AU599782B2 - Chain saw safety guard - Google Patents

Description

P"141 0 9782 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

Form FOR OFFICE 'JSE Class Int. Class 0000,Application Number: a0a00 a Lodged: 00 00 a 0 0 g 0 @00000 0 0 Complete Specification-Lodged: Accepted: Published: Priority: Related Art: This document containsth amendments made Linder Section 49 and is correct for printing, TO BE COMPLETED BY APPLICANT CLIFTON LEIGH MILLER and R2NALD LAWRY KERRISON Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: 3 Riverview Road, Riverside, LAUNCESTON, TASMANIA 171 Rosevears Drive, LEGANA, TASMANIA CLIFTON LEIGH MILLER and RONALD LAWRY KERRISON SANDERCOCK, SMITH BEADLE 207 Riversdale Road, Box Hawthorli, Victoria, 3122 Complete Specification for the invention entitled: CHAIN SAW SAFETY GUARD The following statement is a full description of this invention, including the best method of performing it known to me:- 2 1 CHAIN SAW SAFETY GUARD 2 FIELD OF THE INVENTION 3 This invention relates to protective devices for chain 4 saws, and more particularly to chain saw guards of the type which reduce the possibility of injury when a chain saw is 6 used.

7 BACKGROUND OF THE INVENTION 8 The increasing use of chain saws has resulted in an 9 increasing number of chain saw accidents, many of which are S 10 extremely serious. One of the primary causes of accidents 11 involving chain saws is the problem of chain s w kickback.

12 Kickback usua ly occurs when the chain first engages the i 13 object to be cut and can cause the saw to fly out of i 14 control, often rotating in the air and striking the user while the blade is still in motion.

16 Many chain saws now include safety devices such as 17 chain brakes which are intended to operate when kickback I 18 occurs. However, the operating mechanisms for such devices 19 often become clogged with saw dust preventing oroper operation and the brake mechanisms involved may not be 21 properly serviced thereby resulting in operational failures 22 in use. Certainly, the increasing incidence of chain saw 23 accidents would seem to indicate that such mechanisms have 24 not been enti -ey effective.

Other forms of safety device have also been proposed 26 over the years including that shown in United ,States Patent 27 No. 4335513 Owens. This patent describes a bar which is 28 pivotted to the handle of the chain saw to overlie the top 29 run of the chain at a fixed spacing therefrom to avoid 8804 8, !kgspe.032,miller.spe, ii 3 contact between the chain and the bar. While the concept behind the safety bar described in this Patent is commendable, the device has never been commercialized and suffers from a number of disadvantages. Firstly, the device is only suitable for "in line" chain saw handles, that is, where the handle is situated in alignment with the cutter bar of the saw, and such chain saws are quite rare. Secondly, the mounting of the safety bar on the handle of the chain saw prevents the use of the device with chain saws having chain brakes or anti-vibration devices fitted V,0o" thereto, since such devices occupy the space in which the safety o bar is intended to be positioned. Thirdly, the mounting of the 0 S° safety bar on the handle of an existing chain saw would severely S0 0 weaken the strength of the handle so that the device is really 6 only suitable for use with a handle which is has been specifically manufactured with a mounting fitting adapted to accept the pivot mechanism for the safety bar.

SUMMARY OF THE INVENTION AND OBJECTS It is an object of th?, present invention to provide an improved protective device for a chain saw which is capable of being securely fitted to an existing chain saw and which at least reduces the difficulties associated with the other shortcomings described above.

In one form, the present invention provides a protective device for a chain saw, comprising mounting bracket means, pivot means carried by said bracket means, an elongate protecting bar attached to said pivot means, and means for biasing said bar towards a rest position in which the bar extends in use generally tbspe.047/miller 90 5 1 i.~ 4 i

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parallel to the chain of said chain saw, said mounting bracket means includes a member having a top portion and depending side portions which in use are positioned on either side of the chain bar of the chain saw, said pivot means being carried by said bracket means and said protecting bar being positioned so that a portion thereof engages said top portion to maintain said bar in its rest position and to prevent contact with said chain saw, said bracket means having means formed in or attached to at least one of said side portions for attachment of said bracket means to 0 the chain saw.

By the use of the mounting barcket defined, the device is more asily and securely attached to most types of chain saws in a manner which reduces the incidence of clogging by saw dust.

0 The device described in U.S. Patent 4,335,513 has a further shortcoming in that it must be manually pivotted to enable boring or undercut operations to be performed and since this reduces the ft control which the operator has over the saw, such an operation is regarded as being potentially dangerous. Thus in a preferred form, the bar has an end portion which projects in use beyond the end of the chain saw to enable non-manual actuation of the bar, as described further below.

BRIEF DESCRIPTION OF THE DRAWINGS Two presently preferred embodiments of the invention will now be described with reference to the accompanying drawings in which:- Fig. 1 is a fragmentary side elevation of a protected dcevice embodying the invention showing one manner of fitting to I chain tbspe.047/miller 90 5 1 L 7 4asaw; Fig. 2 is a sectional end elevation of the device shown in Fig. 1 taken along the line 2-2 of Fig. 1; Fig. 3 is a sectional end elevational of the protection bar taken along the line 3-3 in Fig. 1; Fig. 4 is a perspective view of the mounting plates associated with the mounting bracket for the protective device shown in Fig. 1; Fig. 5 shows schematically how the protective device operates to allow the chain saw to be used effectively, and Fig. 6 is a fragmentary elevation of a modification showing the use of upper and lower protection bars, and 9 o 0 0 SFig. 7 is a detailed view of a modified end fitting for the protecting bar.

$6* C 4 C0 r .CB tbspe.047/miller 90 5 1 1 2 DESCRIPTION OF PREFERRED EMBODIMENTS.

3 Referring firstly to Figs 1-4 of the drawings, the 4 chain saw protective device embodying the invention will be seen to comprise a mounting bracket 1 of rectangular U- 6 shaped configuration in end elevation (see Fig. 2) having a 7 top member 2 from which depend side members 3 and 4, each 8 of which is provided with forwardly projecting portions 9 which are shaped to define saw dogs 7. Tha forwardly 10 projecting portions 5 of side portions 3 and 4 support a 11 pivot bolt 8 which is positioned forwardly of and parallel o a 12 to the top member 2, as wel 1 as a bolt 9 carrying a .a 13 rotatable sleeve which is positioned adjacent the free end 14 of the side members 3 and 4 to rigidly space the side o 15 members 3 and 4 and to provide a roeatablc contact which °o 16 prevents significant damage in the even that the chain S 17 contacts the sleeve 13 The pivot bolt 8 carries a short support bar 11 of 19 rectangular channel-shaped configuration which in turn 20 carries an elongate protection bar 12 which is detachably 444404 21 secured to the support bar 11. A torq spring 13 22 surrounds the pivot bolt and engages the suppi, bar 11 and 23 the top member 2 of the bracket 1 to bias the support bar 11 24 towards engagement with the top member 2 to maintain the protection bar 12 parallel to the top run of the chain in t use.

27 The mounting bracket 1 carries a first mounting plate 28 14 which is secured thereto by bolts 15 and 16. The bolts 29 15 and 16 are received in cross-slotted holes 14a and 14b 880418, !kgspe.032,miller.spe, 6 1 formed in the plate 14 to allow for the plate 14 to be 2 adjustably postioned with respect to the bracket 1. The 3 mounting plate 14 is formed with a central shallow channel 4 portion 17 which receives one end of a second mounting plate 18 having a pair of elongate openings 19 and 19a by means of 6 which the plate 18 may be bolted to the body of the chain 7 saw using the chain bar securing bolt(s) 20, The end 3 portion of the second mounting plate 18 has its edges formed 9 with serrations 13a and the sides of the channel portion 17 10 are correspondingly serrated at 17a so that the second o a 11 mounting plate 13 may be rigidly but adjustably engaged in 0 S" o 12 the channel 17.

""oo 13 The plate 18 is preferably formed with an offset 14 portion 18b to allow the plate to be used for attachment to o, 15 different types of chain saw. By inverting the plate 18 15 that portion of the plate 18 having the opening 19a may be 17 laterally repositioned to al low for different positioning of 18 chain bar mounting bolts. The offset 18b further allows for 19 the plates 14 and 13 to be mounted on either side of the *0 0 S 20 mounting bracket 1, and to be mounted with the offset 21 position in or out, thereby effectively laturally 22 repositioning the bracket 1 and the bar 12 to suit various 23 saws.

24 While the first and second mountiny plates 14 and 18 may be manufactured as a single piece to suit a particular 26 make of chain saw or range of chain saws, the above 27 described connection between the plates 14 and 18 is 28 preferr since it al lows the mounting bracket 1 to be 29 secured to the widest range of different types of chain 8 80418,!kgspe.032,miller.spe, _I -7 c:1 1 2 3 4 6 7 8 9 t 12 13 14 17 13 19 21 22 23 24 26 27 28 29 7 saws. In some instances it may be necessary to position packing washers between the body of the chain saw and the plate 18 to facilitate rigid connection of the plate by means of the chain bar bolts. Similarly, the structure of the mounting bracket 1 may be modified to enable its direct attachment to the chain bar mounting bolt(s) or to a specifically provided mounting point on the body of the chain saw. Of course, different components may be provided to enable the device to be connected to chain saws having widely varying types of chain bar mounting bolts and in this regard the above described combination of plates 14 and 18 may be found to be most convenient.

The protecting bar 12 is in the present embodiment made from extruded PVC or the like and has a generally U-shaped cross-section with downwardly depending legs 19 and formed with ribs 21 positioned to engage groove(s) 21a formed in the sides of the support bar 11. The bar 12 is also formed with opposed grooves 22 within which edges of a protective steel or other strip 23 may be received to reduce damage to the bar in the event that chain contact occurs.

The strip 23 is held in position by bending its ends in the manne' shown in Fig. 1 over the top of the bar 12.

The bar 12 also supports a shaped end fitting 24 of moulded plastics material which extends from the end of the bar and has a generally curved nose portion which promotes outward deflection of the bar on engagement with an object to be cut by the chain saw. It will be noted from Fig 1 of the drawings that the end of the bar 12 and the end fitting 24 project beyond the end of the chain saw in use and an 880418, kgspe. 032.miller.spe,

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8 1 overhang of the order of 100mm has been found to be 2 satisfactory. This overhang al lows the bar 12 to be 3 pivotted away From the chain saw by engagement with the 4 object to be cut to enable boring and undercut operations to be performed without the need to manual ly pivot the bar 12.

6 The different modes of operation of a chain saw fitted 7 with the protective device embodying the invention will be 3 clearly understood from the schematic representations 9 appearing in Fig. 5 of the drawings. It will be appreciated Q m 10 that a normal top cut wil l cause the bar 12 to be pivotted a 4 11 against the action of the spring 13 as the bar engages the S 12 top of the object being cut. Boring, operations may be 13 performed by engaging the end fitting 24 against the object 14 to be bored to pi vot the arm 12 sufficiently so that the end 15 of the chai n saw may engage the object. As boring o, 16 progresses, the bar 12 is progressively pivotted by 17 engagement with the object in the manner shown in Fig. 13 If desired, the protecting bar 12 may be held out of 19 its operative position by means of a wire stay 26 engaging holes 27 and 28 in the side member 3 and the support bar 11.

21 The stay 26 is preferably formed with an intermediate bend 22 such that in the event that kickback occurs during operation 23 of the chain saw in this mode, the stay 26 will collapse so 24 that the protecting bar 12 may reassume its operative position.

26 Referring now to Fig. 5 of the drawings, a modification 27 in which an additional safety bar 12 and support bar 11 are 28 pivotal ly attached to the bolt 9 at the lower end of the (1) 29 to provide protection for the lower run of the chain. The 88 0 4 18, kgspe.032,miller.spe, 9o 4 4 4 4 4 4 94 4 4 4a 4 44 $4* 4 4P~oe bar 12 at the lower end is preferably longer than the bar 12 at the upper end so that the lower bar may be first displaced to enable normal top cut operations to be performed.

To restrain the mounting bracket 1 against vibration and to further render rigid the attachment of the bracket 1 to the chain saw, a short stabil izing link 30 may be attached to the bolt 8 by means of a nut 31, with the opposite end of the link 30 being attached to the body of the saw using the one of the attachment bolts used to attach the saw dogs present on most chain saws. The stabilizing link 30 is most useful where the chain bar is attached by means of a single bolt or nut.

