Background of the Invention Many types of stands and hand tools which are adjustable in length comprise at least two telescopically related elongate members that can be selectively locked together at various relative positions. Perhaps the most common way of doing this is by providing a series of holes on both of the elongate members which can be placed into registration and then passing a pin through a pair of registered holes. An alternate mechanism is an eccentric cam which is operated by rotating one element relative to the other to selectively lock and unlock the members to effect a variation in length. Such eccentric cams are often used in the telescopic handles of swimming pool scoops. It is also known to use various clamps to selectively lock and unlock the two elements to allow adjustment in length.

Summary of the Invention It is an object of the present invention to provide an alternate length adjustment mechanism.

It is a further object of the invention to provide a stand or support incorporating such a mechanism.

According to a first aspect of the present invention there is provided a length adjustment mechanism including at least: an elongate member provided along its length with a plurality of spaced apart stops; guide means through which the elongate member can slide in the direction of its length;

locking means rotationally coupled to said guide means through which said elongate member can axially slide said locking means having first and second opposite axial ends and means located at said first axial end for engaging a selected stop by rotation of said locking means relative to said guide means member in the space between said selected stop and an adjacent stop to lock the elongate member against sliding through the guide means to allow adjustment of the length of the elongate member extending beyond the guide means.

Preferably said locking means includes a sleeve provided with a transversely extending wall at said first axial end, said transversely extending wall having an opening through which said elongate member passes, said opening of a configuration complementary to a transverse section of one of said stops.

Preferably said means for engaging includes one or more recesses or channels for receiving said selected stop, each of said one or more recesses or channels disposed on said transversely extending wall and having opposite side walls that prevent rotation of the elongate member relative to said locking means while the selected stop is received in said one or more recesses or channels.

Preferably each stop includes a plurality of protrusions equally spaced around the length of the elongate member.

Preferably said guide means is formed with a passageway having a transverse configuration complementary to said transverse section, to prevent rotation of the elongate member within said guide means.

According to another aspect of the present invention there is provided a stand for supporting the load, the stand comprising a hollow tubular leg and a length adjustment mechanism in accordance with a first aspect of the present invention with said elongate member slideably retained within the hollow tubular leg and said guide means held on an upper end of the hollow tubular leg wherein the elongate member can be extended from the hollow tubular leg and selectively locked at one of a plurality of positions between

adjacent stops to thereby allow adjustment of the length of the stand.

Preferably said elongate member is provided at an end located outside of the hollow tubular leg with a screw threaded portion and the stand includes a head threadingly coupled to the screw thread portion to allow further adjustment in the length of the stand.

Preferably the screw threaded portion and the head are configured to allow adjustment in length in the order of the distance between adjacent stops on the elongate member, whereby in use, coarse adjustment of the length of the stand is obtained by extension of the elongate member from the hollow tubular member and locking the elongate member by operation of the rotatable lock and fine adjustment of the length can be obtained by screwing the head along the length of the screw threaded portion.

Brief Description of the Drawings Embodiments of the present invention will now be described by example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of an elongate member incorporated in the length adjustment mechanism; Figure 2 is a front view of the member shown in Figure 1; Figure 3 is a view of section 3-3 of Figure 1 ; Figure 4 is a view of section 4-4 of Figure 2; Figure 5 is a perspective view of a guide means used in the length adjustment mechanism; Figure 6 is a view of section 6-6 shown in Figure 6; Figure 7 is a perspective view of a rotatable lock incorporated in the length

adjustment mechanism; Figure 8 is a side view of the rotatable lock shown in Figure 7; Figure 9 is a view of section AA shown in Figure 8; Figure 10 is a front view of the rotatable lock shown in Figure 7; Figure 11 is a schematic representation of a stand incorporating an embodiment of the length adjustment mechanism; Figures 12,13 & 14 illustrate components of a head that can be incorporated into the stand depicted in Figure 11.

Detailed Description of the Preferred Embodiments Referring to the accompanying drawings, and in particular to Figure 11, the length adjustment mechanism 10 includes an elongate member 12, a guide 14, and a rotatable lock 16. The elongate member 12 is provided along its length with a plurality of spaced apart stops 18. The guide 14 is configured so that the elongate member 12 can slide through it in a direction of its length, and sits atop a tubular leg or housing 15 in which the member 12 can side. The rotatable lock 16 is formed so that the elongate member 12 can slide through it. However the rotatable lock 16 is also provided with means in the form of recesses or channels 20 (refer Figure 7) for engaging a selected stop 18 by rotation of the lock 16 relative to the guide 14 in the space 22 between the selected stop and an adjacent stop, to lock the elongate member 12 against sliding through the guide 14. This thereby allows adjustment of the length of the elongate member 12 extending beyond the guide 14.

