FRONT WHEEL SUSPENSION SYSTEM FOR MOTORCYCLES

Abstract: Front wheel suspension system for motorcycles comprising relatively spring-mounted elements being associated to the front wheel (7) on the one side and to the ball-head (3) of the motorcycle on the other side. Said spring-mounted elements are constituted on the one side by one single support arm (1), which arm is connected to the ball-head of the motorcycle and extends along only one side of the front wheel and is provi­ ded with guide means (12, 13) and on the other side by a shift piece (2), which shift piece is rotatably connected to the shaft of the front wheel and is also provided with guide means, the guide means of said support arm and of said shift piece cooperating with each other. A shock damper means is connected on the one side to the front wheel through the shift piece and on the other side to the support arm.

Description: The invention relates to a front wheel suspension system for motorcycles comprising elements which are spring-mounted with respect to one another, one of said elements being a single support arm extending along only one side of the front wheel and being coupled through co-operating guide means with an element being rotatably mounted on the front wheel shaft, said support arm being connected to the ball-head of the motorcycle and shock damper means being provided between the support arm and the front wheel shaft A front wheel suspension system of this type is known from the document FR-A-2 380 181. In that known system the element (3) being rotatably mounted on the front wheel shaft (2) is executed as a forklike element. The guide means coupling the support arm (5) with the forklike element (3) has the form of a pivot connection (4, X). The support arm is bended in a plane parallel to the front wheel in such a manner that the bended portion of the support arm will extend in front of the front wheel shaft (2). The axis y-y of the upper part of the support arm is offset with respect to the imaginary line extending at a right angle through the front wheel shaft axis and being parallel to the said axis y-y. During the suspension travel or spring movements of the front wheel said offset is changing between minimal and maximal values corresponding with respectively the fully extended and fully compressed conditions of the shock damper means. That changement of the offset values occurring during the said suspension travel of the front wheel will result in a substantial changement of the socalled "trail" of the front wheel, said trail being defined as the horizontal distance - measured on the horizontal path - between the points in which the axis y-y of the support arm resp. the line extending through the front wheel shaft axis and being normal to the said horizontal path intersect the said horizontal path. As the said trail will be the most important factor as to the steering geometry and provides for the exact relation between the stability in forward direction and the manoeuvrability of the vehicle the important changement of the follower distance occuring with the known front wheel suspension system will entail consequently great disadvantages. The object of the present invention is to obviate the disadvantages of telescoping forth type front suspensions. To this end the present invention provides for a front wheel suspension system for motorcyles comprising elements which are spring-mounted with respect to one another, one of said elements being a support arm extending along only one side of the front wheel and being coupled through co-operating guide means with an element being rotatably mounted on the front wheel shaft, said support arm being connected to the ball-head of the motorcycle and shock damper means being provided between the support arm and the front wheel shaft, characterised in that the said guide means are constituted by substantially straight guide ways which are provided on both the support arm and the element-herein referred to as shift piece - being rotatably mounted on the front wheel shaft, and in that the shock damper means is connected on the one side to the front wheel through the shift piece and on the other side to the support arm By these measures of the present invention a front wheel suspension system is obtained in which the offset of the suspension system does not change at all and the trail but little during the suspension travel or spring movements of the front wheel with the advantageous result that an optimal steering geometry as well as an optimal relation between the stability in forward direction and manoeuvrability are obtained. In a preferred embodiment of the front wheel suspension system according to the present invention the shift piece is provided with a groovelike chamber opening at the side opposed to the front wheel shaft, in which chamber a pair of guide ways are formed being symmetrical to the front wheel shaft, said guide ways cooperating with a pair of guide ways being formed on the outside of the support arm, in which the guide ways of both the support arm and the shift piece are substantially V-shaped in cross-section. Preferably the guide ways of both the support arm and the shift piece are coated with a wear resistent material which offers the possibility to manufacture the support arm and the shift piece from a light weight material, such as aluminium, in which e.g. hardened steel as the wear resistent material can be chosen. Preferably needle bearings are provided between the guide ways of both the support arm and the shift piece or between the wear resistent coating materials of such guide ways. In a preferred embodiment the shift piece is fixed on the shaft of the front wheel by the intermediary of a wheel bearing. In a preferred embodiment of the present invention the support arm is provided with a chamber being substantially symmetrical with respect to the shaft of the front wheel and opening on the side opposed to the front wheel shaft, in which the shock-damper means are placed substantially in the chamber of the support arm, the axes of the front wheel shaft and of the shock-damper means respectively being substantially perpendicular to each other. By way of example a preferred embodiment of the front wheel suspension system according to the present invention is explained further with reference to the accompanying drawings, in which : Fig.1 is a side view of the front wheel of a motorcycle having a suspension system according to the invention, Fig.2 is a front view of the front wheel and suspension system according to line C-C in Figure 1, Fig.3 is a cross-sectional view according to line A-A in Figure 1, and Fig.4 shows on an enlarged scale a cross-section of the front wheel suspension according to line B-B in Figure 1. As shown in the drawings the front wheel suspension system according to the present invention comprises essentially a pair of elements being spring-mounted with respect to each other and consisting of one single support arm 1 and a shift piece 2. The support arm 1 is connected to the ball-head 3 of the motorcycle and has a bended configuration (see front view of fig.2) such that said support arm extends along one side of the front wheel 7. The support arm 1 is provided with guide means which in the example of the embodiment shown in the figures are formed as a pair of substantially straight guide ways 4,5 on the outside of the arm said guide ways being substantially V-shaped in cross-section (see Fig.4) and extending substantially symmetrically with respect to the shaft 6 of the front wheel 7 and being coated with a wear resistent material 8,9. Through the intermediary of a wheel bearing 10 the shift piece 2 is rotably mounted on the shaft 6 of the front wheel 7. The shift piece 2 is also provided with guide means which cooperate with the guide means of the support arm 1. In the example of the embodiment shown in the figures the shift piece 2 is provided with a groovelike chamber 11 opening at the side opposed to the front wheel shaft 6 in which chamber a pair of substantially straight guide ways 12,13 are formed. Said guide ways 12,13 are substantially V-shaped in cross-section and are symmetrical to the front wheel shaft and are also coated with a wear resistent material 14,15. Coating the guide ways with a wear resistent material offers the possibility to manufacture both the support arm and the shift piece from a light weight material, such as aluminium, while as the resistent material e.g. hardened steel can be used. Needle bearings 16 are inserted between the wear resistent materials of the guide ways 4,12 and 5,13 of the support arm and the shift piece respectively. The support arm 1 comprises a chamber 17 which is substantially symmetrical with respect to the front wheel shaft and opens at the side opposed to said front wheel shaft. A shock damper 18 being constructed in a manner known per se is placed in said chamber 17 and is connected to the support arm 1 on the one side and to the shift piece 2 on the other side. The shock damper 18 is arranged in such a way that the axes of the shock damper 18 and the shaft 6 of the front wheel 7 are perpendicular to each other. As appears especially from Fig. 3 the front wheel shaft 6 is provided with a hub 19 that is an integral part of the shaft and against which hub the front wheel is mounted on the shaft 6 by means of a wheel nut 20. Finally a usual disc brake 21 is present the constructive details of which are not shown further herein.

Claims: 1. Front wheel suspension system for motorcycles comprising elements which are spring-mounted with respect to one another, one of said elements being a single support arm extending along only one side of the front wheel and being coupled through co-operating guide means with an element being rotatably mounted on the front wheel shaft, said support arm being connected to the ball-head of the motorcycle and shock damper means being provided between the support arm and the front wheel shaft, characterised in that the said guide means are constituted by substantially straight guide ways (4, 5; 12, 13) which are provided on both the support arm (1) and the element (2) - herein referred to as shift piece- which rotatably supports the front wheel (7), and in that the shock damper means (18) is connected on the one side to the front wheel (7) through the shift piece (2) and on the other side to the support arm (1). 2. Front wheel suspension system according to claim 1, characterised in that the shift piece (2) is provided with a groovelike chamber (11) opening at the side opposed to the front wheel shaft (6), in which chamber (11) a pair of guide ways (12,13) are formed being symmetrical to the front wheel shaft (6), said guide ways (12,13) cooperating with a pair of guide ways (4,5) being formed on the outside of the support arm (1). 3. Front wheel suspension system according to claim 1 or 2, characterised in that the guide ways (4,5;12,13) of both the support arm (1) and the shift piece (2) are substantially V-shaped in cross-section. 4. Front wheel suspension system according to one or more of the claims 1 to 3, characterised in that the guide ways (4,5;12,13) of both the support arm (1) and the shift piece (2) are coated with a wear resistent material (14,15). 5. Front wheel suspension system according to one or more of the claims 1 to 4, characterised in that needle bearings (16) are provided between the guide ways (4,5;12,13) of both the support arm (1) and the shift piece (2) or between the wear resistent coating material (14,15) of such guide ways. 6. Front wheel suspension system according to one of more of the claims 1 to 5, characterised in that the shift piece (2) is fixed on the shaft (6) of the front wheel (7) by the intermediary of a wheel bearing. 7. Front wheel suspension system according to one or more of the claims 1 to 6, characterised in that the support arm (1) is provided with a chamber (17) being substantially symmetrical with respect to the shaft (6) of the front wheel (7) and opening on the side opposed to the front wheel shaft (6), in which the shock damper means (18) are placed substantially in the chamber (17) of the support arm (1), the axes of the shaft (6) of the front wheel (7) and of the shock damper means (18) respectively being substantially perpendicular to each other.

Inventors: VERKUYLEN, ADRIANUS HENRICUS IGNATIUS
Applicants: PETERS, WILLEM
Application year: 1988
Main classification: B62K25
IPC codes: B62K25