CA1218935A - Motorcycle drive wheel suspension system - Google Patents
Motorcycle drive wheel suspension systemInfo
- Publication number
- CA1218935A CA1218935A CA000465547A CA465547A CA1218935A CA 1218935 A CA1218935 A CA 1218935A CA 000465547 A CA000465547 A CA 000465547A CA 465547 A CA465547 A CA 465547A CA 1218935 A CA1218935 A CA 1218935A
- Authority
- CA
- Canada
- Prior art keywords
- wheel
- swing arm
- levers
- motor
- sprocket
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Axle Suspensions And Sidecars For Cycles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A suspension system for the drive wheel of a motor-powered vehicle driven by a chain cooperating with sprockets on the engine and wheel shafts. The suspension system com-prises a linkage arrangement associated with the swing arm, with the linkage parts positioned in the region between the wheel and the motor, with the swing arm substantially in a plane containing the axes of the engine and wheel sprockets, and with linkage components defining or approxi-mating a parallelogram configuration.
A suspension system for the drive wheel of a motor-powered vehicle driven by a chain cooperating with sprockets on the engine and wheel shafts. The suspension system com-prises a linkage arrangement associated with the swing arm, with the linkage parts positioned in the region between the wheel and the motor, with the swing arm substantially in a plane containing the axes of the engine and wheel sprockets, and with linkage components defining or approxi-mating a parallelogram configuration.
Description
MOTORCYCL~, DRIVE WHEEL SUSPENSION SYSTEM
CROSS REFERENCE:
_.
The present application discloses improvements over my prior Canadian Application Serial No. 424,494, filed April 8, 1983, and my corresponding issued U.S.A. Patent No. 4,408,674.
BACKGROU~D AND STATE~IEMT OF OBJECTS:
This invention relates to a drive wheel suspen-sion system for a motorcycle of the kind in which the drive wheel is driven by a chain cooperating with sprockets pro-vided on the engine shaft and on the wheel shaft. In such motorcycles, it has been common practice to employ a swing arm or mounting the wheel, the swing arm having a pivot usually located in the region between the engine sprocket and the periphery of the driven wheel. With this config-uration, the motion of the swing arm, which accompanies deflection of the wheel, results in change in the length of the path to be followed by the drive chain interconnect-ing the engine and wheel sprockets; and a chain slack take up device is commonly employed in order to maintain proper driving engagement of the chain with the sprockets. In addition, with this prior arrangement, certain undesirable forces are present in the motorcycle, especially during -1- ~;, , acceleration and braking. One such undesirable force is commonly referred to as "squat", i.e., a force tending to cause the rider's seat to deflect downwardly during accel-eration.
It has also been known ~see for example U.S.A.
patent #4,058,181) ~o provide a parallelogram type of swing arm suspension arrangement for mounting the drive wheel, this arrangement, in effect, comprising multiple swing arms located above and below the axes of the driving sprockets, the multiple swing arms being interconnected and arranged to provide for pivotal motion of the drive wheel about the axis of the engine sprocket, thereby eliminating the change in the length of the chain path. Although this makes pos-sible elimination of the chain slack take up device, the prior art arrangement has a number of disadvantages, notably the fact that the multiple swing arm elements used for the parallelogram arrangement of said prior patent extensively increase the mass of the parts which must move with the wheel. Moreover, with the multiple swing arms located above and below the axes of the sprockets, certain undesirable forces during acceleration and braking are still present in the overall structure of the motorcycle, and, in fact, are even exaggerated.
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According to ~he present invention, provision is made for a parallelogram lînkage adapted to be associated with the inner or pivoted end of the swing arm preferably in a region between the periphery of the wheel and the axis of the engine sprocket, but arranged to provide an effective swing arm axis which is coincident with the axis of the engine sprocket. By locating the linkage parts in the region between the periphery of the wheel and the axis of the engine sprocket, the weight o~ the parts involved is concentrated relatively close to the effective axis of swing motion. This greatly reduces the overall weight oE the parts and also reduces the inertia of the parts moving with the wheel and, consequently, improves the responsiveness of the wheel under various operating conditions including, for example, travel over rough terrain such as is commonly encountered in motocross racing. Still further, the ar-rangement of the invention provides for use of a swing arm structure lying substantially in a plane containing the axes of the driving and driven sprockets, and this reduces certain of the undesirable forces which tend to occur es-pecially during acceleration.
The invention also contemplates association of the deflection resisting mechanism, such as a typical shock absorbing or shock strut device, with the parallelogram linkage parts located close to the effective swing motion axisr these parts being arranged to provide a reaction point 1~3~
on the frame of the motorcycle which is relatively close to the overall center of gravi~y of the motorcycle, thereby minimizing tendency for the action of the shock strut to cause the attitude of the motorcycle as a whole to change in consequence of substantial wheel deflection.
The invention also provides several alternative parallelogram suspension arrangements having the advantages hereinabove mentioned, but still further providing addi-tional advantages. In one such alternative embodiment, multiple levers and links are employed in order to increase the overall strength of the linkage. In another aspect of the alternative embodiments, provision is made for al-ternative location of certain of the parts of the linkage mechanism, thereby readily adapting the parallelogram ar-rangement of the invention to motorcycles of different con-struction, as will be explained hereinafter.
Still further, with linkage and swing arm arrange-ments of the kind herein disclosed, various of the advan-tages above referred to may be attained, even when certain of tbe linkage elements do not precisely define a parallelo-gram linkaye. In view of this, greater flexibility is pro vided with respect to the location of the linkage pivots on the motorcycle frame.
According to some of the embodiments of the invention certain of the suspension linkage elements are positioned at somewhat oblique angles with respect to other linkage elements, thereby providing for reducing the forces which tend to induce "squat" when accelleration occurs.
BRIEF DESCRIPTION OF T~IE DR~WINGS:
How the foregoing and other ob~ects and advantages are attained will be clear from the followiny description referring to the accompanying drawings, which illustrate three structural embodiments, and also several diagrammatic alternatives Eor certain of the parts.
Figures 1 to 7 show one structural embodiment:
Figure 1 is an overall side elevational view of a motorcycle equipped with one form of the drive wheel sus-pension of the present invention;
Figure 2 is an enlarged view of the embodiment of Figure 1, showing the rear portion of the motorcycle including the driving wheel, with the wheel positioned in the normal or static load supporting position;
Figure 3 is a view similar to Fiyure 2 but illus-trating the wheel in partially deflected position;
~35 E'igure 4 is a view similar to Figures 2 and 3 but illustrating the wheel in an upper deflected position near the top of the stroke;
Figure 5 is a partial vertical sectional view of the embodiment of Figures 1 to 7, with certain parts, shown as indicated by the section line 5-5 on ~igure 3;
Figure 6 is a plan view of certain parts taken in general in the manner indicated by the line 6-6 on Fig-ure 3; and Figure 7 is a perspective view of some of the linkage parts associated with the swing arm, these parts being arranged in the manner provided by the present in-vention.
Figures 8, 9 and 10 show a second structural embodiment .
Figure 8 is a view similar to Figure 5 but illus-trating the second embodiment;
Figure 9 is a view similar to Figure 6; and Figure 10 is a perspective view similar to Figure 7 but illustrating the second embodiment.
Figures 11 and 12 show a third structural embodiment~
.
Figure 11 is a view similar to Figure 3 but illus-trating the third embodiment; and Figure 12 is a perspective view similar to ~igures 7 and 10 but illustrating the third embod:iment.
Figures 13 to 21 diagrammatically show alternative linkage and pivot locations:
Figures 13, 14 and 15 diagrammatically illustrate three different positions of an alternative embodiment;
Figures 16, 17 and 18 diagrammatically illustrate three different positions of another alternative embodiment;
and Figures 19, 20 and 21 illustrate still another alternative embodiment.
Figure 22-26 illustrate another alternative pivot location:
Figure 22 is a view similiar to Figure 3 but illus-trating an alternative arrangement of one of the links of the suspension mechanism;
Figure 23 is a perspective view similiar to Figure 7, but showing the alternative arrangemen~ of Figure 22;
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Figures 24, 25, and 26 are diagramatic views illus-trating the action of the suspension parts when arranged as disclosed in Figures 22 and 23.
DETAILED DESCRIPTION OF THE DRAWINGS-.
