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BACKGROUND OF THE INVENTION
This invention relates to a frame for a vehicle such as a snowmobile and more particularly to an improved fabricated frame structure for such vehicles.
In snowmobiles and particularly the larger versions of snowmobiles, the frame assembly is generally comprised of two main frame subassemblies. The first is a comprised primarily of generally inverted U-shaped sheet metal member that supports the
seat of the snowmobile on its upper surface and which encloses and overlies the drive belt. A front frame subassembly is generally made up of a pair of side plates that are reinforced by a plurality of box-shaped cross members that extend between the
side plates. The engine, the front skis and steering mechanism are all carried by this front frame assembly.
Because of the construction, it is necessary to locate the cross members in such a way that they are either detachable or will clear the engine and other components supported thereby. This frequently results in sacrifices in strength and
rigidity.
More importantly, however, the aforenoted type of front frame subassembly requires considerable manual labor for fabrication and assembly. A wide variety of welds or rivets or other fasteners are required to secure all of the components
together, some of which must be detachable for service purposes.
It is, therefore, a principal object of this invention to provide an improved front frame assembly for a snowmobile.
It is a further object of this invention to provide a simplified yet highly rigid front frame assembly for a snowmobile that can be easily and economically manufactured and fabricated.
SUMMARY OF THE INVENTION
This invention is adapted to be adapted in a frame assembly for a snowmobile or the like which is comprised of a U-shaped sheet metal assembly having a pair of vertically-extending spaced apart side wall portions joined at one end by a
horizontally extending joining portion. A bulkhead formed from an alloy casting spans the side walls and is rigidly affixed thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a snowmobile constructed in accordance with the invention.
FIG. 2 is an enlarged top plan view showing the forward portion of the snowmobile.
FIG. 3 is a side elevational view of the frame assembly for the snowmobile on a slightly larger scale than that of FIG. 1.
FIG. 4 is a top plan view, in part similar to FIG. 2, but with the snowmobile body broken away and portions of the frame shown in section so as to illustrate a portion of the steering mechanism for the front skis.
FIG. 5 is an enlarged side elevational view looking in the same direction of FIG. 3, but showing only the front portion of the frame.
FIG. 6 is a top plan view of the front frame portion on the same scale as FIG. 5.
FIG. 7 is a side elevational view of the same components shown in FIG. 4, but on a slightly smaller scale, to illustrate the steering mechanism for the front skis.
FIG. 8 is an enlarged rear elevational view of the front bulkhead casting for the front frame sub assembly.
FIG. 9 is a side elevational view of the front frame bulkhead casting.
FIG. 10 is a top plan view of the exhaust manifold and exhaust system for the engine with only the exhaust system mounting components of the snowmobile frame illustrated.
FIG. 11 is a cross-sectional view of the exhaust manifold taken along the line 11--11 of FIG. 12.
FIG. 12 is a cross-sectional view of the exhaust manifold taken generally along the line 12--12 of FIG. 11.
FIG. 13 is a view with portions broken away showing the reversing transmission and control mechanisms therefor.
FIG. 14 is an enlarged cross-sectional view through the reversing transmission mechanism taken along the line 14--14 of FIG. 13.
FIG. 15 is a view looking in the direction opposite that of FIG. 13, but showing only the reversing transmission control actuating lever system.
FIG. 16 is a side elevational view showing the brake mechanism associated with the transmission control and also with the parking brake.
FIG. 17 is a partial cross-sectional view showing the shifting fork of the transmission mechanism and the actuating portion therefor.
FIG. 18 is a view looking in the same direction as FIG. 13, but showing the association of the transmission to the battery for the vehicle and illustrating the battery mounting arrangement.
FIG. 19 is a top plan view showing the handlebar and the controls associated therewith.
FIG. 20 is a top plan view showing the parking brake control and its association with the parking brake which has been shown out of position to illustrate it in this figure.
FIG. 21 is a side elevational view showing the engine and its cooling system with other portions of the snowmobile removed or shown in phantom.
FIG. 22 is a top plan view of the same assemblage shown in FIG. 21.
FIG. 23 is a cross-sectional view taken through and showing the front radiator on a larger scale and taken along the line 23--23 of both FIGS. 22 and 24.
