A WHEEL, ESPECIALLY FOR A GARDEN VEHICLE, AS WELL AS THE USE OF SUCH A WHEEL

Abstract: A wheel for a vehicle that is intended to be driven over sensitive surfaces, such as lawns or ground surfaces that are to be sown with grass seed and/or rolled. The wheel includes a hub (4), a tread (2) generally coaxial with the hub, and an elastic coupling means (5, 6) between the hub (4) and the wheel tread (2). The tread (2) has the form of a circular-cylindrical rigid lattice construction. The elastic coupling device (5, 6) is adapted to permit an angular setting of at least 1:20 between the tread axis and the hub axis in a vertical plane in respect of a nominal vertical load transfer from the vehicle to the centre (Z) of the wheel. The invention also relates to the use of such a wheel.

Description: A WHEEL, ESPECIALLY FOR A GARDEN VEHICLE, AS WELL AS THE USE OF SUCH A WHEEL The invention relates to a wheel, especially to a garden vehicle wheel, of the kind defined in the preamble of Claim 1. It is well known to use a four-wheel motorcycle as a transport vehicle and towing vehicle for different tools and implements when performing gardening work on large grassed areas. These vehicles have relatively large wheels with wide ground abutment surfaces. All of the wheels are, of course, driven by the motor. In conjunction with work on lawns or in conjunction with the preparation of lawns, it is usual to tow an open-mesh roller or lattice-constructed roller over areas of ground that have been laid with top-soil on which grass seed is to be sown and then rolled. Rolling of the sown area is important, in order for the seed to grow in the best way. It shall also be ensured that the area is rolled with a uniform surface pressure. When rolling the surface of the area, the edges of the roller and/or the wheels of the towing vehicle are liable to form in the ground/soil tracks that can remain in the rolled surfaces, particularly when the ground is soft, has a changing, undulating topography, and so on. The load bearing of capacity of wet lawns can also be poor, causing the wheels of a vehicle of the aforedescribed kind to leave troublesome tracks in the lawn (in the foundation surface of the lawn). Accordingly, one object of the invention is to reduce the risk of a roller of a vehicle of the aforesaid kind leaving tracks in a ground surface being rolled, and also to reduce the risk of the vehicle wheels leaving troublesome tracks in a lawn on a ground surface and in a ground surface to be rolled. This object is achieved with a wheel of the design defined in Claim 1. Further embodiments of the inventive wheel are set forth in the accompanying dependent Claims. There is thus provided in accordance with the invention a wheel which is particularly well suited for a four-wheel motorcycle or like vehicle, so as to enable the vehicle to run gently and sensitively over established lawns or over ground surfaces on which top-soil has been lain, without risk of troublesome tracks being formed. This achieved as a result of the special construction of the inventive wheel. A four-wheel vehicle of the aforedefined kind will have a total weight of about 240 kg, including the weight of the driver. Each wheel will then transfer a load of about 60 kg to the underlying surface. The width of the lattice or open- mesh drum is of the order of 40 cm and its diameter is roughly 80 cm. In unfavourable instances, the wheel can be subjected to a drive torque in a vertical plane that contains the wheel axle, in the proximity of 100 N . According to the invention, the elastic coupling means of the wheel shall be adapted to generate an angular position of at least 1:20 between the tread axis and the hub axle. The invention will now be described with reference to a schematically illustrated embodiment and also with reference to the accompanying drawing. Fig. 1 is a side view of an inventive wheel. Fig. 2 is an axial sectional view taken on the line II-II in Fig. 1. Fig. 3 is a schematic illustration of the wheel with an angular setting between the axis of the wheel tread and the hub- axle. Figs. 1 and 2 illustrate a wheel which includes a circular- cylindrical lattice tread 2 which is provided on its inside with angularly separated bars 3 that distribute load generally in an axial direction. The wheel also includes a hub 4 which is coaxial with the tread 2 and which carries elastic coupling elements 5. Spokes 6 extend generally radially between the coupling elements 5 and the load distributing bars, so as to support the hub 4 coaxially with the tread 2. The elastic coupling elements 5 may comprise rubber blocks. As shown in Fig. 2, the hub 4 has the form of an annular flange 41 which is placed in the centre plane of the tread 2 and provided with bolt holes 42. A shaft 7 of a four-wheel drive motorcycle carries a connecting shield 71 with bolt holes or bolts 72 for coaxial connection with the shield 71 of the hub flange 41. The wheel can be considered to be subjected to a load corresponding to a quarter of the total weight of the vehicle including the weight of the driver. A reaction force from the underlying surface on the inventive wheel can cause the wheel tread 2 to rotate so that its axis X2 is swung in a vertical plane that also contains the geometric axis XI of the vehicle drive shaft 7. This relative swinging movement in the vertical plane between the axes XI , X2 is permitted by virtue of the coupling devices 5 being elastically resilient. In accordance with the invention, the elastic resiliency of the coupling devices is chosen so that the angular setting will be at least 1:20 with respect to the maximum torque that can occur in the described loading situation. Referring to Fig. 3, it can be assumed that the axis XI is horizontal and that one end of the wheel tread 2 rests against a horizontal underlying surface 8. If the width of the tread 2 is b and the smallest distance between the other edge of the tread 2 and the underlying surface 8 is a then a:b shall be ≥ 120. a :b will preferably at least equal 1:10. In the illustrated embodiment, the vertical load acting from the shaft 7 on the wheel may be about 60 kg in one embodiment, wherewith the torque in the plane of Fig. 3 around the intersection point Z between axes XI, X2 in the plane of the wheel flange 41 will be about 100 mm when the diameter is 80 cm and a :b is 1:20. The elastic coupling devices 5 shall then be dimensioned to establish this relationship. The invention thus provides a wheel that has a very high tilting capacity in the axial plane, this large tilting capacity constituting the condition that enables the wheel to run on a sensitive underlying surface of varying undulation or inclination, without the edge parts of the tread leaving troublesome tracks in a soft and sensitive underlying surface.

Claims: CLAIMS 1. A wheel for a vehicle that is intended to be driven over sensitive underlying surfaces, such as lawns or ground surfaces that shall be sown with grass seed and/or rolled, said wheel including a hub (4), a wheel tread (2) which is generally coaxial with the hub, and an elastic coupling means (5, 7) between the hub (4) and the tread (2), characterised in that the tread (2) has the form of a circular-cylindrical rigid lattice work; and in that the elastic coupling device (5, 6) is adapted to permit an angular setting of at least 1:20 between the tread axis and the hub axis in a vertical plane in response to nominal vertical load transmission from the vehicle to the wheel centre (Z). 2. A wheel according to Claim 1, characterised in that the elastic coupling means includes one or more rubber elements (5). 3. A wheel according to Claim 2, characterised in that connecting elements 83, 6) connect between the tread (2) and the rubber element/elements ( 5 ) . 4. A wheel according to any one of Claims 1-3, characterised in that the angular setting is established for a vertical wheel load of at least 500 N. 5. The use of a wheel according to any one of Claims 1-4 on a motor vehicle which is intended to be driven over sensitive ground surfaces, such as on wet lawns or over surfaces on which top soil has been laid and which are to be sown and rolled.

Inventors: LUNDGREN KJELL, LUNDGREN, KJELL
Applicants: LUNDGREN KJELL, LUNDGREN, KJELL
Application year: 1999
Main classification: B60B9
IPC codes: B60B9