The motorcycle illustrated in all of the drawings is typical of motorcycles employed for motocross racing;
and while the invention is applicable to vehicles of a variety of types, the arrangement o~ the invention is par-ticularly des:irable for motorcycles, and especially for motorcycles used for motocross racing. The invention is, therefore, illustrated and described in relation to such specific use.
The motorcycle of all embodiments shown includes main frame components indicated at 8, 9, 10, 11 and 12.
The framing provides for support of an engine as indicated at 13, a rider's seat 14 and a fuel tank 15.
Other parts of the motorcycle of all embodiments include the following parts. Thus, the front wheel is in-dicated at 16 and the rear wheel at 17, these wheels being mounted on the frame structure, only portions of which are shown. The front wheel may be carried in any known manner, as by the fork 18 e~bodying shock absorbers 19 supported ~Z~
in a steering head 20 which is connected with the frame elements 8 and 10. The usual cycle steering handles 21 may be provided~ The engine 13 and other equipment is posi tioned in the space defined by the frame elements 8, 9 and 10 .
In the embodiment of Figures 1 to 7, the suspen-sion system for the rear or driving wheel 17 includes a swing arm 22 of a type commonly employed on motorcycles and comprising a forked structure embracing the rear wheel 17, as is clearly shown in Figure 6. Commonly, the swing arm has heretofore been pivotally mounted at some point on the frame structure, usually to the rear of the enyine;
but in accordance wi.th the present invention, the swing arm is mounted in a novel manner fully described herein-after.
The drive system for the rear wheel 17 includes a sprocket 23 mounted on the engine shaft and a sprocket 24 mounted on the wheel 17, with a drive chain 25 engag-ing the engine and wheel sprockets, as clearly appears in the drawings.
For the purpose of eliminating change in the length of the path of the drive chain 25, it is desirable that the motion of the swing arm 22 occur about the center 25 of the engine sprocket 23. However, the direct pivotal mounting of the swing arm 22 on the shaft or axis 26 is _g_ not practical because of interference with o~her parts and the undesired complexity of having the swing arm connected with the engine drive shaft, thereby interfering with sepa-rate mounting and removal of the engine and of other parts~
With the foregoing in mind, in all embodiments, the invention provides a suspension system which achieves the objective of providing for pivotal motion of the swing arm 22 about or substantially about the axis of the engine or drive sprocket shaft 26; but this is accomplished without the complexity of direct pivotal mounting of the swing arm on the axis 26. In accordance with most of the embodiments o~ the invention, a suspension linkage system is provided having an eEfective pivotal axis for the swing arm which is either coincident with or close to the axis of the sprocket 23, which latter is also customarily coincident with the engine shaft. In such embodiments, the commonly used chain slack take-up device may be eliminated. However, various of the linkage arrangements herein disclosed achieve re-duction in undesirable forces, even where the swing arm motion is not coincident with the axis of the driving sprocket, as brought out more fully hereinafter.
In the first embodiment, as shown in Figures 1 to 7, the structure provided includes a pair of levers 27 and 28 which are pivotally mounted on axes 29 and 30, car-ried by mounting brackets secured to the motorcycle framing, one offset above and the other offset below the sprocket 123~
shaft 26. These two levers lie in vertical planes laterally offset from each other and extend in a direction toward the drive wheel 17. The free ends of these levers are inter-connected by a linkage system including a shaft 31, having at one end, an upwardly extended link arm 32, and at the other end, a downwardly extended link arm 33.
~ he swing arm 22 is mounted on the shaft 31; and the lower pivoted arm 28 has an extension 28a with which a link 34 is pivoted, the link 34 being extended upwardly for pivotal attachment to the swing arm 22 at the pivot point 35.
The link parts 31, 33, 28a, 34, and the swing arm 22 itself, constitute a parallelogram linkage which, because of its suspension by means of arms 27 and 28, pro-vides an effective axis of swing motion for the swing arm 22, which axis is coincident with the sprocket shaft 26.
It will be noted that this parallelogram linkage, providing the desired center of swing motion for the swing arm and thus for the drive wheel 17, is arranged in a manner to conc2ntrate the parts close to the effective swing motion axis for the swing arm, thereby minimizing inertia effects on the deflection of the wheel itself.
It is also preferred in accordance with various embodiments of the present invention that the shock absorber mechanism, preferably including both a spring and hydraulic damper, be arranged to react on the linkage, such as above ~2~
describedr rather than at an outboard point on the swing arm itself. Thus, the mechanism for yieldably resisting upward deflection of the drive wheel includes a shock absorber mechanism comprising a spring and hydraulic damper unit generally indicated at 36, this unit or assembly being compress-ible between the end abutment elements 37 and 38. In the embodiment shown, the lower terminal element 37 extends downwardly through an aperture 22a in the swing arm 22 and is pivotally connected at 28b with the arm extension 28a;
and the upper terminal element 38 is pivotally connected with one arm 39 of a bellcrank pivoted on the frame oE the motorcycle at 40 and having another arm 41 pivotally connected by means of link 42 with the pivot axis 43 which serves also to interconnect the linkage parts 27 and 32.
For reasons more fully explained in my copend-ing application Serial No. 351,630 above fully identifiedj the linkage associated with the shocls strut, including the bellcrank having arms 39 and 41, is arranged so that in the static or normal load position, as represented by Figure
CROSS REFERENCE:
_.
The present application discloses improvements over my prior Canadian Application Serial No. 424,494, filed April 8, 1983, and my corresponding issued U.S.A. Patent No. 4,408,674.
BACKGROU~D AND STATE~IEMT OF OBJECTS:
This invention relates to a drive wheel suspen-sion system for a motorcycle of the kind in which the drive wheel is driven by a chain cooperating with sprockets pro-vided on the engine shaft and on the wheel shaft. In such motorcycles, it has been common practice to employ a swing arm or mounting the wheel, the swing arm having a pivot usually located in the region between the engine sprocket and the periphery of the driven wheel. With this config-uration, the motion of the swing arm, which accompanies deflection of the wheel, results in change in the length of the path to be followed by the drive chain interconnect-ing the engine and wheel sprockets; and a chain slack take up device is commonly employed in order to maintain proper driving engagement of the chain with the sprockets. In addition, with this prior arrangement, certain undesirable forces are present in the motorcycle, especially during -1- ~;, , acceleration and braking. One such undesirable force is commonly referred to as "squat", i.e., a force tending to cause the rider's seat to deflect downwardly during accel-eration.
It has also been known ~see for example U.S.A.
patent #4,058,181) ~o provide a parallelogram type of swing arm suspension arrangement for mounting the drive wheel, this arrangement, in effect, comprising multiple swing arms located above and below the axes of the driving sprockets, the multiple swing arms being interconnected and arranged to provide for pivotal motion of the drive wheel about the axis of the engine sprocket, thereby eliminating the change in the length of the chain path. Although this makes pos-sible elimination of the chain slack take up device, the prior art arrangement has a number of disadvantages, notably the fact that the multiple swing arm elements used for the parallelogram arrangement of said prior patent extensively increase the mass of the parts which must move with the wheel. Moreover, with the multiple swing arms located above and below the axes of the sprockets, certain undesirable forces during acceleration and braking are still present in the overall structure of the motorcycle, and, in fact, are even exaggerated.
lZ3~
According to ~he present invention, provision is made for a parallelogram lînkage adapted to be associated with the inner or pivoted end of the swing arm preferably in a region between the periphery of the wheel and the axis of the engine sprocket, but arranged to provide an effective swing arm axis which is coincident with the axis of the engine sprocket. By locating the linkage parts in the region between the periphery of the wheel and the axis of the engine sprocket, the weight o~ the parts involved is concentrated relatively close to the effective axis of swing motion. This greatly reduces the overall weight oE the parts and also reduces the inertia of the parts moving with the wheel and, consequently, improves the responsiveness of the wheel under various operating conditions including, for example, travel over rough terrain such as is commonly encountered in motocross racing. Still further, the ar-rangement of the invention provides for use of a swing arm structure lying substantially in a plane containing the axes of the driving and driven sprockets, and this reduces certain of the undesirable forces which tend to occur es-pecially during acceleration.
The invention also contemplates association of the deflection resisting mechanism, such as a typical shock absorbing or shock strut device, with the parallelogram linkage parts located close to the effective swing motion axisr these parts being arranged to provide a reaction point 1~3~
on the frame of the motorcycle which is relatively close to the overall center of gravi~y of the motorcycle, thereby minimizing tendency for the action of the shock strut to cause the attitude of the motorcycle as a whole to change in consequence of substantial wheel deflection.
The invention also provides several alternative parallelogram suspension arrangements having the advantages hereinabove mentioned, but still further providing addi-tional advantages. In one such alternative embodiment, multiple levers and links are employed in order to increase the overall strength of the linkage. In another aspect of the alternative embodiments, provision is made for al-ternative location of certain of the parts of the linkage mechanism, thereby readily adapting the parallelogram ar-rangement of the invention to motorcycles of different con-struction, as will be explained hereinafter.
Still further, with linkage and swing arm arrange-ments of the kind herein disclosed, various of the advan-tages above referred to may be attained, even when certain of tbe linkage elements do not precisely define a parallelo-gram linkaye. In view of this, greater flexibility is pro vided with respect to the location of the linkage pivots on the motorcycle frame.
According to some of the embodiments of the invention certain of the suspension linkage elements are positioned at somewhat oblique angles with respect to other linkage elements, thereby providing for reducing the forces which tend to induce "squat" when accelleration occurs.
BRIEF DESCRIPTION OF T~IE DR~WINGS:
How the foregoing and other ob~ects and advantages are attained will be clear from the followiny description referring to the accompanying drawings, which illustrate three structural embodiments, and also several diagrammatic alternatives Eor certain of the parts.
Figures 1 to 7 show one structural embodiment:
Figure 1 is an overall side elevational view of a motorcycle equipped with one form of the drive wheel sus-pension of the present invention;
Figure 2 is an enlarged view of the embodiment of Figure 1, showing the rear portion of the motorcycle including the driving wheel, with the wheel positioned in the normal or static load supporting position;
Figure 3 is a view similar to Fiyure 2 but illus-trating the wheel in partially deflected position;
~35 E'igure 4 is a view similar to Figures 2 and 3 but illustrating the wheel in an upper deflected position near the top of the stroke;
Figure 5 is a partial vertical sectional view of the embodiment of Figures 1 to 7, with certain parts, shown as indicated by the section line 5-5 on ~igure 3;
Figure 6 is a plan view of certain parts taken in general in the manner indicated by the line 6-6 on Fig-ure 3; and Figure 7 is a perspective view of some of the linkage parts associated with the swing arm, these parts being arranged in the manner provided by the present in-vention.
Figures 8, 9 and 10 show a second structural embodiment .
Figure 8 is a view similar to Figure 5 but illus-trating the second embodiment;
Figure 9 is a view similar to Figure 6; and Figure 10 is a perspective view similar to Figure 7 but illustrating the second embodiment.
Figures 11 and 12 show a third structural embodiment~
.
Figure 11 is a view similar to Figure 3 but illus-trating the third embodiment; and Figure 12 is a perspective view similar to ~igures 7 and 10 but illustrating the third embod:iment.
Figures 13 to 21 diagrammatically show alternative linkage and pivot locations:
Figures 13, 14 and 15 diagrammatically illustrate three different positions of an alternative embodiment;
Figures 16, 17 and 18 diagrammatically illustrate three different positions of another alternative embodiment;
and Figures 19, 20 and 21 illustrate still another alternative embodiment.
Figure 22-26 illustrate another alternative pivot location:
Figure 22 is a view similiar to Figure 3 but illus-trating an alternative arrangement of one of the links of the suspension mechanism;
Figure 23 is a perspective view similiar to Figure 7, but showing the alternative arrangemen~ of Figure 22;
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Figures 24, 25, and 26 are diagramatic views illus-trating the action of the suspension parts when arranged as disclosed in Figures 22 and 23.
DETAILED DESCRIPTION OF THE DRAWINGS-.
The motorcycle illustrated in all of the drawings is typical of motorcycles employed for motocross racing;
and while the invention is applicable to vehicles of a variety of types, the arrangement o~ the invention is par-ticularly des:irable for motorcycles, and especially for motorcycles used for motocross racing. The invention is, therefore, illustrated and described in relation to such specific use.
The motorcycle of all embodiments shown includes main frame components indicated at 8, 9, 10, 11 and 12.
The framing provides for support of an engine as indicated at 13, a rider's seat 14 and a fuel tank 15.
Other parts of the motorcycle of all embodiments include the following parts. Thus, the front wheel is in-dicated at 16 and the rear wheel at 17, these wheels being mounted on the frame structure, only portions of which are shown. The front wheel may be carried in any known manner, as by the fork 18 e~bodying shock absorbers 19 supported ~Z~
in a steering head 20 which is connected with the frame elements 8 and 10. The usual cycle steering handles 21 may be provided~ The engine 13 and other equipment is posi tioned in the space defined by the frame elements 8, 9 and 10 .
In the embodiment of Figures 1 to 7, the suspen-sion system for the rear or driving wheel 17 includes a swing arm 22 of a type commonly employed on motorcycles and comprising a forked structure embracing the rear wheel 17, as is clearly shown in Figure 6. Commonly, the swing arm has heretofore been pivotally mounted at some point on the frame structure, usually to the rear of the enyine;
but in accordance wi.th the present invention, the swing arm is mounted in a novel manner fully described herein-after.
The drive system for the rear wheel 17 includes a sprocket 23 mounted on the engine shaft and a sprocket 24 mounted on the wheel 17, with a drive chain 25 engag-ing the engine and wheel sprockets, as clearly appears in the drawings.
For the purpose of eliminating change in the length of the path of the drive chain 25, it is desirable that the motion of the swing arm 22 occur about the center 25 of the engine sprocket 23. However, the direct pivotal mounting of the swing arm 22 on the shaft or axis 26 is _g_ not practical because of interference with o~her parts and the undesired complexity of having the swing arm connected with the engine drive shaft, thereby interfering with sepa-rate mounting and removal of the engine and of other parts~
With the foregoing in mind, in all embodiments, the invention provides a suspension system which achieves the objective of providing for pivotal motion of the swing arm 22 about or substantially about the axis of the engine or drive sprocket shaft 26; but this is accomplished without the complexity of direct pivotal mounting of the swing arm on the axis 26. In accordance with most of the embodiments o~ the invention, a suspension linkage system is provided having an eEfective pivotal axis for the swing arm which is either coincident with or close to the axis of the sprocket 23, which latter is also customarily coincident with the engine shaft. In such embodiments, the commonly used chain slack take-up device may be eliminated. However, various of the linkage arrangements herein disclosed achieve re-duction in undesirable forces, even where the swing arm motion is not coincident with the axis of the driving sprocket, as brought out more fully hereinafter.
In the first embodiment, as shown in Figures 1 to 7, the structure provided includes a pair of levers 27 and 28 which are pivotally mounted on axes 29 and 30, car-ried by mounting brackets secured to the motorcycle framing, one offset above and the other offset below the sprocket 123~
shaft 26. These two levers lie in vertical planes laterally offset from each other and extend in a direction toward the drive wheel 17. The free ends of these levers are inter-connected by a linkage system including a shaft 31, having at one end, an upwardly extended link arm 32, and at the other end, a downwardly extended link arm 33.
~ he swing arm 22 is mounted on the shaft 31; and the lower pivoted arm 28 has an extension 28a with which a link 34 is pivoted, the link 34 being extended upwardly for pivotal attachment to the swing arm 22 at the pivot point 35.
The link parts 31, 33, 28a, 34, and the swing arm 22 itself, constitute a parallelogram linkage which, because of its suspension by means of arms 27 and 28, pro-vides an effective axis of swing motion for the swing arm 22, which axis is coincident with the sprocket shaft 26.
It will be noted that this parallelogram linkage, providing the desired center of swing motion for the swing arm and thus for the drive wheel 17, is arranged in a manner to conc2ntrate the parts close to the effective swing motion axis for the swing arm, thereby minimizing inertia effects on the deflection of the wheel itself.
It is also preferred in accordance with various embodiments of the present invention that the shock absorber mechanism, preferably including both a spring and hydraulic damper, be arranged to react on the linkage, such as above ~2~
describedr rather than at an outboard point on the swing arm itself. Thus, the mechanism for yieldably resisting upward deflection of the drive wheel includes a shock absorber mechanism comprising a spring and hydraulic damper unit generally indicated at 36, this unit or assembly being compress-ible between the end abutment elements 37 and 38. In the embodiment shown, the lower terminal element 37 extends downwardly through an aperture 22a in the swing arm 22 and is pivotally connected at 28b with the arm extension 28a;
and the upper terminal element 38 is pivotally connected with one arm 39 of a bellcrank pivoted on the frame oE the motorcycle at 40 and having another arm 41 pivotally connected by means of link 42 with the pivot axis 43 which serves also to interconnect the linkage parts 27 and 32.
