DE2654273A1 - CHAINSAW - Google Patents

Description

TEXTRON INC.

40 V / Estminster Street

Providence, Rhode Island 02903

CHAINSAW

The invention relates to motorized chain saws, and in particular an anti-kickback device to prevent kickback or slinging of the Saw.

Chainsaws are widely used nowadays by professional forestry loggers as well as by laypeople such as homeowners, farmers, farmers, and the like. Considerable research and expense has been devoted to cutting performance and durability to improve chainsaws and at the same time reduce their manufacturing costs and their risk of accidents. When used correctly, the chainsaw is relatively safe. However, situations can arise during their use which pose a danger to the user. In this context it should be mentioned that the largest number of accidents with chainsaws are caused by so-called skidding or kickback. This phenomenon occurs

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when the chain comes into initial contact during its revolution around the nose portion of the guide body occurs with an object. Then the chainsaw is thrown or knocked back against the user, whereby it can cause serious injuries to the user, depending on the force of the kickback and depending on the extent to which the user is prepared for the occurrence of a kickback is.

The industry is aware that the occurrence of the backlash is a general danger and is the main cause of chain saw accidents. The cause is partly due to the inexperience of many users, so that even small setbacks are dangerous when the user is not ready. On the other hand, they are often also very experienced, professional Users who keep a close eye on the risk of kickback, unable to control kickback, This is because it is impossible to predict when a kickback will occur and because of the considerable kickback forces.

Han has therefore made considerable research and experimentation to determine the causes and frequency of setbacks, namely in the Hope to solve and eliminate this problem. For example, in Sweden commissioned the safety Counsel National Board of Industrial Safety the Swedish National Machine Testing with an investigation to order alongside other factors the spin frequency of motorized ones Detect chainsaws. The Swedish National Machine Testing carried out a series of comparative tests, '

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the results of which on February 6, 1974 in a pamphlet entitled "The Throw Tendency and Cutting Capacity of Power Saw Chains". Also were previous tests conducted by the Swedish Forest Products Research Laboratory to determine the skid range and to determine the spin frequency when sawing with different chains. The results were published in the 1970 "Forest Products Research Laboratory Report, Series B, No. 37" published. The results of this and other experiments show, that regardless of the type of The chain used is always at risk of kickback if the chain rotates around the the upper portion of the nose region of the guide body is brought into contact with an object.

A variety of measures have been taken in an effort to reduce the risk of setback, but to date none of these measures has been able to prevent setbacks from occurring. An earlier attempt was to fasten a shield on the housing of the chain saw in order to prevent in this way that the upper run aer chain touches the user in check. However, shields of this type are disadvantageous, primarily because they do not prevent kickback, but merely work to reduce the risk of kickback. Another disadvantage is that the chainsaw becomes heavier and that the user's overview is often blocked. The shield can also hinder the sawing process.

Another measure was the introduction of a so-called safety chain to eliminate the danger

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of setbacks. Considerable research has been carried out to develop a particular safety chain that has a reduced tendency to kick back. While advances have been made in this area, it has not been possible to develop chains that do not have the ability to kick back while in use. The main disadvantage of the so-called safety chain is that the design changes made to the chain to limit kickback have a negative effect on the cutting performance of the chain. A further disadvantage is that depends on the kickback tendency of a chain of a plurality of chain properties, for example of the form of adjustment, the chain state, the cutting angle, the sharpness, the degree of wear and the chain tension. Accordingly, a change in any one of these factors affects the kickback tendency of the chainsaw. - ■ ■

Another measure to deal with the kickback problem was the introduction of the chain brake. Chain brake mechanisms are typically built into the chain saw housing and respond to the chain saw's movement during kickback to automatically and quickly decelerate and stop the chain before it touches the user. Chain brakes typically require a stop time on the order of 100 milliseconds to be effective. The chain brake mechanisms currently available are essentially effective when the chainsaw is new. However, after a short period of on-site use, the mechanism becomes dirty, sawdust and other debris, increasing the stop time to too long to be effective. The chain brake mechanism will also corrode and rust

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often after prolonged use of the chainsaw, making it even more ineffective. Another disadvantage of chain brakes is that the user assumes that the chain brake will automatically and safely stop the chain in the event of a kickback and thereby bring him completely out of danger. As a result, the user tends to be less careful than he otherwise would be. Unfortunately, the Kottenbrake only stops the chain from moving and has no effect on the chainsaw kicking back hard, which can still cause serious injury to the user. In addition, the Kettenbrernsen are progressively less effective while using d r chainsaw, and the user has no practical means by which it can periodically check the performance of the chain brake. Another disadvantage of most chain brake mechanisms is that they rely on a lever or the like. respond, which is swiveled by the user in the initial phase of kickback in order to operate the chain brake. In some sawing operations, however, for example when making a felling cut, the user holds the saw in such a way that the pivoting device is bypassed while it is being pushed back. This means that the chain brake remains inactive. This disadvantage has been overcome to some extent by the use of inertial chain brakes, but it is still a problem with most chain brakes. Legislation in some countries is in the process of making chain brake mechanisms mandatory for all motorized chain saws. However, this is undesirable, not only because of the ineffectiveness of chain brakes to prevent kickback, but rather

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also because of the increased cost of chainsaws that one Chain brake mechanism brings with it.

The main object of the invention is to provide a To create an anti-kickback device that prevents chainsaws from kicking back at all, and this is in contrast to prior art devices which attempt after kickback has occurred to control and compensate for the latter. The device according to the invention is therefore intended to kick back effectively avoid the chainsaws and thereby overcome the disadvantages of the prior art indicated above. The device should be economical to manufacture, require no maintenance, be stable and have durable construction and also be more effective than known devices, which prevents injuries due to kicking back.

Furthermore, the possibility should be created within the scope of the invention to provide an anti-kickback device which is releasably attached in the nose area of the guide body and can accordingly be removed so that the saw can be used for drilling and other operations in which the chain used while circulating over the nasal area.

In addition, the anti-kickback device according to the invention should have the advantage that they Construction prevents the chainsaw from being pulled out of a cut, forcing the user will lift the saw out of the cut; this will prevent injuries to the legs that would otherwise

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occur when pulling the saw out of the cut could.

According to a further aspect, the anti-kickback device according to the invention to be able to touch the chain while it is around the nose area of the Guide body to prevent running around with the ground so that objects can be cut while doing this lie lengthwise on the floor.

The invention is also directed to the creation of a guide body for the saw chain, which is releasably attached to a Chainsaw housing is attached and in its nose area carries an anti-kickback device that during effective kickback when using the chainsaw prevented.

Finally, the invention is directed at creating a motor-driven chain saw with an anti-kickback device in the nose region of the guide body, to prevent flashback in We.ise effective during use of the saw.

In one of its embodiments, the anti-kickback device is according to the invention characterized by a plate-shaped element which is detachable in the nose area of the Guide body is attached and extends arcuately over a predetermined sector of the nose area as well as projecting radially outwardly beyond the nasal area by a distance greater than the outermost radial extension of the chain as it travels over the nose area, causing the chain to come into contact is prevented with any object in that section in which it runs over the nose section. The plate-shaped element can end in an inwardly turned lip which extends against the guide body to keep the chain around the nasal

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include the area in an effective manner. The anti-kickback device can be permanently or detachably attached to the guide body. After another, preferred one Embodiment are two complementary, plate-shaped elements attached to opposite sides of the guide body, each element in a bent lip ends, which is directed inward against the other bent lip, in this way the Complete the chain as it circulates over the nasal area. The two plate-shaped elements can be permanently or detachably attached to the guide body. If the guide body is a construction made up of plates, the inventive Anti-kickback device consist of an extension of the outer side plate of the guide body, this construction is possible regardless of whether the anti-kickback device is made a plate-shaped element or is composed of two plate-shaped elements.

'Further advantages and features of the invention result from the following description of preferred exemplary embodiments in connection with the enclosed Drawing. The drawing shows:

Figure 1 is a perspective view of a motorized chainsaw with an anti-kickback device according to the invention;

FIG. 2 is a diagram for explaining the kickback phenomenon;

FIG. 3 shows a side view of an exemplary embodiment for a chainsaw guide body with an anti-kickback device according to the invention;

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Figure 4 is a cross section taken along line 4-4 in Figure 3;

Figure 5 is a side view of a further embodiment for a chainsaw guide body with a Anti-kickback device according to the invention;

Figure 6 is a cross section taken along line 6-6 in Figure 5;

FIG. 7 shows a side view of a further exemplary embodiment for a chainsaw guide body with a Anti-kickback device according to the invention;

8 is a cross section along the line 8-8 in Figure 7;

FIG. 9 shows a side view of a further exemplary embodiment for a chainsaw guide body an anti-kickback device according to the invention;

Figure 10 is a cross section taken along line 10-10 in Figure 9;

FIG. 11 shows a side view of a further exemplary embodiment for a chainsaw guide body with a Anti-kickback device according to the invention;

Figure 12 is a cross section taken along line 12-12 in Figure 11.

Figure 1 shows an example of a motor-driven chain saw equipped with an anti-kickback device according to the invention. It is a chain saw designed to be operated by a single user. The chain saw comprising a drive unit with a motor 10 which is fixed to the housing of the chain saw and drive-

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moderately connected to a chain 11, which is about a guide body 12 runs. The engine 10 is a single cylinder internal combustion engine known in the art Design type. On the housing, a front handle 14 and a rear handle 15 are attached to a Allow individual users to hold and operate the chainsaw. At the nasal area of the Guide body 12 is an anti-kickback device 20 attached. Your radial extension is sufficient, sufficient to project far beyond the outermost radial extent of the chain 11. This will keep the chain in place while it's over runs the nasal area, prevented from touching any objects.

Before the various possible embodiments of the anti-kickback device according to the invention are described in detail, it appears useful to discuss the phenomenon of kickback in order to contribute to a better understanding and better appreciation of the invention. Figure 2 shows a diagram to explain in which some kickback forces are generated during use of a motorized chain saw. The chain and its direction of movement around the guide body are indicated as dash-dotted arrows. For explanation it is assumed that the chain comes into contact with a stationary object at the point shown in the drawing. As soon as it is touched, the object exerts a reaction force on the saw. The latter acts tangentially to the curved path of movement of the chain. This reaction force is referred to as the impact force or kickback force and is shown as a dashed arrow.

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According to FIG. 2, the kickback force can be broken down into its horizontal and vertical components. The horizontal component is directed in the axial direction along the guide body and tends to move the chainsaw backwards towards the user. The vertical component is called the rotary component and tends to move the saw upwards and to rotate it around its center of gravity. The rotational force is the upward force that acts on the nose section of the guide body and the saw can be rotated about its center of gravity, while the axial force is the force that acts through the guide body to the rear along the axis of the guide body. It is the combination of these two forces that the saw up and .rückwärts against "moves the user. This kind of movement of the chain saw is the phenomenon known under the name check or skidding. While the setback is the considerable kinetic energy in The rotating parts of the chainsaw are abruptly converted into an upward and backward movement of the saw against the user, which is an extremely dangerous condition.

Numerous studies have been carried out to determine the principal factors responsible for kickback and the zone where the maximum kickback occurs. According to the invention, it was found that the zone of maximum kickback is essentially between 10 and 40 above the center line of the nose section of the guide body. This area is shown in dashed lines in the figure and represents the stroke area.

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All references to kickback or slinging in the present description relate to reaction effects that occur in the nasal area of the guide body. The kickback phenomenon must be distinguished from other reactions, in particular from those reactions which occur when the upper or lower run of the chain is brought into contact with an object. If the upper run of the chain is brought into contact with an object, this condition is called an undercut, with the reaction force directed axially backwards towards the user. This condition does not represent too great a risk, as there is no vertical or rotary component. The only movement of the chainsaw is directed backwards towards the user. Similarly, when the lower run of the chain is brought into contact with an object, the reaction force is axially forward so that the saw is pulled forward toward the object. This is the common way in which chainsaws are used.

In Figure 2, the outline of the anti-kickback device 20 is superimposed on the guide body. It follows readily that this device effectively eliminates and prevents kickback by preventing the chain from touching an object while the chain is running over the nose portion of the guide body. Since the maximum kickback occurs in the range of 10 to 40 above the center line of the guide body, the anti-kickback device can be designed with an included angle of 90 °. It thus prevents kickback within a range of 45 above and below the center line of the guide body. The preferred one

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closed angle is between 90 and 120 but can be up to 180 if desired. Most guide bodies are designed so that they do not have a predetermined upper or lower edge. There is thus the possibility of fastening the guide body to the housing of the chainsaw in the opposite manner in each case, so that the upper edge in one orientation becomes the lower edge in the opposite orientation. You can use it to turn the guide body over after a certain period of use »whereby the worn lower edge becomes the upper edge, while the relatively little worn upper edge forms the lower edge. This extends the effective life of the guide body. For this reason, according to the invention, the included angle can extend evenly upwards and downwards, based on the center line, so that the anti-kickback device is effective regardless of the orientation of the guide body. From the above it follows that the anti-kickback device according to the invention completely prevents any kickback, regardless of the chain speed and regardless of the angle relative to the center line at which the object comes into contact with the rabbit area. In contrast to known devices which only sought to "prevent the effects of the kickback after it has occurred, the anti-kickback device according to the invention already avoids the occurrence of the kickback. This is an essential advantage.

An exemplary embodiment of the anti-kickback device will now be described in detail with reference to FIGS. 3 and 4. The anti-kickback device 20 has a substantially plate-shaped element with a side wall 21 which is in the shape of a sector of a circle

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having, and with a connecting portion 22 for connection the device to the guide body of the chainsaw. The side wall 21 has two radial edges 23 and 24 which lie on radii of the sector, as shown in dashed lines Lines in Figure 3 is shown. The included angle between the radial edges 23 and 24 is preferably between 90 and 120, which actually results in a kickback over the entire range, in which a kickback could so''n occur, is avoided. If desired, you can choose the included angle Increase to 1S0. The side wall 21 has a peripheral edge 25, which is the outermost tips of the radial Edges 23 and 24 connects to one another.

According to Figures 3 and 4, the anti-kickback device 20 is attached to a guide body which has a layered construction. It should be noted, however, that this device can be attached to guide bodies in the same way and can be used with guide bodies which have a solid construction. It is well known that guide bodies can be built as a solid structure or as a plate structure. A solid guide body normally consists of a single steel plate whose peripheral edge is machined to form a circumferential groove for guiding the chain. A layered guide body can consist of three steel plates whose combined wall thickness corresponds to the thickness of the desired guide body this case have the two outer plates of the same size and shape, while the iMittelplatte which lies between the two outer plates, while a similar shape but having a smaller size. thus, when these plates are assembled, the peripheral edge of the center plate at a distance is within the circumferential edges of the two outer plates, creating a circumferential groove for guiding the chain.

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In the illustrated construction of the guide body consisting of layers, a sprocket is rotatably mounted in its nose area between its outer plates, as shown in broken lines. The middle plate is shortened so that there remains a free space to accommodate the sprocket. Such chain wheels are well known and are used to support the guidance of the chain around the curved nose area and thus to reduce the friction and the chain load and to extend the service life of the guide body and chain.

According to a special feature of the invention, the anti-kickback device 20 can be either permanently or detachably attached to the nose area of the guide body, in both cases a rigid connection which does not allow any relative movements between the device 20 and the guide body. In the embodiment according to FIGS. 3 and 4, the anti-kickback device is permanently attached. The fastening means comprise four rivets, in this case those rivets which are used to fasten the sprocket to the guide body. The rivets are inserted through holes in the connecting section 22, so that in this way the permanent connection between the nose area of the guide body and the device 20 is created. The non-detachable fastening is the preferred construction, since the user of the chainsaw prevents the anti-kickback device from being removed. This ensures that the anti-kickback device is attached to the chain saw whenever it is used. In certain applications, however, it may be desirable "to remove the anti-kickback device. The professional woodworker will do the latter if he wants to use the wet area of the chainsaw for drilling."

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“For this reason it may be practical in some cases to detachably attach the anti-kickback device”

Another aspect of the invention is best shown in FIG. 4. Then that part of the side wall 21 which extends beyond the nose area of the guide body is widened outwards in order to adapt to the chain 11 and to create sufficient free space for it that the cutting operation of the chain is not hindered "i4an can form the expanded section in that one bends the plate-shaped member to the outside, -wherein a rising wall portion 21a is formed to which a turn of radially extending, flat V </ andabschnitt 21b connects . The latter protrudes beyond the outermost tip of the chain. The outer edge of the wall section 21b is bent inward to form an inwardly directed wall section 21c in the form of a bent lip. The wall portions 21 define-a to 21c of the side wall 21 of the annular cavity for receiving the chain, in adaptation to letztere.-currency-rend normal use of the chain saw, it is unlikely that an object which might cause a setback from the Side comes into contact with the chain instead of the front »Therefore, it is usually not necessary to completely encapsulate the chain to avoid kickback. The annular cavity can therefore remain open on one side. However, it is essential that the side wall 21 extends in the radial direction at least over the outermost extent of the chain while it is running around the nose area, so that when the user tries to bring the nose area of the guide body into contact with an object, the end of the side wall 21 strikes the object and a contact between

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Object and chain prevented.

An advantage of this embodiment is that the anti-Rückschlagvorrichrtung is designed as a unitary construction in one piece, which simplifies its manufacture and attachment to the guide body. In addition, the anti-kickback device not fully abkapselt the nose area of the guide body. The J-Cette can therefore be exchanged in a simple manner without the need to remove the anti-kickback device made of a different material with comparable strength. In this way the weight of the chainsaw is not increased unnecessarily.

FIGS. 5 and 6 show a further exemplary embodiment of an anti-kickback device, to be precise in application to a guide body of solid construction. This anti-kickback device 30 consists of two complementary sections 31 and 32 which are each attached to opposite sides of the nose area of the guide body. The section 31 has a side wall 33 and a connecting section 35, the latter being formed in one piece and preferably formed from a single part of a plastic-like raw material. The side wall 33 has an enlarged wall section 33a, which is similar in its curvature to the curved nose area and overlays the latter. The widened wall section 33a continues into an adjoining, flat wall section 33b, which in turn is integral with an inwardly curved wall section 33c and / or. is connected to such a lip. Similarly, the other element 32 has a side wall 34 which is connected to an attachment portion 36 and an enlarged wall portion 3Aa,

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one flat flange portion 34b and one curved inward Has wall portion 34c.

In the present embodiment, the two elements 31 and 32 are detachably connected to the nose area of the guide body by means of a set of screws and nuts. According to the drawing, three threaded screws 37 extend through openings in both elements and through openings in the guide body, the elements being held in place by locking washers 38 and nuts 39 screwed onto the ends of the screws. Although a screw and nut fastening was shown here for the sake of explanation, it should be pointed out that all corresponding fastening and connecting means can be used to fasten the anti-kickback device to the guide body. It should also be pointed out that the anti-kickback device can be releasably connected in the same way to a guide body made up of plates.

As best seen from Figure 6, the anti-kickback device 30 forms according to its attachment to the nose area de.s guide body an annular cavity around abkapselt the chain during its path around the nasal area substantially. Sufficient play is ensured so that the device does not obstruct the movement of the chain. In this embodiment, the radial extension of the two side walls 33 and 34 including their inwardly curved wall sections 33c and 34c effectively prevents the chain from touching any object while it is running over the nose area of the guide body. Accordingly, the chainsaw cannot kick back.

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if the anti-kickback device is attached.

If desired, the anti-kickback device 30 can be removed quickly by simply turning the nuts 39 and unscrews the lock washers 37. The fact that 'in this embodiment the chain is completely from the anti-kickback device is encapsulated, it is necessary to replace the chain with this device removable. *

Figures 7 and 8 show a further embodiment of an anti-kickback device according to the invention. This anti-kickback device 40 is inextricably connected to a guide body made up of plates. Otherwise, the device 40 is constructed similarly to the construction according to FIGS. 5 and 6, except that the inwardly directed wall sections or lips are missing. More precisely, the anti-kickback device 40 comprises two complementary elements 41 and 42, each having side walls 43 and 44 and fastening portions 45 and 46, respectively. It is unnecessary to mention further details, since these correspond to FIGS. 5 and 6. The non-detachable attachment of the anti-kickback device 40 to the laminated guide body is provided by rivets, which are provided to attach the chain wheel.

In this embodiment, the peripheral edges of each element 41 and 42 do not have inwardly curved edges Wall sections or lips, so that each side wall consists of a simple sector of a circle with a stepped shape consists. Also, the distance between the two elements 41 and 42 is so narrow that it is extremely unlikely

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that an object which is able to cause kickback can be introduced between the two elements during the sawing process. Accordingly, it is unnecessary sichj the edges of the elements 41 and 42 to bend inward _s um'einem setback avoid "It is only necessary to put the two elements so far apart that, interference is avoided with the chain" Even should the two Elements be preferred radially over the outermost radial extent of the chain encircling the nose section.

According to the further exemplary embodiment according to FIGS. 9 and 10, the anti-kickback device 50 consists of extensions on the side plates of the guide body. This embodiment is only suitable for guide bodies made up of plates, since massive guide bodies do not have side plates. According to FIGS. The left outer side plate 51 carries an extension 52 with an enlarged edge portion 52a and a flat V-wall portion 52b. Similarly, the right outer side panel 54 carries an extension 55 with an enlarged flange portion 55a and a flat wall portion 5b. The widened wall sections 52a and 55a are bent outward enough to match the width of the chain = In addition, the flat wall sections 52b and 55b extend radially outward enough to prevent the chain from moving around to abut the nose area of the guide body against an object. The anti-kickback device 50 is inextricably linked to the guide body because it is part of the

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represents the latter. Additional components are not required.

In this exemplary embodiment, the marginal edges of the guide body extensions are not bent inwards, which means that the chain can be easily removed and replaced. If desired, one of the flat wall sections 52b or 55b or both wall sections can be bent inward by a small amount, provided that there is sufficient free space to allow the chain to be removed. As explained above, to prevent kickback during normal use of the saw it is not necessary to bend the edges inward as it is extremely unlikely that an object capable of kickback would be between the two Extensions 52 and 55 will fit.

In the further embodiment of the anti-kickback device according to the invention according to FIGS. 11 and 12, this device 60 consists of a connection. 'Extension of only one of the outer side plates of a guide body built up in layers. According to the drawing, the right outer side plate 61 carries an extension 62 which, according to its shape, is designed as an anti-kickback device 60. The extension 62 has an extended wall portion 62a that is bent from the guide body to the outside and terminating in a flat wall portion 62b. The latter has a radial extension that is greater than that of the chain. A wall section 62c bent inwardly as a lip is connected to the flat wall section 62b, the wall sections 62a, 62b and 62c forming an annular cavity for receiving the chain. With such a construction, the anti-kickback device effectively prevents contact of the around the nose area

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running chain with some object.

In all embodiments, the anti-kickback device extends over a predetermined angular range of the nose section and protrudes over the nose section in the radial direction by an amount which is greater than the radial extent of the chain. In this way it is prevented that the chain strikes against any object while it is running around the predetermined angular range of the nose section. A kickback of the chainsaw cannot occur, since the anti-kickback device prevents the chain from touching any object in the area in which kickbacks would be possible. Consequently, when using a chain saw having an anti-kickback device according to the invention, it is impossible for the user to induce kickback conditions since he is unable to bring the chain into contact with any object as it moves around the nose area due to the presence of the anti-kickback device.

The anti-kickback device according to the invention has further secondary parts, apart from the fact that it prevents kickback. Jams, for example, when cutting a bar ο .'dgl. the saw in the beam, the user has no way of pulling the chainsaw backwards out of the cut, due to the arrangement of the anti-kickback device which is arranged on the guide body. Rather, the user has to lift the saw upwards. The advantage here is that injuries to the legs, which could otherwise occur if the chainsaw were pulled out of the cut with the chain running, are avoided. Another advantage is that the anti-kickback device in the nose area of the guide body

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effectively prevents it from coming into contact with the ground. It is well known that dirt and other contaminants cause it rapid dulling of the cutting edges the chain, which happens again and again when the user Cuts objects lying on the ground. At a Chainsaws equipped with an anti-kickback device, on the other hand, will touch the chain • Interfered with the earth when using the nasal area dragging across the floor. ^ This avoids one of the essential causes of the chain becoming dull.

It should also be mentioned that modifications and adaptations are readily possible within the scope of the invention.

In summary, the invention provides an anti-kickback device to prevent a chainsaw from kicking back. In one embodiment, this device exists from a plate-shaped element, which on

Is attached to the nose area of a guide body and in the;

essentially has the shape of a sector of a circle, which extends arcuately over a predetermined sector of the nose area and projects radially outward from the nose area by a distance which is greater than the outermost radial extension of the chain as it travels over the nose area, by one Avoid contact of the chain with any object in the area in which the chain moves over the nose area. This prevents kickback which could otherwise occur. The plate-shaped element can terminate in an inwardly curved lip which is inwardly

is directed against the guide body to the chain I.

to essentially enclose 'i during their way over the nasal area. The device can be unsolvable or detachable!

attached to the guide body. For another ^: i

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Embodiment are two complementary plate-shaped Elements attached to opposite sides of the guide body, each element in an inwardly curved manner Lip, which is directed inward against the other lip, in order to keep the chain in this way their way around the nasal area. The two plate-shaped elements can be undetachable or detachable Guide body be attached. Owns the guide body a history construction, so can the anti-kickback device be designed as an extension of at least one of the side plates of the guide body. This construction can also be used when the anti-kickback device consists of two extensions of the side plates, ie consists of two plate-shaped elements.

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Claims (24)

PATENT CLAIMS 1 J Motorized; One-man chainsaw with a housing, with a guide body attached to the housing, which carries a device for guiding a chain on its peripheral edge, with a chain running over the peripheral edge of the guide body and with a device which has a pair of handles attached to the frame to allow a single user to hold and manipulate the chainsaw while it is operating,
marked by an anti-kickback device (20,30,40,50,60), which on Nose portion of the guide body (12) is attached and extends only over the nose area as well during use of the chain saw when sawing an object takes effect around the chain (11) when walking around to prevent a predetermined sector of the nasal area from contacting the object and thereby effectively preventing the chainsaw from kicking back against the user. 709831/0250 Il Ι | , j, » 2. Chainsaw according to claim 1, characterized in that that the anti-kickback device is inextricably linked to the nose area is attached. 3. Chainsaw according to claim 1, characterized in that that the anti-kickback device is releasably attached to the nose area. 4. Chain saw according to one of claims 1 to 3, characterized in that the anti-kickback device has a plate-shaped element which is attached to one side of the nose region of the guide body and has a substantially circular sector which extends over a predetermined angular range of the nose region and protrudes radially outwardly therefrom by a distance which is greater than the outermost radial extension of the chain, so that the chain is prevented from contact with the object during its revolution around the nose region. 5. Chainsaw according to claim 4, characterized in that the anti-kickback device has a further plate-shaped element which is attached to the other side of the nose area of the guide body and corresponds in its shape to that of the first-mentioned plate-shaped element, which to the first. Side of the nose area of the guide body is attached. 6. Chainsaw according to claim 4 or 5, characterized in that 709831/0250 -32- that at least one of the plate-shaped elements ent-. , long its outer circumferential edge carries an inwardly curved lip which protrudes inward, around the chain during to partially enclose their way over the nasal area. . 7. Chainsaw according to one of claims 4 to 6, characterized in that that the guide body is constructed as a layered construction and has a central plate which lies between two outer plates / and that the plate-shaped element is an integral extension of one of the. two outer plates. ' 8. chainsaw according to one of claims 4 to 6, characterized in that that the guide body is constructed as a layered construction and has a central plate which lies between two outer plates, and that the plate-shaped. Elements each form an integral extension of the associated outer panels. 9. guide body for a one-man chainsaw having disposed on the Urnfangskante means for guiding a chain during use of the guide body, characterized by an anti-kickback device which is attached to the nose area of the guide body and extends only over the nose area and prevents the chain during its way over a predetermined sector of the nose area during the use of the chain saw by a single user to saw the object touch, making a 'kick-back of the chain saw is prevented against the user effectively. 709831/0250 10. Guide body according to claim 9, characterized in that that the anti-kickback device is permanently attached to the nose area. 11. Guide body according to claim 9, characterized in that that the anti-kickback device is releasably attached to the nose area. 12. Guide body according to one of claims 9 to 11, characterized, that the anti-kickback device has a plate-shaped element which is attached to one side of the nose area of the guide body and has a section shaped essentially as a circular sector which extends over a predetermined sector of the nose area and projects in the radial direction therefrom by a distance, which is greater than the outermost radial extension of the chain, so that the chain is prevented from contact with the object during its revolution around the nose area. 13. Guide body according to one of claims 9 to 12, characterized in that that the anti-kickback device is another plate-shaped Has element which is attached to the other side of the nose region of the guide body and in its shape corresponds to that of the first plate-shaped element, which faces the first-mentioned side of the nasal region. is arranged rich of the guide body. 14. Guide body according to claim 12 or 13, characterized in that 709831/0250 •> I) that at least one of the plate-shaped elements along its outer peripheral edge is an inwardly curved one
Lip facing inwards to partially close the chain as it travels over the nasal area
enclose. 15. Guide body according to one of claims 9 to 14, characterized, that it has a layered construction and a Has central plate, which lies between two outer plates, and that the plate-shaped element is a one-piece Forms extension of one of the two outer plates. 16. Guide body according to one of claims 9 to 14, characterized, that it has a layered construction and a t-'vibrating plate which has two outer plates and that the plate-shaped elements each have one form an integral extension of the associated outer side panels. 17. Anti-kickback device for a guide body a one-man chainsaw to prevent kickback the chainsaw, marked by a plate-shaped element having a fastening portion for fastening the device to one side of the nose region of the guide body and having a side wall which is formed in one piece with the fastening portion and is essentially shaped as a sector of a circle and is dimensioned such that it extends over a predetermined sector of the nose region and from this protrudes radially by a distance which is greater than the outermost radial extent of the chain during its movement over the
Nasal area, whereby the chain is in that 709831/0250 1 I I -30 - rich, in which it runs over the nasal area contact with any objects is prevented, so that kicking back the chainsaw in more effective Way is prevented; wherein the plate-shaped element has no handle and its shape does not offer the possibility of using the chainsaw to be grasped manually by another person. 18. Anti-kickback device according to claim 17, characterized by another plate-shaped element similar to that after Claim 17 disposed on the other side of the nose portion. 19. Anti-kickback device according to claim 17, characterized in that that the side wall portion carries on its outer peripheral edge an inwardly curved lip which is directed inwardly in order to partially cover the chain as it passes over the nose area. 20. Anti-kickback device according to claim 18, characterized in that that at least one of the side wall sections. along its outer peripheral edge an inwardly curved one Lip facing inward to partially close the chain as it travels over the nasal area enclose. 21. Chainsaw according to one of claims 1 to 8, characterized in that that the anti-kickback device is arranged immovably on the nose area of the guide body. 22. I-lotor-operated one-man chainsaw with a Guide body which carries a device for guiding a chain on its peripheral edge and with one along it 709831/0250 the circumferential edge of the guide body movable chain,
marked by an anti-kickback device attached to the nose area of the
Guide body is arranged and extends only along the nose area and when the chain saw is used by a single user to saw an object in an effective manner prevents the chain from coming into contact with the object during .Ihres over a predetermined sector of the nose area, whereby a kickback of the chainsaw against the user is actually avoided, the anti-kickback device not having any handles. and its shape
does not offer the opportunity to use the
Chainsaw picked up manually by a second person
to become. 23. Guide body according to one of claims 9 to 16,
characterized, that the anti-kickback device is so small in size
and is of such a shape that it cannot be manually grasped by a second person while the chainsaw is in use. 24. Guide body according to one of claims 9 to 16 and 23, characterized, that the anti-kickback device is arranged immovably on the nose area of the guide body. 709831/0250