WO2002097201A1

WO2002097201A1 - A coupling assembly

Info

Publication number: WO2002097201A1
Application number: PCT/AU2002/000682
Authority: WO
Inventors: Norman John Smith
Original assignee: Ephemere Pty Ltd
Priority date: 2001-05-29
Filing date: 2002-05-29
Publication date: 2002-12-05
Also published as: AUPR533701A0

Abstract

A coupling assembly (10) for detachably attaching an implement having first and second link pins to a hydraulic arm of heavy machinery. The coupling assembly (10) has a first pair of parallel load transmitting plates (13, 14) interconnected by a transverse plate (15) and a second pair of parallel load transmitting plates (20, 21) interconnected by an end plate (36). Each first load transmitting plate (13, 14) has apertures enabling attachment by hinge pins (18, 19) to the hydraulic arm. The coupling assembly (10) has two recesses (22) engagable with the first link pin, a hook assembly (12) having hook members (24, 25) engagable with the second link pin. The assembly (10) also has indicator members (34, 35) which pivot with the hook members (24, 25) and extend through openings (37, 38) of the end plate (36) when the hook members (24, 25) have disengaged the second link pin. The indicator members (34, 35) in this extended position serve as a warning that the second link pin has been disengaged.

Description

A COUPLING ASSEMBLY TECHNICAL FIELD

This invention relates to a coupling assembly for attaching implements to heavy duty machinery. In particular, the invention concerns a coupling assembly having an indicator for indicating when implements are not properly attached to heavy duty machinery.

BACKGROUND ART Heavy duty machinery, such as excavators and backhoes, are used to operate various implements, including excavator buckets, ripping teeth, drills, and hydraulic or pneumatic hammers. Such implements are typically connected to a hydraulic arm of heavy machinery with a pair of link pins that extend through corresponding apertures of the arm and implement. Since most implements are designed to carry out a specific operation, they may need to be exchanged for other types of implements over the course of a day so that the machinery can carry out the range of operations required on an excavation or construction site (ie. excavating soil, breaking up rocks or hard earth, leveling, trench digging, removing earth and rocks).

Disadvantages with using link pins include that implement exchanges must be carried out manually, implement exchanges are time consuming and add to the downtime of the machinery, and exchanges often require the assistance of a second operator. In order to overcome these disadvantages, coupling assemblies, often referred to as "quick hitches", have been proposed. Quick hitch coupling assemblies typically have a pair of load transmitting plates with apertures through which hinge pins can extend to fit the assembly to an end of a hydraulic arm. Such assemblies further include means for detachably engaging a pair of link pins of the implement. In general, an assembly of this type has one or more recesses which are fixed and engage a first link pin, as well as one or more hooks for engaging a second link pin, and the hooks are movable between a pin-engaging position and a pin-release position. Quick hitch coupling assemblies may be operated manually or hydraulically. An advantage of the hydraulic assemblies is that an implement can be engaged automatically by activation of a hydraulic cylinder. Typically, the hydraulic coupling assembly is powered by the hydraulic system of the machinery to which the assembly is coupled.

Although quick hitch coupling assemblies may enable implements to be exchanged quickly and efficiently, in practice they have been known to fail and to result in inadvertent detachment of the implement. This has resulted in death or serious injury to workers. The detachment of a hydraulic coupling assembly can occur if there is a drop in hydraulic pressure. To protect against such a pressure drop, hydraulic lock valves and/or control valves may be built into the hydraulic circuit of the coupling assembly. However, hydraulic coupling assemblies have been known to fail despite such safety measures. Moreover, coupling assemblies and implements are subjected to significant forces and during use hooks have been known to slip, thereby resulting in the implement becoming loose or disengaging the assembly. Manual coupling assemblies also suffer from this problem.

There have been a number of proposals designed to address the problem of inadvertent slippage and disengagement of an implement from a coupling assembly. One proposal has been to modify the design of the hooks that engage the second link pin. This approach may be used with either hydraulic or manual coupling assemblies. Another approach has been to operate a hydraulic coupling assembly at relatively high hydraulic pressures. In practice, however, such systems are still known to fail. As an additional safety measure, it has been proposed to incorporate safety pins into both manual and hydraulic coupling assemblies. The safety pins are typically inserted behind the hooks so as to prevent disengagement of the hooks from the link pin.

Safety pins, when properly inserted, have been shown to be effective in avoiding accidents. However, the use of safety pins relies upon manual intervention; that is, an operator of the machinery must dismount from the cabin of the machinery to withdraw the safety pins prior to implement exchange and reinsert the pins afterwards. This adds to the downtime of the machinery. Some operators, in an attempt to increase productivity, do not engage the safety pins. Still further, the safety pins extend from the body of the coupling assembly, and in use, the pins can be damaged when narrow trenches or the like are being dug. Damage to the safety pins can reduce their effectiveness and may be difficult and time consuming to remove.