For reasons more fully explained in my copend-ing application Serial No. 351,630 above fully identifiedj the linkage associated with the shocls strut, including the bellcrank having arms 39 and 41, is arranged so that in the static or normal load position, as represented by Figure
2, the axis of the link 42 is positioned to react in the tangent position in relation to the motion of the arm 41 about the bellcrank pivot 40, as is indicated by the dot and dash lines applied to Figure 2. Similarly, in the posi-tion of maximum deflection, the axis of the shock absorber 36 is positioned to react at the point of tangency of the 93~
connection point between the shock absorber and the arm 39 of the bellcrank, as is indicated by dot and dash axis lines as applied to Figure 4~ For reasons fully brought out in my copending applications above identified, these relationships provide a desirable progressive increase in the resistance to deflection of the wheel as the deflection progresses frQm the static or normal load position repre-sented by Figure 2 to the maximum load position represented by Figure 4.
The arrangement of the linkage for the swing arm and for the shock resisting mechanism not only minimizes the inertia effects oE these parts in relation to the motion or deflection of the driving wheel, but still further, the disposition of these various parts is important ~rom the standpoint of concentrating those parts close to the center of gravity of the motorcycle as a whole. Moreover, the geometry of the parts as described has special advantages in minimizing tendency for the deflection resisting forces to induce or contribute to undesirable motions of the motor-cycle about its overall center of gravity.
The arrangement of the present invention is char-acterized by the fact that the driving wheel is, in effect, more isolated from the remainder of the motorcycle, par-ticularly with regard to the motions of the drive wheel and the dynamic and inertia forces involved in such motions and also in the action of the shock absorber or other motion-resisting mechanism.
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Still further, the linkage parts involved in the arrangement of the present invention may be accommodated in a smaller lateral or transverse space than is the case with certain other suspension mechanisms of the prior art.
Because of this, notwithstanding the fact that the link-age provides a parallelogram effect causing the motion of the drive wheel to occur about the axis of the driving sprocket, the relatively small overall lateral dimension of the parts provides ground clearance at the two sides of the motorcycle even when making sharp turns, which ground clearance is greater than in many prior suspension arrange-ments. Because of this increased lateral ground clearance, various parts, especially the suspension parts, may be mounted in lower positions, with consequent lowering of the overall center of gravity of the motorcycle; and this is of advantage for reasons well understood in this art.
Turning now to the alternative structural embodi-ments shown respectively in Figures 8, 9 and 10, in Figures 11 and 12, and in Figures 22 and 23, it is first noted that these alternative embodiments also have the advantages above referred to; but in addition, the alternative embodiments have further or collateral advantages, as will be pointed out following the detailed description of each one of the alternative arrangements.
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In all of the alternative arrangements, many of the reference numerals applied are the same as those used in the description of the first embodiment: contained in Figures 1 to 7; and in general, the modified or additional parts of the alternative embodiments are identified by similar reference numerals incorporating prime markings or letters, as will be pointed out.
Consider first the alternative embodiment of Fig-ures 8 to 10 inclusive. The general distinction between this embodiment and the first embodiment lies in the fact that certain of the linkage components have been multiplied or duplicated, as compared with the first embodiment. Thus, note, for example, that in Figure 7 of the first embodiment, a pair of levers 27 and 28 are provided, one being located at each side of the vertical plane of the drive wheel.
Similarly, a pair of arms 32 and 33 associated with said levexs 27 and 28 are provided, one being located at each side of the vertical plane of the drive wheel. Compari-son of Figure 10 of the second embodiment with Figure 7 of the first embodiment will immediately disclose that these levers and arms have been duplicated. Thus, as shown in Figure 10, a pair of levers 27 and 27' are located at one side of the vertical plane of the drive wheel and another pair of levers 28 and 28' are located at the other side ~IL8~3~
of that vertical plane. Similarly, a pair of arms 32 and 32', cooperating with the levers 27 and 27', are provided at one side and a pair of arms 33 and 33l, cooperating with the levers 28 and 28', are provided at the other side.
These parts will also be found in Figures 8 and 9~ The arms 32 and 32' at one side, and the arms 33 and 33' at the other side, are rigidly connected with each other in pairs in order to provide the desired parallelogram linkage arrangement.
By virtue of this duplication, the mechanism can withstand very much greater wheel suspension forces, so that this arrangement can effectively be used in motorcycles of considerably larger size and weight. The arrangement of Figures 8 to 10 also has the advantage that the various forces are more uniformly distributed between various parts of the suspension mechanism and also between ~he suspension mechanism and the frame of the motorcycle.
As will be seen from Figures 8, 9 and 10, the pairs of levers 27 and 27' and 28 and 28' are pivoted about axes 29 and 29' and 30 and 30', the pivots 29 and 30l being coaxial and located above, and the pivots 29' and 30 being coaxial and located below the driving sprocket axis 26, and thereby providing the desired motion of the swing arm iZ1~
about the axis of the sprocket, as in the first embodiment~
Since the pivots 29 and 29' and 30 and 30' are located in an upright plane containing the axis of the driving sprocket~
the desired parallelogram action of the suspension linka~e is provided.
Turning now to the embodiment shown in Figures 11 and 12, it is again noted that numerous reference char-acters employed in ~he description of the first embodiment, and some of which also are described in connection with the second embodiment, are used in the same manner as in Figures 11 and 12; and it is not believed that duplicate description of these parts is needed.
Stated briefly and generally, the embodiment of Figures 11 and 12 differs from the embodiment of Figures 1 to 7 in two important respects. First, the arrangement of Figures 11 and 12 includes multiple levers and arms, as in the embodiment of Figures 8 to 10; and in addition, in the embodiment of Figures 11 and 12, as distinguished from both the first embodiment and also the second embodi-ment, the principal levers of the parallelogram linkage are pivotally mounted on axes on the frame of the motor-cycle, which axes are all located below the axis 26 of the driving sprocket 23. In the embodiment of Figures 8 to 10, and in the first embodiment, these principal levers of the parallelogram linkage are arranged so that pivot axes are provided both above and below the axis of the sprocket.
~2~
More speciEically, in Figures 11 and 12, it will be noted that at one side of the mechanism, the principal levers 27' and 27" have pivot axes 29' and 29" both of which are spaced below the axis 26 of the sprocket 23 (but pref-erably lie in a common vertical generally upright plane with the axis 26 of the sprocket 23). Similarly, at the other side of the mechanism, the principal levers 28 and 28" are provided with axes 30 and 30" which are also both spaced below the axis 26 of the sprocket 23 but lie in the same plane as the pivot axes of the levers at the other side.
In the embodiment of Figures 11 and 12, the arms which interconnect the parallel levers, i.e., the arms in-dicated at 32" and 33", each comprise a rigid arm struc-ture to which the levers 27' and 27" at one side are pivotally connected r and to which the arms 28' and 28" at the other side are pivotally connected. These arms 32" and 33" ex-tend above the upper levers 27" and 28" to provide for sup-port of the crosstie 31 on which the swing arm 22 is pivoted, as in the other embodiments. As seen in Figure 11, the link 34 between the extension 28a of the arm 28 and the swing arm provides, in combination with the inner portion of the swing arm9 the arms 32" and 33", and the arm 28a, a second parallelogram linkage which as described above in connection with the first embodiment provides the desired motion of the swing arm 22 about the axis 26 of the driving sprocket 23.
~3 8~g~$
From the above, it will be seen that the same type of parallelogram linkages and motions are provided by the embodiment in Figures 11 and 12, and this affords various of the advantages described above in connection with Figures l to 7.
It will also be understood that the same type of shock absorber mechanism indicated at 36 may be employed in either the second or third embodiments, in the same gen-eral manner as in the first embodiment. This mechanism receives the motion of the swing arm through the connection 42 in the embodiments illustrated in Figures 8 to 10 and ll and 12, in the same general manner as described above with reference to Figures l to 7.
