AU2012100209A4 - Brush cutter assembly - Google Patents

Abstract

A brush cutter assembly (20) for a brush cutter (10) has a base plate (21) with equally spaced holes (25) about the rim (26). Two or three cutter 5 blades (40) are mountable on the base plate (21), each cutter blade having spaced mounting holes (47, 48). The spacing's between the mounting holes (47, 48) on each cutter blade (40) match the spacing's between adjacent holes (25) in the base plate (21). Fasteners (30) releasably secure the cutter blades (40) to the base plate (21). C~C) 7 - / /o C%/ (0 It-

Description

P/00/012 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: "BRUSH CUTTER ASSEMBLY" The following statement is a full description of this invention, including the best method of performing it known to me/us: 1 TITLE: BRUSH CUTTER ASSEMBLY BACKGROUND OF THE INVENTION: 5 1. Field of the Invention: [0001] This invention relates to a brush cutter assembly. [0002] The invention particularly relates, but is not limited to, a cutter assembly for a brush- or grass-cutter used to cut / control weeds, grasses and other plant materials. 10 2. Prior art: {0003] Brush cutters have a drive shaft within an elongated, hollow tool body, where one end of the drive shaft is connected to a small electric motor or spark-ignition engine, and the other end of the drive shaft is connected to a hub arranged to receive the cutting members. The drive 15 shaft may be rigid, and may be provided with an angle-drive at the lower end, adjacent the hub; or be flexible (e.g. formed from a cable) to accommodate a curvature in the tool body. [0004] Typically, two types of cutter members are mounted on the hub: a) two or more blades extend from a support disc or cruciform mountable 20 on the hub, each blade extending substantially radially and secured by a fixing bolt or stud; or b) two polymer lines extend from a drum mounted on the hub, the lines being selectively extendable from the hub e.g. as the lines break. [0005] Damage / wear on the blades e.g. from striking rocks or other 25 debris; or the breaking of the lines; are sources of frustration for the operators of brush cutters. SUMMARY OF THE INVENTION; 30 [0006] It is an object of the present invention to provide a brush cutter assembly which overcomes, or at least ameliorates, the problems or disadvantages of the prior art brush cutters hereinbefore described. 1144307_1S:\NrPortb1\FAKDocs\GADAMS\1 144307_1.DOC 2 [0007] Other preferred objects will become apparent from the following description. [0008] In one aspect, the present invention resides in a brush cutter assembly including: 5 a base member mountable on a hub, or drive shaft, of a brush cutter; a plurality of equally spaced holes in the base member; a plurality of cutter blades, mountable on the based member, each cutter blade having at least two mounting holes; and a plurality of fasteners to mount the cutter blades on the base member; 10 the respective spacing's between the holes on the base member and the mounting holes on the cutter blades being selected so that two or more cutter blades can be mounted on the base member at equal spacing's between adjacent cutter blades. [0009] Preferably, an axis interconnecting the mounting holes on each 15 cutter blade is transverse to a longitudinal axis of the cutter blade. [0010] Preferably, the spacing between adjacent holes on the base member is equal to the spacing between adjacent mounting holes on each cutter blade. [0011] Preferably, the base member has six holes; and 20 each cutter blade has two mounting holes; so that two or three cutter blades are selectively mountable on the base member at equal spacing's. [0012] Preferably, each cutter blade has a substantially isosceles triangle shape in top plan view, where each mounting hole is adjacent a base side 25 of the cutter blade. Preferably, the cutter blade has convergent cutting edges which are inclined relative to a bottom face of the cutter blade. [0013] Preferably, in a second aspect, the present invention resides in a brush cutter fitted with the cutter assembly hereinbefore described. 30 BRIEF DESCRIPTION OF THE DRAWINGS: [0014] To enable the invention to be fully understood, preferred 1144307_1S:\NrPortbl\FAKDocs\GADAMS\1 144307_1.DOC 3 embodiments will now be described with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of a cutter assembly, in accordance with the present invention, fitted to a brush cutter (shown in dashed lines); 5 FIG. 2 is a top plan view of the cutter assembly fitted with three cutter blades; FIG. 3 is a similar view of the cutter assembly fitted with two cutter blades; and FIG. 4 is a sectional side view taken on line 4-4 on FIG. 3 10 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS: [0015] Referring to FIG. 1, a brush cutter 10 has an elongate tubular body 11 which encloses a drive shaft (not shown). A small, e.g. 50cc petrol 15 engine (not shown) is provided at the upper end of the cutter body 11 and is connected to the input end of the drive shaft. An angle- drive gearbox 12 is provided at the lower end of the cutter body 11 and has a hub (not shown), to mount the cutter assembly 20, which is driven by the output end of the drive shaft. 20 [0016] A safety guard 13 is mounted on the cutter body 11 to provide protection for the operator from the cutter assembly 20 and/or the material cut and any debris e.g. stones struck by the cutter blades 40. [0017] Hand grips (not shown) are also provided on the body 11 and/or engine to enable the operator to control the operation of the brush cutter 25 10. [0017] The cutter assembly 20 has a base plate 21 releasably mountable on the hub. A mounting stud (not shown) passes through a central hole 22 in the base plate 21, and the mounting stud secures the base plate 21 to the hub. The mounting stud is usually provided with a washer and locking 30 member e.g. a spring-washer, to prevent accidental release of the base plate 21 from the hub. The head of the mounting stud is preferably "domed" to provide a ground-engaging "rest" or "spacer" for the cutter 1144307_1S.\NrPortbl\FAKDocs\GADAMS\1 144307_1.DOC 4 assembly, to maintain the latter out of contact with the ground. [0018] The base plate 21 is formed from a circular piece of e.g. 6mm steel plate, which has the central hole 22 formed there-through. The annular portion around the central hole 22 engages a complementary mounting 5 face on the underside of the hub. [0019] Six holes 25 are provided at equal spacing's around rim 26 of the base plate 21, with the holes 25 dimensioned to receive respective fasteners 30, each fastener 30 comprising a bolt 31 and locking nut 32, where the locking nuts 32 have polymer threads which provide a self 10 locking feature. [0020] Each cutter blade 40 has a substantially-planar body 41, which is substantially triangular in plan view. The blade body 41 is formed from high-tensile steel, and has a base side 42 and cutting sides 43, 44 arranged in a substantially-isosceles triangle configuration. Inclined 15 cutting edges 45, 46 are provided along the cutting sides 43, 44. [0021] Mounting holes 47, 48 are provided through the blade body 41, the mounting holes 47, 48 being located adjacent the junction of the base side with the cutting sides 42, 43 respectively. [0022] The spacing's between the mounting holes 47, 48 on each cutter 20 blade 40 is identical to the spacing's between adjacent pairs of holes 25 on the base plate 21. [0023] As illustrated in FIGS. 1 and 2, three cutter blades 40 may be mounted on the base plate 21. [0024] Alternatively, as illustrated in FIGS. 3 and 4, only two cutter blades 25 40 may be mounted on the base plate 21. [0025] The choice of only mounting two cutter blades 40 on the base plate 21 may arise, inter alia, when: a) the material being cut is too dense and/or too thick for the motor or engine to drive the cutter assembly within the desired operating range; or 30 b) a cutter blade 40 fails e.g. after striking a hidden obstacle, and no replacement is available - the remaining two cutter blades 40 can be located diametrically opposed on the base plate 21 without loss of 1144307_1S:\NrPortbl\FAKDocs\GADAMS\1 144307_1.DOC 5 balance. [0026] The cutter blades 40 illustrated may be purchased off-the-shelf as blades for the knife bars of mowers or grain harvesters. [0027] The skilled addressee will appreciate that specially- designed 5 cutter blades may be chosen e.g. for specific cutting tasks. [0028] The skilled addressee will appreciate that; a) the diameter of the base plate 21; b) the number of holes 25 in the base plate 21; c) the number of mounting holes 47, 48 in the cutter blades 40; and 10 d) the spacing's between the holes 25 and mounting holes 47, 48; amongst other design features may be varied to enable four or more cutter blades 40 to be mounted on the base plate. Typically the number of cutter blades 40 will be a multiple of two or a multiple of three, to enable balance of the cutter assembly 20 to be maintained. 15 [0029] The spacing's between the adjacent holes can be arranged so that a cutter blade 40 may overlie a hole 25 intermediate the holes 25 receiving the fasteners 30 mounting the cutter blade 40 to the base plate 21. [0030] The skilled addressee will also appreciate the dimensions and/or 20 materials for manufacture of the respective components can be varied to suit different power sources, materials to be cut, operator's skills and capabilities, or like design factors. For example, the base plate 21 may have a raised central mounting portion , with an annular abutment face, around the central hole 22, to engage the complementary mounting face 25 on the underside of the hub. [0031] The skilled addressee will further appreciate that the base plate 21 may be substituted by a base member having a central portion mountable on the hub, with a plurality of e.g. substantially radially-extending mounting arms or stubs, each having at least two holes 25 to mount a 30 respective cutter blade 40. [0032] Various other changes and modifications may be made to the embodiments described and illustrated without departing from the present 1144307_1S:\NrPortbI\FAKDocs\GADAMS\1144307_1.DOC 6 invention. 5 10 15 20 25 30 1144307_1 S:\NrPortbl\FAKDocs\GADAMS\1 144307_ .DOC

Claims (5)

1. A brush cutter assembly including: a base member mountable on a hub, or drive shaft, of a brush cutter; 5 a plurality of equally spaced holes in the base member; a plurality of cutter blades, mountable on the based member, each cutter blade having at least two mounting holes; and a plurality of fasteners to mount the cutter blades on the base member; the respective spacing's between the holes on the base member and the 10 mounting holes on the cutter blades being selected so that two or more cutter blades can be mounted on the base member at equal spacing's between adjacent cutter blades.

2. A brush cutter assembly as claimed in claim 1, wherein: 15 an axis interconnecting the mounting holes on each cutter blade is transverse to a longitudinal axis of the cutter blade; and the spacing between adjacent holes on the base member is equal to the spacing between adjacent mounting holes on each cutter blade. 20

3. A brush cutter assembly as claimed in claim 2, wherein: the base member has six holes; and each cutter blade has two mounting holes; so that two or three cutter blades are selectively mountable on the base member at equal spacing's. 25

4. A brush cutter assembly as claimed in any one of claims 1 to 3, wherein: each cutter blade has a substantially isosceles triangle shape in top plan view; 30 each mounting hole is adjacent a base side of the cutter blade; and optionally, the cutter blade has convergent cutting edges which are inclined relative to a bottom face of the cutter blade. 11443071 S:\NrPortbl\FAKDocs\GADAMS\1 144307_1.DOC 8

5. A brush cutter fitted with the brush cutter assembly as claimed in any one of claims 1 to 4. 5 10 15 20 25 30 1144307_1S:\NrPortbFAKDocs\GADAMS\1 1443071.DOC