AU723305B1 - Adaptor hitch with locking pin - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicants: BARRY KOSTER and BRENDA KOSTER Actual Inventor: BARRY KOSTER Address for Service: Invention Title: CULLEN CO., Patent Trade Mark Attorneys, 239 George Street, Brisbane, QId. 4000, Australia.

ADAPTOR HITCH WITH LOCKING PIN The following statement is a full description of this invention, including the best method of performing it known to us: THIS INVENTION relates to adaptors for connecting or attaching implements and other tools to the end of operating arms, such as adaptors of the "quickhitch" type.

In particular, the invention is directed to a locking pin mechanism for such adaptors, to lock the implements or tools in engagement with the adaptor.

BACKGROUND ART Adaptors are used on the end of operating arms and booms of hydraulic excavators, backhoes and other earthmoving machinery to permit quick and interchangeable attachment of ground engaging tools and other implements to such arms and booms. One such adaptor, known as the "quickhitch" adaptor, comprises two sets of caliper-like latch arms which are inserted between spaced bars or bucket pins on the implement, and then opened outwardly to hook onto the bars or pins and hold the implement.

Typically, one set of latch arms is operated hydraulically. To date, the principal disadvantage of such quickhitch adaptors has been the lack of a true failsafe locking system.

Known adaptors use a simple pin which is manually inserted to lock the moveable set of latch arms in position. However, such pins must be manually inserted and removed by the operator in a tedious, and potentially dangerous, operation.

It is also known to use a hydraulic ram mounted externally to the adaptor frame for inserting a locking pin. However, it has been found that such external rams are knocked off the adaptor or otherwise damaged on a regular basis as they are exposed to impact during operation of the implements.

It is an object of the present invention to provide an improved locking pin mechanism for a hitchtype adaptor.

SUMMARY OF THE INVENTION In one broad form, this invention provides an adaptor of the type used to connect implements interchangeably to the end of an operating boom or arm, the adaptor having at least one latch arm assembly moveable between a first position at which the implement is releasable from the adaptor, and a second position at which the implement is held onto the adaptor, and a locking pin mechanism having a remote controlled pin member adapted to mechanically lock the latch arm assembly in its second position, the locking pin mechanism being located substantially within the adaptor in use.

Typically, the locking pin mechanism comprises a hydraulic cylinder controlled by an operator in the host machine. The pin member is the piston of the hydraulic cylinder, or is connected to the piston of the hydraulic cylinder. The pin member is insertible behind the latch arm assembly when it is in its second position, to lock the latch arm assembly in that position.

The locking pin mechanism is located substantially within the adaptor. In the preferred embodiment, the adaptor comprises two side plates, and the hydraulic cylinder and pin of the locking pin mechanism are located substantially between the two side plates. In this manner, the locking pin mechanism is protected from damage during normal operation of the implement.

In the preferred embodiment, the locking pin engages in an aperture in a side plate. Advantageously, a third plate is provided, intermediate the hydraulic cylinder and the side plate containing the aperture, so that when the locking pin is extended into the aperture, it extends between the third plate and the side plate. In this manner, the pin is placed in double shear, and provides additional resistance to retraction of the latch 'rm assembly.

Preferably, a spring is provided in the hydraulic cylinder to bias the pin towards its extended (engaged)position. In the event of hydraulic failure, the pin will remain engaged in its locking position, and hydraulic pressure needs to be applied to the pin to retract it, thereby providing failsafe locking.

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view illustrating an adaptor mounted to the end of an excavator arm; Fig. 2 is a perspective view of the working end of the adaptor, showing the mounting of the locking pin mechanism; Fig. 3 is an exploded view of the adaptor of Fig. 2; Fig. 4 is a part-sectional elevation of the adaptor of Fig. 2 with the locking pin disengaged; Fig. 5 is a part-sectional elevation of the adaptor of Fig. 2 with the locking pin engaged; Fig. 6 is a part-sectional plan view of the adaptor of Fig. 1 with the locking pin disengaged; Fig. 7 is a part-sectional plan view of the adaptor of Fig. 2 with the lockingpin engaged; and Fig. 8 is a drawing of the hydraulic circuit for the locking pin mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in Fig. i, an adaptor 10 is mounted to the end of an arm or boom 11, typically an excavator arm or the lifting arms of an earthmoving machine. The adaptor 10 is pivotally connected to the arm 11 by pins inserted through pinholes 12. The adaptor 10 can be pivoted relative to the arm 11 by the operator from the cab or control panel of the host machine.