In considering the embodiment of Figures ll and 12, it is particularly to be noted that the fixed pivots for the principal levers 27' and 27" and 28 and 28" are both positioned in spaced relation below the axis 26 of the driving sprocket 23; and this i5 of advantage in main-taining the overall center of gravity of the wheel suspen-sion linkage at a location as low as possible. However, from the standpoint of the action of the linkage, it would also be possible to mount the principal levers 27' and 27"
and the levers 28 and 28" on pivots all located above the axis of the sprocket. In some cycle constructions, this would provide increased clearance for connection and inter-connection of the parts, but it is preferred to locate the parallel links below the sprocket as in Figures ll and 12.
In the preferred construction of any of the above described arrangements, it is contemplated ~hat the prin-cipal parallel levers at both sides are preferably mounted on pivots which lie in or at least close to the same upright plane as the axis 26 of the driving sprocket; and for most installations, this coplanar arrangement is preferred whether both of the lever pivots at each side are located either above or below the axis of the driving sprocket, and also in arrangements (such as in Figures 1 to 7) in which one lever pivot is located above the sprocket and the other lever pivot below the sprocket.
Figures 13 to ~1 diagrammatically illustrate sev-eral variants with respect to locations o~ lever and link pivots. From various of these figures, it will be seen that geometric variations from precise parallelograms may be used. In some instances, substantially equal and oppo-site inclination of the levers may be adopted while still retaining linkage motion approximating the action of a true parallelogram. Thus, the need for a slack take-up device for the drive chain may be avoided, even if the linkage does not precisely correspond to a parallelogram. Moreover, in some installations, for instance where especially diffi-cult clearance problems are encountered, it may even be preferred to depart from a pure parallelogram to an extent requiring use of a chain slack take-up device. In some cases, this may still provide a desirable improvement with respect to dynamic forces, such as decreased tendency for acceleration to induce "squat".
In considering the various diagrammatic illustra~
tions of Figures 13 to 21, it is first noted that all of these diagrams have reference characters identifying the principal components which are involved in the motions of the suspension mechanism. Referring, for example~ to Figure 13, it will be seen that the motor or driving sprocket is diagrammatically indicated at A, and the wheel or driven sprocket is diagrammatically indicated at B. The inter-connecting chain is indicated by the letter C.
The swing arm provided for the driviny wheel is indicated by the letter D, and at its inner end, this swing arm is mounted by means of a pair of levers E-E which are mounted on fi~ed points as is indicated and which are pivotally interconnected by the link F, the swing arm D being pivotally mounted on the link F.
The lower lever E has an extension El rigid with the lower link E and extending in the direction of the wheel.
This lever extension El is pivotally connected with the swing arm D by means of the swing arm link G. The general structural relationship of these parts will readily be under-stood by comparison with any of the structural embodiments hereinabove fully described and illustrated in various of Figures 1 to 12.
~8~3~
Referring now more specifically to the embodiment diagrammatically illustrated in Figures li, 14 and 15, it is first noted that in this particular embodiment, the two levers E-E, instead of being substantially parallel ~o each other, diverge from each other to positions respectively above and below the driving sprocket A. With this "diver-gent" geometry, when the driven wheel is deflected down-wardly, for instance, to a position such as indicated in Figure 14, notwithstanding the divergent arrangement of the levers E, the swing arm D, and its pivotal connection with the link F, still remains substantially in alignment with the axes of the motor and wheel sprockets, in view of which the chain path is not appreciably changed. There-fore, a chain slack take-up device would not necessarily be needed. The same condition prevails upon upward deflec-tion of the driving wheel, for instance, to the position indicated in Figure 15. Although no substantial change in chain path length occurs, this arrangement actually does slightly alter the chain path length.
Turning now to the embodiment shown in Figures 16, 17 and 18, it is to be noted that the links and levers are again indicated by the same reference letters; but in this alternative embodiment, the levers E-E are po~itioned at different distances from the axis of the driving sprocket A. Both of the levers have been raised so that the upper lever ~ now lies in a position farther removed from the ~22-~L2~ 3S
axis of the sprocket A than is the case with the lower lever E. When the parts are interconnected in the manner indi-cated in Figure 16, with the swing arm D and its pivot lo-cated in a plane containing the axes of ~he driving and driven sprockets, downward deflection of the driven wheel to the position indicated in Figure 17 still does not ex-tensively alter the position oE the swing arm and its pivot with respect to the plane containing the axes of the driving and driven sprockets.
From the above, it will be seen that in the embodi-ment of Figures 16, 17 and 18, deflection of the driven wheel does not extensively alter the chain length.
Similar results are achieved when employing an arrangement, such as shown in Figures 19, 20 and 21, in which the levers E-E converge rather than diverge from each other. Here again, deflection of the driven wheel does not appreciably change the position of the swing arm and its pivot with respect to the plane containing the axes of the driving and driven sprockets A and B.
It will be understood that in any of these arrange-ments where the length of the path of the chain between the driving and driven sprockets remains substantially the same in different positions of the driven wheel, the employ-ment of a slack take-up device is not necessary.
$
In all embodiments disclosed, the tendency for the rear end oE the motorcycle frame to deflect downwardly ("squat") in acceleration, is greatly reduced as compared with prior art suspensions, and this reduction is effected with the primary levers of the linkage either parallel, or diverging or converging.
From the foregoing, it will be seen that great flexibility is provided by the arrangements of the present invention with respect to se~ection of points on the framing of the motorcycle on which to mount the pivots for the pri-mary supportiny levers in the various embodiments disclosed.
Although certain forces, such as "squat" forces occurring during acceleration, may vary somewhat depending upon the specific lever and pivot arrangement employed, nevertheless, forces of this type are greatly reduced in all embodiments herein disclosed, as compared with various prior art suspension mechanisms.
The improvement with respect to reduction of "squat" is particularly significant in the embodiment de-scribed here below and illustrated in Figures 22 - 26 in-clusive. The general arrangement of these figures is very close to the arrangement of the first embodiment, shown in Figures 1 - 7 inclusive. Most of the reference numbers used in the description of Figures 1 - 7 are equally appli-cable to Figures 22 - 26, and most of those reference num-bers have actually been applied to Figures 22 - 26.
~8~g~
The chief differences between the structure of Figures 1 7 on the one hand and the stru~ture of Figures 22 - 26 on the other hand is the positioning of the swing arm link which interconnects the swing arm 22 with the inboard portions of the suspension linkage. In Figures 22 - 26 this swing arm link is identified by the reference number 34a and examination of the figures will show that the swing arm link 34a has a pivotal connection 35a with the swing arm 22 and extends downwardly at an inwardly incline angle with its lower end pivoted to a portion of the suspension linkage. In the specific embodiment shown in Figures 22 - 26, the swing arm link 34a is pivotally connected at its lower end with the outward extension 28a of the lower arm or lever 28 of the inboard portion of the linkage.
From this it will be seen that the s~ing arm link 34a in the embodiment of Figures 22 - 26 is extended from the swing arm in a direction forming an oblique angle with respect to the generally upright link 32 and 33 of the inboard linkage parts. Specifically, the swing arm link 34a is extended in a direction forming an acute angle with respect to the generally upright link 32 of the inboard suspension coupling mechanism.
~2~L8~93~3;
Figures 24, 25 and 26 diagramatically illustrate the ~eometric interrelationship of the major components of the system structurally shown in Figur~es 22 and 23, Figure 24 showing the p~rts in the mid or partially deflected position of the suspension. Figure 25 shows the relationship of the parts at the maximum upward deflected position; and Figure 26 shows the relationship of the parts at the lowermost wheel position.
From Figures 24, 25 and 26 it will be observed that the angle of the swing arm link 34a with respect to the swing arm 22 changes with deflection, the angle on the inboard side being the smallest in the maximum upward deflected position shown in Figure 25.
In consequence of the action of the parts when positioned as disclosed in this embodiment, there is a very considerable reduction in the tendency toward l'squat", i.e.
in the tendency for the rear end of the cycle to deflect downwardly in consequency of acceleration of the cycle.
This is desirable for most motorcycles and is especially important in motorcycles used for motocross racing because of the extensive and repeated acceleration used in such racing.
connection point between the shock absorber and the arm 39 of the bellcrank, as is indicated by dot and dash axis lines as applied to Figure 4~ For reasons fully brought out in my copending applications above identified, these relationships provide a desirable progressive increase in the resistance to deflection of the wheel as the deflection progresses frQm the static or normal load position repre-sented by Figure 2 to the maximum load position represented by Figure 4.
