AU682632B2 - Cushioning mechanism - Google Patents

Description

P/00/01 128/5/91 Regulation 3,2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT

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S Name of Applicant: Actual Inventor(s): Address for service is: Invention Title: JAMES CHAD DELIU and MICHAEL DELIU JAMES CHAD DELIU WIRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR "CUSHIONING MECHANISM" Details of Associated Provisional Application No(s): PN4185 The following statement is a full description of this invention, including the best method of performing it known to me:- -2- The present invention relates to a cushioning mechanism for cushioning shocks imparted to a device which is subjected to impart during use.

The cushioning mechanism has been devised particularly, although not solely, for cushioning imparts which are imparted to a digging or other ground working tool such as a spade or shovel, The cushioning mechanism may also have application to various other devices including crutches and walking sticks.

When a shovel is used, it is common for shocks to be imparted through the handle thereof to the user when the shovel impacts with the ground or other material in which the digging operation is being performed. This is particularly so in circumstances where the shovel strikes a hard object such as rock. The shocks imparted to the user can cause discomfort, and in some cases injury, to the user particularly if the user is exposed to such shocks over an extended period of time.

It would be advantageous for a device which is subject to impact loadings to 15 incorporate a mechanism which cushions shocks imparted to it.

The present invention provides a cushioning mechanism comprising first and second members having a normal condition, the first and second members being arranged for reciprocal movement with respect to each other out of said normal condition along an axis, a first bearing portion fixed with respect to the 20 first member, a second bearing portion fixed with i'espect to the second member, and a third bearing portion fixed with respect to the first member and positioned on the opposed side of the second bearing portion with respect to the first bearing portion, a first resilient means operating between the first and second bearing portions, and a second resilient means operating between the second and third bearing portions, whereby the first resilient means yieldingly resists movement of the first and second members out of said normal condition in one direction for cushioning an impacting force generating such movement, and said I ~lls~ -3second resilient means yieldinglys resist return relative movement between the first and second members beyond the normal condition.

With this arrangement, when a device such as a shovel which incorporates such a cushioning mechanism is subjected to a shock loading, the reactionary force transmitted to the device causes inward relative movement between the first and second members. This inward movement is yieldingly resisted by the first resilient means operating between the first and second bearing portions so as to cushion the impact. Following dissipation of the impacting force, the compressed state of the first resilient means provides a spring force which acts between the first and second bearing portions to cause the first and second members to move in the outward direction with respect to each other towards the normal condition. In the likely event that the outward movement of the first and second members continues beyond (and thus overshoots) the normal condition, the second resilient means acting between the second bearing portion and the third bearing portion is caused to undergo compression and in doing so yieldingly resists such overshooting movement.

The first and second resilient means may yieldingly resist movement with substantially the same force or there may be a differential between: the forces.

In regard to the latter, it may be convenient to yieldingly resist inward movement of the first and second members from the normal condition with a larger force than that which yieldingly resists outward movement.

0*0° The first and second resilient means each may comprise a compression spring.

0 9 The first and second members may be telescopically connected to provide for the reciprocal movement with respect to each other.

The first and second members may be of tubular construction.

It may be desirable to prevent relative rotation between the first and second members in which case a suitable means may be provided to prevent such rs7 -rrap -4rotation. One such means may comprise a longitudinal track provided between the first and second members.

The third bearing portion may be slidably supported within the second tubular member and fixed to the first bearing portion for sliding movement therewith relative to the second member.

The third bearing portion may be fixed to the first bearing portion by way of a connecting means such as an axial stem slidably passing through the second bearing portion which is positioned between the first and third bearing portions, The cushioning mechanism may be incorporated in the shank portion of the head of a shovel or in the handle thereof.

The invention also provides a handle for a digging or other ground working tool, said handle incorporating a cushioning mechanism as set forth hereinbefore.

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9999 9 The invention still further provides a device (such as a shovel, a crutch or a walking stick) incorporating a cushioning mechanism as set forth hereinbefore.

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which: Fig. 1 is a perspective view of a shovel incorporating a cushioning mechanism according to the first embodiment; Fig. 2 is a sectional view of the cushioning mechanism fitted into the handle of the shovel shown in Fig. 1, with the cushioning mechanism being shown in a normal condition; o *9 *O 9

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Fig. 3 is a view similar to Fig. 2, except that the cushioning mechanism is shown in a condition in which it has been compressed as a result of an impact loading on the shovel; Fig. 4 is a sectional view of a cushioning mechanism according to a second embodiment; Fig. 5 is a perspective view of one tye of crutch incorporating the cushioning mechanism of the first embodiment; Fig. 6 is a perspective view of a walking stick incorporating the cushioning mechanism of the first embodiment; Fig. 7 is a perspective of another type of crutch incorporating the cushioning mechanism of the first embodiment; Fig. 8 is a perspective view of a shovel of the long-handled type incorporating a cushioning mechanism according to a second oo ooo embodiment; 15 Fig. 9 is a sectional view of part of the cushioning mechanism of Fig. 8; Fig. 10 is a cross-sectional view along the line 10-10 of Fig. 9; and Fig. 11 is a schematic view of a hand grip for the handle of the shovel, the hand grip incorporating a pair of cushioning mechanisms according to a ***third embodiment.

S 20 In Figs. 1 to 3 of the drawings, there is shown a shovel 10 comprising a shovel head 11 and handle 13. The shovel head 11 includes a blade portion 15 and a shank portion 17 which receives one end of the handle 13. The handle 13 incorporates a hand grip 18 at the free end thereof.

I -6- A cushioning mechanism 19 according to the first embodiment is incorporated in the handle 13 at a location towards the shovel head 11 such that any shocks transmitted to the shovel head can be cushioned by the cushioning mechanism 19, thereby retarding such shocks before they are transmitted to a user gripping the handle 13. The cushioning mechanism 19 is positioned in the handle 13 between a lower section 14 thereof and the hand grip 18.

The cushioning mechanism 19 comprises a first member 21 of tubular construction and a second member 22 also of tubular construction telescopically received within the first member. The first and second tubular members 21, 22 are each of circular cross-section. The telescopic arrangement allows the first and second members tubular 21, 22 to reciprocate one with respect to the other along an axis coincident with their respective longitudinal axes.

The cushioning mechanism 19 has a sleeve 25 at one end thereof for receiving a lower section 14 of the handle 13. The lower section 14 of the handle 13 is secured in position within the sleeve 25 by way of suitable fixing means such as securing rivets 29 passing through securing holes 31 formed in the sleeve.

The hand grip 18 is attached to the upper end of the second tubular member 22 in any suitable fashion such as securing rivets 32.

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A bush assembly 33 is provided between the first and second tubular members 20 21, 22 to facilitate sliding movement therebetween. The bush assembly comprises a sleeve 34 formed of material having a low sliding co-efficient of il friction, such as nylon. A seal 35 in the form of an O-ring is positioned at each S end of the sleeve 34. The sleeve 34 and the two seals 35 are accommodated in an expanded portion 36 at the upper end of the first tubular member 21. The t oo expanded portion 36 includes a rolled lip 37 which retains the sleeve 34 and two seals 35 in position at the upper end of the first tubular member 21.

9 Illp I -7- The cushioning mechanism 19 includes a first bearing portion 41, a second bearing portion 42 and a third bearing portion 43.

The first bearing portion 41 is in the form of a first circular plate 45 received within, and fixed with respect to, the first tubular member 21. The plate 45 is of circular construction and is welded in position within the first tubular member 21.

The plate 45 provides a partition which divides the interior of the first tubular member into two opposed sections 47, 49 each of which opens onto a respective one of the ends of the first tubular member. The section 47 provides the sleeve 25 which receives the lower section 14 of the handle 13. The section 49 slidably receives the inner portion of the second tubular member 22.

The second bearing portion 42 comprises a piston assembly 51 mounlted on the inner end of the second tubular member 22. The piston assembly 51 comprises a circular upper plate 53 welded or otherwise fixed within the second tubular member 22 at a location spaced inwardly from the inner end thereof. The piston o:"e assembly 51 further comprises a piston member 55 having a first portion 57 and a second portion 59 contiguous with, but of larger diameter than, the first portion thereby to define a step 60 between the first and second portions. The first portion 57 is received within the space between the plate 53 and the inner end of the second tubular member 22, with the step 60 butting against the end face .oo.

20 of the second tubular member 22 at the inner end thereof. The second portion 59 of the piston member 55 is of marginally larger diameter than the second member 22 and slidably engages the inner wall of the first tubular member 21.

The piston member 55 is formed of a suitable plastics material such as nylon having a low sliding co-efficient of friction. The piston assembly 51 still further comprises a circular lower plate 61 positioned on the exposed face of the piston member The piston assembly 51 is provided with a plurality of holes 52 extending between the opposed end faces 62, 63 thereof to allow air flow through the piston assembly, as will be explained later. The holes 52 extend through the two

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-8circular plates 53 and 61 respectively, and the piston member 55. The piston assembly is also provided with a central aperture 64.

The third bearing portion 43 is in the form of a further piston assembly supported within the second, tubular member 22 for sliding movement with respect thereto. The piston assembly 65 is mounted on an axial stem 67 which is fixed at its lower end 68 to the first plate 45 and which sidably extends through the central aperture 64 formed in the piston assembly 51. The axial stem 67 has an upper section 71 zn-d a lower section 72. The piston assembly 65 is mounted on the upper section 71 of the axial stem 67 so that it moves in unison with the first plate 45 and thus the first tubular member 21.

The piston assembly 65 comprises a piston member 73 formed of material such as nylon having a low co-efficient of friction for sliding engagement with the inner wall of the second tubular member 22. A seal 74 in the form of an O-ring is accommodated in a cirumferential groove formed in the outer periphery of the piston member 73.

The piston member 73 is retained on the upper section 71 of the axial stem 67 by way of a nut 77 in threaded engagement with a male threaded formation 79 on the axial stem. The position of the piston member 73 on the axial stem 67 can be adjusted to a limited extent by movement of the nut 77 along the threaded formation 79 of the axial stem 67, the purpose of which will become apparent later. A lock mechanism 81 is provided to prevent the nut 77 from inadvertently S detachirig from the threaded section 79 of the axial stem 67.

The pis.on assembly 65 further comprises a rigid lower plate 83 positioled against the lower face of the piston member 73.

The lower section 72 of the axial stem 67 extends through the central aperture 64 of the piston assembly 51. With this arrangement, the piston assembly 51 slides along the lower section 72 of the axial stem 67 as the first and second

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-9tubular members 21, 22 undergo telescopic movement. The lower section 72 of the axial stem 67 is of a cross-section which is non-circular, such as rectangular.

The central apertures 64 in the piston assembly 51 is of a complementary shape. With this arrangement, the lower section 72 provides a longitudinal track along which the piston assembly 51 can slide but about which it cannot rotate. In this way, the first and second tubular members 21, 22 are restrained from rotation relative to each other.

The cushioning member 19 is provided with two cushioning chambers 85, 86 on opposed sides of the second bearing portion 42. The cushioning chamber 85 is defined within the first member 21 between the first bearing portion 41 and the second bearing portion 42. The cushioning chamber 86 is defined within the second member 22 between the second bearing portion 42 and the third bearing portion 43.

The cushioning chamber 85 accommodates a first resilient means 91 in the form S 15 of a tapered helical compression spring which acts between the first bearing portion 41 and the second bearing portion 42.

The cush!oning chamber 86 accommodates a second resilient means 92 in the form of a helical compression spring which acts between the second bearing portion 42 and the third bearing portion 43.

S 20 The lower plate 61 of the piston assembly 51 is provided to protect the piston member 55 from damage from contact with the spring 91. Similarly, the lower plate 83 on the piston assembly 65 is provided to protect the piston member 010.

ffrom damage by the helical spring 92.

The forces of the first and second compression springs 91, 92 establish a state of equilibrium which provides a normal condition for the first and second members 21 and 22, respectively. The first and second members 21, 22 can move out of the normal condition in eitt the inward direction with respect to 1- I each other or the outward direction with respect to each other, such movement however being resisted by compression of one of the springs.

The axial holes 52 in the piston assembly 51 forming part of the ,cOnd bearing portion 42 allows air to move between the two compression chambers 85, 86 on relative movement between the first and second members 21, 22. This ensures that relative movement between the two members 21, 22 is not inhibited by air being confined within the respective chambers and subjected to compression.

Tension on the two compression springs 91, 92 is selectively adjustable by adjustment of the position of the third bearing portion 43. This is achieved by rotation of the nut 77 to vary its axial position on the threaded formation 79 of the axial stem 67, thereby altering the position of the piston assembly 65 relative to the axial stem and so adjusting the pre-load on the two compression springs.

Access to the nut 77 for adjustment purposes is provided by way of an access opening (not shown) in the hand grip 18. The access opening is closed by a removable closure 95 such as a plug.

o •In operation, the shovel is used in the conventional way with the user gripping the handle 17 above the cushioning mechanism 19. If the shovel head 17 impacts upon a hard surface which would otherwise impart a shock to the user b I and possibly cause comfort or damage, the first and second members 21 and 22 respectively are caused to move inwardly with respect to each other with the first compression spring 91 yieldingly resisting such movement as it acts between the first bearing portion 41 and the second bearing portion 42. Once the impacting force has subsided, the compressive force of the spring 91 acts on the first and second bearing portions to cause the first and second members 21, 22 to move outwardly with respect to each other, so returning the first and second members towards the no'rnal condition. In the likely event that the first and second members over shoot the normal condition, the second spring 92 C pl C 1 e~~l -11 yieldingly resists such over shooting movement and urges the first and second members to return towards the normal condition.

The cushioning effect provided by the cushioning mechanism 19 is effective both when the shovel is used in the conventional fashion and also in circumstances where the handle of the shovel is used as a ram. The latter is not an uncommon situation where a shovel is inverted and used as a ram for the purposes of consolidating soil or other material.

Referring to Fig. 4 of the drawings, there is shown a cushioning mechanism according to a second embodiment. The cushioning mechanism according to the second embodiment is similar to the first embodiment except that the expanded portion 36 of the first tubular member 21 is formed in two sections 96, 97.

Section 96 is formed integrally with the first tubular member 21 and section 97 is threadabiy engaged to section 96. This arrangement provides for easier assembly of the two tubular members 21, 22. It also provides easier access to the bush assembly 33 for servicing.

It should be appreciated that the cushioning mechanism 19 according to the :i embodiments may be used in other devices that a shovel, in this regard, Fig. shows the cushioning mechanism '19 according to the first embodiment incorporated into a crutch 101. Similarly, Fig. 6 shows the cushioning mechanism 19 according to the first embodiment incorporated in a walking stick 103. The cushionng provided by the cushioning mechanism reduces stress imparted to users, of the crutch arnd walking stick and so make these devices more comfortable and safe' tc use. Indeed, it may be that a user of the crutch 101 will be able to support his or her weight on the shoulder supporting portion 105 of the crutch -ithout risking a shoulder injury. This is not usually possible with a conventional crutch. Fig. 7 shows the cushioning mechanism 19 incorporated into another type of crutch 107.

i C-- -12 Referring now to Figs, 8, 9 and 10, there is shown a long-handled shovel comprising a shovel head 111 and a handle 113. The head 111 include a blade portion 115 and a shank portion 117 which receives one end of the handle 113.

A cushioning mechanism 119 according to a third embodiment is incorporated in the handle 113 at a location towards the head 111 such that any shocks transmitted to the shovel head can be cushioned by the cushioning mechanism 119, thereby retarding such forces before they are transmitted to a user gripping the handle 113.

The cushioning mechanism comprises a first member 121 of tubular construction and a second member 122 of tubular construction telescopically received within the first member. The telescopic arrangement allows the first and secod members 121 and 122 respectively to reciprocate one with respect to another along an axis coincident with their respective longitudinal axis.

The first member 121 includes two opposed end sections 123 ar, 15 respectfully, and an intermediate section 127 between the two end sections.

.0 The end section 123 slidably receives the second member 122. The end section 125 provides a sleeve for receiving the outer portion 127 of the handle 113. The outer portion 127 of the handle is secured in position within the sleeve 125 by suitable fixing means such as securing rivets 129 passing through a S 20 securing holes 131 formed in the sleeve 125. The wasted section 127 provides a shoulder 133, the purpose of which will be explained later.

A restraining means 135 operates between the first and second members 21 and 23 to prevent relative rotation therebetween while allowing the reciprocal movement. As best seen in Fig, 9 of the drawings, the restraining means 135 comprises a pair of opposed tracks 137, each comprising a longitudinal rib 139 formed on the first member 121 slidingly received in a longitudinal recess 141 formed on the second member 122. Cooperation between the longitudinal rib i -13- 139 and the longitudinal recess 141 allows the necessary reciprocal movement while restraining any relative rotational movement.

A first bearing portion 143 in the form of a circular first plate is received within, and fixed with respect to, the first member 121. The plate 143 is of circular construction and bears against the annular shoulder 133 as best seen in Fig. 8 of the drawings. A second bearing portion 145 in the form of a circular second plate is fixed to the inner end of the second member 122. With this arrangement, the second plate 145 is slidably received within the outer section 123 of the first member 121. A third bearing portion 147 in the form of a circular third plate is slidably received within the tubular second member 122. The third plate 147 is fixed with respect to the first plate 143, and thus the first member 121, by way of a rigid axial stem 150. The axial stem 150 slidably extends through an aperture 153 formed in the second plate 145 and is fixed at one end to the first plate 143 and fixed at the other end to the third plate 147.

A fist- resilikent means 51 in the form of a helical compression spring acts between the first plate 143 and the second plate 145. A second resilient means 52 also in the form of a helical compression spring acts between the second :}"plate 145 and the third plate 147.

o The forces of the first and second compression springs 151 and 153 establish a state of equilibrium which provides a normal condition for the first and second members 121 and 122 respectively. The first and second members 121, 122 can move out of the normal condition in either the inward direction with respect to each other or the outward direction with respect to each other and such movement is yieldingly resisted in a similar fashion to that described in relation to the first embodiment, Turning now to Fig. 11 of the drawings, there is shown a hand grip 160 which is adapted to be fitted on to the upper end of a handle of a shovel or spade. The hand grip 160 comprises a sleeve 163 adapted to be secured onto the end of -14the handle. The sleeve 163 supports a yoke structure 165 which includes two opposed side portions 167 between which a grip portion 169 is supported. Each side portion 167 incorporates a cushioning mechanism 171 according to a fourth embodiment. The cushioning mechanism 171 is of somewhat similar construction to the cushioning mechanism of the first embodiment. Each side portion 167 comprises an upper section 173 and a lower section 175 which are in telescopic relationship for reciprocal movement with respect to each other, The upper section 173 provides the first member of the cushioning mechanism 171 and the lower section 175 provides the second member of the cushioning mechanism 171.

The cushioning mechanisms 171 provide cushioning for impacting forces transmitted to a user gripping the grip portion 169, in a similar fashion to the cushioning provided by the cushioning mechanism of the first embodiment.

From the foregoing, it is evident that the present invention provides a simple yet highly effective way of cushioning shocks to which a user of devices such as shovels, crutches and walking sticks may be exposed. With cushioning of the shocks, the devices are more comfortable to use and there is less likelihood of users being exposed to injury as a result of the shocks.

It should be appreciated that the scope of the invention is not limited to the scope of the various embodiments described.

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Claims (14)

1. A cushioning mechanism comprising first and second members having a normal condition, the first and second members being arranged for reciprocal movement with respect to each other out of said normal condition along an axis, a first bearing portion fixed with respect to the first member, a second bearing portion fixed with respect to the second member, and a third bearing portion fixed with respect to the first member and positioned on the opposed side of the second bearing portion with respect to the first bearing portion, a first resilient means operatinlg between the first and second bearing portions, and a second resilient means operating between the second and third bearing portions, whereby the first resilient means yieldingly resists movement of the first and second members out of said normal condition in one direction for cushioning an impacting force generating such movement, and said second resilient means yieldingly 15 resists return relative movement between the first and second members o CO beyond the normal condition. 0

2. A cushioning mechanism according to claim 1, wherein the first resilient means comprises a compression spring.

3. A cushioning mechanism according to claim 1 or 2, wherein the second resilient means comprises a compression spring- 0

4. A cushioning mechanism according to claim 1, 2 or 3, wherein the f.,st and second members are telescopically connected to provide for the reciprocal movement with respect to each other. A cushioning mechanism according to claim 4, wherein the first and second members are each of tubular constructions. L' -16-

6. A cushioning mechanism according to any one of the preceding claims further comprising restraining means for restraining the first and second members against rotation one with respect to the other.

7. A cushioning mechanism according to claim 6, wherein the restrainirg means comprises a longitudinal track provided between the first and second members.

8. A cushioning mechanism according to any one of the preceding claims wherein the third bearing portion is slidably supported within the second member and fixed to the first bearing portion for sliding movement therewith relative to the second member.

9. A cushioning mechanism according to claim 8, wherein the third bearing portion is fixed to the first bearing portion by way of a connecting means slidably passing through the second bearing portion. A cushioning mechanism according to any one of the preceding claims S 15 incorporated in the shank portion of the head of a shovel or in the handle 5 thereof.

11.A handle for a digging or other ground working tool, said handle *:incorporating a cushioning mechanism as claimed in any one of the preceding claims.

12. A ground working tool incorporating a cushioning mechanism according to any one of claims 1 to 9.

13. A crutch incorporating a cushioning mechanism according to any one of claims 1 to 9.

14. A walking stick incorporating a cushioning mechanism according to any one of claims I to 9. ii i ~a ear -17- A cushioning mechanism substantially as herein described with reference to the accompanying drawings.

16. A device incorporating a cushioning mechanism substantially as herein describer with reference to the accompanying drawings. Dated this fifth day of March 1996. JAMES CHAD DELIU and MICHAEL DELIU Applicants WRAY ASSOCIATES Perth, Western Australia Patent Attorneys for the Applicants *0 00 so, 4* S 96 0000 5 good .60. sea 0 5.55 S 5

55.. 55.9 S S iWER--d -18- ABSTRACT A cushioning mechanism (19) for cushioning shocks impacted to a device such as a shovel. The cushioning mechanism (19) first and second members (21, 22) which have a normal condition and which are arranged for reciprocal movement with respect to each other out of said normal condition along an axis. A first bearing portion (41) is fixed with respect to the first member and a second bearing portion (42) is fixed with respect to the second member. A third bearing portion (43) fixed with respect to the first member (21) and positioned on the opposed side of the second bearing portion (42) with respect to the first bearing portion A first resilient means (91) operates between the first and second bearing portions (41, 42) and a second resilient means (92) operates between the second and third bearing portions (42, 43). With the arrangement, the fist resilient means (91) yieldingly resists movement of the first and second members (1 1, 12) out of said normal condition in one direction for cushioning an impacting force generating such movement, and said second resilient means (92) yieldingly resists return relative movement between the first and second members (11, 12) beyond the normal condition. oo 0 So *S S i 4lra