It is therefore an object of the present invention to provide a coupling assembly which may at least partially overcome the above disadvantages, or to provide the public with a useful choice. DISCLOSURE OF INVENTION

According to the present invention there is provided a coupling assembly for detachably attaching an implement having first and second link pins to a hydraulic arm of heavy machinery, said assembly comprising: a pair of parallel load transmitting plates interconnected by a transverse plate, each load transmitting plate having apertures enabling attachment by hinge pins to the hydraulic arm; at least one recess engagable with the first link pin; a hook assembly having at least one hook member engagable with the second link pin, wherein the hook member is movable between a pin-engaging position and a pin-release position; and an indicator which indicates when the hook member has moved from the pin-engaging position.

The indicator can be any suitable type of visible and/or audible indicating or warning device known to persons skilled in the art. Preferably, the indicator is of the sort that can be sighted by an operator operating the heavy machinery. More preferably, the indicator comprises at least one indicator member operatively connected to the hook assembly whereby movement of the hook member from the pin-engaging position results in movement of the indicator member to a warning position, in which position the indicator member can be sighted by an operator operating the machinery. The indicator member can be any suitable shape. Preferably, the indicator member has an elongate portion and an end sleeve portion pivotally connected to the hook member. The elongate portion can be, for instance, a pin, a rod or an 1-bolt. Preferably, the coupling assembly comprises a second pair of parallel load transmitting plates interconnected by an end plate, wherein the second pair of plates extends substantially in spaced parallel planes to the first pair of load transmitting plates and in the opposite direction to the first pair of plates.

The hook assembly is preferably pivotally mounted between the second pair of plates and the indicator member is movable between a retracted position substantially within an interior defined by the second pair of plates and the end plate, and the warning position, whereby the elongate portion of the indicator member extends substantially outside of the interior through an aperture of the end plate. Preferably, the hook assembly has two hooks interconnected by a sleeve and the sleeve is pinned for rotation between the second pair of plates.

Preferably, the indicator further has a second indicator member and each indicator member is pivotally connected to a said hook member.

Each hook member can have a lower hooking portion for engaging the second link pin and an upper tab, or pair of tabs, to which, or between which, is pinned the end sleeve portion of each said indicator member. As the hook members pivot between the pin-release and pin-engagement positions, the indicator members pivot between the extended warning position and the retracted position, respectively. The coupling assembly can further have biasing means for biasing each hook member into the pin-engaging position. The biasing means can comprise, for instance, a spring extending about the indicator member between the end sleeve portion and the end plate.

Preferably, the coupling assembly has a further recess engagable with the first link pin, each recess is located at a corresponding end of the plates of the second pair of plates and each recess faces away from the end plate. BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described by way of example with reference to the drawings in which:

Figure 1 is a perspective view of a coupling assembly according to an embodiment of the invention;

Figure 2 is a side elevation view of the assembly of Figure 1 ; Figure 3 is a detailed view of Figure 2;

Figure 4 is a magnified view of part of the assembly shown in Figure 3; and Figure 5 is an exploded view of the assembly shown in Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION In all of the drawings, like reference numerals refer to like parts. The figures show a quick hitch coupling assembly 10 for detachably attaching implements having first and second link pins to a hydraulic arm of heavy machinery. The coupling assembly 10 can, for instance, be used to attach an excavator bucket to an excavator.

The coupling assembly 10 has a first pair of parallel load transmitting plates 13, 14 interconnected by a transverse plate 15, a pair of recesses 22 (only one of which is shown) enabling engagement with the first link pin (not shown), a hook assembly 12 (see Figure 5) having a pair of pivotable hook members 24, 25 for engaging the second link pin (not shown), and a pair of indicator members 34, 35 which indicate when the hook members 24, 25 have disengaged the second link pin.

The first load transmitting plates 13, 14 have opposed pairs of apertures and various bushes 60 through which hinge pins 18, 19 extend so as to attach the coupling assembly 10 to the end of the hydraulic arm.

The coupling assembly 10 has a second pair of parallel load transmitting plates 20, 21 interconnected by an end plate 36. Plates 20, 21 extend substantially in spaced parallel planes to plates 13, 14 and in the opposite direction to plates 13, 14. A recess 22 is located at a corresponding end of each plate 20, 21. The hook assembly 12 is pivotally mounted between the plates 20, 21 adjacent the end plate 36 and is actuated by a hydraulic ram (not shown) that is powered by a hydraulic system of the heavy machinery by means well known in the art. The end plate 36 has a pair of openings 37, 38 that are lined with bushes.

