GB2481037A

GB2481037A - Chainsaw with Vibration Damping Between Guide Bar and Body

Info

Publication number: GB2481037A
Application number: GB201009637A
Authority: GB
Inventors: Richard John Olley
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-06-09
Filing date: 2010-06-09
Publication date: 2011-12-14
Also published as: GB201009637D0

Abstract

A chainsaw 101 comprises a guide bar 105 releasably mounted to a main body 103, an endless cutting chain driven around the periphery of the guide bar by a drive sprocket, the guide bar being able to rotate or translate relative to the main body in the plane of the guide bar, such movement being restricted by resilient members. The bar may be pivotably mounted using an axle (111, figure 3) extending between a pair of clamping plates 115, translation along the axle being prevented. Resilient members may be springs, synthetic rubber mounts or metal studs 119 lined with a resilient material 123 e.g. silicone. The axle may serve as a tensioning mechanism by being longitudinally adjustable, or a tensioning member may be provided. Thus the guide bar is mechanically isolated from the user reducing vibration.

Description

Low-Vibration Chainsaw

Field of the Invention

This invention relates to a chainsaw arranged to have reduced levels of vibration during use. The chainsaw comprises a main body to which is mounted an elongate guide bar. An endless cutting chain is driven around the periphery of the guide bar.

More particularly, the invention relates to a chainsaw in which the guide bar mounting reduces the transmission of vibration from the guide bar to the main body and the user. The invention also relates to a method of reducing the transmission of vibration from the elongate guide bar of a chainsaw to a user.

Background to the Invention

A conventional chainsaw comprises an elongate guide bar which is rigidly clamped at one end to a main body of the saw. A cutting chain in an endless loop is supported in a groove formed around the periphery of the guide bar and is engaged by a drive sprocket mounted to the main body adjacent to the end of the guide bar.

The sprocket is driven by a prime mover, such as a two-stroke internal combustion engine, via a drive mechanism which may include a clutch. The main body is provided with one or more handles, typically two handles, by which the user controls the chainsaw.

In use of the chainsaw, vibration is transmitted from the main body to the user via the handles. It has long been recognised that such vibration may cause discomfort to the user. Moreover, the long term negative health effects of exposure to such vibration have been well documented. In particular, exposure to excessive vibration over long periods of time can cause the user to develop Hand Arm Vibration Syndrome, or "White Finger".

It is known to reduce the transmission of vibration from the main body to the user by providing a degree of mechanical isolation between the main body and the handle and/or the user. For example, the handles of known chainsaws are typically lined with a resilient material which absorbs some of the vibration. Handles may also be provided with more complicated suspension mechanisms comprising metal springs.

Electrically heated handles may also help to prevent Hand Arm Vibration Syndrome by encouraging circulation to the fingers.

Although the known techniques for reducing the transmission of vibration from the main body of a chainsaw to the user and for preventing Hand Arm Vibration Syndrome are effective, a degree of residual vibration is still transmitted. This level of residual vibration may still be sufficient to practically limit the time for which a user may safely use a chainsaw. Furthermore, some of the known suspension mechanisms for chainsaw handles are complicated and expensive to implement.

There is accordingly a need for further effective techniques for reducing the transmission of vibration from a chainsaw to a user.

Summary of the Invention

According to a first aspect of the invention, there is provided a chainsaw comprising a main body and an elongate guide bar releasably mounted to the main body, the main body having a drive sprocket for driving an endless cutting chain around the periphery of the guide bar, wherein the guide bar is able to rotate or translate relative to main body in a plane of the guide bar, and wherein such movement of the guide bar relative to the main body is restricted by one or more resilient members.

Contrary to conventional understanding, much of the vibration generated by a chainsaw emanates from the guide bar and the cutting chain, not from the prime mover and transmission. In particular, a significant amount of vibration is generated as the cutting links of the chain rotate as they cut and as the chain instantaneously accelerates and decelerates. The invention has been conceived in recognition of the fact that the transmission of such vibration to a user may be reduced by providing mechanical isolation between the main body and the guide bar. Such isolation may be in addition to mechanical isolation between the main body and the handle and/or the user provided by suspension mechanisms, etc. A preferred embodiment of the invention is a chainsaw comprising a main body and an elongate guide bar releasably mounted to the main body, the main body having a drive sprocket for driving an endless cutting chain around the periphery of the guide bar, wherein the guide bar is pivotally mounted to the main body such that translational movement of the guide bar relative to the main body is prevented, and wherein rotational movement of the guide bar relative to the main body is restricted by one or more resilient members fixed to the main body which act on the guide bar when it is rotated.

In use of the chainsaw, the invention allows a small degree of rotational freedom of the guide bar relative to the main body. Rotational freedom is preferred over translational freedom because the effects on cutting chain tension are less.

Rotational movement of the guide bar is, however, resisted by the resilient members, which serve to absorb some of the vibration of the guide bar. The resilient members may have a spring function only, for example from torsion springs, or have spring and damping functions, for example from synthetic rubber mounts.

The resilient members may be arranged such that the guide bar can only be rotated by loading the guide bar against the action of the resilient members. In use of the chainsaw, vibration of the guide bar causes minute amounts of alternating rotational movement which loads the resilient members.

The pivotal mounting of the guide bar may comprise a transversely-extending first opening in the guide bar which is engaged by a transversely-extending axle, the axle being fixed to the main body or to a component fixed to the main body, for example by clamping. Alternatively, the pivotal mounting could comprise a transversely-extending axle fixed to the guide bar and openings in either the main body or in a component fixed to the main body.

The axle may extend between a pair of clamping plates arranged for clamping in the transverse direction, the axle and the clamping plates together defining a clamping member. The clamping member may be arranged to be clamped to the main body such that the clamping does not prevent the guide bar from rotating. For example, the clamping member could be clamped between clamping surfaces of the main body and a side cover of the chainsaw. The mounting of the guide bar may be such that transverse movement of the guide bar along the axle is substantially prevented.

Surfaces of the clamping member which contact the guide bar may be provided with a low-friction lining. Alternatively, the low friction lining may be provided to surfaces of the guide bar which contact the clamping member.

In embodiments of the invention, the chainsaw may be provided with a mechanism for tensioning the cutting chain, for example comprising a longitudinally adjustable tensioning member which engages a corresponding hole in the guide bar. The tensioning mechanism may be arranged such that it does not prevent the rotational movement of the guide bar described above, for example by providing the tensioning hole in the guide bar with an arcuate shape.

In alternative embodiments, the longitudinal position of the transversely-extending axle is adjustable for varying the tension in the cutting chain. In other words, the axle further serves as the tensioning member of the tensioning mechanism and the need for a separate tensioning member is avoided. In this case, the tensioning mechanism comprises a means for rigidly locking the longitudinal positional of the axle/tensioning member such that chain tension is unable to drift over time.

The pivotal mounting of the guide bar may be positioned towards the proximal end of the guide bar; that is, towards the end of the guide bar which is mounted to the main body. The pivotal mounting is preferably positioned close to the drive sprocket, since the variation in chain tension as the guide bar rotates is thereby minimised. In embodiments, the pivotal mounting may even be extended away from the guide bar towards the drive sprocket, for example by an arm. In preferred embodiments, however, the pivotal mounting is within the bounds of the guide bar, for example no more than O.20L, preferably no more than O.15L, and more preferably no more than O.1OL, from the proximal end of the guide bar, where L is the total length of the guide bar.

The resilient members may each comprises a transversely-extending metal stud lined with a resilient material, for example in the form of a resilient sleeve. The resilient material may be a synthetic rubber material such as a silicone material.

The resilient material may be surrounded by a second sleeve formed of a harder material such as metal, against which the guide bar may bear. The resilient members may be fixed to the main body or to a component which is itself fixed to the main body.

Each of the studs may engage a respective second opening in the guide bar. The second openings in the guide bar may be elongate openings which extend in the longitudinal direction, wherein a width of the second openings is substantially equal to a diameter of the studs. In this way, the longitudinal position of the guide bar may be adjusted relative to the studs for tensioning the cutting chain before the pivotal mounting of the guide bar is fixed.

An end of the each of the studs may be threaded for use in securing the guide bar to the main body. For example, the guide bar may be clamped between the main body and a side cover and the side cover may be attached by fastening threaded nuts onto the studs.

A preferred embodiment comprises a pair of resilient members arranged on longitudinally opposite sides of the pivotal mounting. In this arrangement, the resilient members and the pivotal mounting preferably lie on an imaginary line which extends in the longitudinal direction.

The chainsaw may further comprise other conventional features, including one or more handles for controlling the chainsaw in use. The handles may be provided with suspension mechanisms for mechanically isolating them form the main body. A prime mover, for example in the form of an electric motor or internal combustion engine may be provided. A transmission mechanism may be provided for coupling the prime mover to the drive sprocket, for example via a clutch. A side cover may be provided such that the guide bar is secured between the side cover and the main body.

According to another aspect of the invention, there is provided a method of reducing the transmission of vibration from the elongate guide bar of a chainsaw to a user, the chainsaw comprising a main body and the guide bar releasably mounted to the main body, the main body having a drive sprocket for driving an endless cutting chain around the periphery of the guide bar, the method comprising pivotally mounting the guide bar to the main body such that translational movement of the guide bar relative to the main body is prevented, wherein rotational movement of the guide bar relative to the main body is restricted by one or more resilient members fixed to the main body which act on the guide bar when it is rotated.

Other features and aspects of the invention will become apparent from the following description of specific embodiments of the invention.

Brief Description of the Drawings

Specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. la is a diagram showing certain components of a conventional chainsaw; Fig. lb is a horizontal cross-sectional view of the chainsaw shown in Fig.l a for use in explaining the mounting of the guide bar to the main body; Fig. 2 is a diagram corresponding to a side view of a chainsaw according to the invention; and Fig. 3 is a diagram corresponding to a cross-sectional view of certain components of the chainsaw shown in Fig. 2, taken along line A-A.

Detailed Description

The invention provides a chainsaw comprising a main body and an elongate guide bar releasably mounted to the main body. The main body has a drive sprocket for driving an endless cutting chain around the periphery of the guide bar. According to the invention, the guide bar is pivotally mounted to the main body such that translational movement of the guide bar relative to the main body is prevented.

Rotational movement of the guide bar relative to the main body is restricted by one or more resilient members fixed to the main body which act on the guide bar when it is rotated. The resilient members serve to absorb vibration of the guide bar so that it is not transmitted to the main body (and thereby to the user).

A known chainsaw I will first be described with reference to Figs. Ia and lb. Fig. la is a schematic diagram showing certain components of the chainsaw 1 from the side. The chainsaw 1 comprises a main body 3 to which an elongate guide bar 5 is releasably mounted to extend away from the main body 3 in a longitudinal direction.

The guide bar 5 is mounted against a clamping surface of the main body 3 and is clamped between the clamping surface and a corresponding surface of a side cover 19, which has been omitted from Fig. la to enable the other components to be seen.

The clamping surface of the main body 3 is provided with a pair of threaded studs 7 which extend in a transverse direction away from the main body 3. The threaded studs 7 pass through a longitudinal slot 9 formed in the guide bar 5 and are used to fasten the side cover to the main body 3 so that the guide bar 5 is rigidly clamped therebetween. The longitudinal slot 9 formed in the guide bar 5 enables the longitudinal position of the guide bar 5 to be adjusted before it is rigidly clamped in place.

A periphery of the guide bar 5 is provided with a channel (not shown) into which is received an endless cutting chain 11. A distal end of the guide bar 5 is provided with a sprocket (not shown) to enable the cutting chain 11 to run smoothly along the channel. The cutting chain 11 comprises a plurality of chain links, at least some of which are provided with outwardly facing cutting teeth for cutting through timber.

The main body 3 of the chainsaw 1 houses a prime mover in the form of a two stroke internal combustion engine or electric motor (not shown). An output shaft of the prime mover is coupled to a drive sprocket 13 via a transmission mechanism which may include a clutch (not shown). The drive sprocket 13 is mounted to the main body 3 to be adjacent to and in line with a proximal end of the guide bar 5.

The cutting chain 11 extends around the drive sprocket 13 such that the sprocket 13 is able to drive the cutting chain 11 along the channel formed in the periphery of the guide bar 5 during use of the chainsaw.

The main body 3 is also provided with one or more handles 15 which may be used to control the chainsaw 1 during use. At least one of the handles 15 may be provided with controls for operating the prime mover and/or the clutch. The handles are typically lined with a resilient material or are provided with suspension mechanisms (not shown) to reduce the amount of vibration which is transmitted from the main body 3 to the user during use of the chainsaw 1.

In use of the chainsaw 1 it is important that the cutting chain 11 is suitably tensioned. If the tension of the chain is too low the chain may escape from the groove in which it is supported, which could lead to damage to the chainsaw 1 or injury to the user. Insufficient chain tension may also lead to sub-optimal cutting caused by rotation of the cutting links. Conversely, too much tension in the cutting chain 11 may cause unnecessary wear on the chain 11 and guide bar 5 and lead to poor operating efficiency. The cutting chain 11 slowly lengthens over the course of its lifetime, thereby causing a gradual reduction in tension which must be periodically reset.

The conventional chainsaw I shown in Figs. Ia and lb is provided with a manually operated mechanism for adjusting cutting chain tension. The adjustment mechanism comprises a tensioning member 17 having a transversely-extending pin which engages with a hole the guide bar 5 and can be controlled to slide in the longitudinal direction. Movement of the tensioning member 17 in the direction away from the drive sprocket 13 increases the separation between the drive sprocket 13 and the guide bar 5 to thereby increase chain tension. Conversely, movement of the tensioning member 17 in the direction towards the drive sprocket 13 reduces the separation between the drive sprocket 13 and the guide bar 5 to thereby reduce chain tension.

The cutting chain tension adjustment mechanism of the chainsaw shown in Fig. la is shown more clearly in Fig. 1 b, which is a horizontal cross-sectional view through the pin of the tensioning member 17. Fig. lb shows the guide bar 5 rigidly clamped between the main body 3 and side cover 19 of the chainsaw 1. The tension adjustment mechanism comprises a threaded bolt 21 which engages a threaded bore formed in the pin of the tensioning member 17. The threaded bolt 21 is mounted longitudinally in the main body 3 such that it can be manually turned by a hand tool. The tensioning member 17 is mounted in a longitudinal track 23 formed in the main body 3 such that it can slide longitudinally. Use of a hand tool to turn the threaded bolt 21 causes engagement with the threaded bore of the tensioning member 17 and thereby longitudinal movement of the tensioning member 17.

To use the chainsaw 1, the cutting chain tension may first be reset by adjusting the longitudinal position of the tensioning member 17, before the guide bar 5 is rigidly clamped between the main body 3 and the side cover 19 by tightening the threaded nuts onto the threaded studs 7. The chainsaw I is then operated by the user and vibration is transmitted from the cutting chain and the guide bar to the main body.

Some of the vibration from the cutting chain 11 and the guide bar 3 is transmitted to the user via the handles 15.

The invention provides a chainsaw in which the main body is partly-mechanically isolated from the guide bar and the cutting chain to thereby reduce the amount of vibration which is transmitted to the main body (and thereby to the user). The invention recognises that most of the vibration of the guide bar can be absorbed by allowing a limited degree of freedom of the guide bar, particularly rotational freedom about a transversely-extending axis.

An exemplary embodiment of a chainsaw 101 according to the invention will now be described with reference to Figs. 2 and 3. Only minor modifications to the components of a conventional chainsaw are necessary to implement the invention and it may be possible to apply the invention to existing chainsaws by simply replacing or modifying these components.

Fig. 2 is a diagram corresponding to a side view of the chainsaw 101 according to the invention. Fig. 3 is a diagram corresponding to a cross-sectional view of certain components of the chainsaw 101 shown in Fig. 2, taken along line A-A. The diagrams illustrate the main body 103, the guide bar 105 and other features specifically related to the invention. Other features, such as the drive sprocket, the cutting chain, the handles and the side cover have been omitted.

As will be seen with reference to the figures, the basic configuration of the chainsaw 101 is the same as that of the known chainsaw shown in Fig. la and lb. Accordingly, the guide bar 105 is mounted between the main body 103 and the side cover 107.

The guide bar 105 is mounted to the chainsaw 101 via a rigid clamping member 109 which enables the guide bar 105 to rotate relative to the main body 103 without allowing translational movement of the guide bar 105. The clamping member 109 comprises a transversely-extending axle 111 which extends through a circular opening 113 in the guide bar 105. The axle 111 is joined at its ends to clamping plates 115a, 115b arranged on either side of the guide bar 105. The clamping plates 115a, 115b define flat outer clamping surfaces extending parallel to the surfaces of the guide bar 105. The clamping member 109 is configured such that the clamping surfaces are spaced apart by a distance which exceeds the width of the guide bar 105. The clamping surfaces may be provided with a high friction finish or coating.

The surfaces of the clamping member 109 which face towards the guide bar 105 are lined with a low friction member 117. This includes the inner surfaces of the clamping plates 11 5a, 11 Sb and the surface of the axle 111. The low friction member 117 may be coated with a low friction material such as polytetrafluoroethylene (PTFE). Alternatively, the surfaces of the clamping member 109 or the guide bar 105 may be directly coated with the low friction material and the low friction member 117 omitted. The surfaces of the clamping member 109 and the guide bar 105 are arranged to be close fitting, such that the guide bar 105 can freely rotate about the clamping member 109 without there being any play in the pivotal mounting. The inner surfaces of the clamping plates llSa, llSb and/or the lining member 117 are arranged to slide against recessed portions of the guide bar 105 to help prevent any pivoting of the guide bar 105 in the transverse direction (side to side movement).

The assembly consisting of the guide bar 105 and the clamping member 109 is clamped between the main body 103 and the side cover 107. For this purpose, two metal studs 119a, 119b extend from a clamping surface of the main body 103 in a transverse direction and pass though longitudinal slots 121a, 121b in the guide bar 105. The longitudinal slots 121a, 121b are provided on either side of the circular opening 113 such that all three of the openings 121 a, 121 b, 113 define an imaginary line which extends in the longitudinal direction. It will also be noted that the clamping plates 11 5a, 1 15b of the clamping member 109 and the lining member are locally cut away to avoid covering the longitudinal slots 121a, 121b, even when the guide bar 105 rotates slightly relative to the clamping member 109.

The metal studs 11 9a, 11 9b extending from the main body 103 are provided with resilient sleeves 123a, 123b formed of a synthetic rubber material. Depending on the hardness and durability of the resilient sleeves 123a, 123b, they may be provided with outer sleeves (not shown) formed of a more robust material such as metal. An outer diameter of the resilient sleeves 123a, 123b is equal to a width of the longitudinal slots 121a, 121b such that, when the guide bar 105 is mounted on the studs 119a, 119b, the longitudinal position of the guide bar 105 relative to the drive sprocket (not shown) can be adjusted in order to vary the tension in the cutting chain (not shown), without allowing any movement in the width direction of the slots 121a, 121b. For this purpose, a conventional cutting chain tension adjustment mechanism, including a tensioning member 125, of the type described above with reference to Figs. la and lb is provided. The adjustment mechanism is arranged such that, once the tension has been set and the guide bar 105 clamped in place, the tensioning member 125 can be released in such a way as to allow some rotation of the guide bar 105 about its pivotal mounting. This may be achieved by oversizing the hole that is engaged by the tensioning member 125 and then retracting the tensioning mechanism after the guide bar assembly has been rigidly clamped.

Alternatively, the hole that is engaged by the tensioning member 125 may be provided with an arcuate shape, such that the tensioning pin traverses the arcuate hole during rotation of the guide bar 105 about its pivotal mounting.

Assembly and use of the chainsaw 101 according to the invention will now be described.

The cutting chain (not shown) is first placed onto the guide bar 105 and the guide bar 105 is then assembled onto the main body 103 of the chainsaw 101 by aligning the longitudinal slots 121a, 121b of the guide bar 105 with the studs 119a, 119b extending from the main body 103. As the guide bar 105 is placed against the main body 103, the longitudinal position of the guide bar 105 is adjusted so that the tensioning member 125 engages the corresponding hole in the guide bar 105 and the cutting chain is placed around the drive sprocket (not shown). The side cover 107 is then assembled over the guide bar 105 and threaded nuts (not shown) are loosely placed on threaded ends of the studs 119a, 119b.

The cutting chain tensioning mechanism is then used to set the tension of the cutting chain by adjusting the longitudinal position of the guide bar 105 relative to the drive sprocket.

Once the correct chain tension has been set, the threaded nuts are tightened until the clamping member 109 is rigidly clamped between the main body 103 and the side cover 107. As illustrated in Fig. 3, in the clamped configuration, there is a spacing between the guide bar 105 and the main body 103/side cover 107 which allows the guide bar 105 to pivot about the axle 111 of the clamping member 109.

This pivoting causes the guide bar 105 to bear against and compress the resilient sleeves 123a, 123b.

In use of the chainsaw 101, cutting chain tension is substantially maintained by the pivotal mounting of the guide bar 105 about the axle 111 of the clamping member 109, whereby translational movement of the guide bar 105 relative to the drive sprocket is prevented. Vibration of the guide bar 105 causes rotation of the guide bar 105 about the pivotal mounting and is at least partially absorbed by the spring and damping properties of the resilient sleeves 123a, 123b. In this way, the transmission of vibration to the main body 103 (and the user) may be reduced.

A specific embodiment of the invention as been described hereinabove. Various changes and modifications may be made without departing from the scope of the invention.

For example, the guide bar could be pivotally mounted about the tensioning member of the cutting chain tensioning mechanism. In this arrangement, the need for a clamping member could be avoided, but the tensioning member would need to be rigidly locked in position, for example using a pair of ratchet mechanisms extending in opposite longitudinal directions. In such an embodiment the guide bar would need not to be rigidly clamped in position.

In embodiments, seals such as large "0" rings may be provided between the guide bar and the main body and between the guide bar and the side cover to keep the narrow space between these components clean. "0" ring seals may also be provided between the guide bar and the main body to provide a sealed conduit for oil which is pumped from the main body into an oil feed hole in the guide bar.

In other embodiments of the invention, the guide bar may be provided with greater (or different) freedom of movement relative to the main body, for example both rotational and translational movement. In one embodiment, the clamping member may be omitted and the guide bar may be clamped between the main body and the side cover with sheets of resilient material arranged on either side of the guide bar to allow some limited freedom of movement. In this embodiment, the sheets of resilient material serve as the resilient members, since their resilience restricts the in-plane movement of the guide bar.

Claims

Claims 1. A chainsaw comprising a main body and an elongate guide bar releasably mounted to the main body, the main body having a drive sprocket for driving an endless cutting chain around the periphery of the guide bar, wherein the guide bar is able to rotate or translate relative to main body in a plane of the guide bar, and wherein such movement of the guide bar relative to the main body is restricted by one or more resilient members.
2. A chainsaw according to claim 1, wherein the guide bar is pivotally mounted to the main body such that translational movement of the guide bar relative to the main body is prevented, and wherein rotational movement of the guide bar relative to the main body is restricted by one or more resilient members fixed to the main body which act on the guide bar when it is rotated.
3. A chainsaw according to claim 2, wherein the resilient members are arranged such that the guide bar can only be rotated by loading the guide bar against the action of the resilient members.
4. A chainsaw according to claim 2 or 3, wherein the pivotal mounting of the guide bar comprises a transversely-extending first opening in the guide bar which is engaged by a transversely-extending axle, the axle being fixed to the main body.
5. A chainsaw according to claim 4, wherein the axle extends between a pair of clamping plates, the axle and the clamping plates together defining a clamping member, wherein the clamping member is arranged to be clamped to the main body such that the clamping does not prevent the guide bar from rotating.
6. A chainsaw according to claim 5, wherein surfaces of the clamping member which contact the guide bar are provided with a low-friction lining.
7. A chainsaw according to claim 4, wherein the longitudinal position of the axle is adjustable for varying the tension of the cutting chain.
8. A chainsaw according to any of claims 2 to 7, wherein the pivotal mounting of the guide bar is positioned no more than O.20L from an end of the guide bar which faces the drive sprocket, where L is the total length of the guide bar.
9. A chainsaw according to any of claims 2 to 8, wherein the resilient members each comprises a transversely-extending metal stud lined with a resilient material.
10. A chainsaw according to claim 9, wherein each of the studs engages a second opening in the guide bar.
II. A chainsaw according to claim 10, wherein the second openings in the guide bar are elongate openings which extend in the longitudinal direction to enable the longitudinal position of the guide bar to be adjusted relative to the studs, and wherein a width of the second openings is substantially equal to a diameter of the studs.
12. A chainsaw according to claim 11, wherein an end of the each of the studs is threaded for use in securing the guide bar to the main body.
13. A chainsaw according to any of claims 9 to 12, wherein the resilient material comprises a synthetic rubber material.
14. A chainsaw according to any of claims 2 to 13, comprising a pair of resilient members arranged on longitudinally opposite sides of the pivotal mounting.
15. A chainsaw according to any preceding claim, further comprising at least one of: one or more handles for controlling the chainsaw in use; a prime mover and a transmission mechanism for driving the drive sprocket; and a side cover arranged such that the guide bar is secured between the side cover and the main body.
16. A method of reducing the transmission of vibration from the elongate guide bar of a chainsaw to a user, the chainsaw comprising a main body and the guide bar releasably mounted to the main body, the main body having a drive sprocket for driving an endless cutting chain around the periphery of the guide bar, the method comprising pivotally mounting the guide bar to the main body such that translational movement of the guide bar relative to the main body is prevented, wherein rotational movement of the guide bar relative to the main body is restricted by one or more resilient members fixed to the main body which act on the guide bar when it is rotated.