As shown more clearly in Figs. 2 and 3, the adaptor 10 has two sets of caliper-like latch arms 13, 14 for releasable attachment to an earthworking implement or other tool attachment. One set of latch arms 13 is fixed relative to the adaptor 10, while the other set 14 is pivotable between a retracted position ,and an extended position away from the fixed arms 13. Typically, the fixed latch arms 13 are integrally formed portions of two side plates 16A, 16B of the adaptor. The moveable latch arms 14 are pivotable about a pin 17 extending between the side plates 16A, 16B.

The latch arms 14 are opened and closed by a hydraulic cylinder 15 controllable by the operator in the control cab of the host machine.

The implement or other attachment (not shown) normally has two spaced bars. With the latch arms 14 retracted, the adaptor 10 is maneuvered to insert the latch arms 13, 14 between the two bars, and hook the fixed arms 13 to one of the bars. The hydraulic cylinder 15 is then extended so that the other set of latch arms 14 engages the other bar. In this manner, the implement is firmly grasped by the adaptor To ensure that the latch arms 13, 14 do not disengage from the implement, e.g. in the event of hydraulic failure, a locking pin mechanism is used to mechanically lock the moveable latch arms 14 in their extended position.

The moveable latch arms 14 have a lug 14A with a part-circular notch or recess 14B (Fig. When the latch arms 14 are pivoted to their extended position as shown in Fig. 5, the notch 14B registers with a corresponding circular aperture 18 in side plate 16B.

The locking pin mechanism comprises a hydraulic cylinder 20 which is inserted through an aperture in side plate 16A and is located substantially in the space between side plates 16A and 16B. Typically, the hydraulic cylinder has a 50mm bore, and its piston ram 21 has a stroke. The cylinder is fixed to plate 16A with socket head bolts.

The hydraulic cylinder 20 is aligned with the aperture 18 in the opposed side plate 16B, and the piston ram 21 acts as a locking pin which is pushed into the aperture 18 by hydraulic force exerted on the piston. A spring 22 located within the cylinder 20 prevents retraction of the locking pin in the event of a hydraulic failure.

Typically, a spring-loaded marker pin 23 is provided in the aperture 18. The marker pin 23 is pushed out by the pin 21 when it engages in the socket 18, thereby providing a visual indication that the latch arms are mechanically locked.

Preferably, an additional guide plate 24 is welded in the adaptor frame, between the side plates 16A, 16B. The guide plate 24 has an aperture therein which is aligned with the locking pin 21, and dimensioned to permit the locking pin to pass through the guide plate 24, in a close fit. The guide plate 24 not only provides a guide for the locking pin 21, but more importantly, it (in conjunction with the side plate 16B) provides double shear force on the pin 21 when it is extended. The guide plate 24 also prevents the lug 14A imparting bending forces on the hydraulic cylinder The hydraulic circuit for the locking pin mechanism is shown schematically in Fig. 8. The hydraulic cylinder 20 is controlled by a set of sequence valves 31 which transfer hydraulic fluid from the main hydraulic lines that operate the cylinder 15 and cylinder 20. The valves 30, 31 are arranged to ensure that the locking pin 21 is extended into socket 18 after the latch arms 14 have been extended, and retracted from the socket 18 before the latch arms are retracted.

