Background to the Invention A need exists for extracting items from substrates. For example, to remove fence posts or droppers a high force is required to be exerted on the dropper to effect removal of the fence post from a substrate such as the ground. Particularly in respect of posts that have been in the ground for a long time, the posts are bedded in and a high force is required to effect initial displacement of the post relative to the ground. The same applies in respect of other items which need to be removed from a substrate such as tent pegs, or the like.

Summary of the Invention According to the invention, there is provided an extraction device which includes an elongate element defining a toothed rack; a housing displaceably arranged on the elongate element, the housing defining receiving formations for receiving an engaging means, the engaging means engaging the item to be extracted in use; a lever assembly supported by the housing, the lever assembly defining a pair of clamping levers displaceably arranged relatively to each other; and a displacement means displaceably supported on the housing for effecting movement of the levers of the lever assembly along the toothed rack of the elongate element.

The device may include a base member. The elongate element may be releasably secured, via a first end of the elongate element, to the base member for enabling the elongate element to be used on base members of various shapes and dimensions. The base member may be in the form of a base plate having a spigot-like formation extending from the base plate. The elongate element may have, at the first end, a socket defining element which fits over the spigot-like formation.

An opposed end of the elongate element may carry an end cap. The end cap may include a retaining means for retaining the displacement means in an inoperative position for storage and transportation purposes.

The displacement means may be in the form of an operating arm which is pivotally mounted on the housing.

The lever assembly may include a mounting formation which is pivotally mounted relative to the housing, the operating arm being mounted on the mounting formation. The mounting formation may include a bush in which a handle of the operating arm is received and a mounting flange projecting from an end the bush.

A first lever of the lever assembly may be pivotally carried proximate a free end of the mounting formation. The first lever may be journalled with respect to said free end via a journal. A passage may be defined through the journal for receiving a pivot pin via which the operating arm is pivotally mounted to the housing. A second lever of the lever assembly may be pivotally mounted to the mounting formation on a web portion in line with the bush.

The first lever and the second lever may be resiliently connected together by a resiliently flexible connecting member. The resiliently flexible connecting member may be in the form of a coil spring.

The lever assembly may include a control means for variably controlling a distance between the levers. The control means may include a latch. The latch may be accommodated in a holder mounted to the housing.

The latch may engage the second lever such that, when the housing is at an operatively lower end of the elongate element to commence extraction of an item, an initial upstroke of the operating arm ensures that only one tooth of displacement is effected by the second lever so that maximum mechanical advantage is achieved.

The control means may include a release means which, after the first upstroke, is engaged by a part of the lever assembly to release the latch from the second lever and to displace the latch into a retracted position out of engagement with the second lever. When the latch has released the second lever, on each upstroke of the operating arm, a plurality of teeth of the rack may be traversed by the second, lower lever on each upstroke, after the first upstroke, of the operating arm.

Further, the arrangement of the levers is such that, on an upstroke of the operating arm, the second, lower lever may traverse the teeth while, on a downstroke of the operating arm, the first, upper lever traverses the teeth.

In addition, when the operating arm is brought into a position lying parallel with the elongate element, both levers may be released from the teeth of the toothed rack enabling the operating arm to be moved to a lower, start position on the elongate element. With this motion, the latch is re-engaged with the lower lever.

The control means may include a keep for retaining the latch in its retracted position, ie. out of engagement with the second lever.

Brief Description of the Drawings The invention is now described by way of example with reference to the accompanying drawings in which:- Figure 1 shows a three dimensional view of an extraction device, in accordance with the invention; Figure 2 shows a three dimensional view of a part of a first embodiment of the device of Figure 1; Figure 3 shows a three dimensional view of the first embodiment of the part of the device shown in Figure 2 including a control means; Figure 4a shows a schematic representation of the control means in a first position; Figure 4b shows a schematic representation of the control means in a second position; Figure 5 shows a three dimensional view of a part of a second embodiment of the device; and Figure 6 shows a three dimensional view of the second embodiment of the part of the device shown in Figure 5.

Detailed Description of the Drawings In the drawings, reference numeral 10 generally designates an extraction device, in accordance with the invention. The device 10 includes an elongate element in the form of a toothed rack 12 having a stiffening portion 14 and a spine portion 16 defining a plurality of teeth 18.

