WO1993002010A1

WO1993002010A1 - Grapple lifting implement

Info

Publication number: WO1993002010A1
Application number: PCT/AU1992/000351
Authority: WO
Inventors: Geoffrey Wilfred Lucas
Original assignee: Geoffrey Wilfred Lucas
Priority date: 1991-07-19
Filing date: 1992-07-15
Publication date: 1993-02-04

Abstract

The invention relates to a lifting implement incorporating a grapple device adapted to be mounted on a self-propelled lifting device and operable to pick up and hold loads such as logs, stumps, rocks, pipes, hay bales, wool bales and other bulk material for carrying and placement as required. The grapple device consisting of an upper jaw member (10) and a lower jaw member (8) pivotally connected in a linkage system (16-23) is wholly mechanical in operation and does not require separate controls for the operation of the jaw members (8, 10). The device is operable when the lower jaw member (8) is engageable under a load and when lifted the downwardly applied weight on the lower jaw member (8) causes the upper jaw member (10), through the operation of the linkage system (16, 23), to close onto the load which is then securely held between the jaw members (8, 10) and may be lifted through the load lifting linkage of the lifting device. A manually operated release mechanism (27-30) is also provided.

Description

GRAPPLE LIFTING IMPLEMENT Field of the Invention

THIS INVENTION relates to a lifting implement incorporating a grapple device adapted to be mounted on the three point linkage of a tractor or like machine and operable to pick up and hold non-fragile items such as logs, stumps, rocks, pipes, hay bales, wool bales and other bulk material for carrying and placement as required.

Whilst the implement of the present invention is primarily designed for fitment to the three point hydraulic linkage of a tractor, it could also be attached to and operable from other self propelled lifting devices such as forklifts, bobcats and front end loaders.

Background of the Invention

Grapple devices are known for attachment to tractors but such known devices comprise hydraulically operated grapple members requiring individual control means and subject to damage in use of the hydraulic mechanisms and the hydraulic fluid supply lines.

It is an object of the present invention to provide a grapple-type lifting implement which is wholly mechanical in operation and operable directly through a load-lifting linkage system of a self-propelled lifting device such as the three point linkage of a tractor, without the necessity of separate controls for the operation of the grapple jaw members.

It is also an object of the present invention to provide manually operable release means to disengage the grapple jaws to allow an item being carried to be dropped or released therefrom at a desired location. Summary of the Invention In accordance with the invention there is provided a lifting implement incorporating a grapple device comprising a jib pole member having means at one end thereof for pivotal attachment to a load-lifting linkage system of a self-propelled lifting device and upper and lower grapple jaw members pivotally mounted on each other at the other end of the jib pole member and connected through a linkage system actuable on a load being engaged by the lower grapple jaw member to bring the upper grapple jaw member downwards to firmly engage with and hold the load between the grapple jaw members. The lower jaw member is pivotally mounted on said other end of the jib pole member and the linkage system is connected between the lower jaw member, the upper jaw member and the jib pole member.

In accordance with a further aspect of the invention there is provided a manually operable jaw release mechanism pivotally mounted between the jib pole member and the upper grapple jaw member and operable to actuate said linkage system to open said upper and lower jaw members and allow a load to be dropped or released therefrom.

In order that the invention and its manner of performance may be more fully understood reference will now be made to an embodiment of the invention as illustrated in the accompanying drawings wherein:- Description of the Drawings

Figure 1 is a perspective view of the lifting implement with a load being engaged therewith; Figure 2 is a perspective view of the lifting implement with the load lifted and securely engaged between the implement jaw members; Figure 3 is a view similar to Figure 2 and illustrating hidden parts in broken line;

Figure 4 is a side elevation after operation of the overcentre toggle trip mechanism;

Figure 5 is a side elevation of the jaws in the drop position after operation of the overcentre toggle trip mechanism;

Figure 6 is a perspective view of the connection of the jaw members; and Figure 7 is a cross-sectional view taken along the line 7-7 of Figure 6. Description of the Preferred Embodiments