More specifically, when the switch shown in Fig. 8 is opened, hydraulic oil flows to cylinder causing it to open the latch arms 14. When the latch arms 1 14 are fully opened, the lug 14A clears the opening of waperture 18. Further, after the latch arms 14 have been opened out to their extreme position, pressure builds up in the piston end of cylinder 15, activating the sequence valve 30. This allows oil to flow under pressure to the piston end of the cylinder 20 to drive the locking pin 21 into the aperture 18. Retraction of the latch arms 14 is then prevented mechanically, as the lug 14A abuts against the locking pin 21. Hence, the latch arms cannot be released from the implement unless the locking pin is first withdrawn.

When it is desired to disengage the implement from the adaptor, the switch (Fig. normally provided in the operator's cabin, is closed to cause hydraulic oil to flow under pressure to the rod end of cylinder 20 and retract the safety locking pin, thereby permitting the latch arms to be withdrawn. Pressure builds up in the rod end of cylinder 20, activating the sequence valve 31 and permitting oil to flow under pressure to the rod end of cylinder 15. The cylinder 15 retracts the latch arms 14 to thereby release the implement. In the event of hydraulic failure the spring 22 keeps the pin 21 engaged in aperture 18, and the latch arms cannot disengage from the implement.

The locking pin mechanism of this invention has several advantages, including S The locking pin mechanism is located substantially within the adaptor 10 between the side plates 16A, 16B and thereby protected from damage in use.

The guide plate 24 and side plate 16B provide double shear pin resistance to retraction of the latch arms 14.

The spring-loaded locking pin 21 remains kengaged even in the event of complete hydraulic failure.

7a The foregoing describes only one embodiment of the invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention.

For example, the adaptor need not necessarily be separate from the boom or arm; it can be a part of the boom or arm.

Claims (12)

1. An adaptor of the type used to connect implements interchangeably to the end of an operating boom or arm, the adaptor having at least one latch arm assembly moveable between a first position at which the implement is releasable from the adaptor, and a second position at which the implement is held onto the adaptor, and a locking pin mechanism having a remote controlled pin member adapted to mechanically lock the latch arm assembly in its second position, the locking pin mechanism being located substantially -within the adaptor in use.

2. An adaptor as claimed in claim i, wherein the pin member is moveable between an engaged position at which it mechanically locks the latch arm assembly in its second position and a disengaged position at which it does not obstruct movement of the latch arm assembly back to its first position.

3. An adaptor as claimed in claim 2, wherein the locking pin mechanism includes a hydraulic cylinder for moving the pin member between its engaged and disengaged positions.

4. An adaptor as claimed in claim 3, wherein the pin member is a piston ram, or is connected to a piston ram, of the hydraulic cylinder.

An adaptor as claimed in claim 3 or 4, further comprising a spring associated with the hydraulic cylinder for biasing the pin member to its engaged position.

6. An adaptor as claimed in any one of claims 3 to the adaptor having two spaced side walls, and the hydraulic cylinder being located substantially between the side walls.

7. An adaptor as claimed in claim 6, wherein the pin member engages in one of the side walls when in its engaged position.

8. An adaptor as claimed in claim 7, further comprising an additional plate member having an aperture through which the pin member passes, the plate member being spaced from said one side wall, such that the pin member is placed in double shear between said one side wall and the plate member.

9. An adaptor of the type used to mount implements interchangeably to the end of an operating boom or arm, the adaptor having two spaced side walls, and at least one latch arm adapted to hold an implement to the adaptor, and a remote controlled locking pin assembly adapted to mechanically lock the latch arm in position, characterised in that the locking pin assembly is located substantially between the two side walls.

An adaptor as claimed in claim 9, wherein the locking pin assembly includes a hydraulically-operated spring-loaded locking pin.

11. An adaptor as claimed in claim 9, wherein the locking pin assembly includes a pin member adapted to engage a side wall to lock the latch armin position.

12. A remote-controlled locking pin mechanism for an adaptor of the type used to connect an implement to the end of an operating boom or arm, the locking pin mechanism being substantially as hereinbefore described with reference to the accompanying drawings. DATED this fifteenth day of May 2000 BARRY KOSTER and BRENDA KOSTER By their Patent Attorneys Cullen Co.