The rack 12 is releasably mounted on a base member or base plate 20 via a spigot-like formation (not shown) protruding from the base plate 20.

The spigot-like formation is removably received in a socket defining element 22 of the rack 12. The rack 12 is secured to the base plate 20 via an'R'pin 24.

A housing 26 is displaceably arranged on the rack 12. The housing 26 defines a pair of bosses 28 on which an engaging means (not shown) is securable. The device 10 is intended for use in extracting elements such as wooden stakes, metal pins, posts and pegs from the ground. Accordingly, various engaging means may be removably secured to the housing 26, via the bosses 28, to facilitate extraction of various shapes and types of elements.

Also, with this arrangement an engaging means which has an engaging function, for engaging the element to be extracted, arranged at ground level can be carried on the housing 26.

The housing 26 houses a lever assembly 30 (Figures 2 and 3). The lever assembly 30 comprises a first, pivoting lever 32 and a second, swinging lever 34. Each lever 32 and 34 is shaped to mesh with the teeth 18 of the rack 12.

Further, a displacement means in the form of an operating arm 36 is pivotally secured to the housing 26. The operating arm 36 comprises an arm member 38 which is removably received in a mounting formation or bush 40.

The bush 40 has a mounting flange 42 extending from an end opposite the end of the bush 40 in which the arm member 38 of the operating arm 36 is received. The mounting flange 42 has a transversely extending foot portion 42.1 which is pivotally secured to the housing 26 via a pivot pin 44. The pivot pin 44 is removable for enabling the operating arm 36 to be removed from the housing 26. The pivot pin 44 also defines a pivot axis for the first lever 32.

It is to be noted, in Figure 1 of the drawings, that an operatively upper end of the rack 12 has an end cap 45 which supports a retaining clip 46. The clip 46 engages the operating arm 36 and, more specifically, a handle portion 48 to retain the operating arm 36 in substantially parallel relationship to the rack 12 for transportation and/or storage purposes.

The first lever or pawl 32 is pivotally secured via a journal 50 to the foot portion 42.1 of the mounting flange 42, proximate a free end of the foot portion 42.1 of the mounting flange 42. The journal 50 defines a passage 52 through it through which the pivot pin 44 is receivable.

The second, swinging lever 34 is also pivotally secured, via a pivot pin 54, to the mounting flange 42. The levers 32 and 34 are resiliently secured

together via a resiliently flexible element in the form of a coil spring 56. The coil spring 56 is anchored, at its first end, to a pin 58 in the swinging lever 34 and, at an opposed end, to a tail portion 59 which projects from the lever 32.

The tail portion 59 is shown more clearly in Figure 3 of the drawings. Also, as shown more clearly in Figure 3 of the drawings, the swinging lever 34 includes a detent pin 60 which engages the teeth 18 of the rack 14.

The lever assembly 30 includes a control means or mechanism 62 which controls the distance between the levers 32 and 34, as will be described in greater detail below. The control mechanism 62 includes a latch 64 mounted at one end of a carrier 76. The carrier 76 is resiliently biased via a coil spring 66 relative to a holder 68. The latch 64 projects from one side of the holder 68 and a pin 70, which is carried on an opposed end of the carrier 76, projects from an opposed end of the holder 68. In use, the holder 68 is secured to a casing of the housing 26 to allow the latch 64 and the pin 70 to protrude through openings in the casing into the housing 26.

When the latch 64 extends from the holder 68, the latch 64 engages a bearing surface 72 on the swinging lever 34. This limits the amount by which the lever 34 can be displaced relative to the mounting flange 42 of the operating arm 36 towards the lever 32.

In use, when the device 10 is placed in position relative to an element which is to be extracted, the operating arm 36 is raised to its vertical position.

This causes both levers 32 and 34 to be disengaged from the rack 12 and allows the housing 26 to slide to the bottom of the rack 12. As the operating arm 36 is pivoted in the direction of arrow 74 (Fig. 1), the lower, swinging lever 34 engages the rack 12 at the first or bottom tooth 18 of the rack 12.

This is achieved by means of the latch 64 engaging the bearing surface 72 of the swinging lever 34 and, in so doing, inhibiting the degree of displacement of the swinging lever 34 relative to the upper lever 32.

It will be appreciated that, in this orientation, a pivot axis defined by the pivot pin 54, via which the lever 34 is pivotally connected to the operating arm 36, is close to the pivot points about which the levers 32 and 34 pivot relative to those teeth 18 on the rack 12 with which the levers 32 and 34 are then meshing. As a result of this, the mechanical effort which is required to pivot the operating arm 36 in the direction of the arrow 74 is less than would be required if the lever 34 had, initially, engaged one of the higher teeth 18. In other words, greater mechanical advantage is achieved.

When the operating arm 36 pivots further in the direction of the arrow 74, the pivoting lever 32 is displaced upwardly along the teeth 18 of the rack 12. Also, as the mounting flange 42 of the operating arm 36 pivots and approaches the lower limit of its downward stroke, the head of the pivot pin 54 bears against the carrier 76 of the control mechanism 62 causing it to be withdrawn into the holder 68 as shown in Figure 4a of the drawings. This, in turn causes the latch 64 to disengage from the bearing surface 72 of the swinging lever 34 and a slot 69 in the edge of the latch 64 is engaged by a keep 71 in the holder 68 to retain the carrier 76 in the position shown in Figure 4a of the drawings.

Accordingly, on a succeeding upstroke, ie. when the operating arm 36 is moved in a direction opposite to that of arrow 74, the swinging lever 34 is now in a position to be displaced more than one tooth at a time along the rack 12, preferably by about four teeth 18. On the subsequent downstroke of the operating arm 36 the pivoting lever 32 is displaced by a corresponding number of teeth 18.

To collapse the device 10 such that the housing 26 again moves towards the base plate 20, the operating arm 36 is moved to its substantially parallel orientation relative to the rack 12. When this occurs, the foot portion 42.1 of the mounting formation 42 engages the pin 70 which compresses the spring 66 allowing the slot 69 of the latch to be withdrawn out of engagement with the keep 71. This causes the latch 64 to protrude from the holder 68 under the action of the spring 66 as shown in Figure 4b of the drawings. In that position the latch 64 again bears against the bearing surface 72 of the lower lever 34 limiting the travel of the lower lever 34. Moving the operating arm 36 to its position substantially parallel with the rack 12 also causes the levers 32 and 34 to be moved out of meshing engagement with the teeth 18 of the rack 12 to allow the housing 26 to slide towards the base 20.

Referring now to Figures 5 and 6 of the drawings, a second embodiment of the invention is illustrated. With reference to the previous drawings, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment of the invention, the upper lever or pawl 32 is mounted via a gusset plate 80 to the foot portion 42.1 of the mounting flange 42.

The mounting flange 42, in turn, has a spigot portion (not shown) which is received in a socket portion of the arm member 38 of the operating arm 36. A support member 82 of the mounting flange 42 projects upwardly and bears against a front of the arm member 38 of the operating arm 36.

Further, the upper lever 32 includes a lever arm 84. The lever arm 84 is manually operable by a user of the device to disengage the upper lever 32 from the teeth 18 of the rack 14.

In a similar fashion to the swinging lever 34, the upper lever 32, in this embodiment of the invention, engages the teeth 18 by means of a pin 86.

Finally, it is to be noted that the coil spring 56 is anchored to the upper lever 32 by a pin (not shown) with the tail portion 59 of the first embodiment being omitted.

In Figure 5 of the drawings, the holder 68 of the control mechanism 62 is shown partially cut away to indicate the mounting of the carrier 76 within the holder 68.

The operation of the second embodiment of the invention illustrated in Figures 5 and 6 of the drawings is, in all material respects, the same as the operation of the embodiment of the invention described with reference to Figures 1 to 3 of the drawings.

It is a particular advantage of the invention that a control mechanism 62 is provided which, initially, limits displacement of the levers 32 and 34 relative to each other. In so doing, maximum mechanical advantage can be obtained initially in order to commence extraction of the required element. It will be appreciated that, initially, considerable force is required to commence extraction of an element. Thereafter, the housing 26 can be moved up the rack 12, approximately four teeth 18 at a time, to facilitate rapid extraction of the item on which the device 10 is acting. One of skill in the art will appreciate that less leverage or mechanical effort is required once the initial pull on the item to be extracted has been effected.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.