing an attachment 2, e.g. of an excavator spoon, one that can be pushed back and forth Latch 4, which is, for example, conical and into a appropriately shaped, preferably conical, recording 3 am Attachment 2 can be inserted. The locking device also has 1 (rigid) hook 5 behind one Engage clutch rod 6 on attachment 2.

1 shows a position in which the implement 2 on the quick-change device 1 only by means of the hooks 5 is coupled, the bolt 4 not yet in the receptacle 3 is introduced. The position in which the implement 2 with the Quick-change device 1 is coupled, is shown in Fig. 2. The latch 4 is in the receptacle 3 on the attachment 2nd inserted.

3 to 5 show, the latch 4 is in a box-like Recording room of the quick-change device 1, consisting out of four walls 7, 8, 9 and 10 slidably guided. To the Adjusting the bolt 4 is a pressure medium cylinder 11 (Locking cylinder), preferably a hydraulic cylinder, arranged inside the box-like receiving space and with the bolt 4 coupled. By pressing the Locking cylinder 11, the bolt 4 in its in 3 and 5 shown advanced operative position shifted in which it is shaped in the shape which is preferably opposite to it 3 engages the attachment 2 and this with the Quick change device 1 connects securely.

In order to prevent the latch 4 from unintentionally e.g. in the event of failure of the hydraulic system, which lock cylinder 11 actuated, moved back from the receptacle 3, whereupon subsequently the connection between the quick-change device 1 and the attachment 2 would solve is a Safety bolt 15 is provided.

3 and 4 is in the embodiment shown the locking pin 15 the piston rod one on the wall 8, a hole in this completely mounted pressure medium cylinder 16, which is spring-loaded, in such a way that the safety pin 15 (= the piston rod of the cylinder 16) in the absence of pressure into its operative position shown in FIGS. 3 and 4 is advanced in which it is next to that in the box-like Receiving space arranged end 14 of the bolt 4 arranged is. This reliably prevents the bolt 4 unintentionally withdraws or is pushed back.

Because the cylinder 16 is spring-loaded, the Safety bolt 15 behind the end 14 of the extended bolt 4 advanced so that this also in the event of a defect in the Hydraulics of the locking cylinder 11 no longer retreat can. This is the locking described the quick-change device 1 automatically takes effect.

If the quick-change device 1 is to be opened again, can, for example via the hydraulic circuit that the Locking cylinder 11 of the quick-change device 1 acted on the piston rod side, the cylinder 16 so be applied that the locking bolt 15 and the bolt 4 of the quick-change device 1 are withdrawn can. The attachment 2 can then by the quick-change device 1 can be removed.

Instead of the described embodiment of the locking bolt 15 with (hydraulic) cylinder 16 can also be a safety bolt 15 can be provided which is mechanically, e.g. by hand is to be operated from.

This (mechanical) embodiment of the securing bolt 15 is preferred, but not exclusively, for quick change devices 1 used, in which the bolt 4 is to be adjusted mechanically. Such a quick-change device 1 show FIGS. 8 to 11. In the case of FIGS 11 shown embodiment of the quick-change device 1 is for adjusting the bolt 4 in and out of its operative position an adjusting spindle 20 is provided with which the bolt 4 from the box-shaped recording space can be pulled out when on the quick-change device 1 to fix an attachment 2 is. To disconnect the quick-change device 1 and attachment 2, the latch 4 by appropriate Actuate the adjusting spindle 20 again in the quick-change device 1 or their box-shaped receptacle pushed back.

The securing bolt 15 is in the in FIGS. 11 and 12 embodiment shown through a hole in the side wall 10 of the box-shaped receiving space of the quick-change device 1 inserted bolt, which is connected to a tab 36 is, which has a hole 17 through which in its Active position pushed locking pin 15 on the outside the wall 10 attached pin 18 protrudes. Around the safety bolt 15 secure against inadvertent slipping out, can a folding pin through a transverse hole 19 in pin 18 or a pin is pushed.

6, 7, 13 and 14 show another embodiment a locking bolt 15, namely FIGS. 6 and 7 on Example of an actuable by means of a hydraulic cylinder 11 Riegel 4 and Fig. 13 using the example of one with a Spindle 20 operable bolt 4 of a quick-change device 1. Fig. 6 shows the locking pin 15 in its unlocked position (also Fig. 13 and 14) and Fig. 7 the securing bolt 15 in its the movement of the bolt 4 blocking operative position.

