WO1982000939A1

WO1982000939A1 - Lawn mower with power-operated cutter

Info

Publication number: WO1982000939A1
Application number: PCT/SE1981/000276
Authority: WO
Inventors: I Andersson
Original assignee: I Andersson
Priority date: 1980-09-24
Filing date: 1981-09-23
Publication date: 1982-04-01
Also published as: NO151176B; BE890489A; NO151176C; NO813133L; EP0060853A1; SE426284B; SE8009187L

Abstract

The lawn mower of the invention has a cutter (3) which rotates about a vertical axis within a hood (2). The mower is carried by a single pair of wheels (4) directly or indirectly carried by a wheel axle (1) rearwardly of the hood. A support member (5) provides at least one additional, at least intermittently effective supporting surface remote from and forwardly of, or forwardly of and rearwardly of the supports provided by the wheels for preventing substantial tipping of the machine. The support member permits omission of a second pair of wheels forwardly of the axis of rotation of the cutter so that the cutter can cut the grass before this having been flattened by any wheels. The support member also permits a low forward hood periphery edge having no upwardly projecting portions and comprising preferably at least 250`.

Description

Lawn Mower with Power-Operated Cutter

The invention relates to wheeled lawn mowers having a power- 5 operated cutter rotating about a vertical axis of rotation.

Conventional lawn mowers have many drawbacks. They are heavy and to permit their operation in such a manner that the rotating cutter will work in a plane substantially parallel with the lawn

10 they must be provided with wheels (usually four) mounted on two axles separated from each other in the driving direction. The four wheels makes turning the machine difficult and especially the front pair of wheels constitute upwardly projecting obstacles at the edge of the hood whic7ι impedes or prevents cutting the

15 grass near house walls, tree trunks etc. as well as the insertion of the mower under low branches or other plant portions. Also, when using conventional lawn mowers the grass is flattened by the wheels before the cutter can cut the grass in the strips along which the wheels move and therefore some long grass often remains

20 uncut. At the edges of the lawn the pair of wheels which is outside the lawn often either moves at a higher level than the lawn so. that the cutter will rotate obliquely upwardly towards the edge of the lawn and leave a progressively higher grass toward the edge and sometimes also a strip of completely uncut

25 grass, or said pair of wheels will move at a lower level than the lawn so that the cutter will rotate obliquely downwards towards the lawn edge, often "scalping" the lawn along the edge. Theoretically, the machine could be operated in such a manner that one of the pairs of wheels is held at a sufficiently

30 elevated level to make the cutter rotate in a plane tolerably

⁽ parallel with the lawn but in practice this is very difficult if

I - not impossible since the conventional lawn mower is rather heavy

(the weight generally is in excess of 20 kg) and since the handles cannot be made sufficiently torsionally rigid in view of

35 weight and economy considerations. Where conventional lawn mower are provided with a receptacle for collecting the cut grass the receptacle is usually mounted to project outwardly to one side. This necessitates cutting from one direction only near obstacles such as trees, bushes, fences, house walls etc. i.e. in such a manner that the grass receptacle projects from the side of the machine facing away from the obstacle. This often causes loss of time, and sometimes it is impossible. Eventhough the conventional lawn mowers are provided with grass receptacles they often leave some of the cut material on the lawn since the combination of the lawn mower and receptacle does not effectively collect all the grass cut. The cut grass is apt to spread over paths and so called grass reinforcements, and this grass is apt to adhere to shoe soles to be carried into houses and apartments. If the lawn mower is not provided with a receptacle the cut grass tends to collect in bundles or wads.

Ihe object of the invention is a lawn mower with a power-operated cutter rotating about a vertical axis and which does not have the above drawbacks. Thus, the lawn mower of the invention is to be of low weight (less than 10 kg), it shall make possible optimum accessability around bushes, trees, fence posts, under fences and along house walls, palings etc. It shall be easily turnable and it shall cut the grass completely and without scalping the lawn also along lawn edges. These objects are attained through the lawn mower according to the claims.

Embodiments of the invention are described in the following specification and shown in the accompanying drawings, wherein: ^•

FIG. 1 is a side elevational view of a first embodiment of the lawn mower according to the invention,

FIG. 2 is a side elevational view showing primarily the cutter hood of the machine of Fig. 1, the right wheel, with respect to the intended driving direction, being removed to show details

O PI behind said wheel,

FIG. 3 is a top plan view of the cutter hood and portions adjacent thereto,

FIG. 4 is a rear view of the cutter hood and portions adjacent thereto,

FIG. 5 is a view similar to Fig. 2, the side of the cutter hood next to the view being cut away to show the rotating cutter and to more clearly show the support member,

FIG. 6 is a bottom view of the cutter hood and portions adjacent thereto,

FIG. 7 is a bottom view of a second embodiment of the lawn mower according to the invention, and

FIG. 8 is a bottom view of a third βribodiment.

The embodiment of the lawn mower of the invention shown in Figs. 1-6 comprises one single wheel axle 1 which with respect to the driving direction is positioned rearwardly of the protecting hood 2 of the rotating cutter 3. This disposal of wheel axle 1 permits a short axle so that wheels 4 can be disposed relatively close to each other, specifically close enough to permit rotating cutter 3 to have larger effective diameter than the distance between the exterior sides of wheels 4. This together with the fact that the lawn mower has no front pair of wheels means for one thing that the machine is very easily turned during driving and for another that no wheels will be running in uncut grass, and therefore the grass will nowhere be flattened before being cut, this in its turn involving that the mower according to the invention will leave no strips of uncut or imperfectly cut grass. The possibility of omitting a front wheel axle and a front pair of wheels has been gained through a very important feature of the invention, viz. a sliding member 5 directly or indirectly attached to wheel axle 1 and adapted to engage the ground when the machine is being driven. Member 5 extends at least forwardly from the wheel axle and in a plane which is substantially parallel with the plane of rotation of cutter 3, beyond the centre of rotation of cutter 3 and, with the machine in the position of use, substantially vertically below said centre of rotation and further somewhat forwardly in the vertical median plane, preferably, however, no farther than to a point somewhat inside cutter hood 2. Support member 5 may be a tube or other section member. At the front end thereof there is attached to its underside a sliding member 6 in the form of a relatively thin and preferably downwardly somewhat tapering plate, preferably circular and of a relatively wear resistant material and capable of sliding with reasonably little resistance.

Support member 5 and its sliding member 6 are placed at such a level with respect to the portions of the wheels engaging the lawn that sliding member 6, when the mower is being driven, normally is a small distance, one or a few centimeters, above the surface of the ground. Normally, sliding member 6 does not skid on the lawn but if during operation the mower should be tipped somewhat in such a manner that the hood would tend to touch the ground the tipping motion will be stopped before this can take place by support member 5 and sliding member 6 as is immediately clear- rom the figures of the drawings.

Preferably, as in the embodiment of Figs. 1-6, support member 5 is adapted to extend forwardly as well as rearwardly from the wheel axle, and preferably as far or not fully as far rearwardly as forwardly. As at the front end there is at the rear end thereof provided a sliding member 6 which like front sliding 6 normally is somewhat above the ground but which prevents substantial tipping of hood 2 and thus cutter 3 in the direction

OMPI upwardly-rearward ly. Support member 5 thus shaped hence effectively prevents the mower from tipping to such degree that hood 3 will touch the ground or that the cutter will be tilted and lifted enough for the cutting action to be adversely affected.

The omission of a front wheel axle and a front pair of wheels made possible by support member 6 in its turn permits a very low front mower portion. Actually, the whole perimeter of hood 2 can be made very low - it need not be made higher than to allow free rotation of cutter 3 under the interior surface thereof - so that the mower will have a very low profile without any upwardly projecting portions, from the front peripheral surface, with respect to the driving direction, of one wheel 4, along the front peripheral edge of hood 2 and to the front peripheral surface of the other wheel 4. For this reason the mower can be moved into areas below even very low branches etc. The peripheral portion of the mower which is free of any projecting portions may comprise up to about 250° on account of the design made possible by support member 5. The mower may be moved very close to tree trunks and other objects along the whole of the said arc, and therefore cutting can be carried out without difficulty also immediately adjacent such obstacles. In order to inhibit as little as possible the ability of cutter 3 to cut close to objects hood 2 is preferably circular about the rotor axis, at least along the front portion of the periphery from one wheel to the other.

Support member 5 may consist of one single piece of a straight tube or other section member which extends substantially in the median plane of the mower. However, it will have better stability if shaped about as shown in Fig. 6. Here, the rear portion of support member 5 has the shape of a Y and the ends 7 of the mutually angled arms may be formed to constitute bearings rotatable about axle 1. In the embodiment of Figs. 1-6 support member 5 extends forwardly with only one arm which originates at and preferably constitutes a direct continuation of one end 7 and extending therefrom first to a point vertically below the centre of rotation of cutter 3 and from there in the vertical median plane of the mower up to the front end the position of which has been indicated above.

Member 5 may be somewhat resilient to permit the mower to tip somewhat about the wheel axle in opposition to the spring action of member 5 when the single sliding member 6 or one of two sliding members 6 is in contact with the ground. To prevent the tipping motion, when hood 2 tips forwardly-downwar ly, from becoming large enough to create the risk that cutter 3 will touch the ground or member 5 a washer 8 is preferably provided on the top face of member 5 opposite the lower end of the cutter shaft to permit the latter to more or less momentarily engage and rotate against washer 8.

As mentioned member 5 permits the mower of the invention to have only one wheel axle 1 and only one pair of wheels 4 placed substantially rearwardly of hood 2. This in its turn permits setting the working . level of the mower with only one single set screw 9. This may fqr instance be adapted to be threaded into or out of a nut 10 and to raise or lower axle 1 via links 11 and 12.

In the embodiment of Figs. 1-6 wheels 4 are not directly journalled in wheel axle 1. This is disposed at a lover level than the one of the axes of rotation of wheels 4 allowing axle 1 to be directly used for holding support member 5 as explained above. Instead, each wheel 4 in this case is provided with a stub shaft journalled in an upper end of the substantially vertical arm of a toggle link 13. At the portion thereof where the two arms of the toggle link 13 meet the toggle link is fixed at the end of the wheel axle and is rotatably journalled in hood 2 at the end of its substantially horizontal arm. Link 12 is fixed in member 5 which is also journalled in axle 1 (Fig. 2). In the embodiment shown in Fig. 7 support member 5 comprises two forwardly directed, mutually parallel arms extending on each side of and somewhat beyond the centre of rotation of cutter 3. They are interconnected fcy a transverse member which carries a cutter axle stop washer 8. The arrangement of two forwardly directed arms makes the mower somewhat less prone to tilt about the longitudinal axis which is advantageous in certain situations.

For instance, this makes possible cutting somewhat closer to a lawn edge where the ground level outside the lawn is lower than the ground level of the lawn without the mower tilting appreciably about the longitudinal axis, than with the embodiment having only one centrally extending, forwardly directed support member arm.

A similar advantage is obtained with the embodiment according to Fig. 8 where support member 5 consists of two arms which are parallel with each other and with the longitudinal axis (or driving direction) of the mower and which extend on each side of the longitudinal axis of the mower, the said arms being interconnected at their ends through transverse members which preferably are curved so as to be concave toward wheel axle 1. Also, they are interconnected by a transverse member carrying a cutter axle stop washer 8. In this case no sliding members 6 are needed since the function of such members may be assumed by the preferably curved members, interconnecting the ends of the parallel support member arms.

Preferably hood 2 is shaped to gradually turn into a duct or conduit 14 of the shape of a volute opening between the mower handles 12 (Figs. 1 and 2) and to which a laterally rotatable adapter 16 may be connected. To the latter may be connected a receptacle 17 for collecting the cut grass and which on account of the shape and positioning of conduit 14 can be placed between handles 12 to permit mowing also close to walls and in optional directions without receptacle 17 interfering.

OMPI To make the mower collection function more efficient cutter 3 preferably is shaped such that in addition to cutting it will also function as a suction fan. To improve the latter function motor 18 is given a higher speed of revolution than is usual for conventional lawn mowers.

Claims

1. A lawn mower having wheels (4) , a cutter (3 ) driven by a motor (18) and rotating in a horizontal plane and protected by an open bottom hood (2 ) carrying the motor, and a driving handle (15) directly or indirectly connecte to the hood, characterized in that it is carried by one single pair of wheels (4) directly or indirectly mounted on a wheel axle (1) which with respect to the intended driving direction is positioned rearwardly of the hood (2) and extends transver sally thereto, and that a support member (5) in combination with the two wheels is adapted to provide at least one during operation of the mower at least intermittently effective support surface remote from and forwardly of, or forwardly and rearwardly of the support provided by the wheels, the support member being positioned with respect to the level of the plane of rotation of the cutter (3) such that the support surface or surfaces thereof will prevent substantial tipping of the lawn mower and therewith of the plane of rotation of the cutter in the direction forwardly-downwardly, or forwardly-dcwnwardly and rearwardly-upwardly.

2. The lawn mower of claim 1, characterized in that the support member (5) consists of one or several section members extending forwardly, or forwardly and rearwardly from the wheel axle (1) to a position forwardly of the centre of rotation of the cutter (3) and rearwardly of the foremost portion of the hood (2) or one hand to the said position and on the other hand to a position rearwardly of the wheel axle and substantially at the same perpendicular distance therefrom as, or at a shorter distance therefrom than the distance of the first-mentioned position frcm the wheel axle.

3. The lawn mower of claim 1 or 2, characterized in that the support member (5 ) consists of a section member and either comprises a rear Y-shaped portion the stem of which is positioned hindmost and the arms of which forming an angle with each other have their ends directly or indirectly connected with the wheel

OMPI axle (1), and a front portion constituting a direct continuation in the forward direction of one of said ends and extending from the wheel axle toward a point which, in the position of use of the mower, is substantially vertically below the centre of rotation of the cutter (3) and from this point in substantially the vertical median plane of the mower to a point between said point vertically below the centre of rotation of the cutter and the interior edge of the hood (2), or comprises said rear Y- shaped portion and a portion formed by two continuations forwardly of the arms forming an angle with each other of the rearward portion, said continuations extending from the ends of said arms forward substantially parallel with the vertical median plane of the mower to positions between a vertical transverse plane containing the centre of rotation of the cutter and the interior face of the hood, and that at each forward and rearward end of the support member and on the underside of the support member there is provided a sliding member (6) adapted during driving of the mower to at least intermittently slidably engage the ground and preferably formed as a circular plate of a cross- section which tapers somewhat downwardly toward a sliding surface, the bottom surface of each sliding member constituting one of said support surfaces remote frcm the wheel axle.

4. I e lawn mower of claim 1 or 2, characterized in that the support member (5) consists of two parallel section members extending on either side of the vertical median plane of the mower and extending forwardly from the wheel axle (1) to a position between a vertical transverse plane containing the centre of rotation of the cutter (3) and the interior face of the hood (2) and rearwardly substantially as far or not oompletely as far, and transverse members which are preferably curved and concave towards the wheel axle and which connect the ends of said section members and provide said support, surfaces remote from the wheel axle.

5. The lawn mower of any preceding claim, characterized in that the support member (5) carries a step member (8) vertically below the shaft of the cutter (3 ) and adapted to more or less temporarily be engaged by the lower end of the cutter shaft.

6. The lawn mower of ^"any preceding claim, characterized in that the wheel axle (1) is positioned sufficiently rearwardly of the centre of rotation of the cutter and the wheels (4 ) sufficiently close to each other on the axle for the arc along the front peripheral edge between the wheels of the preferably substantially circular hood (2 ) to comprise at least 250°, and that the effective diameter of the cutter is larger than the distance between the exterior faces of the wheels, the hood in the zone next to the outer edge and at least along said arc not having a higher profile than required to permit free rotation of the cutter within the hood.