The invention refers to the one-leg bicycle pedalling mechanism that enables simple bicycle pedalling to people who cannot bend one knee.
The invention has been classifie into class B 62M 5/00 of the international patent classification.
The technical problem successfully solved by the invention in question involves the design and the construction of such pedalling mechanism and/or of such driving system that will enable riding of a bicycle even to handicapped persons, in particular those who cannot bend one knee.
The bicycle pedalling methods known hitherto are primarily based on removal of the non-functional leg from the freely rotating crank, fixed to the front gear of the chain driving mechanism. The problem occurring at such ride lies in the fact that the cyclist pushing only one crank with his healthy leg in a certain part of the turn reaches the slack point which can only be overcome by pushing the same crank and/or pedal on the respective crank (usually with the back of his foot) beyond this slack point.
Such pedalling of the bicycle is impractical and for many a cyclist even dangerous because the cyclist is not stable in such position. In order to prevent the removal of the foot from the crank pedal in the slack point, the
pedal may be provided with a clamp for insertion of one's foot, whereby the pedal and the crank can be"pulled"beyond the slack point. Such approach, too, is impractical and dangerous because of the very high risk that the cyclist with one handicapped leg and the other one fixed into the loop on the pedal may fall.
The one-leg bicycle pedalling mechanism referred to in this invention and mounted on the handicapped leg side is constructed in the way that it is freely rotating in the currently active sense of rotation and at the same time in the currently idle sense of rotation stiffly fixed to the chain transmission mechanism with the chain running on its rim.
The invention will be explained in detail on the concrete example and the corresponding picture: Figure 1 Pedalling mechanism referred to in this invention, in cross- section The mounting of the one-leg bicycle pedalling mechanism, such as referred to in this invention, is shown in Figure 1.
In case of a normal bicycle a pair of cranks is mounted on the chain transmission in the way that both cranks are stiffly connected with the chain transmission and spaced one from another by a 180° angle. In such crank position a cyclist with healthy legs can pedal the bicycle by pushing that active crank that is in its upper position at the respective moment. At
the moment when the active crank reaches its lower position (due to the above described mounting of cranks) the idle crank automatically comes into its upper-active position. This involves the conversion of alternative pedalling of cranks into rotation of the chain transmission over which runs the chain which is usually connected with the gear of the rear driving wheel.
Handicapped persons who cannot push the crank with one leg in case of a normal bicycle cannot use one crank; moreover, the rotation of the crank on the side of his handicapped leg is even an obstacle for them.
Therefore, in the concrete case of this invention, the crank 1 on the side of the handicapped leg is fixed to the axle 4 that connects both cranks 1, 1'via the coupling 3 which allows for free rotation of the crank 1 in the active sense and for stiff connection with axle 4 in the opposite sense.
The coupling 3 may be designed as a gear wheel with a one-way clutch or as a similar coupling enabling in one sense stiff connection of the crank 1 to the axle 4 and in the other sense free rotation of the crank 1. The crank 1 mounted in this way offers two advantages over the known mounting of cranks. The first one is that on the handicapped leg side the crank is always in the lower position, so that the handicapped leg can rest thereon, whereas the stiff connection in the idle sense of crank pedalling serves for overcoming the slack angle of the active crank which requires from the cyclist only to push his leg slightly forwards. This makes the active crank overcome the slack point. In this way the cyclist with a stiff knee can
normally pedal his bicycle with his heatthy leg and needs not fix his healthy or handicapped leg into the pedal loops, wherefore the handicapped person's ride is more safe. As a rule the crank 1 fixed to the axle 4 via the coupling 3 is always the crank that is not directly fixed to the chain transmission 2. With a normal bicycle this is usually always the left crank. In case of a handicapped right leg it is necessary to transfer the chain transmission 2 to the left side and accordingly also to turn the pedalled wheel, which, however imposes no limitation on the realization of this invention.
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