FIG. 24 is an enlarged top plan view of the front radiator.
FIG. 25 is a cross-sectional view taken along the line 25--25 of FIG. 21 and shows one of the side radiators.
FIG. 26 is a top plan view, in part similar to FIG. 22 and shows another embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
The Overall Snowmobile
Referring now in detail initially to FIGS. 1 and 2, a snowmobile constructed in accordance with an embodiment of the invention is identified generally by the reference numeral 31. Although the invention relates to a frame assembly for a vehicle,
a snowmobile is depicted as a typical environment in which the invention may be practiced. This is a typical environment because the invention has particular utility with frames of the type generally used with snowmobiles.
The snowmobile 31 is comprised of a frame assembly, indicated generally by the reference numeral 32. This frame assembly will be described later in more detail by particular reference to FIGS. 3-9. However, the frame assembly 32 is comprised
primarily of a fabricated rear frame subassembly 33, and a fabricated front frame subassembly, indicated generally by the reference numeral 34. The front frame assembly 34 includes a cast bulkhead 35 having a construction which will also be described
later by reference to FIGS. 3-9 and specifically to FIGS. 8 and 9.
A body cowling 36 is mounted over the forward portion of the front frame assembly 34 and cooperates with the rear frame assembly 33 so as to form a rider's area to the rear of a controlling handlebar assembly 37. Directly to the rear of the
handlebar assembly 37 there is positioned a fuel tank 38 and a rider's seat 39 is disposed to the rear of this fuel tank. The area to the rear of the rider's seat 39 is partially elevated at 41 so as to form a rear storage compartment 42 that is
accessible through an openable closure 43.
The body assembly 36 further includes a cowling or windshield 44 disposed to the front of the handlebar assembly 37 in protecting relationship to the rider or riders. A front bumper 45 is affixed to the front of the body 36 via the frame
assembly 32 in a manner which will also be described.
A pair of front skis 46 are supported for suspension and dirigible movement at the front of the snowmobile 31 and specifically by the front frame assembly 34 in a manner which also will be described in more detail later. Basically, these skis 46
are supported within tubular members 47 by a suspension system which will be described and which tubular members 47 permit steering movement of the skis 46 under control of the handlebar assembly 37. As noted, this construction will be described in more
detail later.
A drive belt 48 is supported at the rear of the snowmobile 31 beneath the seat 39 and specifically beneath an inverted U-shape portion of the rear frame subassembly 33. This drive belt assembly 48 is supported at its lower surface by a pair of
guide rails 49 that carry a plurality of idler rollers 51 and a main rear idler roller 52.
An idler roller 53 is mounted by the frame assembly and also cooperates to form the path for the drive belt 48. The drive belt 48 is supported from the frame assembly 32 by a suitable suspension system which may be of any known type. This
includes a front linkage 54 and associated cushioning unit (not shown). A rear linkage assembly 55 and additional cushion unit which is also not shown supports the rear end of the guide rails 49 and the drive belt 48.
Since the invention does not deal with the details of the suspension system for either the front skis 46 other than how they are carried by the front frame subassembly 34 or the drive belt 48, where any details of these suspensions systems are
not illustrated or described, any conventional structure may be utilized as should be readily apparent to those skilled in the art.
An internal combustion engine, indicated generally by the reference number 56 is mounted in the frame assembly 32 and specifically the front frame subassembly 34 in a manner which will be described. The engine 56 is of the three-cylinder in-line
liquid cooled type and operates on a two-stroke crankcase compression principle.
The engine 56 drives the drive belt 48 in a manner which will be described. However, this drive assembly includes a continuously variable belt-type transmission, indicated generally by the reference numeral 57 which is placed on the left-hand
side of the is snowmobile 31 as viewed by a seated operator. This drive belt assembly 57 drives an intermediate shaft 58 which is journaled in the frame assembly 32 in a manner which also will be described. A final drive 59 that includes a reversing
transmission drives the drive belt 48 through a drive belt shaft, to be described later along with the reversing transmission by particular reference to FIGS. 13-15.
The Frame Assembly
The construction of the frame assembly 32 will now be described by particular reference to FIGS. 3-9. As has been previously noted, the frame assembly 32 is made up of two primary frame subassemblies comprised of a rear frame subassembly 33 and
a front frame subassembly 34.
The rear frame subassembly 33 is comprised of a pressing or stamping made from a sheet metal, such as steel, aluminum or aluminum alloy. It has a generally inverted U-shaped configuration that consists of a horizontally extending planar upper
portion 61 upon which the seat 39 is supported. The upper portion has a pair of depending side portions 62, each of which has an outwardly extending portion 63 and 64 that form foot areas for accommodating the feet of a seated rider. These foot areas
63 and 64 are generally coextensive in length with the seat 39 and extend rearwardly beyond the rear portion of the seat 39 to lie along the outer sides of the storage compartment 42.
At its forward end, the rear frame subassembly 33 is formed with an outstanding flange portion 65 which is adapted to nest around the forward frame subassembly 34 and be affixed to it as by welding, riveting, or a combination thereof. By so
forming the rear frame subassembly 33, the connection can be very robust and encompass a large surface area. In addition, since there are no bent flanges, the strength of the assembly is increased.
The front frame subassembly 34 is also constructed primarily from a sheet metal pressing, indicated generally by the reference numeral 66 and which has a U-shaped configuration that is comprised of a lower wall part 67 extends generally
horizontally, although it has a pair of angularly related portions. A pair of upstanding side walls 68 and 69 are formed integrally with this lower wall 67.
The side wall 68 is formed with a generally oval-shaped opening 71 which aligned with the engine 56 and which facilitates passage therethrough a portion of the engine and drive train, as will become apparent.
The opposing side wall 69 is formed with a slotted opening 72 which extends through its upper peripheral edge and which is sized so as to facilitate insertion of the engine between the side members 68 and 69. The upper end of the opening 72 is
closed by a closure plate 73 once the engine is in place. This closure plate 73 is detachably connected to the side wall 69, as by threaded fasteners or the like. By closing the opening 72, the side wall 69 is reinforced and, yet, the engine 56 can be
easily installed and removed.
An intermediate reinforcing member, indicated generally by the reference numeral 74, extends between the side walls 68 and 69, and has flange portions that are affixed thereto as by welding, riveting, or a combination thereof. This reinforcing
member 74 is comprised of a rear, horizontally extending portion 75 which is generally aligned with the rear frame upper wall portion 61. The portion 75 terminates at its forward end in a downwardly sloped part 76 which forms a cradle into which the
engine 56 can be positioned and upon which it can be supported.
A sub frame cross-member 77 extends forwardly of the wall portion 76 and is connected thereto, as well as to the side walls 68 and 69, and the lower wall 67, as by welding, riveting, or the like.
Openings 78 are formed in the forward portions of the side walls 68 and 69, so as to provide lightening of the assembly and access to various components, as will be noted. This is done without reducing the overall strength of the assembly.
As has been previously noted, the forward end of the front frame subassembly 34 is closed by a bulkhead, indicated generally by the reference numeral 35. This bulkhead 35 has a configuration as best seen in FIGS. 8 and 9.
The bulkhead 35 is formed primarily as a casting from aluminum or aluminum alloy. The upper surface of the bulkhead 35 is provided with an arcuate recess 79 that is defined by a U-shaped wall portion thereof. The U shaped recess is provided to
clear the exhaust system, as will be described later.
This U-shaped wall portion 79 is bounded by a pair of outer side walls 81 and 82, along which the forward sides of the side walls 68 and 69 nest. These forward portions of the side walls 68 and 69 can thus be affixed directly to the bulkhead 35
by riveting, welding, or a combination thereof. Alternatively, threaded fasteners may be utilized. In any of the these events, the structure provides a very good reinforcing and, again, because the joint is formed by planar surfaces, there will be no
local stress risers that could weaken the overall construction.
These bulkhead side walls 81 and 82 have curved surfaces and the rear face of the bulkhead 35 is provided with a plurality of reinforcing ribs 83 that run diagonally thereacross so as to add to the rigidity of the structure without significantly
increasing its weight. Also, since the ribs 83 extend on the rear side of the bulkhead 35, they will not be subject to the accumulation of foreign material as if they had faced forwardly. The ribs 83 are formed on the protected side of the bulkhead 35
and, thus, will be able to kept fairly clean by their own internal construction. That is, the ribs 83, by being formed on the rear side of the bulkhead, will not be subject to collection of debris as if they were forwardly facing.
The sides of the bulkhead 35 are provided with a pair of embossments 84 that are adapted to receive threaded fasteners for affixing a bumper sub frame 85 thereto. This bumper sub frame 85 appears in most detail in FIGS. 2 and 3, and permits the
front bumper 45 to be attached directly thereto around an intervening lower portion 86 of the body 36. Hence, the bumper 45 will be very robust and any forces exerted thereto will be transmitted directly to the frame assembly 32.
The Front Suspension
The suspension arrangement for the front skis 46 and for the steering thereof will now be described by primary reference to FIGS. 2, 4 and 7. The front skis 46, as has been noted, are supported for steering movement by means a pair of tubes 47.
These tubes 47 are supported for suspension travel by a pair of suspension arms 87 which have a jointed connection 88 to the tubular member 49 at their outer ends. The inner ends of these suspension arms 87 are pivotally supported on the bulkhead 35 by
a pivotal support structure which is not shown, but which is affixed to the bulkhead 35 by means of bosses 89 (FIG. 8) formed in the bulkhead assembly 35 and reinforced by the ribs 83.
In addition to the suspension arms 87, trailing arms 91 are affixed at their forward ends to the tubular members 47. The rear ends of the trailing arms 91 are pivotally connected to the frame assembly and specifically to the rear portion of the
front frame subassembly 34 in known manner.
The upper ends of the pins which support the skis 46 for steering movement in the tubular members 47 have connected to them steering arms 92. These steering arms 92 are controlled by tie rods 93 that have hime joints 94 at their outer ends for
pivotal connection to the steering arms 92. The inner ends of the tie rods 93 are connected by further hime joints 95 to a bell crank assembly 96 of the steering mechanism, indicated generally by the reference numeral 97. The steering bell crank 96 is
pivotally supported on a pivot shaft 98 which is affixed to a boss 99 (FIGS. 6 and 8) of the bulkhead 35 at the center of the recess 79.
A drag link 101 is connected by a hime joint 102 to the bell crank 96 at its forward end. The rear end of the drag link 101 is connected by a further hime joint 103 to a pivot arm 104 that is affixed to the lower end of a steering shaft 105.
The lower end of the steering shaft 105 is journaled in a bearing assembly 106 that is mounted to the frame assembly 34 in a manner which will be described later. The upper end of the steering shaft 105 is journaled by a further bearing 107 that is
mounted on an extension 108 of the frame assembly. The handlebar assembly 37 is affixed to the upper end of the steering shaft 105 in a known manner for steering of the front skis 46.
It should be noted that the frame member 74 and specifically its inclined portion 76 is formed with an enlarged opening 109 through which the steering mechanism can be readily accessed.
The Engine and Exhaust System
A portion of the construction of the engine 56 will now be described by primary reference to FIGS. 1 and 2. As has been noted, the engine 56 is, in the illustrated embodiment, of the three-cylinder in-line type and operates on a two-stroke
crankcase compression principle. The engine 56 is also liquid cooled, as has been noted, and is comprised of a cylinder block 111 which extends generally transversely across the frame assembly 32 as has been previously described. This engine cylinder
block 111 is supported by suitable engine mounts in the cradle formed by the front frame subassembly 34 and specifically by the frame members 74 and 77. The cylinder block 111 is formed with three transversely aligned cylinder bores that are closed by a
cylinder head assembly 112 that is affixed to the upper end of the cylinder block 111 in any well-known manner.
An air box 113 is mounted in the rear portion of the front frame subassembly 34 and is covered by the body cover 36. This air box 113 delivers air to charge formers 114 which may be comprised of carburetors that serve intake ports of the engine
through short connecting manifolds.
The charge thus formed is delivered to the crankcase chambers of the engine for compression and transfer through scavenge passages to the combustion chambers of the engine. This charge is then fired by spark plugs 115 that are mounted in the
cylinder head assembly 112. The spark plugs 115 are fired by a spark control box 116 that is conveniently mounted on the upper portion of the air box 113 so as to be cooled by the air flow therethrough.
The charge which is exhausted from the combustion chambers through exhaust ports formed in the front of the cylinder block 111 and delivered to an exhaust system, indicated generally by the reference numeral 117.
The exhaust system 117 is shown in most detail in FIGS. 10-12 and will be described by reference thereto. This exhaust system includes an exhaust manifold assembly, indicated generally by the reference numeral 118. This exhaust manifold
assembly 118 is comprised of a pair of end runners 119 and 121 and a center runner 122. Each runner 119, 121, and 122 has the same general construction. That is, the runners 119, 121, and 122 are formed by semi-cylindrical portions that have flanges
that are welded together to form the tubular shape thereof as best seen in FIG. 11.
The end runners 119 and 121 join with the center runner 122 close to the discharge end thereof. A collector pipe 123 is joined at the discharge end thereof. This collector pipe 123 has a flanged connection 124 to an expansion chamber device
125. This joint 124 is held together by a spring-type clamp assembly 126.
The expansion chamber device 125 generally curves around an area to clear the steering shaft 115 and is supported on the upper side of the bulkhead 35 within the recess 79. The expansion chamber device 125, in turn, has its discharge end
connected by a further spring-held flange connection 127 to a muffler 128. The muffler 128 is supported upon a boss portion 129 of the bulkhead 35 and held in place to the frame subassembly 34 by a spring clip 129. Exhaust gases are discharged to the
atmosphere through a suitable exhaust pipe.
Obviously, the exhaust manifold 118 is quite compact and relatively short in length. This is done so as to provide a high degree of exhaust efficiency and good tuning for good high-speed performance. However, because of the fact that the end
branch pipes 119 and 121 are connected to the center branch pipe 122 in close proximity and in close proximity to the engine exhaust ports, the engine may experience pulse-back effects that inhibit the charging efficiency and thus can provide dips in the
power curve.
This falloff in engine performance at low speeds is avoided by providing a pair of expansion chambers, indicated by the reference numerals 131 and 132, best shown in FIGS. 11 and 12 and which have a restricted communication with the branch pipes
119 and 122 and 122 and 121.
These expansion chambers 131 and 132 are easily formed by top plates 133 and bottom plates 134 that are affixed, as by welding, to the upper and lower tubular portions of the pipe branches 119, 122, and 121. The volume of these expansion
chambers 131 and 132 is adjusted by providing a vertically extending closure plate 135 across the rearward end of each set of plates 133 and 134.
Each of the end branch pipes 119 and 121 is provided with a respective relatively small communication opening 136 and 137 that is disposed in the angular area .theta..sub.1 formed by the juncture of the branch pipes 119 and 122 and 122 and 121.
In a like manner, the center branch pipe 122 is formed with a pair of openings 138 and 139 so that the openings 136, 138, 137, and 139 are in this angular area .theta..sub.1. This angular area .theta..sub.1 is greater than the angular area .theta..sub.2
formed where the branch pipes 119 and 121 are joined by the plates 135 so as to afford free access to this area of the exhaust gases.
By providing these small expansion chambers 131 and 132 it is possible to not only reduce the dip in the power curve that occurs a low speed but also to improve the power throughout the entire engine speed range.
Finally, the cylinder block side of the branch pipes 119, 121, and 122 is reinforced by a flange plate 141 that is provided with apertures so that it can be affixed to the cylinder block 111 of the engine 56.
The Transmission
The arrangement by which the engine 56 drives the drive belt 48 will now be described by reference to FIGS. 1, 2, 13 and 14. As has been previously noted, this transmission includes the continuously variable transmission (CVT) indicated
generally by the reference numeral 57. This continuously variable transmission 57 includes a driving pulley 142 which is driven from the engine crankshaft 143 via a centrifugal clutch. The variable driving pulley 142 drives a drive belt 143 which, in
turn, drives a driven variable pulley 144.
The driven pulley 144 is associated with the intermediate shaft 58. This intermediate shaft 58 extends transversely across the width of the snowmobile frame 32 and terminates at an end that is journaled in an anti-friction bearing 145. The
bearing 145 is supported within a transmission casing, indicated generally by the reference numeral 146 that comprises a first member 147 that is affixed to the frame side wall 69. This defines a cavity into which the shaft 58 extends. This cavity is
closed by a cover plate 148 that is affixed to the plate 147 with a seal 149 formed therebetween.
The end of the intermediate drive shaft 58 that extends into the transmission case 146 has affixed to it a driving sprocket 151. The driving sprocket 151 has a key connection to the intermediate shaft 58 and is held thereon by a retaining nut
152.
This sprocket 151 drives a drive chain 153 which, as best seen in FIG. 13, is engaged with a reverse drive sprocket 154 and a forward drive sprocket 155. Both the reverse drive sprocket 154 and the forward drive sprocket 155 rotate in the same
direction. However, they are coupled in a different manner to a belt driving shaft 156 which forms the output shaft of the final drive reversing transmission, which transmission is indicated as noted generally by the reference numeral 59 and which
includes a reversing drive, as will be described.
Lubricant may be received in the transmission case 146 for lubricating the driving components. The lubricant level may be checked by a dip stick 160.
The reverse drive sprocket 154 is journaled on a stub shaft 157 which is mounted in the casing between the members 147 and 148. The forward driving sprocket 155 is rotatably journaled by means of a needle-bearing assembly 158 on the belt driving
shaft 156. In this regard, it should be noted that the belt driving shaft 156 extends through the forward end of the drive belt 48 and has one or more lugs on it which are engaged with corresponding lugs of the drive belt 48 to drive it in a manner well
known in this art.
The belt-driving shaft 156 is journaled at one end by a bearing 159 that is fixed to the transmission case 147. The other end of the belt driving shaft 156 may be journaled in a similar bearing carried at the opposite side of the frame assembly
32 and which is not shown.
The reverse drive gear 154 is coupled for rotation with a further reverse drive gear 161, as by drive pins 162. The second reverse drive gear 161 is also journaled on the stub shaft 157 by needle bearings, indicated by the reference numeral 163.
A combined gear and dog clutch member, indicated generally by the reference numeral 164 is splined for rotation with the belt drive shaft 156 outwardly of the forward driving sprocket 155. Actually, the reverse gear and dog clutching member 164
is splined on a tubular stub shaft 165 which in turn has a splined connection to the belt drive shaft 156 inwardly of the needle bearing 158 and which is held axially in place by a retainer element 166 and nut 167.
In the forward drive mode, as shown in the solid line view of FIG. 14, dog clutching elements 168 are engaged with the forward drive sprocket 155 so as to establish a driving relationship between this sprocket, the reverse drive gear and dog
clutching member 164 and the belt driving shaft.
When the reverse driving gear and dog clutching member 164 is shifted to the right as shown in FIG. 14 to the phantom line position, the teeth 169 of the gear 164 will be brought into meshing relationship with the teeth of the second reverse
drive gear 161. At this time, the gear 164, stub shaft 165, and belt driving shaft 156 will be driven in an opposite direction or the reverse drive direction. Hence, a very compact but highly effective forward reverse transmission is provided by this
mechanism.
The Transmission Control
The shifting mechanism by which this transmission reversal is obtained will now be described by primary reference to FIGS. 13-15, and 17. The shifting of the transmission 59 between its forward drive mode and its reverse drive mode is controlled
by an operator control shift lever, indicated generally by the reference numeral 171 and which is mounted on the right-hand side of the vehicle in close proximity to the handlebar 37.
This shifting mechanism includes a shift rod 172 that carries a shift knob 173 at one end thereof. The shift rod 172 is connected at its opposite end, as by welding, to a shift bracket 174. The shift bracket 174 is pivotally connected about a
pivot pin 175 to a shift lever 176. The pivotal movement of the bracket 174 about the shift lever 176 is utilized to provide a release for a locking mechanism which locks the shift lever assembly 171 in either its forward and reverse drive positions.
In addition, this pivotal movement is also utilized to actuate a brake, as will be described, so as to retard the rotation of the intermediate shaft 58 so as to facilitate smooth shifting. This braking action occurs temporarily during the movement
between the forward drive position and the reverse drive position as shown in FIG. 13 and which motion will be described in more detail later after the total mechanism is described.
The shift lever 176 is disconnectedly connected to a further bracket mechanism 177 which is pivotally supported on a mounting bracket 178 by means of a further pivot pin 179. The bracket 178 is conveniently affixed to an appropriate portion of
the frame assembly. A tension spring 181 is interlocked between the shift bracket 174 and the plate 177 and normally biases the mechanism to the position wherein the shift rod 172 is pivoted to an upward location as shown in the solid line FWD position
in FIG. 13. This maintains a latch mechanism, indicated generally by the reference numeral 182 in position. This latch mechanism 182 will now be described by primary reference to FIG. 15.
As seen in FIG. 15, the fixed mounting bracket 178 is formed with a first, forward locking notch 183 and a second, reverse locking notch 184. A sliding latch pin 185 has a pivotal connection, at 186 to the shift bracket 174 adjacent the tension
spring 181 and at a location spaced from the pivot pin 175. This latch pin 185 will be reciprocated upwardly or downwardly upon pivotal movement of the shifting bracket 174 around the pivot pin 175.
A headed fastener 187 extends through a key hole slot 188 formed in the lower portion of the latching pin 185 so as to retain it axially in position but to permit this reciprocal motion.
A pin 189 is carried by the mounting bracket 178 and extends into an arcuate slot 191 formed in the plate 177. The arc of the slot 191 is around a radius that is coincident with the axis defined by the pivot pin 179. The length of the slot 191
limits the degree of pivotal movement of the lever 176 about the pivot pin 179.
In order to ensure smooth shifting, the lever shaft 176 and plate 177 have a disconnectable detent connection between them. To this end, the plate 177 is formed with a portion that carries a spring biased plunger 192. This plunger 192 can be
received in a detent recess 193 formed in the plate 177 so as to permit some movement of the shift lever 176 without accompanying movement of the plate 177. This is done so as to permit some movement until the dog clutching elements 168 engage with the
forward drive gear 155.
Continuing to refer to the shift mechanism and now referring primarily to FIG. 13, it will be seen that a first shift link 194 is pivotally connected at one end to the shift plate 177. The opposite end of the shift link 194 is pivotally
connected to a bell crank 195 that is journaled for pivotal movement on the transmission case 146. A further shift link 196 is pivotally connected at one end to the bell crank 195 and at the other end to a shift yoke 197 which also appears in FIG. 17.
This shift yoke 197 is coupled to a shift shaft 198 which is journaled in the transmission housing piece 148 and which carries a shift fork 199. The shift fork 199, in turn, has its end portions received in a shift collar 201 that is formed integrally
with the reverse gear and dog clutching member 164. Hence, pivotal movement of the shift fork 199 moves the reverse gear and dog clutching member 164 between the forward drive position shown in solid lines in FIG. 14 and the reverse drive position shown
in phantom lines in this figure.
This shifting operation is achieved by the motions which will now be described by primary reference to FIGS. 13-15 and primarily FIGS. 13 and 15. Considering the transmission to be in the forward drive position as shown in solid lines in the
figures, the operator first depresses the shift knob 173 so as to pivot the shift rod 172 and shift bracket 174 about the pivotal connection 175 to the shift lever 176. This will cause the shift locking pin 185 to be moved from the solid line position
shown at the left-hand side of FIG. 15 axially outward of the forward locking slot 183. During this time, the tension spring 181 will be loaded.
Having thus released the lock, the operator can then pivot the shift lever 176 and shift plate 177 in a rearward direction which would be counter-clockwise in FIG. 13 and clockwise in FIG. 15. During this shifting motion, the detents 192 and 193
may be released if there is great resistance to shifting. In any event, once the shift is completed, then the locking pin 185 will register with the reverse lock slot 184 of the bracket 178. When the operator then releases the pressure on the shift
knob 173, the locking pin 185 will be urged by the spring 181 into the reverse locking slot 184. This position is shown in phantom lines in FIG. 15.
The Shift Assist Brake
As has been noted, the transmission control mechanism 171 also incorporates an arrangement for braking the rotation of the intermediate driving shaft 58 at the times when the transmission is shifted between its forward drive position and its
reverse drive position. That braking mechanism will now be described by particular reference to FIGS. 13, 14, and 16.
