DescriptionSelf-propelled lawn mowers are commonly used in home gardening. Such mowers relieve the user of the tedious task of pushing the mower over the lawn, which is especially tedious when the mower must be moved uphill on a sloping lawn. However, there are often situations in which the grip between the propelling wheels of the mower and the lawn is insufficient to provide a reliable propelling of the mower. This is for instance the case when the surface of the lawn for some reason is slippery. Also, is case of the propelling wheels of the mower being the front wheels, the gravitational force exerted by the mower on the front wheels may be insufficient to guarantee a reliable propelling force. This problem becomes even greater, when the mower is provided with a container at the rear portion of the mower, in which cut-off grass is collected. The heavier the container becomes, the less will be the propelling grip with the lawn.
There has been proposed devices designed to overcome or at least reduce this problem. One such device is described in US patent application US 2006/0096268 A1 (which application has subsequently been abandoned). The device comprises a thin metal band designed to be fitted around the outer circumferential surface of the propelling wheels. The metal band is provided with a number of radially outwardly extending rectangular plates that during use of the mower penetrates the surface of the lawn and thus increases the grip between the propelling wheels and the lawn.
Although devices of the simple design described in the above US application does enhance the grip between the propelling wheels and the lawn, they also have important disadvantages.
Thus, for instance, when the mower during use has to be turned sharply from one direction to the opposite direction, the rectangular plates exert a considerable resistance against the turning of the mower due to their form and lateral extension. This may lead to damage of the lawn in the region in which the direction of movement of the mower is turned.
Furthermore, if the user during mowing holds back on the handle of the mower and thus impedes the forward movement of the mower, the outwardly extending plates will dig into the upper layer of the lawn and thus rather function as a rotary cultivator, which is certainly not desired, as this will cause severe damage to the lawn.
The invention which the subject matter of EP 3 118 016 A1 that is hereby offered for sale seeks to overcome or at least reduce at least those disadvantages that are described above.
Basically, the invention proposes a wheel accessory that similar to the abovementioned US application comprises a band designed to be applied to the outer circumferential surface of the propelling wheels. An easier turning of the mower during operation is in the invention obtained by replacing the above mentioned rectangular plates with differently designed plates. A preferred design is a triangular plate that only extends laterally over a limited portion of the outer circumferential surface of the propelling wheels.
The problem of avoiding the mower to function as a rotary cultivator and thereby severely damaging the lawn is in the invention solved by incorporating a clutch mechanism in the wheel accessory. Thus, the invention proposes a wheel accessory comprising an inner cylindrical body that can be attached to the outer circumferential surface of the propelling wheel and an outer cylindrical body provided around the inner cylindrical body with a frictional contact surface between the two bodies, On the outer circumferential body of the outer cylindrical body, the grip-enhancing extensions are provided. Thus, whereas the inner cylindrical body is forced to rotate with the propelling wheel, the outer cylindrical body can rotate at a different speed and even stand still, whereby the undesired rotary cultivator effect that causes damage to the lawn can be avoided.
Access to additional documentation:Please inquire
IPC classifications:B60B15/24, B60B15/02
Contact person:Søren Gert Weinrich, SGW Patent IVS