The hook assembly 12 can be more clearly seen in Figure 5. Hook members 24, 25 are interconnected by a sleeve 26. The hook members 24, 25 can pivot about an axle 27 that extends through the sleeve 26 and plates 20, 21. The hook members 24, 25 can pivot between a link pin-engaging position and a pin-release position. In the pin-engaging position a lower portion 24a, 25a of each hook member 24, 25 engages the second link pin. An upper portion 24b, 25b of each hook member 24, 25 has a pair of tabs 28, 29 and each of these tabs 28, 29 has an aperture 30, 31. As seen in Figure 5, apertures 30 and 31 have a common axis. Each indicator member 34, 35 has an elongate portion (ie. an l-bolt) 39,

40 and an end sleeve portion 32, 33. Each of the end sleeve portions 32, 33 is pinned between a respective tab pair 28, 29 with a pin 70 (as seen in Figure 3). With this arrangement, the indicator members 34, 35 not only pivot with the hook members 24, 25, but also pivot relative to the tabs 28, 29. The elongate portions 39, 40 of the indicator members 34, 35 are pivotable between a retracted position substantially within an interior defined by plates 20 and 21 and the end plate 36, and an extended warning position whereby the elongate portions 39, 40 extend substantially outside of the interior through openings 37, 38 of the end plate 36. Figure 3 shows the hook members 24, 25 in the pin-engaging position.

When the hook members 24, 25 pivot in the direction of arrow B towards the pin- release position, the elongate portions 39, 40 extend through openings 37, 38 at an inclined angle.

A coil spring 41 , 42 extends about each elongate portion 39, 40 between the end plate 36 and a shoulder 43, 44 of each end sleeve portion 32, 33. The springs 41 , 42 bias the hook members 24, 25 into the pin-engaging position. In use, when the hook members 24, 25 are moved in the direction of arrow B, the indicator members 34, 35 are moved in direction C and extend through end plate 36 where they are able to be seen by an operator within a cabin of the machinery. When the hook members 24, 25 revert to the pin- engaging position, elongate portions 39, 40 move to the retracted position shown in Figure 3. Springs 41 and 42 assist in maintaining the hook members 24, 25 in the pin-engaging position during use and assist in absorbing impact, thereby minimizing wear and tear on the coupling assembly 10.

The indicator members 34, 35 enable the operator to determine visually from the cabin of the machinery whether the hook members 24, 25 are in the pin- engaging position or pin-release position. This can assist in implement exchange as the operator need not leave the cabin in order to check that the implement is properly engaged. Further, the operator can be alerted if there is any movement of the hook members 24, 25 from the pin-engaging position as the indicator members 34, 35 will move to the extended warning position. The operator can then take immediate action to avoid an accident.

The fact that the operator can readily assess the situation may avoid the need for safety pins as a back up safety feature. However, it will be appreciated that the coupling assembly of the present invention is not limited to an assembly which does not have safety pins or any other safety feature. Further, unlike manually operable safety pins, the indicator of the coupling assembly is not reliant on manual intervention and operates automatically.

It will be appreciated that various changes and modifications may be made to the coupling assembly described herein without departing from the spirit and scope thereof.

Claims

1. A coupling assembly for detachably attaching an implement having first and second link pins to a hydraulic arm of heavy machinery, said assembly comprising: a pair of parallel load transmitting plates interconnected by a transverse plate, each load transmitting plate having apertures enabling attachment by hinge pins to the hydraulic arm; at least one recess engagable with the first link pin; a hook assembly having at least one hook member engagable with the second link pin, wherein the hook member is movable between a pin-engaging position and a pin-release position; and an indicator which indicates when the hook member has moved from the pin-engaging position.

2. The coupling assembly of claim 1 , wherein the indicator comprises at least one indicator member operatively connected to the hook assembly whereby movement of the hook member from the pin-engaging position results in movement of the indicator member to a warning position, in which position the indicator member can be sighted by an operator operating the heavy machinery.

3. The coupling assembly of claim 2, wherein the indicator member has an elongate portion and an end sleeve portion pivotally connected to the hook member.

4. The coupling assembly of claim 3 further comprising a second pair of parallel load transmitting plates interconnected by an end plate, wherein the second pair of plates extends substantially in spaced parallel planes to the first pair of load transmitting plates and in the opposite direction to the first pair of plates.

5. The coupling assembly of claim 4, wherein the hook assembly is pivotally mounted between the second pair of plates and the indicator member is movable between a retracted position substantially within an interior defined by the second pair of plates and the end plate, and the warning position, whereby the elongate portion of the indicator member extends substantially outside of the interior through an aperture of the end plate.

6. The coupling assembly of claim 5, wherein the hook assembly has two hooks interconnected by a sleeve and the sleeve is pinned for rotation between the second pair of plates.

7. The coupling assembly of claim 6, wherein the indicator comprises a second indicator member and each indicator member is pivotally connected to each said hook member.

8. The coupling assembly of claim 7, wherein each hook member has a lower hooking portion for engaging the second link pin and an upper pair of tabs between which is pinned the end sleeve portion of a said indicator member.

9. The coupling assembly of claim 8 further having biasing means for biasing each hook member into the pin-engaging position.

10. The coupling assembly of claim 9, wherein the biasing means comprises a spring extending about the indicator member between the end sleeve portion and the end plate.

11. The coupling assembly of claim 4 further comprising a recess engagable with the first link pin, each recess is located at a corresponding end of the plates of the second pair of plates and each recess faces away from the end plate.