Referring to the drawings the lifting implement of the embodiment illustrated comprises a jib pole member 5 for attachment at one end thereof to a load-lifting linkage system of a self-propelled lifting device. It will be appreciated that the attachment of the jib pole member 5 may be to the 3-point hydraulic linkage of a tractor or may be adapted through suitable linkage members for attachment to other self propelled lifting devices such as forklifts, bobcats, front end loaders and the like. At the other end of the jib pole member 5 a lower jaw member 8 is hingedly attached by pivot pin 7 through cheek plates 9 of said lower jaw member 8 and an upper jaw member 10 is pivotally mounted on lower jaw member 8 through pivot pin 11 located between cheek plates 9 of the lower jaw member and extending through cheek plates 12 of the upper jaw member 10. Upper jaw member 10 is bifurcated at 13 at its outer end for engagement over lower jaw member 8 in a closed or near closed position of the jaw members 8 and 10 and is preferably serrated at 14 to enhance the gripping effect on a load to be engaged between the jaws. A handle 15 is attached to upper jaw member 10 for the purpose of manual release of the jaws. At the pivotal end of upper jaw member 10 there is located a tubular member 16 housing a compression spring 17 engageable by a pin 18 pivotally attached between link members 19 extending downwards for pivotal attachment at 20 on cheek plates 9 of lower jaw member 8. Compression spring 17 and link members 19 act as an overcentre spring linkage operable to hold the jaw members in the open position against gravity forces acting on the feaeer jaw member.^*?. Tubular member 16 is preferably provided with lugs 6 to provide an enlarged bearing area for pin 18 in slots 21 of tubular member 16.

In order to operate the lifting implement to drop or release a load there is provided a manually operable trip mechanism consisting of a screw threaded extensibly adjustable bar member 22 pivotally attached at one end by pin 23 between the lower ends of cheek plates 12 of upper jaw member 10. At its other end bar member 22 is hingedly attached to pivot pin 32 on one end of an' ovoEGcntre toggle 24 pivotally mounted at its other end on pedestal member 25 secured to jib pole member 5. Bar member 22 has a longitudinally extending flange member 26 which is latched in locked position by a flange member 29 extending from and secured at a substantially right angle to a rod member 27 pivotally mounted on a pedestal member 30 on the jib pole member and engageable above and against flange member 26. Attached to the other end of rod member 27 is a rope or the like 28 which, when pulled, releases flange member 29 from its latching engagement on flange member 26 and trips the ovei-ceBtte toggle 24 which swings over in a forward direction with attached bar member 22 under the weight of the load and the jaw members to allow the jaw members to swing down and move apart and drop or release a load held therebetween. In order to reset the grapple device in readiness to engage another load the lower jaw member 8 is engaged with the ground or some other base structure and then moved in the reverse direction to the operation of the grapple device whereby actuation of the linkage system connecting the jaw members moves bar member 22 with toggle member 24 into its latching locked position beneath flange member 29. In operation of the implement of the invention when a load is engaged by the lower jaw member and then raised, the. movement of the lower jaw brings the upper jaw downwards at a ratio of 3:1 of movement of the lower jaw by reason of the linkage system between the jaws and the location of pivots 11, 23, 32 and 7, thereof whereby pivot 11 rotates around pivot 7 with pivot 23 being restrained by adjustable bar member 22 at pivot 32 causing rotation of upper jaw 10 to grasp a load between it and lower jaw 8. Whilst the overcentre spring mechanism 16, 17, 18, 19 and 20 prevents gravity forces from closing the jaw members 8 and 10, and load on the lower jaw 8 that overcomes the overcentre spring mechanism generates by gravity a jaw closure force equal to approximately one half the weight of the load being applied to upper jaw 10 through the mechanical linkage system 7, 23, 22 and 32 thereby applying a compound force on the lower jaw 8 approximately equal to one and one half times the weight of the load being lifted and carried, thus the closure force is directly proportional to the weight of the load to be lifted. This closure or holding force is adequate to hold the load whilst the lifting device is travelling and to allow operations on the load such as chain sawing a log. The grasping action of the jaw members is reversed when the load being carried is placed on the ground or at the point of placement by reason of the lower jaw moving upwards which forces the top jaw away therefrom thereby releasing grasp of the load. In order to prevent excessive opening of the jaw members there may be provided a stop member 31. Bar member 22 being longitudinally adjustable allows for adjustment of the attitude of the lower jaw member 8 to meet varying heights of operation of the implement in lifting a load from ground level or an elevated location thereabove such as the tray of a truck whereby lower jaw member 8 is positioned in a horizontal attitude when engaging the object to be lifted. Jib pole member 5 may be formed, in known manner, so as to be extensible to allow access of the grapple device to locations beyond the normal reach of the implement and retractable for lifting heavy loads.

