This invention relates to apparatus for use with a chain saw, particularly for providing a guard for the chain saw during testing thereof.

When chain saws are being serviced or repaired, it is necessary to run the chain saw for testing purposes. It is not practical for a person to hold each chain saw throughout the period of testing, so that it becomes appropriate to clamp the chain saw in a suitable support such as a vice. This can lead to safety problems when the chain is exposed and also there can be environmental problems in view of the exhaust gases which are produced in saws powered by internal combustion engines, and the noise generated, particularly in confined areas.

According to the present invention there is provided guard apparatus for use with a chain saw, the apparatus comprising means for locating a main body part of the chain saw, means for housing a blade part of the chain saw, and means for clamping the chain saw within the apparatus, whereby the chain saw can be operated for testing purposes under conditions of safety.

Preferably, means are provided for withdrawing exhaust gases from the locating means to a remote location.

Preferably also, the locating means comprises a casing for locating the main body part, the casing being provided with at least one end wall to which is connected the housing means for the blade part, opposed side walls, and a top wall. The gas withdrawing means may be connected to one of the side walls, and said one end wall may be profiled to direct gases emitted within the casing towards the withdraw¬ ing means.

The clamping means may comprise a clamping member removably locatable through a wall of the blade part housing to be engagable with the blade and provide a movable clamp, whereby the blade of the chain saw can be retained while enabling movement of the chain.

The means for withdrawing the exhaust gases may comprise a fan mounted within a ducting, the latter being connected to said one side wall and being adapted to lead to a suitable remote location.

The locating means may be at least partly lined intern¬ ally with a sound absorption material.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which :-

Fig. 1 is a side elevation of an apparatus according to the invention;

Fig. 2 is an end view in the direction of arrow 'A' in Fig. 1 ; and

Fig. 3 is a plan view of the apparatus of Figs. 1 and 2.

Referring to the drawings, a chain saw guard comprises a casing 10 providing a base 12, a first side wall 14 and a second opposed side wall 15 mounting an outwardly projecting wall section 16 of truncated conical form which connects with ducting 18 for a purpose hereinafter described. The casing 10 is further provided with an end wall 20 which is of arcuate form and is connected between respective ends of the opposed side walls, the side wall 14 being of reduced length relative to the opposed side wall. A top wall 22 of the casing 10 has a first fixed section 24 towards the end of the casing defined by the end wall 20 and a second section 26 hingedly connected to the section 24. The casing 10 and the ducting 18 preferably form a welded construction of mild steel plate but it will be appreciated that other materials can be used. The walls 14,15,20 and 22 are pref¬ erably internally lined with a sound absorption material.

Mounted on the end wall 20 to extend therefrom in a direction parallel to the side walls of the casing 10, and

open at the connecting end into the casing 10, there is provided an otherwise closed housing 28 which is profiled to be capable of receiving a blade part of an electric chain saw (not shown). The housing 28 is angled slightly upwardly relative to the base 12 of the casing 10 to accommodate the angle of the blade part of a conventional chain saw, is of appropriate length, and is of relatively narrow width. A chain saw powered by an internal combustion engine, such as a petrol engine, can be located within the apparatus with a main body part supported on the base 12 and the blade part locating within the housing 28. The hinged section 26 of the top wall 22 can be lifted to provide access to the chain saw as desired.

For clamping the chain saw within the guard apparatus there is provided a clamp arrangement comprising a lever clamp 30 having a pivotal mounting on a bracket 32 secured on the outer face of one side of the housing 28, towards the inner end thereof. The clamp 30 has a handle 34 and an operating arm 36 through which is adjustably mounted a threaded operating rod 38. The latter mounts, on the end thereof facing the housing 28, a clamping pad 40 which locates through a circular opening 42 in the housing 38 between the bracket 32 and the wall 20. On the rod 3U out¬ wardly of the pad 40 there is provided a perspex disc (not shown) which, when the rod 38 is in an operating condition,

engages against the outer wall of the housing 28 to close the opening 42. The use of a transparent disc makes the saw blade visible to the operator, to enable safe location of the pad 40.

The lever clamp 30 is shown in the drawings in its operative condition. Movement of the handle 34 away from the housing 28 effects pivoting of the arm 36 to move the rod 38 outwardly. In the operative condition the pad 40 can engage with the saw blade and force the latter against a suitable abutment pad (not shown) secured to the inner wall of the housing 28 opposite the opening 42. The threaded operating rod 38 passes through a threaded nut 44 held by the operating arm 36 to enable adjustment of the effective working length of the rod 38 and thereby adjust the clamp to be able to positively clamp different thicknesses of blade.

Within the ducting 18 there is mounted, on suitable brackets 54, an electric motor 56 mounting a fan 58 which, when rotated, can withdraw any gases from the casing 10 into the ducting 18 and from there to the desired remote location. The profiled wall 20 helps direct gases to the fan 58. The fan 58 may be designed, for example, to be capable of handling fifty-five cubic feet per minute of exhaust gases. A mesh may be provided in the ducting 18 at each side of the fan 58.

In use, when it is desired to test a chain saw after service or repair, the saw is located within the casing 10

on the base 12 thereof with the blade part locating within the housing 28. The operating rod 38 is then adjusted in length to suit the appropriate saw blade and the lever clamp 30 can then be operated to clamp the blade in the housing 28. In this way, the chain saw is retained securely in position during testing while still enabling movement of the chain.

There is thus provided an apparatus which enables running of a chain saw, whether powered by an internal comb¬ ustion engine or an electric motor, with the blade enclosed and thus not providing a hazard to safety. Further, opera¬ tion of the fan 58 will enable withdrawal of any exhaust gases from the chain saw to a remote location thus prevent¬ ing pollution of the premises which would be otherwise harmful to persons therein. The profile of the end wall 20 assists in directing the exhaust gases towards the fan 58. Different makes and designs of chain saw can be used in the same guard apparatus.

It is preferable to internally line the walls 14,15,20 and 22 with a sound absorption material, and to provide a padding, preferably of rubber, on the base 12. This reduces

the noise and vibration to such an extent as to obviate or m_itigate noise damage to personnel in the working environ¬ ment and thereby considerably enhance the working conditions particularly in a confined area. Also it is preferable to so profile the side walls of the casing 10 that upper sections thereof extend rearwardly of lower sections for additional safety. The profile of the overall apparatus is so designed as to prevent damage to personnel in the event of inadvert¬ ent contact with the apparatus, and the size and weight of the apparatus enables transport by one man. Therefore test¬ ing can be carried out on site. On the rear edge of the base 12 there can be provided a tray 60 for retaining screws etc. Also at the front edge of the base 12 a sump (not shown) can be provided for draining of oil from the blade housing 28 through a suitably positioned drain hole, the angle of the housing 28 and the internal profile thereof assisting draining.

Various modifications may be made without departing from the invention. For example, the profile of the casing may be other than that described and shown. The side wall 14 may be replaced by an open mesh if desired. Further, a support frame (not shown) may be provided for supporting the guard apparatus at a suitable height above a floor for oper¬ ator access. An arrangement may also be provided for retaining the chain safely in the apparatus in the event of

chain breakage.

For clamping the chain saw within the guard apparatus, a modified arrangement may comprise a support of U-shaped cross-section, inverted in use, one leg of the support mounting, on an inner face, a fixed clamp. On an outer face of the other leg may be provided an internally threaded boss whereby a clamping screw can be threadably engaged through the boss and through an aligned opening in the leg and pres¬ ent a movable clamp inwardly of the support. The clamping screw may extend laterally outwardly of the casing through a vertical slot in the arcuate end wall, and may be provided externally of the casing with a handle whereby to enable manual adjustment. The support may also have, freely rota¬ tably mounted on its base, a further clamping screw which extends upwardly through the top wall section and through an internally threaded boss mounted on the outer face thereof. The further clamping screw may have a threaded section engageable with the boss, and externally of the casing is provided with a handle whereby turning of the latter provides for vertical adjustment of the support within the casing.

In a further modification a different type of clamp for the saw blade may be provided, for example a lever clamp where the operating rod is movable along its longitudinal

axis for a more effective clamping action if desired.

In another improvement, the blade housing 28 can have another openable part so that, when appropriate, the part can be opened and a card or the like placed over the opening to check the saw is correctly tuned by viewing the oiling of the card.