GB2118813A

GB2118813A - Mower cutter unit

Info

Publication number: GB2118813A
Application number: GB08303789A
Authority: GB
Inventors: Bengt Sandberg
Original assignee: Wartsila Oy AB
Current assignee: Wartsila Oy AB
Priority date: 1982-02-12
Filing date: 1983-02-11
Publication date: 1983-11-09
Also published as: FR2521389B1; GB2118813B; FR2521389A1; FI820463L; FI76667B; DE3304199A1; GB8303789D0; SE8300721D0; IT1161884B; NO830466L; SE8300721L; DE3304199C2; IT8319540A0; FI76667C

Abstract

Mower cutter unit comprises a plurality of rotatable, substantially horizontal, disc-like cutters (19, 20) arranged in a staggered line transverse to the proposed direction of mowing. The axes of rotation (21) of said cutters is somewhat inclined forwards, and the cutters are staggered in their axial direction so that cutter (20) located closest to the front of the unit is axially higher than the cutter (19) located closest to the rear of said unit. <IMAGE>

Description

SPECIFICATION Mower cutter unit The invention relates to a mower cutter unit comprising several rotatable, substantially horizontal, disc-like cutters arranged in a staggered line in the transverse direction of the mower.

Mowers with rotating cutters, such as cylinder mowers and disc mowers, are usually more effective in cutting than cutting bar mowers with reciprocating cutter blades. The disc mower is usually more reliable in function and has better mowing properties than the cylinder mower. Disc mowers, however, are usually more expensive than cylinder mowers, because their power transmission is conventionally based on the use of gear wheels in an oil box, which increases the production costs considerably.

This invention seeks to provide an inexpensive disc mower cutter unit, with at least as good mowing properties, functional reliability and durability as the best known mowers. The invention also seeks to provide a mower suitable for mowing hay on an inclined surface, for example, on road bankings, when the tractor carrying the mower moves on a horizontal surface.

A further aim of the invention is to provide a mower cutter unit, in which a rotary deceleration of a single disc, or even the complete stopping of any disc, has no significant influence on the rotational speed of the other disc(s).

According to the invention a mower cutter unit comprises a plurality of rotatable, substantially horizontal, disc-like cutters arranged in a staggered line transverse to the intended direction of cutting in which the axis of rotation of each said cutter is somewhat inclined towards said intended direction and said cutters are staggered also in the axial directions thereof, the most forward being axially higher than the rearmost cutter of said unit.

By locating the cutters at different levels in the axial direction of their shafts, the cutters can be placed in close relationship without causing mechanical interference of the cutting members.

This does not require synchronisation of the rotation of adjacent cutters. By arranging the cutters in partly overlapping relationship an overlap of adjacent mowing sections is obtained, which gives a good mowing result. Desirably the front edges of the cutters are all at a substantially equal distance from the ground surface. This produces an appearance of even mowing on a mown tract.

By employing an articulated connection between the cutter unit and its driving unit, the mowing of an oblique road banking can be easily carried out, even if the driving unit (e.g. a tractor) moves along the road. Power for rotating the cutters would be transmitted from a power-takeoff shaft of the driving unit via transmission means.

An uncomplicated, inexpensive and reliable power transmission may include an endless belt, which itself allows some tilting of the cutter unit.

A larger tilting angle is obtainable if an adjustable pulley wheel is provided in the endless belt transmission. The power transmission from the driving unit to the mower cutter unit may require one or more universal joints to allow angle variations between connected rotating shafts. The use of an endless belt power transmission in the cutter unit allows a slow-down in the rotational speed of any of the cutters without significant influence on the rotational speed of the other cutters.

Three embodiments of mower cutter unit in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view from behind of a first embodiment of a mower cutter unit according to the invention, Figure 2 is a sectional view taken on the line Il-Il of Figure 1 with the top cover removed, Figure 3 is a sectional view taken on the line Ill-Ill of Figure 1, Figure 4 is a sectional view taken on the line IV--IV of Figure 3, Figure 5 is a view similar to Figure 4 but of a second embodiment of unit according to the invention, Figure 6 is a sectional view of a portion of the embodiment of Figure 5, and Figure 7 is a sectional view similar to Figure 3 but of a third embodiment of cutter unit according to the invention.

In Figure 1 , the numeral 1 generally designates a cutter unit of a mower (not shown in full) and 2a designates a cone belt pulley, which is connectable to a rotating power output shaft 2b of a tractor or the like (not shown) which supports the mower. A cone belt 3 transmits power from the shaft 2b and pulley 2a to a cutter unit generally designated 6. The cone belt 3 passes around a guide wheel 2c and a second cone belt pulley 4 attached to a main shaft 5 of the cutter unit 6. The position of the guide wheel 2c makes it possible to swing the cutter unit 6 to an upright transport position. When mowing, the cutter unit 6 is adjusted by means not shown to be generally parallel with the ground surface.

The cutter unit 6 has a protective case 7, with a front wall 8, in which case the shaft 5 is journalled in a bearing 9. From the belt pulley 4, power is transmitted via the shaft 5, a universal joint 10, 1 0a and a second or power shaft 11 to a first pulley 1 8 of the cutter unit 6. During transport of the mower, the members 10 and 1 Oa can be disconnected from each other. The cutter unit 6 further comprises two parallel bottom plates 1 2 and 1 3. These plates are interconnected by side walls 27. The case 7 is attached to the plate 12 by means of attachment members 1 5. The power shaft 11 is journalled in bearings 1 6 and 1 7 attached to the plates 1 2 and 13, respectively and supports the pulley 18. A second cone belt 26 transmits power from the pulley 18.

In Figure 1 , two disc-like cutters 19 and 20, are shown, of which the cutter 1 9 is positioned slightly behind the cutter 20 with regard to the mowing direction shown by the arrow M in Figure 2. Each cutter is attached to a shaft 21, which is journalled in a bearing 22 attached to the plate 12. A cone belt pulley 23 is attached to each shaft 21 and power is transmitted thereto from the pulley 1 8 by the cone belt 26 tensioned by a belt tightening wheel 24, as shown in Figure 2.

The cutters 1 9, 20 are provided with radial cutter blades 25a and 25b, respectively.

In Figure 2, the case 7 and attachment members 1 5 have been removed. The contact sector (a) of the cone belt 26 with each cutter pulley 23 should be at least 45 . Each cutter blade 25a, 25b comprises one or, as shown, two cutting edges 29. The cutter blades of the two cutters 1 9, 20 are identical. By exchanging the blades 25a and 25b (e.g. from one cutter to the other) the opposite cutting edge 29 will be in the working position, because the cutters 1 9 and 20 rotate in opposite directions. Such an exchange practically doubles the service life of the cutter blades. The cutter blades are attached to the cutter discs by means of screw bolts 30 received in holes 31 (Figure 4).The adjustment of the cutter blade angle is possible by changing or turning a blade support member 32. Numeral 33 in Figure 4 designates an attachment member securing the cutter 19 to its shaft 21.

Plates 12 and 13 have forwardly projecting portions 28, 28a and 28b. At the position of the cutters 1 9 and 20 it is only the cutter blades that extend in front of the projections 28a and 28b.

The mowing direction of the cutter units are shown in Figures 3, 4, 5 and 7 by an arrow M.

The staggering of the cutters is best shown in Figures 3 and 4. This arrangement allows the cutters to be positioned so close that the working areas of adjacent cutters overlap. This is desirable for the mowing efficiency and for the appearance of a mown tract. The cutter unit is somewhat obliquely supported relative to the ground surface as is shown in Figures 4 and 5. The staggering of the cutters 1 9, 20 horizontally and in their axial direction is such, that the distance h between the ground level and the cutter blade ends in their extreme front position is equal for all cutters. A second embodiment of the invention is shown in Figures 5 and 6, where the power transmission to the cutters is disposed below them. The same reference numerals are used for similar integers in Figures 5 to 7 as are used in Figures 1 to 4.In Figure 5 the driving pulley 18, the cutter pulleys 23 and the belt tightening wheel 24 are in a space 1 3a formed between the plates 12 and 13. The space 1 3a can be completely closed or its back wall 1 3b can be left open. There are bearings 1 6a and 22a for the-shafts 11 and 21 arranged basically as bearings 16 and 22 in Figure 1.

Attached to the plate 13 are bearings 17a. Below the plate 13, a runner-like support member 1 3c can be arranged, to lift the plate 13 somewhat above the ground surface. The universal joint 10, 1 0a (Figure 6) makes tilting of the cutter unit possible about any axis passing through the joint, thus permitting the mower unit to cut road banks or verges along a plane inclined to the road surface on which the supporting tractor runs.

A modification of the cutter unit is shown in Figure 7, where the number of cutters has been increased. It is not necessary that the number of cutters in the front and rear rows is equal. The cutters are staggered and driven as in the embodiments already considered. If one cutter is temporarily subject to a heavy load, the rotational speed of this cutter may decrease (or even become zero) without any significant effect on the speed of the belt 26 and thus the rotation speed of the other cutters, which would be impossible if a conventional gear wheel transmission were used to drive the cutters.

The invention is not limited to the embodiments shown, but several modifications thereof are feasible within the scope of the following claims.

Instead of cutter blades flexible whipiike cutters (e.g. metal wire cutters can be used.

Claims

1. A mower cutter unit comprising a plurality of rotatable, substantially horizontal, disc-like cutters arranged in a staggered line transverse to the intended direction of cutting in which the axis of rotation of each said cutter is somewhat inclined towards said intended direction and said cutters are staggered also in the axial directions thereof, the most forward being axially higher than the rearmost cutter of said unit.

2. A unit according to claim 1, in which the cutting areas of adjacent cutters partly overlap.

3. A unit according to claim 1 or 2, which includes means for mounting it in a working position where the horizontal positions of the extreme forwardly positioned part of each cutter are substantially the same for all the cutters,

4. A unit according to any preceding claim, in which the cutter unit is pivotally supported by a driving unit for allowing tilting of the cutter unit relative to the driving unit, and a power transmission is arranged from the driving unit to the cutters, the power transmission being arranged to allow said tilting.

5. A unit according to claim 4, in which a universal joint is disposed in a primary power transmission shaft connected to said cutter unit and that the means for tilting said cutter unit are arranged to tilt it about an axis passing through said universal joint.

6. A unit according to any preceding claim, in which a power transmission for rotating said cutters comprises an endless belt.

7. A mower cutter unit substantially as hereinbefore described with reference to, and as illustrated in Figures 1 to 4, Figures 5 and 6 or Figure 7 of the accompanying drawings.

New claims or amendments to claims filed on 31/5/83.

Superseded claim 3.

New or amended claims: A unit according to claim 1 or 2, which includes means for mounting it in a working position where the distance between the extreme forwardly positioned part of each cutter and the groundtis substantially the same for all the cutters.