Claims

CJLΔIMS .

1. A lifting implement incorporating a grapple device comprising a jib pole member having means at one end thereof for pivotal attachment to a load-lifting linkage system of a self-propelled lifting device and upper and lower grapple jaw members pivotally mounted on each other at the other end of the jib pole member and connected through a linkage system actuable on a load being engaged by the lower grapple jaw member to bring the upper grapple jaw member downwards to firmly engage with and hold the load between the grapple jaw members.

2. A lifting implement according to Claim 1 wherein the lower jaw member is pivotally mounted on said other end of the jib pole member and the linkage system is connected between the lower jaw member, the upper jaw member and the jib pole member.

3. A lifting implement according to Claim 1 or Claim 2 wherein the upper and lower jaw members are formed with spaced apart cheek plates in the region of their pivotal connection and the cheek plates of the upper jaw member are located within the cheek plates of the lower jaw member and wherein a pivot pin extends through the cheek plates of the upper and lower jaw members.

4. A lifting implement according to Claim 3 wherein there is provided a spring- controlled linkage for holding the jaw members open against gravity forces acting on the'inwcj jaw memberscomprising a pair of link members pivotally mounted at their lower ends on the outer side of the lower jaw member cheek plates, a compression spring member located in a tubular member mounted on and between the cheek plates of the upper jaw member, the tubular member having diametrically opposed slots in the upper end thereof housing a pin member secured between the upper ends of said pair of link members and engaging against said spring member in said tubular member.

5. A lifting implement according to any one of Claims 1 to 4 wherein the upper jaw member is bifurcated at its outer end for engagement over lower jaw member in a closed or near closed position of the jaw members.

6. A lifting implement according to any one of the preceding Claims and including a manually operable jaw release mechanism pivotally mounted between the jib pole member and the upper jaw member and operable to actuate said linkage system to open said upper and lower jaw members and allow a load to be released therefrom.

7. A lifting implement according to Claim 6 wherein said manually operable jaw release mechanism comprises a bar member pivotally attached at one end between the lower ends of the cheek plates of the upper jaw member and at its other end to one end of ajϊ oyercentre- toggle member pivotally mounted on the jib pole member and locked in position thereon by a trip mechanism.

8. A lifting implement according to Claim 7 wherein the other end of said toggle member is pivotally mounted on a pedestal member on the jib pole member.

9. A lifting implement according to Claim 7 or Claim 8 wherein said trip mechanism comprises a rod member pivotally mounted on a pedestal member at one end thereof and engaging the end of said bar member pivotally connected to said toggle member in the locked position and whereby actuation of said rod member releases its engagement with the end of said bar member and trips the overcentre . toggle member to allow movement of the bar member to actuate said linkage system and cause the jaw members to swing down and move apart so as to release a load held therebetween.

10. A lifting implement according to Claim 9 wherein an angularly located flange on said rod member engages over a longitudinally extending flange on the bar member whereby lifting of the other end of said rod member as by a rope or the like connected thereto actuates the trip mechanism.

11. A lifting implement according to any one of Claims 7 to 10 wherein said jaw release bar member comprises two screw threaded parts to provide adjustment of the length thereof so as to maintain a horizontal attitude of the lower jaw member at varying operating heights above ground level.

12. A lifting implement according to any one of Claims 7 to 10 wherein the linkage system incorporates the pivotal connection of the jib pole member to the lower jaw member, the pivotal connection of the jaw members and the pivotal connections at each end of the bar member.

13. A lifting implement according to any one of the preceding Claims wherein the jib pole member is extendible lengthwise to allow access of the grapple device to locations beyond the normal reach of the implement and may abe decreased lengthwise for lifting heavy loads.