6, 7 and 13, 13a, 13b, 14a and 14b Embodiment is the locking bolt 15 by a compression coil spring 25 in its operative position shown in FIG. 7 loaded, the compression coil spring 25 in one on the side wall 9 of the box-shaped receiving space the locking device 1 screwed housing 26 added is. At the outer end of the locking bolt 15 is attached a handle 27 which one facing inward Pin 28 carries. To the safety bolt 15 from its operative position 7, an operator attracts the handle 27 and rotates it so that the pin 28 on a console 21 of an attachment 2 rests (position according to 6 and 13). In this position of the securing bolt 15 can the quick-change device 1 either by pressing of the locking cylinder 11 or the adjusting spindle 20 opened and the attachment 2 from the quick-change device 1 be removed. As soon as this is done, the spring presses 25 the locking bolt 15 in contact with the side surface of the bolt 4, with the free end of the pin 28 just next to the outside of the side wall 9 of the box-shaped receiving space the locking device 1 comes to rest.

If on the quick-change device 1 again an implement 2 is to be determined by actuating the bolt 4 the bolt 4 by means of the threaded spindle 20 or by actuation the locking cylinder 11 advanced and that of the side surface of the bolt 4 released safety bolts 15 snaps under the action of its helical compression spring 25 in its operative position (see FIG. 13b) as soon as it is next to the rear end 14 of the bolt 4 is arranged. It can be provided that the pin 28 next to the console 21 on Attachment 2 comes to rest, as shown for example in Fig. 14 is shown.

15 and 16 is for a quick-change device 1 similar to that of Figs. 3 to 5 shown that the inventive Quick-change device 1 a locking control, a visual inspection of the position of the bolt 4 allowed, can be provided.

15 and 16 is on the inner End 14 of the bolt 4 a display stick or a display plate 30 attached, with the bolt 4 retracted on the Cab of an excavator facing side of the locking device 1 from the guide box in which the bolt 4 can be moved is recorded, stands out. This is a visual inspection possible from the cab of the excavator. Once the Bolt 4 is in its active position, is the display device 30 added in the quick-change device 1. So can be checked from the driver's cab by means of a visual inspection Locking, i.e. which ensures the locking Position of the bolt 4, are checked.

17 and 18 show this for a quick change device 1 with adjustment of the bolt 4 by the screw spindle 20. Here too, an indicator 30 is provided which is in line with the rear one End 14 of the bolt 4 is connected and as described above indicates the position of the bolt 4, so that a visual inspection the locked or unlocked position of the lock constantly, even from the cab of the excavator.

The part of the indicator can be used to improve the visual inspection 30, the unlocked position of the bolt 4 from the Recording space of the quick-change device 1 protrudes in the signal color be painted so that it indicates "danger". In the the operative position of the bolt 4 only visible end surface 31 of the indicator 30 is preferably the same Colored like the quick-change device so that "No danger" is displayed and the correct locking between quick-change device 1 and attachment 2 is.

The hydraulic system shown in Fig. 19 is described below:

The bolt 4 of the quick-change device 1 is by the Hydraulic cylinder 11 moved forward or backward. The advanced one (Extended) position of the cylinder 11 corresponds to that advanced, engaging in the receptacle 3 of the attachment 2 Bolt 4 of the quick-change device 1.

The hydraulic cylinder responsible for operating bolt 4 11 is by a check valve 42 (= safety valve), that can be flanged directly onto the hydraulic cylinder 11, secured against unintentional opening of the quick-change device 1.

Since the hydraulic cylinder 11 when adjusting the bolt 4 in the locking position in that the entire piston crown surface is pressurized, more force develops than by acting on the piston ring surface when pulling back of the bolt 4 for unlocking is an additional pressure reducing valve 41 provided with which to balance the force between locking and unlocking, the locking pressure is reduced by 50 bar.

The check valve 42 and the pressure reducing valve 41 are in a common valve block 40 included.

With the quick-change device open or unlocked 1 and before extending the hydraulic cylinder 11 the cylinder 16 is in its retracted position Piston rod (retracted safety pin 15).

When the bolt 4 is extended, the piston rod of the cylinder 16 and thus the safety pin 15 by the spring action of the security cylinder 16 advanced, so that the bolt 4 against unintentional opening (the safety bolt 15 is due to the spring action behind the bolt 4 extended) is locked.

To unlock the quick-change device 1, the hydraulic cylinder 11 pressurized on the piston rod side. At the same time, the check valve 42 (in block 40) becomes hydraulic unlocked, the security cylinder 16 pressurized and the piston rods of cylinders 11 and 16 retracted.

So that the safety cylinder 16 is not accidentally caused by leak oil can be opened, is on the unlocking side Preload valve 45 installed, which only at a pressure of 80 bar opens.

Two 3/2 way ball valves 43 and 46 are used to shut off the Hydraulic system, furthermore these 3/2 way valves 43 and 46 other hydraulic via the same hydraulic circuit controlled work equipment.

In the embodiment of an indicator shown in FIG. 20 30 this is designed as a round rod, which is in a sleeve 50 is led. The sleeve 50 is on the quick-change device attached so that the free end 31 of the indicator 30, so as shown in Fig. 18, for example is coming. In Fig. 20 it is also shown that the interior of the Rifle in the area where the indicator 30 is on its side wall 32 is colored or painted with signal color, is set off, so that signal color when moving the indicator 30 is not damaged.

At the end that is the visible end 31 of the indicator 30 opposite, a collar 52 is fastened via a screw 51, against which a compression coil spring 53 abuts, with their other end abuts a shoulder 54 in the sleeve 50. With the bolt 4 of the quick-change device is one Bolted round rod 55, the 4 on the screw 51 of the indicator 30 and this in Fig. 20 moves to the left so that the free end of the indicator 30 and its area 32 painted with signal color is visible and, as before, for the other embodiments of the safety display device, indicates that the quick-change device is unlocked.

In summary, a preferred embodiment of the Invention can be described as follows:

A quick-change device 1, via which an attachment on The boom of an excavator can be attached in one provided in the quick-change device 1, box-shaped Guided recording room, a bolt 4, which in the locked position in a correspondingly shaped receptacle engages on the attachment.

To operate (pushing the bolt 4 back and forth) can be in the quick-change device 1, a hydraulic cylinder 11 is provided be, the piston rod coupled to the bolt 4 is. The bolt 4 can also be moved forward and backward by means of an adjusting spindle be pushed back.

To inadvertently push back the bolt 4 and thus a loosening of the connection between the attachment and the To avoid quick change device 1 is a safety bolt 15 provided that in its operative position against the Back 14 of the bolt 4 abuts and prevents this be pushed back into the quick-change device 1 can. A hydraulic cylinder is used to actuate the securing bolt 15 16 provided, the piston rod preferably immediately forms the securing bolt 15. The piston in the Hydraulic cylinder 16 is spring-loaded so that when depressurized Cylinder 16 of the locking pin 15 in its operative position is advanced. This ensures that if there is a drop in pressure in the hydraulic system of the safety bolts 15 in any case its active action is postponed.

So that the position of the bolt 4 can be reliably recognized, can the latch 4 may be assigned a display device 30 which with bolt 4 advanced into its operative position the quick-change device 1 is included and the in its non-operative position retracted bolt 4 from the Quick-change device 1 protrudes.

Claims (22)

1. Rapid-change apparatus (1) for fixing attachments (2) to excavator booms, having a bar (4) which is displaceable in the rapid-change apparatus (1) and which can be introduced into a receiver (3) of the attachment (2) to couple the attachment (2) to the rapid-change apparatus (1), there being provided in the rapid-change apparatus (1) a safety element (15) which can be displaced into and out of the active position thereof transversely to the direction of displacement of the bar (4) and which, in the active position thereof, prevents the displacement of the bar (4) out of the receiver (3) of the attachment (2), characterised in that the safety element is a safety bolt (15), in that the safety bolt (15) engages through a hole in a wall (7, 8, 9, 10) of a receiving space, which is arranged in the rapid-change apparatus (1) and which acts as a guide for the bar (4), in that the safety bolt (15), with the bar (4) advanced out of the rapid-change apparatus (1), is arranged beside the end (14) thereof that is received inside the rapid-change apparatus (1), or abuts the end (14), and in that the front end of the safety bolt (15) is arranged beside one of the lateral faces of the bar (4) when the bar (4) is retracted into the rapid-change apparatus.
2. Apparatus according to claim 1, characterised in that a linear motor (16) is provided to displace the safety bolt (15).
3. Apparatus according to claim 2, characterised in that the linear motor is a hydraulic cylinder (16).
4. Apparatus according to claim 3, characterised in that the piston of the hydraulic cylinder (16) is spring-biased into the active position thereof in the sense of an advance of the safety bolt (15).
5. Apparatus according to claim 3 or claim 4, characterised in that the piston rod of the hydraulic cylinder (16) is the safety bolt (15).
6. Apparatus according to claim 1, characterised in that there is connected to the safety bolt (15) a handle (27), by means of which the safety bolt (15) can be displaced into and out of the active position thereof.
7. Apparatus according to claim 6, characterised in that a helical compression spring (25) is associated with the safety bolt (15) and urges the safety bolt (15) in the sense of displacement into the active position thereof.
8. Apparatus according to claim 6 or claim 7, characterised in that a journal (28) is provided on the handle (27) and, after rotation of the handle (27), abuts a component (21) of the rapid-change apparatus (1) or of the attachment (2) and holds the safety bolt (15) in the retracted non-active position thereof.
9. Apparatus according to claim 1, characterised in that there is connected to the safety bolt (15) a bracket (36), by means of which the safety bolt (15) can be fixed in the active position thereof.
10. Apparatus according to claim 9, characterised in that there is provided in the bracket (36) a hole (17), through which a pin (18), which is attached to the outside of one of the walls (7 to 10) of the receiving space, protrudes when the safety bolt (15) is displaced into the active position thereof.
11. Apparatus according to claim 10, characterised in that there is provided at the free end of the pin (18) a transverse drilled hole, through which a retaining pin, for example, a folding pin or a safety pin, can be pushed in order to fix the bracket (36).
12. Apparatus according to any one of claims 3 to 5, characterised in that the hydraulic cylinder (16), which is associated with the safety bolt (15), is pressurised with hydraulic medium via a line which branches off from the line by means of which the cylinder (11) is pressurised with hydraulic medium for the displacement of the bar (4) in the sense of a retraction of the bar (4).
13. Apparatus (1) for fixing attachments (2) to excavator booms, having a bar (4) which is displaceable in the rapid-change apparatus (1) and which can be introduced into a receiver (3) of the attachment (2) to couple the attachment (2) to the rapid-change apparatus (1), and having an indicator device (30), characterised in that the indicator device (30) is attached to the end (14) of the bar (4) that is received inside the rapid-change apparatus (1), and in that the indicator device (30) is received inside the rapid-change apparatus (1) when the bar (4) is advanced into the active position thereof and projects out of the rapid-change apparatus (1) when the bar (4) is retracted into the non-active position thereof.
14. Apparatus (1) for fixing attachments (2) to excavator booms, having a bar (4) which is displaceable in the rapid-change apparatus (1) and which can be introduced into a receiver (3) of the attachment (2) to couple the attachment (2) to the rapid-change apparatus (1), and having an indicator device (30), characterised in that the indicator device (30) is received inside the rapid-change apparatus (1) when the bar (4) is advanced into the active position thereof and projects out of the rapid-change apparatus (1) when the bar (4) is retracted into the non-active position thereof, in that the indicator device is a rod guided in a sleeve (50), and in that a rod (55), which is connected to the bar (4) of the locking apparatus (1), is associated with the end of the indicator device (30) that is located inside the rapid-change apparatus (1).
15. Apparatus according to claim 13, characterised in that the indicator device (30) is rod-shaped or strip-shaped.
16. Apparatus according to claim 14 or claim 15, characterised in that the rod-shaped or strip-shaped indicator device (30) extends in the direction of the displacement axis of the bar (4).
17. Apparatus according to any one of claims 13 to 16, characterised in that the free end, in particular the outwardly directed end face (31), of the indicator device (30) is the same colour as the rapid-change apparatus (1).
18. Apparatus according to any one of claims 13 to 17, characterised in that the lateral faces (32) of the indicator device (30) are coloured in a way which contrasts with the colour of the rapid-change apparatus (1), in particular using signal paint.
19. Apparatus according to any one of claims 13 to 18, characterised in that the indicator device (30) projects beyond the rapid-change apparatus (1) at the side facing the driver's cab of the excavator when the bar (4) is retracted.
20. Apparatus according to any one of claims 14 to 19, characterised in that the indicator device (30) is subject to the action of a spring (53) which urges the indicator device (30) into the position retracted into the rapid-change apparatus (1).
21. Apparatus according to any one of claims 14 to 20, characterised in that the sleeve (50) in the region of the portion (32), provided with signal paint, of the indicator device (30) has spacing from the periphery of the indicator device (30).
22. Apparatus according to any one of claims 14 to 21, characterised in that the helical compression spring (53) is held between a collar (52) on the indicator device (30) and a shoulder in the sleeve (50).

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