Figures 1-4 illustrate the elongate member 12 in greater detail. An upper portion 24 of the elongate member 12 is of a generally cylindrical form, having a circumferential outer surface 26 about which is formed a screw thread 28. Below the upper portion 24 the elongate member 12 is provided with a plurality the stops 18 which are separated, in the direction of the length of member 12, by spaces 22. Each stop 18 is in the form of four

protrusions, tabs or teeth 30 equally spaced circumferentially about an axis of elongate member 12. The stops 18 have a maximum radial extent equal to or less than that of the upper portion 24. In the embodiment shown, the uppermost stop 18 adjacent the upper portion 24 and lower most stop 18 each have a length greater than the intervening stops 18 however this is not an essential aspect of the invention.

Figure 3 illustrates that the protrusions 30 of each stop 18 form a cross in a plane perpendicular to the length (ie axis) of the elongate member 12. Additionally, it is seen that the protrusions 30 of adjacent stops 18 are aligned so as to form passages or flutes 32 along the length of the elongate member 12 that extend from the lower most end of the elongate member 12 to the upper portion 24.

To strengthen the member 12 a metal rod or bar 33 extends along its longitudinal axis, with one end of rod 33 protruding from the lower end of member 12 to form a short stud 35. An opposite end of the bar 33 stops short of the upper end of the member 12. A stop 37 (refer to Figure 11) is attached to the lower end of the member 12 by a screw (not shown) screwing into a threaded hole formed in the stud 35. The stop 37 is in the form of a squat cylinder 39 having a depending spring 41. The cylinder 39 is unable to pass through the guide 14 and thus stops the member 12 from being fully pulled out of the leg 15. The spring 41 bears against the inner circumferential wall of the leg 15 to limit sideways or slopping motion.

Figures 5 and 6 illustrate in detail, the guide 14. The guide 14 is in the general form of a hollow cylinder 34 having an upper end 36 with an internal shape complimentary to a transverse section of the elongate member 12 taken through one of the stops 18 (as shown in Figure 3). More particularly the upper end 36 is formed with an axially extending internal core 38 having a passageway 43 with a transverse section in the configuration of a cross. This ensures that the member 12 can not rotate in the guide 14. A portion 40 of the guide 14 below the core 38 is formed with an increase internal diameter. The internal junction of core 38 and portion 40 forms an internal shoulder 45 in the guide 14.

Figures 7-10 illustrate the rotatable lock 16. The rotatable lock 16 is in the form of a

sleeve having a cylindrical body 42 which is open at its lower axial end 44 and has a wall 46 extending transversely across its upper axial end 47. The wall 46 is formed with a cross-shaped opening 48 that can register with the passageway 43 in guide 14. The recesses or channels 20 are formed on and spaced about the wall 46. Each recess or channel 20 comprises a pair of spaced apart parallel walls 52 extending radially along an upper surface of wall 46.. The recesses 20 are located about wall 46 so that each recess 20 can engage or receive a respective protrusion 30 of a selected stop 18.

A pair of spring clips 55 is formed at the lower end 44 for engaging a lower end of the guide 14. The spring clips 55 are formed integrally with the rotatable lock 16 by making pairs of parallel and closely spaced cuts 56 in the body 42 thereby leaving or creating arms 58. Each arm 58 will have a natural spring action when the material used to the manufacture of the rotatable lock 16 is resilient. In this regard, typically the lock 16 (together with the guide 14 and the elongate member 12) is made from a plastics material such as glass filled nylon. A half arrow head projection 60 is formed on the inside of each arm 58 adjacent the lower end 44.

As schematically represented in Figure 11, the guide 14 fits inside the rotatable lock 16 with the spring clips 55 acting to retain the guide 14 within the rotatable lock 16. Figure 11 further illustrates a stand 62 that incorporates the length adjustment mechanism 10. In broad terms the stand 62 includes a base 66 and a head 68 disposed at respective opposite ends to the elongate member 12. More particularly the leg 15 is provided with a flared outer circumferential flange 69 near its lower end for abutment with an outer peripheral surface 71 of conically shaped base 66 into which the leg 15 is press fit. The flange 69 limits the depth of insertion of the leg 15 into the base 66.

The head 68 is threadingly engages the thread 28 on upper portion 24 of the elongate member 12. While the head 68 can be made as a single unit, it is advantageously made from several components that are assembled together. These components include a conical base 70 shown in Figure 12, a clip 72 as depicted in Figure 13, and a threaded tube 74 as depicted in Figure 14.

The base 70 is identical to the base 66 used at the lower end of the stand 62 and is provided with a socket 76 extending axially from its apex.. The socket 76 has a short annular outside wall 78 and a central through hole 80.

The tube 74 has an internal thread 79 for engaging the thread 28 at the upper end of the member 12. One end of the tube 74 is provided with a reduced diameter portion 82 and closed by a transverse wall 84. A circumferential shoulder 86 is created between the reduced diameter portion 82 and the remaining length of tube 74. The central hole 87 is located in wall 84 in a position so that it can align with the hole 80 in the base 70. To assemble the head 68 the reduced diameter portion 82 is inserted into socket 76 with shoulder 86 resting on the axial end of annular wall 78. The clip 72 is then inserted into the hole 80 from a side opposite the base 70. A spring biased barb 88 on the clip 72 passes through the hole 80 and the hole 87 in the wall 84 of the tube 74 lock the tube 74 to the base 70. In this manner, the tube 74 is able to rotate about its axis relative to the base 70.

Thus, when adjusting the height of the stand 62, the tube 74 can be turned or screwed up and down along the thread 28 on the member 12 without any rotation of the base part 70 of the head 68. Although not shown, a removable rubber sheet or disc can be clipped to the large diameter ends of the base 66 and head 68 to protect the surfaces between which the stand 62 acts, and also to provide slip resistance to the stand 62.

The operational range or height of the stand 62 can be increased by use of a separate extension piece (not shown) that screws onto the thread 28 and is itself provided with an outer thread that can screw into the tube 74. Extensions of different lengths can be provided.

The guide 14 can be held at the top of the leg 15 by an interference fit with the guide 14 resting on internal shoulder 45. If desired however a mechanical fastener such as a rivet can be used to fix the guide 14 in place. Alternately the guide 14 can be formed integrally with the leg 15. This is particularly convenient when the leg 15 and guide 14 are made from plastics materials.

The operation of the stand 62 will now be described.

Assume that the rotatable lock 16 is in a position so that its opening 48 is in alignment with passageway 43 of the guide 14. In its position the elongate member 12 can be pulled upwardly so as to slide through the passageway 43 and opening 48 to a desired extension.

To then lock the elongate member 12, the rotatable lock 16 is rotated through 45O so that respective recesses 50 underlie the protrusions or tabs 30 of the upwardly nearest stop 18.

The rotation of the rotatable lock 16 is allowed or provided for by virtue of the space 22 between that particular stop 18 and the immediately underlying stop 18, through which the wall 46 can pass. The space 22 is of a sufficient height to allow the walls 52 to pass between the adjacent stops 18. The elongate member 12 is then released and drops a short distance (slightly longer than the height of walls 52) so that the protrusions 30 are received in the respective underlying recesses 50 and sit on wall 46. Because the opening 48 and passageway 43 are now out of alignment, the elongate member 12 cannot fall further down back into the leg 15 or be pulled further out of leg 15 beyond the small distance between adjacent stops 18 less the thickness of wall 46. Also because the stops 18 are seated in recesses, the lock cannot be rotated to place the opening 48 and passage 43 into alignment without also simultaneously physically lifting the stops 18 out of the recesses, thus avoiding accidental retraction of the mechanism 10. For fine adjustment of the height of the stand 64 the head 68 can be screwed either upwardly or downwardly as required along the thread 28 on the upper portion 24.

If the length of extension of the mechanism 10 or stand 62 requires to be varied again, the elongate member 12 is pulled up a short distance so as to lift the protrusions 30 out of the recesses 50 and the rotatable lock 16 turned by 45O so that its opening 48 is again in alignment with the passageway 43 of the guide 14. Now the elongate member 12 can be slide up or down as required and then locked in place by rotating the rotatable lock 16 by 45O again in the manner described above.

From the above description, it can be seen how the mechanism 10 provides a simple and efficient means for length adjustment without the use of pins, clamps or other type of fasteners. The mechanism 10 can be incorporated into a stand 62 but also has much wider

application and can be used in any number of tools, implements or devices where length extension is required.

From the above description it will also be apparent that numerous modifications and variations can be made without departing from the basic inventive concepts. For example, each stop 18 is shown as comprising four tabs 30 that are equally spaced about the length of the elongate member 12. However different numbers of protrusions 30 can be used.

Also, the rotatable lock 16 can take numerous different forms. For example, instead of being in the form of a cylinder as shown in the present embodiment, it could be in the form of a disc that is rotatably coupled to the guide 14. These and all further modifications and variations as would be apparent to a person of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the above description and the appended claims.