US 3380493 A
Description (OCR text may contain errors)
April 1968 J. H. GIROUX 3,380,493
SAFETY GUARD FOR CHAIN SAW Fil d July 9 2 Sheets-Sheet 1 INVENTOR .l. H. GIROUX ATTORNEYS v .Filed July 6, 1966 P" 1968 J. H. GIROUX 7 3,380,493
SAFETY GUARD FOR CHAIN SAW 2 Sheets-Sheet f3 INVENTOR .I. H. GIROUX A TTORNEYS United States Patent 3,380,493 SAFETY GUARD FOR CHAIN SAW Joseph H. Giroux, 301 Princess St., Dalhousie, New Brunswick, Canada Filed July 6, 1966, Ser. No. 563,289 7 Claims. (Cl. 143-32) The present invention relates to a safety guard and particularly to a safety guard for chain saws.
It is well known that extreme caution must be used in operating a chain saw because of the large cutting surface presented by such saws and the tendency for the saws tokick-back toward the operator when obstacles are encountered. Due to the nature of the cutting action of a. chain saw wood chips and other vegetation are carried back toward the operator endangering his eyes and preoccupying the operator so that his full concentration is not directed to the important task of correctly handling the saw. Moreover, woodsmen using chain saws day after day, and slashing and cutting this way and that, tend to become careless resulting in serious accidents.
Attempts have been made to provide safety guards for chain saws but these have proved to be generally unsatisfactory. The most satisfactory of these known saw guards have protective metal shields which normally project partially, or completely, over the saw chain and guide bar and may be mounted for pivotal movement to pivot back from the saw chain as the chain proceeds through the wood being cut. Such devices, however, are seldom used and are disliked by woodsmen not only for the reason of increased weight and obstructed visibility, but also as hampering free movement. A chain saw can cut on both the upstroke and downstroke and any attachment on a saw which hampers these unrestricted cutting movements, or obstructs the operators vision thus reducing efficiency, will be discarded by the Woodsman.
The present invention relates to a safety guard for chain saws which is light but durable in construction, presents no obstacle to prevent free cutting movements, and will not obstruct the vision of the operator.
The principal object of the present invention is to provide a safety guard for a chain saw providing maximum protection for the operator, and of lightweight construction, and which will not interfere with the free cutting movement of the saw chain and enable complete visibility of the guide bar and saw chain at all times during a cutting operation.
It is a further object to provide a lightweight safety guard for chain saws of the type having a motor, motor housing and operating and carrying handles, and an elongated saw chain guide bar and saw chain rotatable therearound, said guard having an extendible guard strip pivotally mounted on the housing or handle of the chain saw and pivotable from a position away from the guide bar and saw chain to a position in protective proximity with the saw chain along the uppermost edge of the guide bar.
It is still a further object to provide a lightweight safety guard for chain saws, comprising a protective screencarrying frame and a guard strip mounted on the housing or handle of the chain saw for pivotal movement from -a position away from the guide bar and saw chain, to a position adjacent to the saw chain, upon pressure by the arm or body of the operator of the chain saw, said guard strip being extendible upon contact with the saw chain to protectively cover the saw chain along the upper edge of the guide bar.
These and other objects of the invention will become apparent from the following description in conjunction with the accompanying drawings wherein:
FIG. 1 illustrates, in perspective view, a chain saw of known construction having positioned thereon the safety guard or device of the present invention;
FIG. 2 illustrates a chain saw in use and shows the operation of the safety guard;
FIG. 3 illustrates, in side view, a portion of a known chain saw showing the safety guard attached thereto;
FIG. 4 illustrates, in front view, the chain saw safety guard positioned on a chain saw of known construction;
FIG. 5 is a top view of a portion of the safety guard;
FIG. 6 illustrates, in side sectional view along line 6-6 of FIG. 4, the safety guard removed from the chain saw and with the slide guard feature in retracted position;
FIG. 7 is similar to FIG. 6 but shows the slide guard in extended protective position over the moving chain;
FIG. 8 is an enlarged sectional view of the safety guard taken along line 88 of FIG. 4.
Referring now specifically to the drawings, in FIG. 1 a chain saw of known construction and operation is shown generally at 2 The chain saw consists basically of a motor and motor housing 4, which motor either may be of electric or internal combustion manufacture, operating and carrying handles 6 and 6', an elongated saw chain guide bar 8, and a saw chain 10 carried by the bar 8 and rotating in the direction of arrows 12.
The saw may cut either on the upstroke or downstroke, and it is important that any safety guard leave the full cutting area free, as a guard which covers any portion of the saw chain will quickly be rejected by a Woodsman as impairing efficiency. Due to the direction of rotation of the saw chain the encountering of the chain with any obstacle, or binding of the chain, will kick the saw upwardly from the tree and back toward the operator, as shown by arrow 14 in FIG. 2. Unless the operator is using extreme caution, or the saw is fitted with a suitable safety guard, serious accidents, which at times are fatal, can occur.
In the drawings the guard of this invention is shown as having a U-shaped frame member 16 of tubular material, pivotally secured to the chain saw at the extremity of one of the arms of the U by means of pin 18, which may be a rivet, or a bolt and nut, or the like.
Secured to the other arm of the 'U-shaped frame by means of brackets 20, or other attachment means, is an extendible guard strip shown in the drawings generally at 21, which will be explained in more detail hereafter. The end of strip 21 projects past the end of the arm to which it is fixedly secured and is pivotally secured to the housing of the chain saw by means of a pin 24.
Positioned within the frame 16 is a wire (or the like) screen 26, which should be of a mesh size sufficient to enable substantially unrestricted vision therethrongh and yet be small enough to form a protective screen to protect the operator from flying wood chips. The framing member 16 also serves the important function of pivoting at 18 and 24 toward the chain upon contact with any part of the operators body to bring the associated extendible guard strip 21 in contact with the chain 10, as will be described in more detail hereafter.
In the drawings the framing member is shown as being tubular. This construction enables maximum strength with minimum weight, but other constructions are of course within the scope of the present invention.
The frame 16 may be attached to the handle 6 or housing of the chain saw at any convenient position, and all that is required is that the safety guard is pivotable from the upright out-of-the-way position shown in FIG. 1, to the down position shown in FIG. 2. The frame 16 is normally retained in the position shown in FIG. 1 and completely clear of the saw cutting area by means of a spring 28 fastened at one end to the frame 16 and at the other end to any convenient location on the chain saw housing.
As noted above, secured along one arm of the frame 16, and directly above and intersecting the plane of the chain bar 8, is an extendible guard strip 21 consisting of a stationary guard strip 22, a slide guard strip 30 which is extendible to a length substantially of that of the guide bar 8, and a support sheath 31 which is attached to frame 16 by means of brackets 20.
A specific construction for the extendible guard strip 21 is shown in FIGS. 3 to 8 of the attached drawings, but other constructions are of course possible as long as the novel protective results are obtained. Moreover, the drawings clearly show the end 32 of the stationary guard strip 22 pivotally attached to the chain saw housing and one end of the frame 16 pivotally attached to the guard strip. However both arms of frame 16 could be pivotally attached to the chain saw and the stationary guard strip 22 secured to the frame arm.
The slide guard strip 30 is carried by the stationary guard strip 22 and is extensible or slidable from the retracted position shown in FIG. 6 to the extended position shown in FIG. 7.
The end of the slide guard strip 30, remote from the chain saw motor, is provided with a small flange 34 directed downwardly toward the saw chain, and the other end of the slide guard strip is provided with a small angled flange 36 which rides Within an elongated slot 38 provided in the support sheath 31, enabling longitudinal extension movcment of the slide 30 with respect to the strip 22, but preventing separation of the guard strips 22 and 30 at maximum extension.
During operation of the saw, spring 28 will hold the frame 16 and extendible guard strip assembly 21 in the upright position shown in FIGS. 1, 3 and 4 and clear of the cutting area of the chain 10. The slide guard strip 36 fully retracts within support sheath 31 where it is completely out of the way, preventing obstruction of vision and entanglement with branches, foliage, etc.
When the chain hits an obstacle, or binds and kicksback as it will do in the direction of arrow 14 in FIG. 2, and the kick-back is severe enough and/or the op erator totally unprepared, the frame 16, screen 26 and/or guard strip assembly 21 will contact a portion of the body of the operator, such as his arm as in FIG. 2, and the frame 16 will pivot forwardly against the tension of spring 28 to lower the extendible guard strip 21 into protective proximity over the moving saw chain 10 along the upper edge of guide bar 8, as will clearly be evident from FIG. 2. It should be noted here that the side of the support sheath 31 which will be adjacent the chain 10 may have a longitudinal groove, as shown at 40 in FIG. 8, or should at least be smooth With no transverse projections or irregularities which would interfere with the smooth movement of the saw chain therealong.
The pivoting of extendible guard strip assembly 21 into protective proximity with the chain, will cause the chain to contact flange 34 on slide guard strip 30 and cause strip 30 to slide or extend with respect to stationary guard strip 22 to form an extended guard strip (see FIG. 7) which completely covers the chain on the upper edge of bar 8 in protective fashion, as shown in FIG. 2. Strip 30 will extend only until flange 36 comes to the end of the slot 38 provided in the support sheath 31.
Stop 42 is provided on the chain saw housing to limit the pivotal movement of the guard, to prevent the guard bearing against the hand of the operator holding handle 6.
What I claim is:
1. A safety guard for chain saws of the type having a motor, motor housing, handles, a chain saw guide bar, and saw chain, said guard comprising a frame and an extendible guard strip pivotally secured to the saw housing or handles adjacent the innermost end of the guide bar, the frame and guard strip being pivotable from a position away from the saw chain to a position adjacent with the saw chain, and said guard strip being extendible upon contact with the saw chain to protectively cover the chain along the upper edge of the guide bar.
2. A safety guard according to claim 1, wherein the extendible guard strip is formed of a stationary guard strip and a slide guard strip longitudinally slidable with respect to said stationary guard strip upon contact of a downwardly extending flange carried by the slide guard strip by the saw chain.
3. A safety guard according to claim 1 wherein said frame and said extendible guard strip are normally pivoted to a position away from the saw chain under spring tension.
4. A safety guard according to claim 2 wherein the frame is of generally U-shaped configuration having protective screening positioned within the U-shape.
5. A safety guard according to claim 4 wherein the stationary guard strip is secured to one arm of the U- shaped frame.
6. A safety guard according to claim 1 wherein the frame and extendible guard strip are provided with a protective screen.
7. A safety guard according to claim 4 including a support sheath attached to said frame and wherein said stationary guard strip is secured within said sheath and said slide guard strip is longitudinally slidablc within said sheath.
References Cited UNITED STATES PATENTS 2,937,673 5/1960 Duperron et a1 143-32 3,059,673 10/1962 Woleslagle 143-32 FOREIGN PATENTS 746,304 11/1966 Canada.
DONALD R. SCHRAN, Primary Examiner.