The arrangement of the linkage for the swing arm and for the shock resisting mechanism not only minimizes the inertia effects oE these parts in relation to the motion or deflection of the driving wheel, but still further, the disposition of these various parts is important ~rom the standpoint of concentrating those parts close to the center of gravity of the motorcycle as a whole. Moreover, the geometry of the parts as described has special advantages in minimizing tendency for the deflection resisting forces to induce or contribute to undesirable motions of the motor-cycle about its overall center of gravity.
The arrangement of the present invention is char-acterized by the fact that the driving wheel is, in effect, more isolated from the remainder of the motorcycle, par-ticularly with regard to the motions of the drive wheel and the dynamic and inertia forces involved in such motions and also in the action of the shock absorber or other motion-resisting mechanism.
~Z~93$
Still further, the linkage parts involved in the arrangement of the present invention may be accommodated in a smaller lateral or transverse space than is the case with certain other suspension mechanisms of the prior art.
Because of this, notwithstanding the fact that the link-age provides a parallelogram effect causing the motion of the drive wheel to occur about the axis of the driving sprocket, the relatively small overall lateral dimension of the parts provides ground clearance at the two sides of the motorcycle even when making sharp turns, which ground clearance is greater than in many prior suspension arrange-ments. Because of this increased lateral ground clearance, various parts, especially the suspension parts, may be mounted in lower positions, with consequent lowering of the overall center of gravity of the motorcycle; and this is of advantage for reasons well understood in this art.
Turning now to the alternative structural embodi-ments shown respectively in Figures 8, 9 and 10, in Figures 11 and 12, and in Figures 22 and 23, it is first noted that these alternative embodiments also have the advantages above referred to; but in addition, the alternative embodiments have further or collateral advantages, as will be pointed out following the detailed description of each one of the alternative arrangements.
,~Z~
In all of the alternative arrangements, many of the reference numerals applied are the same as those used in the description of the first embodiment: contained in Figures 1 to 7; and in general, the modified or additional parts of the alternative embodiments are identified by similar reference numerals incorporating prime markings or letters, as will be pointed out.
Consider first the alternative embodiment of Fig-ures 8 to 10 inclusive. The general distinction between this embodiment and the first embodiment lies in the fact that certain of the linkage components have been multiplied or duplicated, as compared with the first embodiment. Thus, note, for example, that in Figure 7 of the first embodiment, a pair of levers 27 and 28 are provided, one being located at each side of the vertical plane of the drive wheel.
Similarly, a pair of arms 32 and 33 associated with said levexs 27 and 28 are provided, one being located at each side of the vertical plane of the drive wheel. Compari-son of Figure 10 of the second embodiment with Figure 7 of the first embodiment will immediately disclose that these levers and arms have been duplicated. Thus, as shown in Figure 10, a pair of levers 27 and 27' are located at one side of the vertical plane of the drive wheel and another pair of levers 28 and 28' are located at the other side ~IL8~3~
of that vertical plane. Similarly, a pair of arms 32 and 32', cooperating with the levers 27 and 27', are provided at one side and a pair of arms 33 and 33l, cooperating with the levers 28 and 28', are provided at the other side.
These parts will also be found in Figures 8 and 9~ The arms 32 and 32' at one side, and the arms 33 and 33' at the other side, are rigidly connected with each other in pairs in order to provide the desired parallelogram linkage arrangement.
By virtue of this duplication, the mechanism can withstand very much greater wheel suspension forces, so that this arrangement can effectively be used in motorcycles of considerably larger size and weight. The arrangement of Figures 8 to 10 also has the advantage that the various forces are more uniformly distributed between various parts of the suspension mechanism and also between ~he suspension mechanism and the frame of the motorcycle.
As will be seen from Figures 8, 9 and 10, the pairs of levers 27 and 27' and 28 and 28' are pivoted about axes 29 and 29' and 30 and 30', the pivots 29 and 30l being coaxial and located above, and the pivots 29' and 30 being coaxial and located below the driving sprocket axis 26, and thereby providing the desired motion of the swing arm iZ1~
about the axis of the sprocket, as in the first embodiment~
Since the pivots 29 and 29' and 30 and 30' are located in an upright plane containing the axis of the driving sprocket~
the desired parallelogram action of the suspension linka~e is provided.
Turning now to the embodiment shown in Figures 11 and 12, it is again noted that numerous reference char-acters employed in ~he description of the first embodiment, and some of which also are described in connection with the second embodiment, are used in the same manner as in Figures 11 and 12; and it is not believed that duplicate description of these parts is needed.
Stated briefly and generally, the embodiment of Figures 11 and 12 differs from the embodiment of Figures 1 to 7 in two important respects. First, the arrangement of Figures 11 and 12 includes multiple levers and arms, as in the embodiment of Figures 8 to 10; and in addition, in the embodiment of Figures 11 and 12, as distinguished from both the first embodiment and also the second embodi-ment, the principal levers of the parallelogram linkage are pivotally mounted on axes on the frame of the motor-cycle, which axes are all located below the axis 26 of the driving sprocket 23. In the embodiment of Figures 8 to 10, and in the first embodiment, these principal levers of the parallelogram linkage are arranged so that pivot axes are provided both above and below the axis of the sprocket.
~2~
More speciEically, in Figures 11 and 12, it will be noted that at one side of the mechanism, the principal levers 27' and 27" have pivot axes 29' and 29" both of which are spaced below the axis 26 of the sprocket 23 (but pref-erably lie in a common vertical generally upright plane with the axis 26 of the sprocket 23). Similarly, at the other side of the mechanism, the principal levers 28 and 28" are provided with axes 30 and 30" which are also both spaced below the axis 26 of the sprocket 23 but lie in the same plane as the pivot axes of the levers at the other side.
In the embodiment of Figures 11 and 12, the arms which interconnect the parallel levers, i.e., the arms in-dicated at 32" and 33", each comprise a rigid arm struc-ture to which the levers 27' and 27" at one side are pivotally connected r and to which the arms 28' and 28" at the other side are pivotally connected. These arms 32" and 33" ex-tend above the upper levers 27" and 28" to provide for sup-port of the crosstie 31 on which the swing arm 22 is pivoted, as in the other embodiments. As seen in Figure 11, the link 34 between the extension 28a of the arm 28 and the swing arm provides, in combination with the inner portion of the swing arm9 the arms 32" and 33", and the arm 28a, a second parallelogram linkage which as described above in connection with the first embodiment provides the desired motion of the swing arm 22 about the axis 26 of the driving sprocket 23.
~3 8~g~$
From the above, it will be seen that the same type of parallelogram linkages and motions are provided by the embodiment in Figures 11 and 12, and this affords various of the advantages described above in connection with Figures l to 7.
It will also be understood that the same type of shock absorber mechanism indicated at 36 may be employed in either the second or third embodiments, in the same gen-eral manner as in the first embodiment. This mechanism receives the motion of the swing arm through the connection 42 in the embodiments illustrated in Figures 8 to 10 and ll and 12, in the same general manner as described above with reference to Figures l to 7.
In considering the embodiment of Figures ll and 12, it is particularly to be noted that the fixed pivots for the principal levers 27' and 27" and 28 and 28" are both positioned in spaced relation below the axis 26 of the driving sprocket 23; and this i5 of advantage in main-taining the overall center of gravity of the wheel suspen-sion linkage at a location as low as possible. However, from the standpoint of the action of the linkage, it would also be possible to mount the principal levers 27' and 27"
and the levers 28 and 28" on pivots all located above the axis of the sprocket. In some cycle constructions, this would provide increased clearance for connection and inter-connection of the parts, but it is preferred to locate the parallel links below the sprocket as in Figures ll and 12.
In the preferred construction of any of the above described arrangements, it is contemplated ~hat the prin-cipal parallel levers at both sides are preferably mounted on pivots which lie in or at least close to the same upright plane as the axis 26 of the driving sprocket; and for most installations, this coplanar arrangement is preferred whether both of the lever pivots at each side are located either above or below the axis of the driving sprocket, and also in arrangements (such as in Figures 1 to 7) in which one lever pivot is located above the sprocket and the other lever pivot below the sprocket.
Figures 13 to ~1 diagrammatically illustrate sev-eral variants with respect to locations o~ lever and link pivots. From various of these figures, it will be seen that geometric variations from precise parallelograms may be used. In some instances, substantially equal and oppo-site inclination of the levers may be adopted while still retaining linkage motion approximating the action of a true parallelogram. Thus, the need for a slack take-up device for the drive chain may be avoided, even if the linkage does not precisely correspond to a parallelogram. Moreover, in some installations, for instance where especially diffi-cult clearance problems are encountered, it may even be preferred to depart from a pure parallelogram to an extent requiring use of a chain slack take-up device. In some cases, this may still provide a desirable improvement with respect to dynamic forces, such as decreased tendency for acceleration to induce "squat".
In considering the various diagrammatic illustra~
tions of Figures 13 to 21, it is first noted that all of these diagrams have reference characters identifying the principal components which are involved in the motions of the suspension mechanism. Referring, for example~ to Figure 13, it will be seen that the motor or driving sprocket is diagrammatically indicated at A, and the wheel or driven sprocket is diagrammatically indicated at B. The inter-connecting chain is indicated by the letter C.
The swing arm provided for the driviny wheel is indicated by the letter D, and at its inner end, this swing arm is mounted by means of a pair of levers E-E which are mounted on fi~ed points as is indicated and which are pivotally interconnected by the link F, the swing arm D being pivotally mounted on the link F.
The lower lever E has an extension El rigid with the lower link E and extending in the direction of the wheel.
This lever extension El is pivotally connected with the swing arm D by means of the swing arm link G. The general structural relationship of these parts will readily be under-stood by comparison with any of the structural embodiments hereinabove fully described and illustrated in various of Figures 1 to 12.
~8~3~
Referring now more specifically to the embodiment diagrammatically illustrated in Figures li, 14 and 15, it is first noted that in this particular embodiment, the two levers E-E, instead of being substantially parallel ~o each other, diverge from each other to positions respectively above and below the driving sprocket A. With this "diver-gent" geometry, when the driven wheel is deflected down-wardly, for instance, to a position such as indicated in Figure 14, notwithstanding the divergent arrangement of the levers E, the swing arm D, and its pivotal connection with the link F, still remains substantially in alignment with the axes of the motor and wheel sprockets, in view of which the chain path is not appreciably changed. There-fore, a chain slack take-up device would not necessarily be needed. The same condition prevails upon upward deflec-tion of the driving wheel, for instance, to the position indicated in Figure 15. Although no substantial change in chain path length occurs, this arrangement actually does slightly alter the chain path length.
Turning now to the embodiment shown in Figures 16, 17 and 18, it is to be noted that the links and levers are again indicated by the same reference letters; but in this alternative embodiment, the levers E-E are po~itioned at different distances from the axis of the driving sprocket A. Both of the levers have been raised so that the upper lever ~ now lies in a position farther removed from the ~22-~L2~ 3S
axis of the sprocket A than is the case with the lower lever E. When the parts are interconnected in the manner indi-cated in Figure 16, with the swing arm D and its pivot lo-cated in a plane containing the axes of ~he driving and driven sprockets, downward deflection of the driven wheel to the position indicated in Figure 17 still does not ex-tensively alter the position oE the swing arm and its pivot with respect to the plane containing the axes of the driving and driven sprockets.
From the above, it will be seen that in the embodi-ment of Figures 16, 17 and 18, deflection of the driven wheel does not extensively alter the chain length.
Similar results are achieved when employing an arrangement, such as shown in Figures 19, 20 and 21, in which the levers E-E converge rather than diverge from each other. Here again, deflection of the driven wheel does not appreciably change the position of the swing arm and its pivot with respect to the plane containing the axes of the driving and driven sprockets A and B.
It will be understood that in any of these arrange-ments where the length of the path of the chain between the driving and driven sprockets remains substantially the same in different positions of the driven wheel, the employ-ment of a slack take-up device is not necessary.
$
In all embodiments disclosed, the tendency for the rear end oE the motorcycle frame to deflect downwardly ("squat") in acceleration, is greatly reduced as compared with prior art suspensions, and this reduction is effected with the primary levers of the linkage either parallel, or diverging or converging.
From the foregoing, it will be seen that great flexibility is provided by the arrangements of the present invention with respect to se~ection of points on the framing of the motorcycle on which to mount the pivots for the pri-mary supportiny levers in the various embodiments disclosed.
Although certain forces, such as "squat" forces occurring during acceleration, may vary somewhat depending upon the specific lever and pivot arrangement employed, nevertheless, forces of this type are greatly reduced in all embodiments herein disclosed, as compared with various prior art suspension mechanisms.
The improvement with respect to reduction of "squat" is particularly significant in the embodiment de-scribed here below and illustrated in Figures 22 - 26 in-clusive. The general arrangement of these figures is very close to the arrangement of the first embodiment, shown in Figures 1 - 7 inclusive. Most of the reference numbers used in the description of Figures 1 - 7 are equally appli-cable to Figures 22 - 26, and most of those reference num-bers have actually been applied to Figures 22 - 26.
~8~g~
The chief differences between the structure of Figures 1 7 on the one hand and the stru~ture of Figures 22 - 26 on the other hand is the positioning of the swing arm link which interconnects the swing arm 22 with the inboard portions of the suspension linkage. In Figures 22 - 26 this swing arm link is identified by the reference number 34a and examination of the figures will show that the swing arm link 34a has a pivotal connection 35a with the swing arm 22 and extends downwardly at an inwardly incline angle with its lower end pivoted to a portion of the suspension linkage. In the specific embodiment shown in Figures 22 - 26, the swing arm link 34a is pivotally connected at its lower end with the outward extension 28a of the lower arm or lever 28 of the inboard portion of the linkage.
From this it will be seen that the s~ing arm link 34a in the embodiment of Figures 22 - 26 is extended from the swing arm in a direction forming an oblique angle with respect to the generally upright link 32 and 33 of the inboard linkage parts. Specifically, the swing arm link 34a is extended in a direction forming an acute angle with respect to the generally upright link 32 of the inboard suspension coupling mechanism.
~2~L8~93~3;
Figures 24, 25 and 26 diagramatically illustrate the ~eometric interrelationship of the major components of the system structurally shown in Figur~es 22 and 23, Figure 24 showing the p~rts in the mid or partially deflected position of the suspension. Figure 25 shows the relationship of the parts at the maximum upward deflected position; and Figure 26 shows the relationship of the parts at the lowermost wheel position.
From Figures 24, 25 and 26 it will be observed that the angle of the swing arm link 34a with respect to the swing arm 22 changes with deflection, the angle on the inboard side being the smallest in the maximum upward deflected position shown in Figure 25.
In consequence of the action of the parts when positioned as disclosed in this embodiment, there is a very considerable reduction in the tendency toward l'squat", i.e.
in the tendency for the rear end of the cycle to deflect downwardly in consequency of acceleration of the cycle.
This is desirable for most motorcycles and is especially important in motorcycles used for motocross racing because of the extensive and repeated acceleration used in such racing.
Claims (16)
1. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on fixed axes spaced one above the other in a plane containing the axis of the motor sprocket, first linkage pivotally interconnecting said levers on axes spaced to provide a first parallelogram linkage, a swing arm for the drive wheel pivotally connected with said first linkage on an axis lying in a plane containing the axes of the motor and wheel sprockets, one of said levers having an extension beyond the first linkage, a swing arm link pivotally interconnecting the swing arm and said extension and forming a second parallelo-gram linkage with said first linkage, the swing arm and said lever extension, the fixed axes for the first and second levers both being located below the axis of the driving sprocket, and means connected with the wheel sus-pension system for resisting drive wheel deflection.
2. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on fixed axes spaced one above the other in a plane containing the axis of the motor sprocket, first linkage pivotally interconnecting said levers on axes spaced to provide a first parallelogram linkage, a swing arm for the drive wheel pivotally connected with said first linkage on an axis lying in a plane containing the axes of the motor and wheel sprockets, one of said levers having an extension beyond the first linkage, a swing arm link pivotally interconnecting the swing arm and said extension and forming a second parallelo-gram linkage with said first linkage, the swing arm and said lever extension, the fixed axes for the first and second levers both being offset vertically and in the same direction from the axis of the driving sprocket, and means connected with the wheel suspension system for resisting drive wheel deflection.
3. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on fixed axes spaced one above the other in a plane containing the axis of the motor sprocket, first linkage pivotally interconnecting said levers on axes spaced to provide a first parallelogram linkage, a swing arm for the drive wheel pivotally connected with said first linkage on an axis lying in a plane containing the axes of the motor and wheel sprockets, one of said levers having an extension beyond the first linkage, a swing arm link pivotally interconnecting the swing arm and said extension and forming a second parallelo-gram linkage with said first linkage, the swing arm and said lever extension, said first and second levers compris-ing pairs of such levers, with one pair located at one side of the vertical plane of the drive wheel and with the other pair located at the other side of said vertical plane, and means connected with the wheel suspension system for resist-ing drive wheel deflection.
4. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, first linkage pivotally interconnecting said levers on second axes in a second generally upright plane between the motor and wheel sprockets, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said first linkage on a transverse axis be-tween the motor and wheel sprockets, one of said levers having an extension beyond the first linkage, a generally upright swing arm link pivotally interconnecting the swing arm and said extension, said second axes being spaced from each other a distance greather than said first axes, and means connected with the wheel suspension system for re-sisting drive wheel deflection.
5. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, first linkage pivotally interconnecting said levers on second axes in a second generally upright plane between the motor and wheel sprockets, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said first linkage on a transverse axis be-tween the motor and wheel sprockets, one of said levers having an extension beyond the first linkage, a generally upright swing arm link pivotally interconnecting the swing arm and said extension, said second axes being spaced from each other a distance less than said first axes, and means connected with the wheel suspension system for resisting drive wheel deflection.
6. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising two pairs of pivoted levers located toward oppo-site sides of the vehicle, each pair of levers including first and second levers pivotally mounted on first axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, for each pair of levers first linkage pivotally interconnecting said levers on second axes in a second generally upright plane between the motor sprocket and the forward edge of the drive wheel, a swing arm for the drive wheel extended forwardly of the wheel and pivotally connected with said first linkage on a transverse axis between the motor sprocket and the front of the wheel, at least one of said levers having an extension beyond the first linkage, a generally upright swing arm link pivotally interconnecting the swing arm and said extension, and means connected with the wheel suspension system for resisting drive wheel deflection.
7. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism including a motor sprocket, a wheel sprocket, and a drive chain con-necting the sprockets, a drive wheel suspension system comprising two pairs of pivoted levers located toward oppo-site sides of the vehicle, each pair of levers including first and second levers pivotally mounted on first axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, for each pair of levers first linkage pivotally interconnecting said levers on second axes in a second generally upright plane between the motor and wheel sprockets, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said first linkage on a trans-verse axis between the motor and wheel sprockets, at least one of said levers having an extension beyond the first linkage, a generally upright swing arm link pivotally in-terconnecting the swing arm and said extension, and means connected with the wheel suspension system for resisting drive wheel deflection.
8. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, first linkage pivotally interconnecting said levers on second axes in a second generally upright plane between the motor and wheel sprockets, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said first linkage on a trans-verse axis between the motor and wheel sprockets, one of said levers having an extension beyond said first linkage in a position vertically offset from the swing arm, a swing arm link extended between the swing arm and said lever ex-tension, a first pivot joint connecting the swing arm link with the swing arm and a second pivot joint connecting the swing arm link with said lever extension, said second pivot joint being closer to the first linkage than said first pivot joint, and means connected with the wheel suspension system for resisting drive wheel deflection.
9. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, and extended from said plane at different angles but in directions generally toward the drive wheel, coupling means interconnecting said levers and providing for concurrent pivotal motion of said levers on said first and second axes, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said coupling means on a swing arm mounting axis lying substantially in a plane containing the axes of the motor and wheel sprockets, linkage connected with at least one of said levers and having a pivotal connection with the swing arm intermediate the axis of the drive wheel and said swing arm mounting axis, and means connected with the wheel suspension system for resisting drive wheel deflection.
10. A construction as defined in Claim 9 in which the coupling means interconnecting the levers includes at least one generally upright link with which the swing arm is pivotally connected, and further in which the linkage which is connected with one of said levers includes a swing arm link pivoted to the swing arm.
11. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a-drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket, and extended from said plane toward the drive wheel, coupling means interconnecting said levers and providing for concurrent pivotal motion of said levers on said first and second axes, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said coupling means on a swing arm mounting axis lying substantially in a plane containing the axes of the motor and wheel sprockets, linkage connected with at least one of said levers and having a pivotal connection with the swing arm intermediate the axis of the drive wheel and said swing arm mounting axis, the coupling means inter-connecting the levers including at least one generally up-right link with which the swing arm is pivotally connected, the linkage which is connected with one of said levers including a swing arm link pivoted to the swing arm and extended therefrom in a direction forming an oblique angle with said generally upright link of the coupling means, and means connected with the wheel suspension system for resisting drive wheel deflection.
12. A construction as defined in Claim 11 in which the swing arm link is extended in a direction forming an acute angle with said generally upright link of the cou-pling means.
13. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a gen-erally upright plane in the region of the axis of the motor sprocket, and extended from said plane toward the drive wheel, coupling means interconnecting said levers and pro-viding for concurrent pivotal motion of said levers on said first and second axes, a swing arm for the drive wheel ex-tended forwardly of the wheel sprocket and pivotally con-nected with said coupling means on a swing arm mounting axis lying substantially in a plane containing the axes of the motor and wheel sprockets, linkage for interrelating the motion of the levers and the swing arm and having a pivotal connection with the swing arm intermediate the axis of the drive wheel and said swing arm mounting axis, the linkage interrelating the motion of the levers and swing arm including a swing arm link pivotally connected with the swing arm and extended generally transverse to the swing arm in a direction forming an oblique angle with said first generally upright plane in the region of the axis of the motor sprocket, and means connected with the wheel suspen-sion system for resisting drive wheel deflection.
14. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a gen-erally upright plane in the region of the axis of the motor sprocket and extended from said plane toward the drive wheel, coupling means interconnecting said levers and pro-viding for concurrent pivotal motion of said levers on said first and second axes, the coupling means including at least one generally upright link, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally con-nected with said upright link on a swing arm mounting axis lying substantially in a plane containing the axes of the motor and wheel sprockets, linkage connected with at least one of said levers and including a swing arm link having a pivotal connection with the swing arm and extended from the swing arm in a direction forming an oblique angle with said generally upright link of the coupling means, and means con-nected with the wheel suspension system for resisting drive wheel deflection.
15. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a first generally upright plane in the region of the axis of the motor sprocket and extended from said plane toward the drive wheel, coupling means interconnecting said levers and pro-viding for concurrent pivotal motion of said levers on said first and second axes, the coupling means including at least one generally upright link lying in a second generally up-right plane between said first upright plane and the drive wheel, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally connected with said up-right link on a swing arm mounting axis lying substantially in a plane containing the axes of the motor and wheel sprock-ets, linkage connected with at least one of the said levers and including a swing arm link having a pivotal connection with the swing arm and with said one lever, the axis of the pivotal connection of the swing arm link with said one lever being offset from said second generally upright plane, and means connected with the wheel suspension system for re-sisting drive wheel deflection.
16. In a motor-powered vehicle having a frame, a drive wheel, a motor, and wheel drive mechanism includ-ing a motor sprocket, a wheel sprocket, and a drive chain connecting the sprockets, a drive wheel suspension system comprising first and second levers pivotally mounted on first and second axes spaced one above the other in a gen-erally upright plane in the region of the axis of the motor sprocket and extended from said plane toward the drive wheel, coupling means interconnecting said levers and providing for concurrent pivotal motion of said levers on said first and second axes, the coupling means including at least one generally upright link, a swing arm for the drive wheel extended forwardly of the wheel sprocket and pivotally con-nected with said upright link on a swing arm mounting axis lying substantially in a plane containing the axes of the motor and wheel sprockets, linkage connected with at least one of said levers and including a swing arm link having a pivotal connection with the swing arm and extended from the swing arm in a direction forming an oblique angle with said generally upright link of the coupling means, the link-age which is connected with one of said levers including an element extended in generally parallel relation to said one of the levers, the swing arm link being connected with said element, and means connected with the wheel suspension system for resisting drive wheel deflection.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/544,091 US4544044A (en) | 1981-06-01 | 1983-10-21 | Motorcycle drive wheel suspension system |
| US544,091 | 1983-10-21 | ||
| US06/577,026 US4558761A (en) | 1981-06-01 | 1984-02-06 | Motorcycle drive wheel suspension system |
| US577,026 | 1984-02-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1218935A true CA1218935A (en) | 1987-03-10 |
Family
ID=27067499
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000465547A Expired CA1218935A (en) | 1983-10-21 | 1984-10-16 | Motorcycle drive wheel suspension system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1218935A (en) |
-
1984
- 1984-10-16 CA CA000465547A patent/CA1218935A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |