CA1317200C - Chain saw safety guard - Google Patents
Chain saw safety guardInfo
- Publication number
- CA1317200C CA1317200C CA 565014 CA565014A CA1317200C CA 1317200 C CA1317200 C CA 1317200C CA 565014 CA565014 CA 565014 CA 565014 A CA565014 A CA 565014A CA 1317200 C CA1317200 C CA 1317200C
- Authority
- CA
- Canada
- Prior art keywords
- chain
- bar
- saw
- protecting
- chain saw
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Abstract
ABSTRACT
A protective device for a chain saw comprising a generally U-shaped mounting bracket carrying pivot means pivotally supporting an elongate protecting bar spring biased towards a rest position in which the bar extends generally parallel to the chain of the chain saw in use, mounting plate means secured to one side of said mounting bracket and having a rearwardly extending portion formed with openings through which the chain bar mounting bolts of the chain saw pass for securement of said mounting plate to the body of the chain saw by means of the chain bar mounting nuts. The protecting bar has an inverted channel shaped configuration which defines a saw dust confining passage through which the saw dust passes in use. The protecting bar extends beyond the end of the chain of the chain saw to enable contact between the bar and the object to be cut without contact between the chain saw and the object. In one embodiment, a further protecting bar is attached to the lower portion of the mounting bracket to extend along the lower run of the chain of the chain saw.
A protective device for a chain saw comprising a generally U-shaped mounting bracket carrying pivot means pivotally supporting an elongate protecting bar spring biased towards a rest position in which the bar extends generally parallel to the chain of the chain saw in use, mounting plate means secured to one side of said mounting bracket and having a rearwardly extending portion formed with openings through which the chain bar mounting bolts of the chain saw pass for securement of said mounting plate to the body of the chain saw by means of the chain bar mounting nuts. The protecting bar has an inverted channel shaped configuration which defines a saw dust confining passage through which the saw dust passes in use. The protecting bar extends beyond the end of the chain of the chain saw to enable contact between the bar and the object to be cut without contact between the chain saw and the object. In one embodiment, a further protecting bar is attached to the lower portion of the mounting bracket to extend along the lower run of the chain of the chain saw.
Description
C~IAI~! SA~I SAFETY ~UAPD
2 FIELD OF THE IrlVENTIO~I
2 FIELD OF THE IrlVENTIO~I
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 BACKGROU~ID 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 extremely serious. One of the primary causes of accidents 11 involving chain saws is the problem of chain saw kickback.
12 ~ickback usually occurs when the chain first enyages the 13 object to be cut and can cause the saw to fly out of 14 control, often rotating in the air and striking the user while the blade is still in motion.
Many chain saws now include safety devices such as 17 chain brakes which are intended to operate when kickback 18 occurs. However, the operating mechanisms for such devices 19 often become clogged with saw dust preventing proper 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 entirely effective.
Other forms of safety devices have also been proposed 26 over the years including that shown in United States Patent 27 ~o. 4335513 Owens. This patent describes a bar which is 28 pivotted to the handle of the chain saw to overlie the top 29 run o-f the chain at a fixed spacing therefrom to avoid ~80418~!kgspe.032,miller.s?e, 1 31 720() 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 commercial-ized 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 thereto, since such devices occupy the space in which the safety bar is intended to be positioned. Thirdly, the mounting of the safety bar on the handle of an existing chain saw would severely weaken the strength of the handle so that the device is really only suitable for use with a handle which has been specifi-cally manufactured with a mounting fitting adapted to accept the pivot mechanism for the safety bar.
Fourthly, the device must be manually pivo-ted to enable boring or undercut operations to be performed, and since this reduces the control which the operator has over the saw, such an operation is regarded as being potentially dangerous. FR-A-2585615, Bec, discloses a protecting device for a chain saw includ-ing chain bar mounting nuts, comprising mounting - 3a -bracket means, pivot means carried by said bracket means, an elongate protecting bar attached to said pivot means, means for biasing said bar towards a rest position in which the bar extends parallel to the chain of said chain saw.
SUMMARY OF THE INVENTION AND OBJECTS
I-t is an object of the 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.
According to the present invention, there is provided a protective device for a chain saw, compris-ing mounting bracket means, pivot means carried by said bracket means, an elongate protecting bar attached to said pivot means, and means for biasing sald bar towards a rest position in which the bar extends in use generally parallel to the chain of said chain saw, characterized in that 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 I 3 1 720() ~ 3b -in its rest position and to prevent con-tact wi-th sa,id 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.
In one form, the present invention provides a ,4 ::
_ 4 _ 1 3 1 720~) 1 protecting device for a chain saw inc1uding chain ~ar 2 mounting nutsl comprising mounting bracket means, pivot 3 means carried by said bracket means, and elongate protecting 4 bar attached to said pivot means, 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 7 bracket means including provision for attachment of said 8 bracket means to the body of the chain saw by means of the 9 chain bar mounting nuts thereof.
B~IEF DESCRIPTION OF THE DRAWI~!GS
11 Two presently preferred embodiments of the invention 12 will now b~e described with reference to the accompanying 13 drawings in which:-14 Fig. 1 is a fragmentary side elevation of a protected15 device embodying the invention showing one manner of fitting 16 to a chain saw;
17 Fig. 2 is a sectional end elevation of the device shown 13 in Fig, 1 taken along the line 2-2 of Fig. l;
19 Fig, 3 is a sectional end elevational of the protectlon bar taken along the line 3-3 in Fig, 1, 21 fig, 4 is a perspective view of the mounting plates 22 associated with the mounting bracket for the protective 23 device shown in Fig, l;
24 Fig, 5 shows schematically how the protactive device operates to allow the chain saw to be used effectively, and 26 Fig, 6 is a fragmentary elevation of a modification 27 showing the use of upper and lower protection bars, and 28 Fig, 7 is a detailed view of a modified end fitting ~or 29 the protectiny bar, 880418,!kgspe,032,miller,spe, 1 31 720() 2 DESCRIPTIO~I OF PREFERRED E~lBODIMENTS.
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 l of rectangular U-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 5 9 which are shaped to define saw dogs 7. The forwardl~
projecting portions 5 of side portions 3 and 4 support a 11 pivot bolt 8 which is positioned forwardly of and parallel 12 to the top member 2, as well as a bolt 9 carrying a 13 rotatable sleeve which is positioned adjacent the free end 14 of the side members 3 and 4 to rigidly space the side members 3 and 4 and to provide a rotatable contact which 16 prevents significant damage in the event that the chain 17 contacts the sleeve 10.
18 The pivot bolt 8 carries a short support bar ll o~
l9 rectangular channel-shaped configuration which in turn carries an elongate protection bar 12 which is detachably 21 secured to the support bar 11. A torsion spring 13 22 surrounds the pivot bolt and engages the support 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 26 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, 1 formed in the plate 14 to allow for the plate 14 to be 2 adjustably postioned Y/ith 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 l9a 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 8 portion of the second mounting plate 18 has its edges formed 9 with serrations 13a and the sides of the channel portion 17 are correspondingly serrated at 17a so that the second 11 mounting plate 18 may be rigidly but adjustably engaged in 12 the channel 17.
13 The plate 18 is preferably formed with an offset 14 portion 18b to allow the plate to be used for attachment to different types of chain saw. By inverting the plate 18 16 that portion of the plate 18 having the opening l9a may be 17 laterally repositioned to allow for different positioning of 18 chain bar mounting bolts. The offset 18b further allo~s for 19 the plates 14 and 18 to be mounted on either s;de of the 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 ~ar 12 to suit various 23 saws.
24 While the first and second mounting 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 preferred since it allows the mounting bracket 1 to be 29 secured to the widest range of different types of chain 880418,!kgspe.032,miller.spe, _ 7 _ l ~l 7 2 ~ ~) 1 saws. In some instances it may be necessary to position 2 packing washers between the body of the chain saw and the 3 plate 18 to facilitate rigid connection of the plate by 4 means of the chain bar bolts. Similarly, the structure of the mounting bracket l may be modified to enable its direct 6 attachment to the chain bar mounting bolt(s) or to a 7 specifically provided mounting point on the body of the 8 chain saw. Of course, different components may be orovided 9 to enable the device to be connected to chain saws having widely varying types of chain bar mounting bolts and in this ll regard the above described combination of plates 14 and l~
12 may be found to be most convenient.
13 The protecting bar 12 is in the present embodiment made 14 from extruded PVC or the like and has a generally U-shaped cross-section with downwardly depending legs l9 and 20 16 formed with ribs 21 positioned to engage groove(s) 21a 17 formed in the sides of the support bar 11. The bar 12 is 18 also formed with opposed grooves 22 within which edges of d l9 protective steel or other strip 23 may be recelved to reduce damage to the bar in the event that chain contact occurs.
21 The strip 23 is held in position by bending its ends in the 22 manner shown in Fig, 1 over the top of the bar 12.
23 The bar 12 also supports a shaped end fitting 24 of 24 moulded plastics material which extends from the end of the bar and has a generally curved nose portion which promotes 26 outward deflection of the bar on engagement with an object 27 to be cut by the chain saw. It will be noted from Fig l of 28 the drawings that the end of the bar 12 and the end fitting 29 24 project beyond the end of the chain saw in use and an 8804l87!kgspe.032,miller.spe, .
~ - 8 _ l 31 720() l overhang of the order of lOOmm has been found to be 2 satisfactory. This overhang allows the bar 12l 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 S be performed without the need to manually pivot the bar 12.
The different modes of operation of a chain saw fitted 7 with the protective device embodying the invention will be 8 clearly understood from the schematic representations 9 appearing in Fig. 5 of the drawings. It will be appreciated that a normal top cut ~ill cause the bar 12 to be pivotted 11 against the action of the spring 13 as the bar engages the 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 pivot the arm 12 sufficiently so that the end of the chain saw may engage the object. As boring 16 progresses, the bar 12 is progressively pivotted by 17 engagement ~/ith the object in the manner shown in Fig. 5.
18 If desired, the protecting bar 12 may be held out of l9 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 25 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 pivotally attached to the bolt 9 at the lower end of the(l~
29 to provide protection for the lower run of the chain. The 880418,!kgspe.032,miller.spe, ` ~
1 bar12 at the lower end is preferably longer than the bar 12 2 at the upper end so that the lower bar may be first 3 displaced to enable normal top cut operations to be 4 performed.
To restrain the mounting bracket 1 against vibration 6 and to further render rigid the attachment of the bracket 1 7 to the chain saw, a short stabilizing link 30 may be 8 attached to the bolt 8 by means of a nut 31, with the 3 opposite end of the link 30 being attached to the body of 1~ the saw using the one of the attachment bolts used to attach 11 the saw dogs present on most chain saws. The stabilizing 12 link 30 is most useful where the chai~ bar is attached by 13 means of a single bolt or nut.
14 Referring now to Fig. 7, it wi11 be noted that the end fitting 24 has been replaced by a rotatable wheel l,~, This 16 arrangement ensures that the bar 12 will move smoothly over 17 the object to be cut on initial contact 18 It will be appreciated from the above that the device 19 embodying the invention provides a simple yet effective means of protecting the user against injury in the event of 21 kickback occurring or in the event of mishandling of the 22 chain saw. Of course, no device can offer complete 23 protection against a careless operator but the device 24 according to the invention will provide protection against injuries due to kickback, In addition, the tunnel defined 26 by the U-shaped protecting bar 12 provides a passage for saw 27 dust which is carried by the chain to travel to the end of 28 the chain rather than spraying upwardly from the top of the 2g chain as normally occurs. This provides an additional 8804181!kgspe,032,miller.spe, 1 31 720() -- 1 o 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 sa~.~, most preferably via the 4 chain bar securing bolt(s) provides a particu1arly 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 8 of different makes and models of chain saw thereby enabling 9 wide spread use of the protective device.
The claims form part of the disclosure of this 11 specification.
~80418,!kgspe.032,miller~spe,
7 BACKGROU~ID 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 extremely serious. One of the primary causes of accidents 11 involving chain saws is the problem of chain saw kickback.
12 ~ickback usually occurs when the chain first enyages the 13 object to be cut and can cause the saw to fly out of 14 control, often rotating in the air and striking the user while the blade is still in motion.
Many chain saws now include safety devices such as 17 chain brakes which are intended to operate when kickback 18 occurs. However, the operating mechanisms for such devices 19 often become clogged with saw dust preventing proper 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 entirely effective.
Other forms of safety devices have also been proposed 26 over the years including that shown in United States Patent 27 ~o. 4335513 Owens. This patent describes a bar which is 28 pivotted to the handle of the chain saw to overlie the top 29 run o-f the chain at a fixed spacing therefrom to avoid ~80418~!kgspe.032,miller.s?e, 1 31 720() 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 commercial-ized 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 thereto, since such devices occupy the space in which the safety bar is intended to be positioned. Thirdly, the mounting of the safety bar on the handle of an existing chain saw would severely weaken the strength of the handle so that the device is really only suitable for use with a handle which has been specifi-cally manufactured with a mounting fitting adapted to accept the pivot mechanism for the safety bar.
Fourthly, the device must be manually pivo-ted to enable boring or undercut operations to be performed, and since this reduces the control which the operator has over the saw, such an operation is regarded as being potentially dangerous. FR-A-2585615, Bec, discloses a protecting device for a chain saw includ-ing chain bar mounting nuts, comprising mounting - 3a -bracket means, pivot means carried by said bracket means, an elongate protecting bar attached to said pivot means, means for biasing said bar towards a rest position in which the bar extends parallel to the chain of said chain saw.
SUMMARY OF THE INVENTION AND OBJECTS
I-t is an object of the 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.
According to the present invention, there is provided a protective device for a chain saw, compris-ing mounting bracket means, pivot means carried by said bracket means, an elongate protecting bar attached to said pivot means, and means for biasing sald bar towards a rest position in which the bar extends in use generally parallel to the chain of said chain saw, characterized in that 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 I 3 1 720() ~ 3b -in its rest position and to prevent con-tact wi-th sa,id 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.
In one form, the present invention provides a ,4 ::
_ 4 _ 1 3 1 720~) 1 protecting device for a chain saw inc1uding chain ~ar 2 mounting nutsl comprising mounting bracket means, pivot 3 means carried by said bracket means, and elongate protecting 4 bar attached to said pivot means, 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 7 bracket means including provision for attachment of said 8 bracket means to the body of the chain saw by means of the 9 chain bar mounting nuts thereof.
B~IEF DESCRIPTION OF THE DRAWI~!GS
11 Two presently preferred embodiments of the invention 12 will now b~e described with reference to the accompanying 13 drawings in which:-14 Fig. 1 is a fragmentary side elevation of a protected15 device embodying the invention showing one manner of fitting 16 to a chain saw;
17 Fig. 2 is a sectional end elevation of the device shown 13 in Fig, 1 taken along the line 2-2 of Fig. l;
19 Fig, 3 is a sectional end elevational of the protectlon bar taken along the line 3-3 in Fig, 1, 21 fig, 4 is a perspective view of the mounting plates 22 associated with the mounting bracket for the protective 23 device shown in Fig, l;
24 Fig, 5 shows schematically how the protactive device operates to allow the chain saw to be used effectively, and 26 Fig, 6 is a fragmentary elevation of a modification 27 showing the use of upper and lower protection bars, and 28 Fig, 7 is a detailed view of a modified end fitting ~or 29 the protectiny bar, 880418,!kgspe,032,miller,spe, 1 31 720() 2 DESCRIPTIO~I OF PREFERRED E~lBODIMENTS.
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 l of rectangular U-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 5 9 which are shaped to define saw dogs 7. The forwardl~
projecting portions 5 of side portions 3 and 4 support a 11 pivot bolt 8 which is positioned forwardly of and parallel 12 to the top member 2, as well as a bolt 9 carrying a 13 rotatable sleeve which is positioned adjacent the free end 14 of the side members 3 and 4 to rigidly space the side members 3 and 4 and to provide a rotatable contact which 16 prevents significant damage in the event that the chain 17 contacts the sleeve 10.
18 The pivot bolt 8 carries a short support bar ll o~
l9 rectangular channel-shaped configuration which in turn carries an elongate protection bar 12 which is detachably 21 secured to the support bar 11. A torsion spring 13 22 surrounds the pivot bolt and engages the support 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 26 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, 1 formed in the plate 14 to allow for the plate 14 to be 2 adjustably postioned Y/ith 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 l9a 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 8 portion of the second mounting plate 18 has its edges formed 9 with serrations 13a and the sides of the channel portion 17 are correspondingly serrated at 17a so that the second 11 mounting plate 18 may be rigidly but adjustably engaged in 12 the channel 17.
13 The plate 18 is preferably formed with an offset 14 portion 18b to allow the plate to be used for attachment to different types of chain saw. By inverting the plate 18 16 that portion of the plate 18 having the opening l9a may be 17 laterally repositioned to allow for different positioning of 18 chain bar mounting bolts. The offset 18b further allo~s for 19 the plates 14 and 18 to be mounted on either s;de of the 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 ~ar 12 to suit various 23 saws.
24 While the first and second mounting 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 preferred since it allows the mounting bracket 1 to be 29 secured to the widest range of different types of chain 880418,!kgspe.032,miller.spe, _ 7 _ l ~l 7 2 ~ ~) 1 saws. In some instances it may be necessary to position 2 packing washers between the body of the chain saw and the 3 plate 18 to facilitate rigid connection of the plate by 4 means of the chain bar bolts. Similarly, the structure of the mounting bracket l may be modified to enable its direct 6 attachment to the chain bar mounting bolt(s) or to a 7 specifically provided mounting point on the body of the 8 chain saw. Of course, different components may be orovided 9 to enable the device to be connected to chain saws having widely varying types of chain bar mounting bolts and in this ll regard the above described combination of plates 14 and l~
12 may be found to be most convenient.
13 The protecting bar 12 is in the present embodiment made 14 from extruded PVC or the like and has a generally U-shaped cross-section with downwardly depending legs l9 and 20 16 formed with ribs 21 positioned to engage groove(s) 21a 17 formed in the sides of the support bar 11. The bar 12 is 18 also formed with opposed grooves 22 within which edges of d l9 protective steel or other strip 23 may be recelved to reduce damage to the bar in the event that chain contact occurs.
21 The strip 23 is held in position by bending its ends in the 22 manner shown in Fig, 1 over the top of the bar 12.
23 The bar 12 also supports a shaped end fitting 24 of 24 moulded plastics material which extends from the end of the bar and has a generally curved nose portion which promotes 26 outward deflection of the bar on engagement with an object 27 to be cut by the chain saw. It will be noted from Fig l of 28 the drawings that the end of the bar 12 and the end fitting 29 24 project beyond the end of the chain saw in use and an 8804l87!kgspe.032,miller.spe, .
~ - 8 _ l 31 720() l overhang of the order of lOOmm has been found to be 2 satisfactory. This overhang allows the bar 12l 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 S be performed without the need to manually pivot the bar 12.
The different modes of operation of a chain saw fitted 7 with the protective device embodying the invention will be 8 clearly understood from the schematic representations 9 appearing in Fig. 5 of the drawings. It will be appreciated that a normal top cut ~ill cause the bar 12 to be pivotted 11 against the action of the spring 13 as the bar engages the 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 pivot the arm 12 sufficiently so that the end of the chain saw may engage the object. As boring 16 progresses, the bar 12 is progressively pivotted by 17 engagement ~/ith the object in the manner shown in Fig. 5.
18 If desired, the protecting bar 12 may be held out of l9 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 25 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 pivotally attached to the bolt 9 at the lower end of the(l~
29 to provide protection for the lower run of the chain. The 880418,!kgspe.032,miller.spe, ` ~
1 bar12 at the lower end is preferably longer than the bar 12 2 at the upper end so that the lower bar may be first 3 displaced to enable normal top cut operations to be 4 performed.
To restrain the mounting bracket 1 against vibration 6 and to further render rigid the attachment of the bracket 1 7 to the chain saw, a short stabilizing link 30 may be 8 attached to the bolt 8 by means of a nut 31, with the 3 opposite end of the link 30 being attached to the body of 1~ the saw using the one of the attachment bolts used to attach 11 the saw dogs present on most chain saws. The stabilizing 12 link 30 is most useful where the chai~ bar is attached by 13 means of a single bolt or nut.
14 Referring now to Fig. 7, it wi11 be noted that the end fitting 24 has been replaced by a rotatable wheel l,~, This 16 arrangement ensures that the bar 12 will move smoothly over 17 the object to be cut on initial contact 18 It will be appreciated from the above that the device 19 embodying the invention provides a simple yet effective means of protecting the user against injury in the event of 21 kickback occurring or in the event of mishandling of the 22 chain saw. Of course, no device can offer complete 23 protection against a careless operator but the device 24 according to the invention will provide protection against injuries due to kickback, In addition, the tunnel defined 26 by the U-shaped protecting bar 12 provides a passage for saw 27 dust which is carried by the chain to travel to the end of 28 the chain rather than spraying upwardly from the top of the 2g chain as normally occurs. This provides an additional 8804181!kgspe,032,miller.spe, 1 31 720() -- 1 o 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 sa~.~, most preferably via the 4 chain bar securing bolt(s) provides a particu1arly 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 8 of different makes and models of chain saw thereby enabling 9 wide spread use of the protective device.
The claims form part of the disclosure of this 11 specification.
~80418,!kgspe.032,miller~spe,
Claims (7)
1. A protective device for a chain saw having a chain mounted on a chain bar, comprising mounting bracket means formed for attachment to the chain saw, pivot means carried by said mounting means, and elongate protecting bar attached to said pivot means, means for biasing said protecting part towards a rest position in which the protecting bar extends in use generally parallel to the chain of said chain saw, said protecting bar having a length such that it extends in said rest position beyond the end of the chain bar and chain and including wheel means rotatably mounted at the free end of said protecting bar such that the outer periphery of said wheel means extends beyond the end of the chain bar and chain in the rest position of the protecting bar to enable engagement between said wheel means on the protecting bar and an object to be cut without contact between the chain of the chain saw and the object to be cut to permit entry of the object to be cut between said protecting bar and upper run of said chain of said chain saw.
2. The protective device of claim 1, wherein said mounting bracket means includes a member having a top portion and depending side portions which in use are positioned on either side of said chain bar of the chain saw, said pivot means being carried by said bracket means whereby said protecting bar is positioned so that a portion thereof engages said top portion to maintain said bar in its rest position and to prevent contact between said protecting bar and said chain of said chain saw, said bracket means having means formed in or attached to at least one of said size portions for attachment of said bracket means to the chain saw.
3. The protective device of claim 2, wherein at least one of said side portions extends forwardly of said top portion and is formed with projections which act as saw dogs.
4. The protective device of claim 1, wherein said protecting bar is generally channel shaped in cross-sectional configuration to define a passage through which saw dust generated by the chain of the chain saw may be contained for discharge from the end of said protecting bar.
5. The protective device of claim 4, wherein said protecting bar is formed with means for receiving a cutting resistant strip which in use faces the chain of the chain saw to minimize damage in the event of contact between the protecting bar and the chain.
6. The protective device of claim 4 or 5, wherein said protecting bar is made from molded plastics material and is removably attached to a short mounting bar which is in turn attached to said pivot means.
7. The protective device of claim 1 or 2, further comprising an additional protecting bar pivotally mounted to said mounting bracket means adjacent the lowermost end thereof whereby said further protecting bar extends in use generally parallel to the lower run of the chain of said chain saw.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPI.1592 | 1987-04-24 | ||
| AUPI159287 | 1987-04-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1317200C true CA1317200C (en) | 1993-05-04 |
Family
ID=3772134
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 565014 Expired - Fee Related CA1317200C (en) | 1987-04-24 | 1988-04-25 | Chain saw safety guard |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1317200C (en) |
-
1988
- 1988-04-25 CA CA 565014 patent/CA1317200C/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |