CA1123479A - Ski suspension for snowmobiles - Google Patents
Ski suspension for snowmobilesInfo
- Publication number
- CA1123479A CA1123479A CA352,975A CA352975A CA1123479A CA 1123479 A CA1123479 A CA 1123479A CA 352975 A CA352975 A CA 352975A CA 1123479 A CA1123479 A CA 1123479A
- Authority
- CA
- Canada
- Prior art keywords
- ski
- snowmobile
- steering
- torsion bar
- arm
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62B—HAND-PROPELLED VEHICLES, e.g. HAND CARTS OR PERAMBULATORS; SLEDGES
- B62B17/00—Accessories or details of sledges
- B62B17/02—Runners
- B62B17/04—Runners resiliently suspended
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Vehicle Body Suspensions (AREA)
Abstract
ABSTRACT
In a snowmobile ski suspension each ski is carried on a trailing swing arm pivotally mounted in the front of the snowmobile.
The swing arm carries a steering tube in which the ski leg is pivotable about a generally upright axis. A hydraulic damper-coil spring assembly is attached between a mounting on the lower end of the swing arm, and a bracket within the front part of the snowmobile, and controls upwards and downwards deflection of the ski assembly. The skis on opposite sides of the vehicle are interconnected by a transverse torsion bar stabilizer which is arranged to transmit deflection forces from the ski on one side to the ski on the opposite side and vice versa, and thus enhance the roll stability of the machine.
In a snowmobile ski suspension each ski is carried on a trailing swing arm pivotally mounted in the front of the snowmobile.
The swing arm carries a steering tube in which the ski leg is pivotable about a generally upright axis. A hydraulic damper-coil spring assembly is attached between a mounting on the lower end of the swing arm, and a bracket within the front part of the snowmobile, and controls upwards and downwards deflection of the ski assembly. The skis on opposite sides of the vehicle are interconnected by a transverse torsion bar stabilizer which is arranged to transmit deflection forces from the ski on one side to the ski on the opposite side and vice versa, and thus enhance the roll stability of the machine.
Description
~ 3~g miS invention relates to improvements in snowmobiles, and in particular to a new or i~,proved ski suspension for snowmobiles and similar vehicles.
Conventionally, snc~mobile ski suspensions have included a bowed leaf spring longitudinally arranged akove the ski, the ends of the spring being connected to the ski, and the upper bowed part of the spring having a bracket by which is connected to the ski leg. The bowed leaf spring is capable of deflection by flattening to accommodate to irregularities in the terrain over which the vehicle is driven, and it is also known to incorporate a hydraulic damper angularly arranged between a forward part of the ski and the ski leg bracket, to dampen such displacements. Such known ski suspensions have proved not altogether satisfactory in terms of ride comfort on very rough terrains, a primary limiting factor in this respect being the relatively small range of deflection which can be accommodated by the leaf spring configuration.
m e present invention provides a snowmobile having a body with a rear part supported on a track belt, and a front part supported upon a ;
pair of laterally spaced steerable ski assemblies, steering means on said body for effecting steering control of said ski assemblies, and suspension means acting between said body and each said ski assembly;
said suspension means comprising a pair of trailing arms each supported on a ~ounting in the front part of the snowmobile and extending downwardly and rearwardly therefrom, said trailing arms being pivotable in their mountings akout a ccm~on transverse axis, torsion bar means extending transversely in said front part and having opposite ends coupled to respective ones of said trailing arms so as to resist relative angular vement of said trailing arms; steering tube means at the lower end of each treiling arn: each ss d ski a:sembly conprising sn elongate ski 7~
runner haying an upwardly curved fxont end a mounting bracket on the upper side of the runner at an intermediate point in its length, an upstanding ski leg and means forming a pivotal connection between said mounting bracket and a lower end of the ski leg on an axis transverse to the length of the ski runner, said ski leg having an upper portion engaged by a respective one of said steering tubes to be pi wtable thereon about a generally upright axis, said steering means being coupled with said ski legs to effect steering control of said ski assemblies through joint pivotal movement of said ski legs, said suspension means further comprising spring means associated with each said trailing arm and operative to urge the associated ski assembly downwardly, and damper means operative to dampen angular movements of each said trailing arm.
The foregoing arrangement enables the suspension to acconmcdate a much larger range of deflection than has hitherto been possible, and accordingly provides a greater degree of comfort to the vehicle occupant, particularly when travelling over rough terrain.
The torsion bar means acts to urge either ski to follow a deflection imposed upon the other, and thus greatly enhances the roll stab~ility of the vehicle. In one preferred arrangement the torsion bar is positioned within a tu~e mounted transversely within the forward part of the sncwmDbile, the ends of the tube forming bearings for the pivotal mounting of the forward upper end of the trailing arms. In this arrangement the ends of the torsion bar extend through the bearings and are connected to radially arranged stabilizer arms the ends of which are in turn attached to the trailing anms.
In another arrangement each steering tube is connected to the `
snowmobile through a pair of trailing arms to provide a parallelogram ', ; ,.
