AU712623B2 - Chainsaw safety device - Google Patents

Description

S F Ref: 379752

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Stephen Robert Snedden Lot 22 Limeburners Creek Road Clarence Town New South

AUSTRALIA

Wales 2321 Actual Inventor(s): Address for Service: Invention Title: Stephen Robert Snedden Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Chainsaw Safety Device ASSOCIATED PROVISIONAL APPLICATION DETAILS [31] Application No(s) [33] Country P00001

AU

[32] Application Date 21 May 1996 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815 _1 p* 1 CHAINSAW SAFETY DEVICE Field of the Invention A mortice is a hole made in the edge of a timber post for example to receive or house another piece sized to fit within the hole (sometimes called a tongue or tenon). The interconnection between the tongue or tenon piece and the mortice is often referred to as a mortice and tenon joint.

When mortice cutting with a chainsaw, dangerous and life threatening rotational kick-back can occur as a result of the interaction of the chainsaw blade with the item being cut. That is, the chain passing around the nose of the chainsaw cutter bar travels in lo a downward direction, causing an upward reaction of the cutter bar when the teeth engage the article being cut.

Object of the Invention It is the object of the present invention to overcome or substantially ameliorate the .above disadvantage and/or more generally to provide a chainsaw safety device adapted to 15 prevent or substantially ameliorate rotational kick-back associated with mortice cutting with the nose or tip of a chainsaw.

Disclosure of the Invention There is disclosed herein a safety device for a chainsaw apparatus, said device •comprising: S 20 a gripping tyne adapted to grip against an article to be cut by teeth at the nose region of the chainsaw apparatus, and means to mount the gripping tynes to the chainsaw apparatus so as to allow 'retraction of the gripping tyne as said article is cut by the chainsaw apparatus.

Preferably, said means to mount the gripping tynes to the chainsaw apparatus 25 comprise a mounting plate securable to a cutter bar of the chainsaw, said plate having *e.mounted thereon a mounting tube through which a rod slidably passes, said rod being connected to said gripping tyne.

Preferably, said gripping tyne is biased in a direction opposite to the direction of retraction by means of a compression coil spring surrounding said rod.

Preferably, said rod further comprises stopper means to prevent it from being fully withdrawn from said mounting tube, said stopper means comprising a pin passing through an aperture in an end of the rod.

Preferably, said safety device comprises a pair of said gripping tynes, a pair of said rods and a pair of said mounting plates, the respective components being adapted for mounting to said chainsaw cutter bar at opposite lateral sides thereof.

Preferably, said tynes are laterally spaced and held in spaced apart relationship by means of spacing devices.

[N:\LIBLL]00891 :KEH Preferably, said mounting tube comprises an internal annular recess at one end thereof into which an end of said compression coil spring is receivable.

Preferably, said spacing devices comprise a bolt passing through respective apertures in said tynes and a spacer sleeve surrounding said bolt positioned between said tynes.

Brief Description of the Drawings A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a schematic elevational view of a safety device for a chainsaw apparatus, io and Fig. 2 is a schematic end elevational view of the safety device of Fig. 1.

Description of the Preferred Embodiment In the accompanying drawings there is schematically depicted a safety device 10 for g* a chainsaw apparatus. The chainsaw apparatus comprises a cutter bar 11 about the 15 periphery of which a chainsaw passes in the direction indicated by arrow A. The chainsaw blade passes the nose or tip 22 of the cutter bar 11 in a downward direction.

o *That is, the reaction of the cutter bar nose or tip 22 would be in an upward direction upon contact with an article to be cut.

safety device 10 comprises a pair of gripping tynes 17, each positioned at laterally opposing locations of the nose or tip 22. Each gripping tyne 17 comprises a S• number of hardened sharpened tips 18 by which the tyne can grip against an article to be S" cut. Each hardened sharpened tip 18 is slightly upwardly directed to firmly grip with the article as the chainsaw blade reacts therewith. To this end, the upper edges 29 of each tip 18 can be upwardly inclined at about 90 The hardened tips 18 are linearly positioned.

A

line extending through each tip is indicated by reference numeral 27 in the drawings.

The cutting tynes 17 are mutually interconnected by means of bolts 26 passing through apertures 25 in each gripping tyne 17. Surrounding each of the bolts 22 is a spacer sleeve 21 which sets the lateral spacing between the two gripping tynes. Should the chain break in operation, the spacer sleeves 21 serve to catch the chain thus preventing possible injury.

Each gripping tyne has welded or otherwise attached thereto a cylindrical rod 13, each rod 13 being parallel and coextensive.

The rods 13 are secured to the gripping tynes 17 such that the angle between the longitudinal axis of each rod and the line 27 passing through the hardened sharpened tips 18 is to be slightly greater than 90'. For example, this angle could be 93'.

Each rod 13 passes through a longitudinal aperture in a mounting tube 19. Each mounting tube 19 is mounted to a respective mounting plate 12 having holes 24 therein.

[N:\LIBLL]00891:KEH The holes 24 receive bolts 28 which secure the mounting plates 12 at opposite sides of the chainsaw bar 11.

At the foreward end of each mounting tube 19 there is provided an annular recess 23.

A compression coil spring 14 surrounds each rod 13. The foreward or distal end of compression spring 14 engages the back edge of the gripping tyne 17. The back or proximal end of the compression spring 14 is received within the annular recess 23 of the mounting tube 19.

To prevent the rod 13 from being forced out of the mounting tube 19, a split pin 16 or the like can pass through an aperture in its proximal end.

In use, the gripping tynes 17 are placed against the article to be cut such as a vertical post. The chainsaw is operated such that the chain passing around the nose portion 22 of the chainsaw bar 11 progresses into the article. The chainsaw bar then enters the post at a safe, fixed angle of entry. During this progression, the rods 11 move 15 backwardly through the mounting tubes 19 against the compression of spring 14. The hardened sharpened tips 18 engage with the article such that countermovement of the tip of the chainsaw is prevented.

Upon completion of the cutting action, the tynes can be allowed to move to their 2 extended position by moving the chainsaw away from the remainder of the article being cut.

.Should it be desired to use the chainsaw in a conventional manner, the mounting plates 12 can be detached from the chainsaw bar 11 by removal of bolts 28.

It should be appreciated that modifications and alterations obvious to those skilled in *the art are not to be considered as beyond the scope of the present invention. For example, rather than providing a pair of laterally opposed gripping tynes 17, a single gripping tyne can be provided where additional means are provided to prevent rotation of the tyne about the longitudinal axis of rod 13. For example, two rods 13 could be °o09o S• provided at one lateral side of the chainsaw bar 11, the distal end of each rod being affixed to a single gripping tyne and the proximal end of each rod passing through a respective mounting tube.

[N:\LIBLL]00891:KEI

Claims (9)

1. A safety device for a chainsaw apparatus, said device comprising: a gripping tyne adapted to grip against an article to be cut by teeth at the nose region of the chainsaw apparatus, and means to mount the gripping tynes to the chainsaw apparatus so as to allow retraction of the gripping tyne as said article is cut by the chainsaw apparatus.

2. The safety device of claim 1, wherein said means to mount the gripping tynes to the chainsaw apparatus comprise a mounting plate securable to a cutter bar of the chainsaw, said plate having mounted thereon a mounting tube through which a rod slidably passes, said rod being connected to said gripping tyne.

3. The safety device of claim 1 or claim 2, wherein said gripping tyne is biased in a direction opposite to the direction of retraction by means of a compression coil spring surrounding said rod.

4. The safety device of any one of the preceding claims, wherein said rod further to.: 15 comprises stopper means to prevent it from being fully withdrawn from said mounting tube, said stopper means comprising a pin passing through an aperture in an end of the t: rod.

5. The safety device of any one of the preceding claims comprising a pair of said gripping tynes, a pair of said rods and a pair of said mounting plates, the respective components being adapted for mounting to said chainsaw cutter bar at opposite lateral sides thereof.

6. The safety device of any one of the preceding claims, wherein said tynes are laterally spaced and held in spaced apart relationship by means of spacing devices. to""

7. The safety device of claim 3 when appended to claim 2, wherein said mounting tube comprises an internal annular recess at one end thereof into which an end of said compression coil spring is receivable.

8. The safety device of claim 5, wherein said spacing devices comprise a bolt passing through respective apertures in said tynes and a spacer sleeve surrounding said bolt positioned between said tynes.

9. A safety device for a chainsaw apparatus, the device being substantially as hereinbefore described with reference to the accompanying drawings. Dated 13 May, 1997 Stephen Robert Snedden Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [N:\LIBLL]00891:KEH