Referring now to Fig. 7, it wil 1 be noted that thg end fitting 24 has been replaced by a rotatable wheel W. This arrangement ensures that the bar 12 wil l move smoothly over the object to be cut on initial contact It will be appreciated from the above that the device embodying the invention provides a simple yet effective means of protecting the user against injury in the event of kickback occurring or in the event of mishandling of the ch in saw. Of course, no device can offer complete protection against a careless operator but the device according to the invention will provide protection against injuries due to kickback, In addition, the tunnel defined by the U-shaped protecting bar 12 provides a passage for saw dust which Is carried by the chain to travel to the end of the chain rather than spraying upwardly from the top of the chain as normally occurs. This provides an additional 8S0418,!kgsp.O.32,niller,tpq, '*SiWsxiWwil 8 Ir -~CI1 10 1 safety feature and reduces the extent to which the user is 2 fouled by sawdust. The attachment of the device in a secure 3 manner to the body of the chain saw, most preferably via the 4 chain bar securing bolt(s) provides a particularly secure means of attachment to the chain saw. In the preferred form 6 described above, the use of interchangeable mounting plates 7 enables the device to be fitted to the widest possible range 3 of different makes and models of chain saw thereby enabling 9 wide spread use of the protective device.

The c laims form part of the disc losure of this 11 soecification.

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Claims (9)

1. A protective device for a chain saw, comprising mounting bracket means, pivot means carried by said bracket means, an elongate protecting bar attached to said pivot means, and means for biasing said bar towards a rest position in which the bar extends in use generally parallel to the chain of said chain saw, said mounting bracket means includes a member having a top portion and depending side portions which in use are positioned on either side of the chain bar of the chain saw, said pivot iQ0.O means being carried by said bracket means and said protecting bar 49 4 being 'ositioned so that a portion thereof engages said top I portion to maintain said bar in its rest position and to prevent *4 44 contact with said chain saw, said bracket means having means formed in or attached to at least one of said side portions for attachment of said bracket means to the chain saw.

2. The protective device of claim 1, wherein at least one of said side portions extends forwardly of said top portion and is formed with projections which act as saw dogs.

3. The protective device of claim 1 or 2, wherein said saw has chain bar mounting bolts, said bracket means is formed for attachment to the body of the chain saw by means of said chain j bar mounting bolts. S4. The protective device of claim 3, wherein said mounting briacket means further includes mounting plate means removably attached to one side portion of said member, said mounting plate means including a rearwardly extending portion having one or more openings through which the chain bar mounting bolts may pass. tbspe.047/miller 90 5 1 _I 4 12 The protective device of claim 4, wherein said mounting plate means comprises a first plate having openings through which attaching bolts may pass to secure said first plate to one side portion of said member, said first plate having a transverse recess receiving one end of a second mounting plate formed with said opening(s), and means in said recess and on said end portion to facilitate adjustable interlocking of said first and second plates.

6. The protective device of claim 5, wherein said second '1iO. mounting plate is formed with an offset position to allow the 4* 0 S* plates to be mounted on either side of said mounting bracket 440440 S' means. 0 S 7. The protective device of any preceding claim, wherein said protecting bar has an end portion which extends in use beyond the end the chain saw to enable engagement between the bar and an object to be cut without contact between the chain saw and the object.

8. The protnctive device of claim 7, wherein said protecting bar has a generally rounded end portion which facilitates smooth contact with object to enable the bar to be pivotted.

9. The protective device of claim 8, wherein said end portion has a wheel rotatably mounted such that the outer periphery of the wheel extends in use behond the end of the chain saw to facilitate engagement between the wheel and an object to be cut without contact between the chain saw and the object. The protective device of any preceding claim, wherein said protecting bar is generally channel shaped in cross-sectional tbspe.047/miller 90 5 1 13 configuration to define a passage through which saw dust generated by the chain saw may be contained for discharge from the end of said bar.

11. The protective device of any preceding claim, wherein said protecting bar is formed with means for receiving cutting resistant strip which in use faces the chain of the chain saw to minimize damage in the event of contact between the bar and the chain.

12. The protective device of -ny preceding claim, wherein said protecting bar is made from molded plastics material and is 00 00 S a removably attached to a short mounting bar which is in turn 0 attached to said pivot means. 0 00 00 0 00 0 13. The protective device of any preceding claim, further 0 comprising an additional protecting bar pivotally mounted to said mounting bracket means adjacent the lower most end thereof such 0 that the further protecting bar extends in use generally parallel So94 So:o to the lower run of the chain of said chain saw.

14.A protective device for a chain saw substantially as 4 hereinafter described with reference to Figures 1 to 4 or Figure 5 or Figure 6 or Figure 7 of the accompanying drawings. DATED this May 1, 1990 SMITH SHELSTON BEADLE Fellows Institute of Patent Attorneys of Australia Patent Attorneys for the Applicant: CLIFTON LEIGH MILLER and RONALD LAWRY KERRISON tbspe.047/miller 90 5 1 v 'r .:7.tI c^c~~