Conventionally, snc~mobile ski suspensions have included a bowed leaf spring longitudinally arranged akove the ski, the ends of the spring being connected to the ski, and the upper bowed part of the spring having a bracket by which is connected to the ski leg. The bowed leaf spring is capable of deflection by flattening to accommodate to irregularities in the terrain over which the vehicle is driven, and it is also known to incorporate a hydraulic damper angularly arranged between a forward part of the ski and the ski leg bracket, to dampen such displacements. Such known ski suspensions have proved not altogether satisfactory in terms of ride comfort on very rough terrains, a primary limiting factor in this respect being the relatively small range of deflection which can be accommodated by the leaf spring configuration.
m e present invention provides a snowmobile having a body with a rear part supported on a track belt, and a front part supported upon a ;
pair of laterally spaced steerable ski assemblies, steering means on said body for effecting steering control of said ski assemblies, and suspension means acting between said body and each said ski assembly;
said suspension means comprising a pair of trailing arms each supported on a ~ounting in the front part of the snowmobile and extending downwardly and rearwardly therefrom, said trailing arms being pivotable in their mountings akout a ccm~on transverse axis, torsion bar means extending transversely in said front part and having opposite ends coupled to respective ones of said trailing arms so as to resist relative angular vement of said trailing arms; steering tube means at the lower end of each treiling arn: each ss d ski a:sembly conprising sn elongate ski 7~
runner haying an upwardly curved fxont end a mounting bracket on the upper side of the runner at an intermediate point in its length, an upstanding ski leg and means forming a pivotal connection between said mounting bracket and a lower end of the ski leg on an axis transverse to the length of the ski runner, said ski leg having an upper portion engaged by a respective one of said steering tubes to be pi wtable thereon about a generally upright axis, said steering means being coupled with said ski legs to effect steering control of said ski assemblies through joint pivotal movement of said ski legs, said suspension means further comprising spring means associated with each said trailing arm and operative to urge the associated ski assembly downwardly, and damper means operative to dampen angular movements of each said trailing arm.
The foregoing arrangement enables the suspension to acconmcdate a much larger range of deflection than has hitherto been possible, and accordingly provides a greater degree of comfort to the vehicle occupant, particularly when travelling over rough terrain.
The torsion bar means acts to urge either ski to follow a deflection imposed upon the other, and thus greatly enhances the roll stab~ility of the vehicle. In one preferred arrangement the torsion bar is positioned within a tu~e mounted transversely within the forward part of the sncwmDbile, the ends of the tube forming bearings for the pivotal mounting of the forward upper end of the trailing arms. In this arrangement the ends of the torsion bar extend through the bearings and are connected to radially arranged stabilizer arms the ends of which are in turn attached to the trailing anms.
In another arrangement each steering tube is connected to the `
snowmobile through a pair of trailing arms to provide a parallelogram ', ; ,.
-2-'~:
steering linkage, there being a separate torsion bar stabilizer associated with each of the pair of trailing arms.
me inventi~n will further be described, by way of example only, with reference to the accompanying drawings, wherein:
Figure 1 is a front perspective view of a snowmobile incorporating an improved ski suspension means in accordance with the in~ention;
Figure 2 is a fragmentary side view of the front part of the sno~mobile;
Figure 3 is a fragmentary perspective view of the improved suspension system;
Figure 4 is an exploded view illustrating ~arious elements of the suspension system schematically;
Figure 5 is a view corresponding to Figure 3 showing a modified suspension system;
Fig~re 6 is a view corresponding to Figure 4 of the mcdified suspension system; and Figure 7 is a view generally corresponding to Figure 3 but showing a modified suspension system.
Referring to Figures 1 to 4, a snowmobile 1 is supported in ;
cRnventional fashion at its forward end upon a laterally spaced pair of ski assemblies 2, and at its rear end upon a ground engaging track belt
steering linkage, there being a separate torsion bar stabilizer associated with each of the pair of trailing arms.
me inventi~n will further be described, by way of example only, with reference to the accompanying drawings, wherein:
Figure 1 is a front perspective view of a snowmobile incorporating an improved ski suspension means in accordance with the in~ention;
Figure 2 is a fragmentary side view of the front part of the sno~mobile;
Figure 3 is a fragmentary perspective view of the improved suspension system;
Figure 4 is an exploded view illustrating ~arious elements of the suspension system schematically;
Figure 5 is a view corresponding to Figure 3 showing a modified suspension system;
Fig~re 6 is a view corresponding to Figure 4 of the mcdified suspension system; and Figure 7 is a view generally corresponding to Figure 3 but showing a modified suspension system.
Referring to Figures 1 to 4, a snowmobile 1 is supported in ;
cRnventional fashion at its forward end upon a laterally spaced pair of ski assemblies 2, and at its rear end upon a ground engaging track belt
3. An engine ~not shcwn) is drivingly connected to the trac~ belt to -propel the vehicle which is steered by operator-controlled handle bars
4 connected to the ski assemblies through a steering mechanism 5.
Referring particularly to Fig~res 2, 3 and 4, it will be seen ;~
that each ski assembly comprises a longitudinally extending sk.i runner 6 having an upwardly curved front end 7. A ski coupler in the form of a mounting bracket 8 is attached to the upper side of the ski runner 6 at 7~
a point intermediate its ends. m e mounting bracket is attached to the ski runner by any suitable means and includes a pair of upstanding longitudinal walls 9 (Figure 4) having aligned apertures 10.
As best seen in Figure 4, a ski leg assembly 11 in the form of an upstanding circular rod 12 with a splined upper end 13 has a bracket 14 at its lower end having a pair of downwardly projecting laterally spaced apertured plates 15 on its underside. m e plates 15 fit between the walls 9 of the mounting bracket 8 Qn the ski assembly, and a bolt 16 or other suitable fastener can be inserted between the aligned holes in the walls 9 and plates 15 to secure the ski leg assembly 11 to the ski assembly 2, and form a pivotal COnneCtiQn therebetween on an axis transverse to the length of the ski.
m e config~rations of the mounting bracket 8 and the ski leg bracket 14 are selected such as to acccwmodate the desired range of pivotal movement between the ski assembly 2 and the ski leg assembly 11 about the pivotal axis provided by the bolt 16, and resilient abutment means such as elastameric blocks 17a and 17b are provided to act as an abutment between these members in defining the limits of such pivotal m~v~ent.
m e ski suspensian system also includes a front tube 18 mounted in spaced longitudinal frame nembers 19 at the front of the snowmobile and extending in a transverse horizontal direction. As best seen in Figure 4, the front tube 18 has outboard ends 20 defined by collars 21, ;
these outboard ends projecting laterally beyond the vertical walls 22 of the frame members 19 into a recessed well 23 formed at each side of the front part of the snowmobile i~bove the resFective ski assembly. me front tube 18 is secured non-rotatably to the frame members 19, and each outboard end has a screw-threaded terminal section 24.
:
~ _4_ 3~7~9 The suspension also includes on each side of the snowmobile a trailing swing arm 25 having at its upper forward end a tubular bearing sleeve 26 adapted to be received over the outboard end 20 of the front tube to form a pivotal mounting for the arm 25 on the front of the snowmobile. m e trailing swing arm extends downwardly and rearwardly from this pivotal mounting and at its rear end has a steering tube 27 which extends at right angles to the sleeve 26. Bushings 28 are received in opposite ends of the steering tube 27 and form bearing means for the ski leg rod 12 which can be inserted therein so that its splined upper end 13 projects above the steering tube 27 as seen in Figures 2 and 3.
Referring to Figure 4, the top sleeve 26 of the trailing swing arm can be passed onto the outboæd end 20 of the front tube 18 until it abuts the coll æ 21, and retained in position by a nut 29 and lockwasher 30 engaged on the threaded terminal section 24, suitable shims 31 being interposed between the lockwasher and the end of the sleeve 26 to provide the required amount of clearance without undue play.
Extending coaxially within the front tube 18 is a stabilizer torsion b æ 32 of a length slightly in excess of that of the tube 18 and having splined ends 33 which project somewhat beyond the ends of the tube 18. m e b,æ 32 is freely rotatable with respect to the tube 18 and is supported therein at each end by a be æing sleeve 34 (Figure 4) received within the screw threaded terminal sections 24 of the tube 18.
Each splined end 33 is engaged in a split eye 35 at one end of a short stabilizer æm 36, the stabilizer æm being non-rotatably secured to the splined end 33 of the torsion bar by a screw-threaded fastener arrangement indicated at 37. m e stabilizer arm 36 extends generally parallel to the swing arm 25 on the outbcard side thereof and is secured thereto at its re æwæd end by a screw-threaded fastener 38. The fastener 38
Referring particularly to Fig~res 2, 3 and 4, it will be seen ;~
that each ski assembly comprises a longitudinally extending sk.i runner 6 having an upwardly curved front end 7. A ski coupler in the form of a mounting bracket 8 is attached to the upper side of the ski runner 6 at 7~
a point intermediate its ends. m e mounting bracket is attached to the ski runner by any suitable means and includes a pair of upstanding longitudinal walls 9 (Figure 4) having aligned apertures 10.
As best seen in Figure 4, a ski leg assembly 11 in the form of an upstanding circular rod 12 with a splined upper end 13 has a bracket 14 at its lower end having a pair of downwardly projecting laterally spaced apertured plates 15 on its underside. m e plates 15 fit between the walls 9 of the mounting bracket 8 Qn the ski assembly, and a bolt 16 or other suitable fastener can be inserted between the aligned holes in the walls 9 and plates 15 to secure the ski leg assembly 11 to the ski assembly 2, and form a pivotal COnneCtiQn therebetween on an axis transverse to the length of the ski.
m e config~rations of the mounting bracket 8 and the ski leg bracket 14 are selected such as to acccwmodate the desired range of pivotal movement between the ski assembly 2 and the ski leg assembly 11 about the pivotal axis provided by the bolt 16, and resilient abutment means such as elastameric blocks 17a and 17b are provided to act as an abutment between these members in defining the limits of such pivotal m~v~ent.
m e ski suspensian system also includes a front tube 18 mounted in spaced longitudinal frame nembers 19 at the front of the snowmobile and extending in a transverse horizontal direction. As best seen in Figure 4, the front tube 18 has outboard ends 20 defined by collars 21, ;
these outboard ends projecting laterally beyond the vertical walls 22 of the frame members 19 into a recessed well 23 formed at each side of the front part of the snowmobile i~bove the resFective ski assembly. me front tube 18 is secured non-rotatably to the frame members 19, and each outboard end has a screw-threaded terminal section 24.
:
~ _4_ 3~7~9 The suspension also includes on each side of the snowmobile a trailing swing arm 25 having at its upper forward end a tubular bearing sleeve 26 adapted to be received over the outboard end 20 of the front tube to form a pivotal mounting for the arm 25 on the front of the snowmobile. m e trailing swing arm extends downwardly and rearwardly from this pivotal mounting and at its rear end has a steering tube 27 which extends at right angles to the sleeve 26. Bushings 28 are received in opposite ends of the steering tube 27 and form bearing means for the ski leg rod 12 which can be inserted therein so that its splined upper end 13 projects above the steering tube 27 as seen in Figures 2 and 3.
Referring to Figure 4, the top sleeve 26 of the trailing swing arm can be passed onto the outboæd end 20 of the front tube 18 until it abuts the coll æ 21, and retained in position by a nut 29 and lockwasher 30 engaged on the threaded terminal section 24, suitable shims 31 being interposed between the lockwasher and the end of the sleeve 26 to provide the required amount of clearance without undue play.
Extending coaxially within the front tube 18 is a stabilizer torsion b æ 32 of a length slightly in excess of that of the tube 18 and having splined ends 33 which project somewhat beyond the ends of the tube 18. m e b,æ 32 is freely rotatable with respect to the tube 18 and is supported therein at each end by a be æing sleeve 34 (Figure 4) received within the screw threaded terminal sections 24 of the tube 18.
Each splined end 33 is engaged in a split eye 35 at one end of a short stabilizer æm 36, the stabilizer æm being non-rotatably secured to the splined end 33 of the torsion bar by a screw-threaded fastener arrangement indicated at 37. m e stabilizer arm 36 extends generally parallel to the swing arm 25 on the outbcard side thereof and is secured thereto at its re æwæd end by a screw-threaded fastener 38. The fastener 38
-5- `
- : : ;. . .: ~ . , .
extends through aligned apertures in the end of the stabilizer arm 36 and a lug 39 (Figure 4~ on the side of the trailing arm 25, the fastener incorporating resilient washers 40 to attenuate the transmission of vibrations from the trailing arm 25 to the stabilizer bar 32 and prevent premature wear of the connection.
From the above described arrangement it will be seen that the stabilizer torsion bar 32 remains unstressed when the trailing c~rms 25 are pivoted in unison, but will act to resist relative angukar movement of the trailing arms, such angular movement producing a torsional stress in the stabilizer bar 32.
Swinging movements of the trailing arms 25 caused by vertical movements of the ski assemblies 2, are controlled by respective coil spring-hydraulic damper units 41 arranged in a generally upright orientation.
Each unit 41 is pivotally mounted at its lower end on a pin 42 (s e Figure 4) projecting laterally inwardly from the lower end of the steering tube 27, and at its upper end on a pin 43 carried on a bracket 44 on the snowmobile frame. The upper end of the unit 41 is enclosed within a resilient boot 45 which forms a seal with the opening in the upper wall of the frame member 19 through which the unit 41 extends, and thus prevents snow or the like entering the cab of the snowmobile through this opening. The pins 42 and 43 are parallel to the top sleeve 26 of the respective swing arm 25, and that the damper units 41 can piv~t slightly in a vertical plane to accommodate to the arcuate path of movement of the pin 41 as the arm 25 swings about its pivotal mounting 20.
The steering means of the snow~obile is best illustrated in Figures 3 and 4 and comprises a steerIng shaft 46 connected to the handlebars 4 and rotatably mounted in the snowmobile cab in suitable 7~
bearing means (not shown). At its lower end the shaft has a radial arm 47. A crank lever 48 is pivDtally mounted at 49 on the frame of the snowmobile, and has two arms extending at right angles therefrom. A
link 50 having ball joints 51 at opposite ends forms a connection between the radial arm 47 and one of the crank lever 48, the latter being arranged to pivot in a substantially horizontal plane.
On the left hand side of the snowmobile (Figures 2 and 3), the splined end 13 of the ski leg projecting above the steering tube 27 has attached thereto a steering arm 52 projecting forwardly substantially at right angles to the ski leg. A tie rod 53 having ball joints at its opposite ends forms a pivoted link swivel connection between the second arm of the lever 48 and the steering arlm 52. On the opposite side of the snowmobile, the corresponding ski leg has a similar steering arm 52a attached to its splined end, and a transverse track rod 54 having ball joints at its opposite ends forms an interconnection between the steering arms on opposite sides of the snowmobile. On the left hand side of the snowmDbile, the tie rod 53 and track rod 54 extend through a large aperture 55 in the vertical wall of the frame 19, this aperture being closed by a substantially rectangular elastic gasket 56 which forms a s~l around the rods 53 and 54 while accommodating large displacements of these rods in the plane of the aperture 55. A similar gasket 57 is provided in the wall of the frame member 19 on the opposite side of the machine to provide a seal which will accomm~date displacements of the track rod 54 at that end.
From the above it will be appreciated that steering movements of the handlebars 4 are transmitted through the shaft 46 link 50, crank lever 48 and tie rod 53 to the steering arm 52 of the left hand ski assembly 2, and thence through the track rod 54 to the steering arm 52a of the right hand ski assembly.
It will be seen that the suspension configuration is such that the elements of the steering means are constrained to follow the deflections of the skis, and the design must be able to accommodate such movements.
Referring to Figure 2, it will be seen that if the ski assembly 2 is moved vertically upwards with respect to the sncwmobile body 1, then the trailing arm 25 will be sw~ng counterclockwise with res~ect to its front mounting causing the associated ends of the tie rod 53 and track rod 54 to move upwardly in an arc about the pivot mounting 20. However since the steering arm 52 extends forwardly, i.e. towards the pivot mounting 20 the actual distance moved by the rod ends is very much less than the upwards deflection of the ski assembly 2, and in fact by suitable design of the geometry of the system, a very large range of deflection of the ski assembly 2 can be accQmmodated. m e effects of deflection of the ski assemblies upon the geometry of the steering system are minimized in two ways. Firstly, the crank lever 48 is displaced close to the right hand side of frame member 19 to miaximize the length of the tie rod 53, and thus minimize lateral movement of this tie rod consequent to the arcuate path described by the tie rod attached to the steering arm 52 upon deflection of the left hand ski assembly 2. Similarly, the length of the track rod 54 minimizes lateral movement of the steering arm 52a caused by deflection of the right hand ski assembly 2. Secondly, the arrangement of the stabilizer torsion bar 32 helps to minimize adverse effects upon the steering geometry of the snowmobile caused by differential deflections of the respective ski asse~blies, by generating a torsiona] ~-stress which resists such differential deflection. mus, if the left hand ski assembly 2 is deflected`upwardly, swinging move~ent of the arm 7~
25 is transmitted through the stabilizer arm 36 to the torsion bar 32 producing a torsional stress therein which in turn acts to induce a corresponding deflection in the ski assembly on the opposite side of the vehicle. me arrangement of the torsion bar stabilizer therefore besides improving the roll stability of the vehicle, also enhances its steering characteristics.
m e above described arrangement provides a suspension system which can accommodate a much greater degree of vertical deflection of the ski assemblies than was possible with prior art structures employing bowed leaf springs. m e actual deflection is determined by the dimensions of the various components and the length and characteristics of the coil spring-hydraulic damper units 41.
me stabilizer torsion bar 32 can have various characteristics selected to match the envisaged conditions of use. me bar 32 can be round, hexagonal, square, or many other desired shapes in cross section, ana within the limits of the inside diameter of the front tube 18, can be of various cross sectional areas to provide the required degree of stiffness. Different cross sectional areas can be acccmmcdated merely by replacing the bearing sleeves 34 with sleeves adapted to accommodate --the desired cross section of the bar 32.
An alternative arrangement is illustrated in Figures 5 and 6 in which like parts are designated by similar reference numerals as in Figures 1 to 4. In Figures 5 and 6, the structure of the ski assemblies, 2a ski leg assemblies lla, coil spring-hydraulic damper units 41a and steering mechanism 5a are substantially identical to the e~bodiment of Figures 1 to 4. ~owever in place of the trailing swing arm 25, there is provided a parallelogram linkage mechanism 58 which includes spaced parallel upper and lower links 59 the lower trailing ends of which are _g _ 3~
pivoted to respective ones of a pair of clevises 60 attached to the steering tube 27a. The upper end of each link 59 cæries a top sleeve 26a carried on a pivotal beæing formed by the outboard end 20a of one of a pair of front tubes 18a mounted on a transverse horizontal axis in the front part of the sncwmobile la. Each front tube 18a houses a stabilizer torsian bar 32a, the splined ends of which are attached through stabilizer arms 36a to respective ones of the links 59 in a manner similar to the mounting of the stabilizer arms 36 in Figures 1 to 4. ;
It will be evident that with the arrangement of Figures 5 and
- : : ;. . .: ~ . , .
extends through aligned apertures in the end of the stabilizer arm 36 and a lug 39 (Figure 4~ on the side of the trailing arm 25, the fastener incorporating resilient washers 40 to attenuate the transmission of vibrations from the trailing arm 25 to the stabilizer bar 32 and prevent premature wear of the connection.
From the above described arrangement it will be seen that the stabilizer torsion bar 32 remains unstressed when the trailing c~rms 25 are pivoted in unison, but will act to resist relative angukar movement of the trailing arms, such angular movement producing a torsional stress in the stabilizer bar 32.
Swinging movements of the trailing arms 25 caused by vertical movements of the ski assemblies 2, are controlled by respective coil spring-hydraulic damper units 41 arranged in a generally upright orientation.
Each unit 41 is pivotally mounted at its lower end on a pin 42 (s e Figure 4) projecting laterally inwardly from the lower end of the steering tube 27, and at its upper end on a pin 43 carried on a bracket 44 on the snowmobile frame. The upper end of the unit 41 is enclosed within a resilient boot 45 which forms a seal with the opening in the upper wall of the frame member 19 through which the unit 41 extends, and thus prevents snow or the like entering the cab of the snowmobile through this opening. The pins 42 and 43 are parallel to the top sleeve 26 of the respective swing arm 25, and that the damper units 41 can piv~t slightly in a vertical plane to accommodate to the arcuate path of movement of the pin 41 as the arm 25 swings about its pivotal mounting 20.
The steering means of the snow~obile is best illustrated in Figures 3 and 4 and comprises a steerIng shaft 46 connected to the handlebars 4 and rotatably mounted in the snowmobile cab in suitable 7~
bearing means (not shown). At its lower end the shaft has a radial arm 47. A crank lever 48 is pivDtally mounted at 49 on the frame of the snowmobile, and has two arms extending at right angles therefrom. A
link 50 having ball joints 51 at opposite ends forms a connection between the radial arm 47 and one of the crank lever 48, the latter being arranged to pivot in a substantially horizontal plane.
On the left hand side of the snowmobile (Figures 2 and 3), the splined end 13 of the ski leg projecting above the steering tube 27 has attached thereto a steering arm 52 projecting forwardly substantially at right angles to the ski leg. A tie rod 53 having ball joints at its opposite ends forms a pivoted link swivel connection between the second arm of the lever 48 and the steering arlm 52. On the opposite side of the snowmobile, the corresponding ski leg has a similar steering arm 52a attached to its splined end, and a transverse track rod 54 having ball joints at its opposite ends forms an interconnection between the steering arms on opposite sides of the snowmobile. On the left hand side of the snowmDbile, the tie rod 53 and track rod 54 extend through a large aperture 55 in the vertical wall of the frame 19, this aperture being closed by a substantially rectangular elastic gasket 56 which forms a s~l around the rods 53 and 54 while accommodating large displacements of these rods in the plane of the aperture 55. A similar gasket 57 is provided in the wall of the frame member 19 on the opposite side of the machine to provide a seal which will accomm~date displacements of the track rod 54 at that end.
From the above it will be appreciated that steering movements of the handlebars 4 are transmitted through the shaft 46 link 50, crank lever 48 and tie rod 53 to the steering arm 52 of the left hand ski assembly 2, and thence through the track rod 54 to the steering arm 52a of the right hand ski assembly.
It will be seen that the suspension configuration is such that the elements of the steering means are constrained to follow the deflections of the skis, and the design must be able to accommodate such movements.
Referring to Figure 2, it will be seen that if the ski assembly 2 is moved vertically upwards with respect to the sncwmobile body 1, then the trailing arm 25 will be sw~ng counterclockwise with res~ect to its front mounting causing the associated ends of the tie rod 53 and track rod 54 to move upwardly in an arc about the pivot mounting 20. However since the steering arm 52 extends forwardly, i.e. towards the pivot mounting 20 the actual distance moved by the rod ends is very much less than the upwards deflection of the ski assembly 2, and in fact by suitable design of the geometry of the system, a very large range of deflection of the ski assembly 2 can be accQmmodated. m e effects of deflection of the ski assemblies upon the geometry of the steering system are minimized in two ways. Firstly, the crank lever 48 is displaced close to the right hand side of frame member 19 to miaximize the length of the tie rod 53, and thus minimize lateral movement of this tie rod consequent to the arcuate path described by the tie rod attached to the steering arm 52 upon deflection of the left hand ski assembly 2. Similarly, the length of the track rod 54 minimizes lateral movement of the steering arm 52a caused by deflection of the right hand ski assembly 2. Secondly, the arrangement of the stabilizer torsion bar 32 helps to minimize adverse effects upon the steering geometry of the snowmobile caused by differential deflections of the respective ski asse~blies, by generating a torsiona] ~-stress which resists such differential deflection. mus, if the left hand ski assembly 2 is deflected`upwardly, swinging move~ent of the arm 7~
25 is transmitted through the stabilizer arm 36 to the torsion bar 32 producing a torsional stress therein which in turn acts to induce a corresponding deflection in the ski assembly on the opposite side of the vehicle. me arrangement of the torsion bar stabilizer therefore besides improving the roll stability of the vehicle, also enhances its steering characteristics.
m e above described arrangement provides a suspension system which can accommodate a much greater degree of vertical deflection of the ski assemblies than was possible with prior art structures employing bowed leaf springs. m e actual deflection is determined by the dimensions of the various components and the length and characteristics of the coil spring-hydraulic damper units 41.
me stabilizer torsion bar 32 can have various characteristics selected to match the envisaged conditions of use. me bar 32 can be round, hexagonal, square, or many other desired shapes in cross section, ana within the limits of the inside diameter of the front tube 18, can be of various cross sectional areas to provide the required degree of stiffness. Different cross sectional areas can be acccmmcdated merely by replacing the bearing sleeves 34 with sleeves adapted to accommodate --the desired cross section of the bar 32.
An alternative arrangement is illustrated in Figures 5 and 6 in which like parts are designated by similar reference numerals as in Figures 1 to 4. In Figures 5 and 6, the structure of the ski assemblies, 2a ski leg assemblies lla, coil spring-hydraulic damper units 41a and steering mechanism 5a are substantially identical to the e~bodiment of Figures 1 to 4. ~owever in place of the trailing swing arm 25, there is provided a parallelogram linkage mechanism 58 which includes spaced parallel upper and lower links 59 the lower trailing ends of which are _g _ 3~
pivoted to respective ones of a pair of clevises 60 attached to the steering tube 27a. The upper end of each link 59 cæries a top sleeve 26a carried on a pivotal beæing formed by the outboard end 20a of one of a pair of front tubes 18a mounted on a transverse horizontal axis in the front part of the sncwmobile la. Each front tube 18a houses a stabilizer torsian bar 32a, the splined ends of which are attached through stabilizer arms 36a to respective ones of the links 59 in a manner similar to the mounting of the stabilizer arms 36 in Figures 1 to 4. ;
It will be evident that with the arrangement of Figures 5 and
6 the attitude of the ski leg 11 is not altered during vertical dis-placement of the ski assembly, but on the contrary always remains parallel to the plane joining the axis of the tubes 18a. Furthermore, the provision of tWD stabilizer torsion bars 32a enables the design to incorporate much greater side-to-side roll stability than is possible with a single torsion bar.
In the m~dified suspension system as shown in Fig~re 7, the torsion bar 32b is not provided within the front tube 18 as is the case in Fig~re 3, but is mDunted separately. The torsion bar 32b is of generally wide U-shaped configuration having a straight transverse central section 32c and rearwardly bent limbs or end sectians 32d. The central section 32c is pivotally supported in a pair of transversely spaced mounting brackets 65 near the ends thereof. The limbs 32d extend rear-wardly from the outer ends of the central section of the torsion bar, and each is pivotally attached to the u~per end of a short connecting link 66 the lower end of which is pivotally connected to the trailing swing arm 25. The link 66 may be of any suitable construction, for example it may oomprise a short central pin the ends of which are in screw ;
: ' -, . .. :. . .. .
~............. ... j .. - . :~
3~
threaded engagement with respective clevises, the lower clevis being pivoted on a pin carried by the trailing swing arm 25, and the upper clevis being pivoted to a pin carried on the torsion bar limb 32d.
For this purpose, the limb 32d is provided with a series of longitudinally spaced holes 67, and by suitable selection of the hole which fo~ms a connection from the link 66 to the torsion bar limb 32d, the character-istics of the suspension can be altered. It will ke appreciated that such adjustment varies the angle of the link 66 relative to both the limb 32d and the trailing arm 25, and accordingly varies the angle of displacement of the limb 32d per unit angular displacement of the trailing swing arm. Thus, the roll stiffeners of the suspension can be selectively varied.
. . . . ,, .- . :
In the m~dified suspension system as shown in Fig~re 7, the torsion bar 32b is not provided within the front tube 18 as is the case in Fig~re 3, but is mDunted separately. The torsion bar 32b is of generally wide U-shaped configuration having a straight transverse central section 32c and rearwardly bent limbs or end sectians 32d. The central section 32c is pivotally supported in a pair of transversely spaced mounting brackets 65 near the ends thereof. The limbs 32d extend rear-wardly from the outer ends of the central section of the torsion bar, and each is pivotally attached to the u~per end of a short connecting link 66 the lower end of which is pivotally connected to the trailing swing arm 25. The link 66 may be of any suitable construction, for example it may oomprise a short central pin the ends of which are in screw ;
: ' -, . .. :. . .. .
~............. ... j .. - . :~
3~
threaded engagement with respective clevises, the lower clevis being pivoted on a pin carried by the trailing swing arm 25, and the upper clevis being pivoted to a pin carried on the torsion bar limb 32d.
For this purpose, the limb 32d is provided with a series of longitudinally spaced holes 67, and by suitable selection of the hole which fo~ms a connection from the link 66 to the torsion bar limb 32d, the character-istics of the suspension can be altered. It will ke appreciated that such adjustment varies the angle of the link 66 relative to both the limb 32d and the trailing arm 25, and accordingly varies the angle of displacement of the limb 32d per unit angular displacement of the trailing swing arm. Thus, the roll stiffeners of the suspension can be selectively varied.
. . . . ,, .- . :
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A snowmobile having a body with a rear part supported on a track belt, and a front part supported upon a pair of laterally spaced steerable ski assemblies, steering means on said body for effecting steering control of said ski assemblies, and suspension means acting between said body and each said ski assembly;
said suspension means comprising a pair of trailing arms each supported on a mounting in the front part of the snowmobile and extending downwardly and rearwardly therefrom, said trailing arms being pivotable in their mountings about a common transverse axis, torsion bar means extending transversely in said front part and having opposite ends coupled to respective ones of said trailing arms so as to resist relative angular movement of said trailing arms;
steering tube means at the lower end of each trailing arm;
each said ski assembly comprising an elongate ski runner having an upwardly curved front end a mounting bracket on the upper side of the runner at an intermediate point in its length, an upstanding ski leg and means forming a pivotal connection between said mounting bracket and a lower end of the ski leg on an axis transverse to the length of the ski runner, said ski leg having an upper portion engaged by a respective one of said steering tubes to be pivotable thereon about a generally upright axis, said steering means being coupled with said ski legs to effect steering control of said ski assemblies through joint pivotal movement of said ski legs, said suspension means further comprising spring means associated with each said trailing arm and operative to urge the associated ski assembly downwardly, and damper means operative to dampen angular movements of each said trailing arm.
said suspension means comprising a pair of trailing arms each supported on a mounting in the front part of the snowmobile and extending downwardly and rearwardly therefrom, said trailing arms being pivotable in their mountings about a common transverse axis, torsion bar means extending transversely in said front part and having opposite ends coupled to respective ones of said trailing arms so as to resist relative angular movement of said trailing arms;
steering tube means at the lower end of each trailing arm;
each said ski assembly comprising an elongate ski runner having an upwardly curved front end a mounting bracket on the upper side of the runner at an intermediate point in its length, an upstanding ski leg and means forming a pivotal connection between said mounting bracket and a lower end of the ski leg on an axis transverse to the length of the ski runner, said ski leg having an upper portion engaged by a respective one of said steering tubes to be pivotable thereon about a generally upright axis, said steering means being coupled with said ski legs to effect steering control of said ski assemblies through joint pivotal movement of said ski legs, said suspension means further comprising spring means associated with each said trailing arm and operative to urge the associated ski assembly downwardly, and damper means operative to dampen angular movements of each said trailing arm.
2. A snowmobile according to claim 1 wherein said steering means includes a steering arm rigidly connected to each said ski leg and extending generally radially thereof towards said common transverse axis, and steering rod means forming a swivel connection with a forward part of each said steering arm.
3. A snowmobile according to claim 1 wherein said torsion bar means comprises a straight torsion bar received within a transverse tube fixed in the front part of the snowmobile, replaceable bearing means being positioned between the end portions of the tube and the torsion bar.
4. A snowmobile according to claim 3 wherein said end portions of the tube form the pivot mountings for the trailing arms.
5. A snowmobile according to claim 3 or claim 4 wherein the torsion bar has ends which project beyond the ends of the tube and each of which carries a radial stabilizer arm which is attached to the respective trailing arm to move therewith.
6. A snowmobile according to claim 1 including two pairs of said trailing arms, each steering tube being pivotally connected to two trailing arms arranged in a parallelogram linkage.
7. A snowmobile according to claim 6 wherein said torsion bar means comprises a pair of straight torsion bars each received within a respective transverse tube fixed in the front part of the snowmobile, replaceable bearing means being positioned between the end portions of each tube and the corresponding torsion bar.
8. A snowmobile according to claim 7 wherein said end portions of the tubes form the pivot mountings for the trailing arms.
9. A snowmobile according to claim 7 or claim 8 wherein each torsion bar has ends which project beyond the ends of the corresponding tube and each of which carries a radially arranged stabilizer arm which is attached to the associated trailing arm to move therewith.
10. A snowmobile according to claim 1, 2 or 6 wherein said torsion bar means has a central section extending transversely and pivotally mounted at the front of the snowmobile, and has opposite end sections in the form of rearwardly directed limbs, each said limb being coupled to the respective trailing arm through a pivoted link.
11. A snowmobile according to claim 1, 2 or 6 wherein said torsion bar means has a central section extending transversely and pivotally mounted at the front of the snowmobile, and has opposite end sections in the form of rearwardly directed limbs, each said limb being coupled to the respective trailing arm through a pivoted link, means being provided to selectively vary the angular relationship between the said pivoted link and said torsion bar limb, and thereby selectively adjust the roll stiffeners of the suspension.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA352,975A CA1123479A (en) | 1980-05-29 | 1980-05-29 | Ski suspension for snowmobiles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA352,975A CA1123479A (en) | 1980-05-29 | 1980-05-29 | Ski suspension for snowmobiles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1123479A true CA1123479A (en) | 1982-05-11 |
Family
ID=4117057
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA352,975A Expired CA1123479A (en) | 1980-05-29 | 1980-05-29 | Ski suspension for snowmobiles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1123479A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6260648B1 (en) | 1999-02-10 | 2001-07-17 | Robert Bessette Technologie Inc. | System for linking a steering rod to a steering gear in a steerable vehicle or a snowmobile |
-
1980
- 1980-05-29 CA CA352,975A patent/CA1123479A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6260648B1 (en) | 1999-02-10 | 2001-07-17 | Robert Bessette Technologie Inc. | System for linking a steering rod to a steering gear in a steerable vehicle or a snowmobile |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4337958A (en) | Suspension and stabilizing system for a snowmobile | |
| US4671521A (en) | Snowmobile ski suspension | |
| US5203585A (en) | Split-beam suspension system | |
| CA2007916C (en) | Snowmobile suspension | |
| US4591173A (en) | Suspension and steering mechanism for a snowmobile | |
| US4781364A (en) | Elastic beam-torsion rod connection | |
| EP0390787B1 (en) | Tractor useful in agriculture or civil engineering with a steerable rigid axle | |
| US4153272A (en) | Torsion rod stabilizer assemblies for vehicular steerable front wheels | |
| US8037961B2 (en) | Snowmobile front suspension | |
| US20060208445A1 (en) | Suspension and steering system | |
| US4275918A (en) | Resilient suspension for the cab of an agricultural tractor | |
| DE102006044151A1 (en) | Independent suspension of double wishbone type | |
| DE3426942A1 (en) | REAR SUSPENSION FOR VEHICLES | |
| US6009966A (en) | Snowmobile front suspension system | |
| US5402859A (en) | Partially sprung differential system for a driving axle independent or deDion suspension system | |
| DE1755113A1 (en) | Suspension of steerable front wheels of motor vehicles | |
| US4690234A (en) | Stabilizing means for snowmobile | |
| US4405140A (en) | Bobsled | |
| CA2217318C (en) | Snowmobile drive belt suspension | |
| US4392668A (en) | Shock-absorbing wheel suspension assembly | |
| EP0167712B1 (en) | Stabiliser for vehicles | |
| CA1123479A (en) | Ski suspension for snowmobiles | |
| CS213347B2 (en) | Axle for the road vehicles | |
| CA2286682C (en) | Front axle suspension | |
| JPS58112814A (en) | Car suspension-system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |