EP3947828A1

EP3947828A1 - Quick coupler for attaching a tool to a hydraulic excavator or other work machine

Info

Publication number: EP3947828A1
Application number: EP20713511.2A
Authority: EP
Inventors: Peter Lauterslager
Original assignee: Caterpillar Work Tools BV
Current assignee: Caterpillar Work Tools BV
Priority date: 2019-03-27
Filing date: 2020-03-16
Publication date: 2022-02-09
Anticipated expiration: 2040-03-16
Also published as: EP3947828C0; GB201904211D0; GB2582595A; EP3947828B1; GB2582595B; WO2020192967A1; CA3133515A1

Abstract

A coupling assembly (30) includes a mount (31) for receiving a tool (20) to releasably mount the tool in a mounted position on a work machine (1), and a retaining body (50) comprising retaining portions (51, 51') and movable relative to the mount (31) between a release position and a retaining position in which the retaining portions (51, 51') retain the tool (20) in the mounted position. The retaining body (50) is movable in translation and also pivotable relative to the mount (31) about a pivot axis (X2) arranged between the retaining portions (51, 51'). Two actuator assemblies (60, 60') are pivotably attached to the retaining body (50) between the pivot axis (X2) and the respective retaining portions (51, 51') to move the retaining body (50) in translation between the release position and the retaining position. The actuator assemblies (60, 60') may be arranged at opposite sides of the mount (31) providing space for a power supply mechanism (70) arranged in-between them.

Description

QUICK COUPLER FOR ATTACHING A TOOL TO A HYDRAULIC EXCAVATOR OR OTHER WORK MACHINE

Technical Field

This disclosure relates to coupling assemblies, commonly referred to as quick couplers, for attaching a tool to a work machine.

Background

Wheeled or tracked work machines such as excavators and backhoe loaders are commonly configured to operate a variety of interchangeable tools such as buckets, grabs, breakers, compactors and the like. Each tool is releasably mounted on a rigid mount attached to the machine so as to transmit forces between the tool and the machine in use. The mount forms part of a coupling assembly, commonly referred to as a quick coupler because it makes it easy to connect and disconnect the tool. The quick coupler includes a rigid retaining body movable by one or more actuators, typically hydraulic actuators, between a release position and a retaining position in which the tool is engaged by two retaining portions of the retaining body, typically configured as wedges, which retain it in fixed relation to the mount.

For example, CA 2727324 A1 discloses a quick coupler having a retaining body movable by a pair of hydraulic actuators. At least one of the actuators has a hydraulic valve which is biased to close on depressurisation of the hydraulic circuit to hold the retaining body in the retaining position in the event of malfunction.

US 7654019 B2 teaches a quick coupler with a retaining body movable by a hydraulic actuator and biased to the retaining position by two springs. A latch is arranged to lock the retaining body in the retaining position.

The tool is typically heavy and so large forces may be applied to the retaining portions when coupling and uncoupling the tool. When the applied forces are unequal the resulting torque will urge the retaining body to rotate about its centre relative to the mount and, if transferred as a bending moment to the actuators, may damage the hydraulic seals.

In order to decouple the cylinders from bending moment resulting from the torque applied to the retaining body it is known to connect the piston rod or rods to the neutral, central region of the retaining body, mid-way between the retaining portions. It is also known to arrange the retaining body to slide in translation along guides which react the applied torque against the mount to prevent the retaining body from rotating.

Quick couplers may incorporate additional equipment such as rotating drives or hydraulic or electrical power connectors for operating moving parts of the tool. However, it is often difficult to fit the required equipment into the available space inside the mount of the quick coupler, most of which is occupied by the hydraulic actuators and guides.

Summary

In accordance with the present disclosure there is provided a coupling assembly for releasably mounting a tool on a work machine.

The coupling assembly includes a mount, a rigid retaining body, and first and second actuator assemblies.

The mount is attachable to a work machine and configured to receive a tool in a mounted position of the tool.

The retaining body is movable relative to the mount between a retaining position and a release position and has first and second retaining portions, the retaining portions being configured: in the retaining position of the retaining body, to retain the tool in the mounted position, and in the release position of the retaining body, to release the tool from the mounted position.

The first and second actuator assemblies are operable to move the retaining body between the retaining and release positions.

The first actuator assembly includes a first actuator, and the second actuator assembly includes a second actuator. The retaining body is pivotably connected to the mount at a pivot axis arranged between the first and second retaining portions, and is movable in translation relative to the mount along a translation axis acollinear with the pivot axis between the engaged and disengaged positions.

The first actuator assembly is pivotably connected to a first region of the retaining body between the first retaining portion and the pivot axis, and the second actuator assembly is pivotably connected to a second region of the retaining body between the second retaining portion and the pivot axis.

Brief Description of the Drawings

Further features and advantages will be evident from the following illustrative embodiment which will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which:

Fig. 1 shows a work machine having a coupling assembly and a tool detached from the coupling assembly;

Fig. 2 shows the tool;

Figs. 3 and 4 show the tool received in the mounted position on the coupling assembly, with the retaining body respectively in the release position (Fig. 3) and the retaining position (Fig. 4);

Fig. 5 is a side view of the coupling assembly with the retaining body in the release position;

Figs. 6 and 7 are an enlarged side view of part of the coupling assembly, showing the retaining body respectively in the release position (Fig. 6) and the retaining position (Fig. 7);

Figs. 8, 9 and 10 are a bottom view of the coupling assembly, showing the retaining body respectively in the release position (Fig. 8), the retaining position (Fig. 9), and a rotated position (Fig. 10); and

Fig. 11 is an enlarged view of the first and second actuators of the coupling assembly with a schematic illustration of the hydraulic circuit. Detailed Description

In this specification, a work machine means a machine which is configured to manipulate and operate a tool mounted on the machine. Typically a work machine will have a gross weight of at least 1 tonne and will include a seat from which an operator can control the movement of the tool. In particular, a work machine may be a vehicle having at least one arm and an arrangement of actuators for moving the arm, wherein the tool is connected at a distal end of the arm. Usually the actuators are hydraulic. The vehicle may be mounted on wheels or tracks and may be configured for example as an excavator or backhoe loader or the like.

By way of example, the work machine may have a gross weight in excess of 5 tonnes, 10 tonnes, or 20 tonnes, up to as much as 100 tonnes or more. Very large work machines such as face shovels may have a gross weight of up to 1000 tonnes or more. The coupling assembly may be configured to transmit a bending moment in excess of lOkNm, 20kNm, or lOOkNm, up to as much as 500kNm or more in use.

Referring to Fig. 1, a coupling assembly 30 includes a rigid mount 31 which in the illustrated embodiment is pivotably attached to the distal end of an arm or stick 2 of a work machine 1 configured as a tracked excavator having a machine body or house 4 rotatably mounted on tracks 5 and containing a seat 6 for the operator. The stick 2 is pivotably mounted at the distal end of another arm or boom 3 which in turn is pivotably mounted on the house 4. Hydraulic actuators 7 are arranged to move the stick 2, boom 3 and mount 31 by hydraulic pressure from a source such as an engine driven hydraulic pump 8 responsive to commands received from the operator via user controls such as a joystick 9.

Referring to Fig. 2, in the illustrated embodiment the tool 20 is configured as a grab with arms 21 pivotable by hydraulic actuators 22 on a rigid tool body 23 responsive to hydraulic pressure which is transmitted from the hydraulic pump 8 to the tool via a hydraulic power transmission coupling 24 mounted on the tool body. The tool body 23 may have two parallel side plates 25 as shown (one of which is visible in Fig. 2, the other being a mirror image), each defining front and rear recesses 26, 27 and a wedge receptacle 28.

Referring to Figs. 5 and 8, the mount 31 may be configured as a rigid steel casting or fabrication having parallel side plates 32 connected by a central portion 37 and supporting outwardly and oppositely projecting front and rear lugs 33, 34. At the forward end of the mount each side plate 32 may define a pair of opposed, spaced-apart, upper and lower guide surfaces 35, 36.

Opposed portions 38, 39 of the central portion 37 of the mount may extend at its forward end along a longitudinal central axis XI of the mount mid-way between the side plates 32 to define another pair of opposed, spaced- apart, upper and lower guide surfaces 40, 41. Two slots 42 may be formed as shown, one in each of the opposed portions 38, 39 to extend along the

longitudinal central axis XI and open through the respective one of the guide surfaces 40, 41. The opposed walls of each slot 42 may be exactly superposed in plan view as seen in Fig. 8 and may define another pair of opposed guide surfaces 43 which extend in spaced relation in parallel with the central longitudinal axis XI.

Each side plate 32 may also define front and rear mounting holes 44, 45 through which pins 10 are inserted to attach the mount 31 to the stick 2 of the work machine.

The mount 31 may be configured as a housing in which the rigid retaining body 50 is arranged to be movable relative to the mount 31 between a retaining position as shown in Figs. 4, 7 and 9 and a release position as shown in Figs. 3, 5, 6 and 8.

The retaining body 50 may be configured as an elongate solid bar, with its opposite end regions defining the first and second retaining portions 51,

51’ which may directly engage the tool body in use and may extend outwardly of the side plates 32 on each side of the mount 31 as shown. The adjacent portions of the retaining body may be slidably received between the upper and lower guide surfaces 35, 36. When considered in end view as best seen in Figs. 6 and 7 each retaining portion 51, 5 may be shaped to form a wedge which may taper towards the rear end of the mount 31.

Referring to Figs. 1, 3 and 4, the tool 20 may be releasably mounted on the work machine 1 by manipulating the boom 3, stick 2 and mount 31 to position the mount 31 over the tool body 23 so that the rear lugs 34 are received in the rear recesses 27, and then pivoting the mount 31 so that the front lugs 33 are received in the front recesses 26, whereby the tool is received on the mount in the mounted position as shown in Fig. 3. With the tool in the mounted position, the retaining body 50 is then moved by the actuator assemblies as further described below from the release position as shown in Fig. 3 to the retaining position as shown in Fig. 4.

The first and second retaining portions 51, 5 are configured, in the retaining position of the retaining body 50, to retain the tool in the mounted position, and in the release position of the retaining body, to release the tool from the mounted position Where as shown the retaining portions 51, 5 are configured as wedges, the first and second retaining portions 51, 5 may engage fittingly, each in a respective one of the wedge receptacles 28 of the tool body 23 to prevent the tool body 23 from rotating relative to the mount 31 so that, in combination with the lugs 33, 34 and other contact surfaces, the retaining portions 51, 5 retain the tool 20 in the mounted position, as shown in Fig. 4.

The retaining body 50 is pivotably connected to the mount 31 at a pivot axis X2 arranged between the first and second retaining portions 51, 5G. The pivot axis X2 may be located mid-way between the retaining portions 51, 5 when considered in the length direction of the retaining body 50, as shown.

The retaining body 50 is movable in translation relative to the mount 31 along a translation axis X3 which is acollinear (which is to say, not collinear) with the pivot axis X2 between the release position and the retaining position as shown respectively in Figs. 8 and 9. The translation axis X3 may be collinear with the longitudinal central axis XI of the mount 31. The pivot axis X2 may be normal to the translation axis X3 and may intersect the translation axis X3, as shown. The retaining body 50 is pivotable about the pivot axis X2 relative to the mount 31 when the pivot axis X2 is positioned along the translation axis X3 anywhere in a range of movement in-between the retaining and release positions, as shown in Fig. 10. In the retaining position the retaining portions 51, 5 G are clamped by the actuator assemblies (to the mount 31 and/or to the tool body 23) so that the retaining body 50 is fixed relative to the mount 31 to retain the tool 20 in the mounted position.

The pivot axis X2 may be fixed relative to the retaining body 50 and movable in translation relative to the mount 31 along the translation axis X3 by movement of the retaining body 50 between the retaining and release positions.

As shown in the illustrated embodiment, this may be achieved by providing an axle 52, which may be a solid (optionally, cylindrical) body fixed to the retaining body 50 to extend outwardly from one or, as illustrated, from both of its opposite (upper and lower) sides as illustrated, so that the central axis of the axle 52 defines the pivot axis X2. In this specification an axle means a shaft or pin, for example, a trunnion or a pair of oppositely directed collinear trunnions as shown, that defines a pivot axis about which the retaining body can rotate at least through a limited angular range. The axle 52 is slidably guided for translation between guide surfaces 43 of the mount 31, which as illustrated may be defined by slots 42 formed in opposed portions 38, 39 of the mount. The middle region of the retaining body from which the axle 52 extends may be slidably received between the spaced guide surfaces 40, 41 formed by the opposed portions 38, 39 of the mount, which may be generally normal to the guide surfaces 43 of the slots 42 that guide the axle 52 in translation.

Thus, the retaining body 50 may both pivot and translate in the same plane while the guide surfaces 43 constrain its translation at the position of the pivot axis X2 to one degree of freedom (along the translation axis X3) in the plane, and the guide surfaces 40, 41 and 35, 36 prevent it from moving out of the plane. First and second actuator assemblies 60, 60’ including first and second actuators 61, 6 G are provided for moving the retaining body 50 between the retaining and release positions.

The first and second actuator assemblies 60, 60’ and actuators 61, 6G may be arranged respectively at first and second sides of the mount, as illustrated, so that a power supply mechanism 70 for supplying power to the tool 20 can be arranged on the mount 31 between the first and second actuator assemblies 60, 60’.

In the illustrated embodiment, the power supply mechanism 70 includes hydraulic connectors 71 which are releasably coupled to the hydraulic power transmission coupling 24 of the tool 20 to transmit hydraulic power from the hydraulic pump 8 to the hydraulic actuators 22 of the tool 20. Alternatively or additionally, the power supply mechanism 70 could include electrical power connectors or a mechanical power connector such as a hydraulically, electrically or shaft driven rotating mechanism or the like, whereby the moving parts of the tool, for example, the arms 21 of the tool 20, can be driven in motion or rotated on the end of the stick 2. A plurality of different tools may be provided to be interchangeably mounted on the coupling assembly 30, and each tool may be provided with corresponding connectors to receive power from the power supply mechanism 70.

Optionally, the power supply mechanism 70 may include further actuators for moving the hydraulic connectors 71 or other connectors in and out of engagement with the corresponding connectors of the tool.

The first actuator assembly 60 is pivotably connected to a first region 53 of the retaining body between the first retaining portion 51 and the pivot axis X2, while the second actuator assembly 60’ is pivotably connected to a second region 53’ of the retaining body 50 between the second retaining portion 51’ and the pivot axis X2.

As exemplified by the illustrated embodiment, the first and second actuator assemblies 60, 60’ may include, respectively, first and second rigid connectors 62, 62’. The first rigid connector 62 is pivotably connected to the first actuator 61 (for example, to the distal end of a respective piston rod 66) and pivotably connected to the first region 53 of the retaining body 50, while the second rigid connector 62’ is pivotably connected to the second actuator 6 (for example, to the distal end of a respective piston rod 66’) and pivotably connected to the second region 53’ of the retaining body 50.

The pivot connection at each end of the rigid connector allows a static part of each actuator to be mounted in fixed relation to the mount 31 while decoupling the actuator from bending moment resulting from torque applied by external forces acting on the retaining portions 51, 5 of the retaining body 50.

In alternative embodiments, the actuators may be connected via a differently configured linkage to the retaining body 50.

As best seen in Fig. 11, the first actuator 61 may include a first piston 63 having a first piston rod 66 and received in a first hydraulic cylinder 64, while the second actuator 6G includes a second piston 63’ having a second piston rod 66’ and received in a second hydraulic cylinder 64’. The first and second pistons 63, 63’ and piston rods 66, 66’ are pivotably connected, respectively to the first and second regions 53, 53’ of the retaining body 50 via respective, first and second linkages, which may comprise first and second, rigid connectors 62, 62’, for example as shown, while the first and second hydraulic cylinders 64, 64’ forming the static parts of the actuators are mounted (for example, in fixtures 46) in fixed relation to the mount 31.

The first actuator assembly 60 may include a first resilient bias element, and the second actuator assembly 60’ may include a second resilient bias element, the first and second resilient bias elements being arranged to urge respectively the first and second retaining portions 51, 5 of the retaining body 50 towards the engaged position of the retaining body 50. (Which is to say, to urge the first and second retaining portions 51, 5 towards the positions that they respectively occupy when the retaining body 50 is in the retaining position.)

Where as shown the actuator assemblies 60, 60’ include rigid connectors 62, 62’, the resilient bias elements may be configured as shown as first and second coil springs 65, 65’, which are arranged concentrically around, respectively, the first and the second rigid connector 62, 62’ to urge, respectively, the first and the second retaining portion 51, 5 of the retaining body 50 towards the engaged position of the retaining body 50 (which is to say, towards the position occupied by the respective, first or second retaining portion 51, 5 when the retaining body 50 is in the retaining position).

The forward end of each coil spring 65, 65’ may bear against the central portion 37 at the forward end of the mount 31 while the rigid connectors 62, 62’ pass through apertures in the central portion 37 of the mount to connect pivotably with the retaining body 50, with each of the apertures being

dimensioned to accommodate the angular displacement of the respective rigid connector 62, 62’ as the retaining body 50 pivots under torque, as shown in Fig. 10

Referring to Fig. 11, the coupling assembly 30 may include a hydraulic circuit 80 having a flow equalizing device 82 for controlling a flow of hydraulic fluid 81 to flow simultaneously at an equal flow rate to or from each of the first and second actuators (61, 6G). As illustrated, the flow equalizing device 82 may be arranged to control the flow rate on the side of the piston at which positive pressure acts to move the retaining body 50 to the release position. In one possible alternative arrangement, it could be arranged on the other side of the piston, on which positive pressure acts to move the retaining body to the retaining position. In a further possible arrangement, two flow equalizing devices could be arranged, each on a different respective side of the pistons. In each case, the flow equalizing device or devices may be arranged to control flow in both inflow and outflow directions, to and from each cylinder. The or each flow equalizing device could be configured for example as a spool type flow divider (as illustrated), or as a gear type flow divider (which is to say, a pair of rotating bodies that displace, relative to each other, an equal volume of hydraulic fluid with each increment of angular motion, and which are mechanically connected together to rotate in synchrony.). The flow equalizing device distributes torque applied to the retaining body 50 between the two actuators, ensuring that the two actuators move in synchrony so that the retaining body 50 is maintained in fixed angular relation (preferably, with its length axis perpendicular) to its axis of translation as it moves between the retaining and release positions.

In such arrangements, the coil springs or other resilient bias elements 65, 65’ will also function as an equalizer, applying a restoring force that opposes unequal forces applied to the retaining portions 51, 5 and urges the retaining body 50 towards a position of symmetry. The synchronized movement of the actuators and the restoring force of the coil springs or other resilient bias elements thus urges the retaining body 50 away from a rotated position as shown in Fig. 10 (which is shown purely for reference although it may rarely if ever occur, and may be entirely precluded by the provision of a flow equalizing device as shown) and towards a non-rotated, symmetrical or rest position which may be as shown in Fig. 8 or Fig. 9, depending on the commanded position of the actuators 61, 61’ between the retaining and release positions.

The restoring force applied by the coil springs or other resilient bias elements 65, 65’ will also urge the retaining body 50 towards the retaining position in the event of failure of either of the actuators 61, 61’.

A locking mechanism may be provided for locking the retaining body 50 in the retaining position. In combination with the restoring force of the resilient bias elements, the locking mechanism provides a failsafe arrangement to move the retaining body 50 to the retaining position and then to lock it in the retaining position in the event of power loss to the actuators.

Where as shown the actuators 61, 6 G are hydraulic, the locking mechanism may comprise a valve arrangement configured to retain hydraulic pressure in the actuators, providing a hydraulic lock to resist movement of the pistons 63, 63’ in a direction towards the release position of the retaining body 50 in the event of a loss of hydraulic pressure in the hydraulic supply to the circuit.

The valve arrangement may be configured as shown as a non return valve 83 for supplying hydraulic fluid from a supply 86 to a volume of the cylinders 64, 64’ to urge the pistons 63, 63’ in a direction towards the retaining position of the retaining body 50. A pilot pressure supply 84 may be arranged as shown to open the non-return valve to allow flow in the return direction to relieve the hydraulic pressure from said volume of the cylinders to allow the pistons to move in a direction towards the release position of the retaining body 50. The pilot operated non-return valve 83 is biased to return to a closed, rest position to prevent flow in the return direction in the absence of hydraulic pressure from the pilot pressure supply 84, which as shown may be connected directly to the supply 85 to that side of the piston on which positive pressure acts to urge the pistons in a direction towards the release position of the retaining body 50. Thus, when positive pressure is not applied in the release direction, the retaining body 50 is locked in the retaining position by the closed non-return valve 83.

In summary, a coupling assembly includes a mount for receiving a tool to releasably mount the tool in a mounted position on a work machine, and a retaining body comprising retaining portions and movable relative to the mount between a release position and a retaining position in which the retaining portions retain the tool in the mounted position. The retaining body is movable in translation and also pivotable relative to the mount about a pivot axis arranged between the retaining portions. Two actuator assemblies are pivotably attached to the retaining body between the pivot axis and the respective retaining portions to move the retaining body in translation between the release position and the retaining position. The actuator assemblies may be arranged at opposite sides of the mount providing space for a power supply mechanism arranged in-between them.

In alternative embodiments, the various actuators may be either electrically or hydraulically operated. The mount, retaining body, actuator assemblies and other components of the novel coupling assembly may be configured differently to those illustrated. The retaining body may be pivotably connected to the mount either directly or indirectly, for example, via a suitable linkage that guides it in translation.

All of the various hydraulic, electrical or other power supply and control functions may be connected to the hydraulic pump 8 or other hydraulic, electrical or mechanical power supply of the work machine 1 and operated by the operator of the work machine 1 responsive to input via the user controls 9. Industrial Applicability

The novel coupling assembly may be used with any suitable work machine and any suitable tool, whether powered or passive. By attaching the actuator assemblies to the first and second regions of the retaining body, the actuators can be arranged towards the sides of the mount to provide more space between them to accommodate a power supply mechanism for supplying power to powered tools. The pivotal attachment of the actuator assemblies in combination with the pivotal and translationally guided connection of the retaining body decouples the actuators from damaging bending moments resulting from torque applied to the retaining portions of the retaining body when coupling or decoupling the tool. External forces are reacted against the rigid mount by the actuator assemblies in combination with the pivot connection which is guided in translation as the retaining body moves between the retaining and release positions.

Many further adaptations are possible within the scope of the claims.

In the claims, reference numerals and characters are provided in parentheses, purely for ease of reference, and are not to be construed as limiting features.

Claims

1. A coupling assembly (30) for releasably mounting a tool (20) on a work machine (1), including:

a mount (31) attachable to a work machine (1) and configured to receive a tool (20) in a mounted position of the tool;

a rigid retaining body (50) movable relative to the mount (31) between a retaining position and a release position and having first and second retaining portions (51, 5 ), the retaining portions (51, 5 ) being configured:

in the retaining position of the retaining body (50), to retain the tool (20) in the mounted position, and

in the release position of the retaining body (50), to release the tool (20) from the mounted position; and

first and second actuator assemblies (60, 60’) operable to move the retaining body (50) between the retaining and release positions,

the first actuator assembly (60) including a first actuator (61), the second actuator assembly (60’) including a second actuator

(6 ); wherein

the retaining body (50) is pivotably connected to the mount (31) at a pivot axis (X2) arranged between the first and second retaining portions (51,

51’),

and is movable in translation relative to the mount (31) along a translation axis (X3) acollinear with the pivot axis (X2) between the retaining and release positions;

and the first actuator assembly (60) is pivotably connected to a first region (53) of the retaining body (50) between the first retaining portion (51) and the pivot axis (X2);

and the second actuator assembly (60’) is pivotably connected to a second region (53’) of the retaining body (50) between the second retaining portion (5 ) and the pivot axis (X2).

2. A coupling assembly (30) according to claim 1, wherein the first actuator assembly (60) includes a first rigid connector (62), and

the second actuator assembly (60’) includes a second rigid connector (62’);

the first rigid connector (62) being pivotably connected to the first actuator (61), and pivotably connected to the first region (53) of the retaining body (50);

the second rigid connector (62’) being pivotably connected to the second actuator (6 ), and pivotably connected to the second region (53’) of the retaining body (50).

3. A coupling assembly (30) according to claim 2, wherein a first coil spring (65) is arranged concentrically around the first rigid connector (62) to urge the first retaining portion (53) of the retaining body (50) towards the retaining position of the retaining body (50), and

a second coil spring (65’) is arranged concentrically around the second rigid connector (62’) to urge the second retaining portion (53’) of the retaining body (50) towards the retaining position of the retaining body (50).

4. A coupling assembly (30) according to claim 1, wherein the first actuator assembly (60) includes a first resilient bias element (65), and the second actuator assembly (60’) includes a second resilient bias element (65’), the first and second resilient bias elements (65, 65’) being arranged to urge respectively the first and second retaining portions (51, 5 ) of the retaining body (50) towards the retaining position of the retaining body (50).

5. A coupling assembly (30) according to claim 1, wherein the first actuator (61) includes a first piston (63) received in a first hydraulic cylinder (64), and the second actuator (6 ) includes a second piston (63’) received in a second hydraulic cylinder (64’);

and further including a hydraulic circuit (80) having a flow equalizing device (82) for controlling a flow of hydraulic fluid (81) to flow simultaneously at an equal flow rate to or from each of the first and second actuators (61, 6 ).

6. A coupling assembly (30) according to claim 1, wherein the first actuator (61) includes a first piston (63) received in a first hydraulic cylinder (64), and the second actuator (6 ) includes a second piston (63’) received in a second hydraulic cylinder (64’), the first and second pistons (63,

63’) being pivotably connected, respectively to the first and second regions (53, 53’) of the retaining body (50) via respective, first and second linkages (62, 62’), the first and second hydraulic cylinders (64, 64’) being mounted in fixed relation to the mount (31).

7. A coupling assembly (30) according to claim 1, wherein the first and second actuator assemblies (60, 60’) are arranged respectively at first and second sides of the mount (31), and a power supply mechanism (70) for supplying power to the tool (20) is arranged on the mount (31) between the first and second actuator assemblies (60, 60’).

8. A coupling assembly (30) according to claim 1, wherein the pivot axis (X2) is fixed relative to the retaining body (50) and movable in translation relative to the mount (31) along the translation axis (X3) by movement of the retaining body (50) between the retaining and release positions.

9. A coupling assembly (30) according to claim 8, wherein the pivot axis (X2) is defined by an axle (52) slidably guided for translation between guide surfaces (43) of the mount (31).

10. A coupling assembly (30) according to claim 9, wherein the guide surfaces (43) are defined by slots (42) formed in opposed portions (38, 39) of the mount (31), the retaining body (50) being slidably received between the opposed portions (38, 39) of the mount (31).