As has been noted, the snowmobile 31 is provided with a main service braking system which service braking system operates on the intermediate driving shaft 58. This main braking system includes a brake disc or rotor 202 which is affixed for
rotation by a keyed connection 203 with the intermediate driving shaft 58. A service or main braking system, indicated generally by the reference numeral 203 is associated with this brake disc 202 for braking the operation of the snowmobile 31 during
normal operation. This main braking system will be described later.
In addition to the main service brake 203, an auxiliary and parking brake caliper assembly, indicated generally by the reference numeral 204 also cooperates with the brake disc 202 for braking its rotation and that of the intermediate drive shaft
58. This caliper 204 includes a pair of scissors like caliper members 205 and 206 that are pivotally connected to each other by a pivot pin 207. The pivot pin 207 is, in turn, fixed to the mounting bracket 178 so as to be held against rotation relative
to the frame assembly 32.
The caliper leg 205 supports a first brake pad 208 that is disposed on one side of the brake disc 202. The caliper leg 206 supports a second brake pad 209 that is disposed on the opposite side of the brake disc 202 in confronting relationship to
the brake pad 208. A torsional spring 211 encircles the pivot pin 207 and urges the brake caliper members 205 and 206 to a released position as shown in FIG. 16.
In order to actuate the caliper assembly 204 to its brake position, a wire actuator assembly, indicated generally by the reference numeral 212 is provided and which cooperates with an extension 210 of the shift actuating bracket 174 so as to
actuate the brake caliper 204 when the lever 174 is pivoted about the pivot pin 175 simultaneously with the release of the shift latch mechanism 182.
To this end, a wire actuator 213 is affixed, as at 214 to the extension 210 of the shift actuating lever 174 at one end of the wire actuator 213. The other end of the wire actuator 213 is connected by a ferrule 215 to the caliper member 205.
A protective sheath 216 of the wire actuator 212 has one end portion 217 affixed to the lever 176 of the shift actuator. The other end of the sheath 216 is affixed, as at 217, to the remaining caliper member 206.
As a result of these connections of the wire actuator 212, when the shift rod 172 and shift lever 174 are pivoted about the pivot pin 175, the wire actuator 213 will be pulled through the sheath 216, and the sheath 216 will be forced in the
opposite direction. This causes the caliper members 205 and 206 to pivot relative to each other in opposite directions about the pivot pin 207 to compress the torsional spring 211. This action brings the brake pads 208 and 209 into braking relationship
with the brake disc 202. Hence, before the shift is actually effected, the brake assembly 204 will be energized, and the rotation of the transmission elements will be braked.
The shift is then executed in the manner aforenoted. After the shift has been completed, the release of the shift rod 172 and shift lever 174 will cause the spring 211 along with the operation of the tension spring 181 to return the mechanism to
its position, and the brake will be released as the shift is completed. It should be readily apparent to those skilled in the art that the brake actuation occurs during the shifting process from forward to reverse, or from reverse to forward.
The Main Throttle and Brake Controls
The throttle control and main braking control for the snowmobile 31 will now be described by reference to FIGS. 2 and 19, for the actuator mechanisms, and to FIG. 14, for the service brake actuating mechanism. Referring first to FIG. 19, the
handlebar assembly 37 is shown in more detail. This includes a main handlebar 218 that has hand grips 219 and 221 at its opposite ends. Associated with the right-hand hand grip 221 is a throttle control lever 222.
This throttle control lever 222 is pivotally supported on the end of the handlebar 218 adjacent the hand grip 221 by a pivot pin 223. A wire actuator 224 is associated with the throttle lever 222 at one end and with the throttle valves of the
carburetors 114 at the opposite end so as to permit the operator to open and close the throttle valves and control the speed of the engine. A suitable return spring is employed so that when the throttle lever 222 is released, the throttle valves will be
returned to their idle position.
Adjacent the handlebar assembly 219 is the service brake control mechanism, indicated generally by the reference numeral 225. This service brake control mechanism includes a mounting bracket 226 that carries a master cylinder 227. A service
brake actuating lever 228 is mounted for pivotal movement on the bracket 226 by a pivot pin 229. Pivotal movement of the service brake lever 228 will pressurize the master cylinder 227 and direct hydraulic fluid under pressure through a brake line 231.
Referring now to FIG. 14, the opposite end of the brake line 231 is connected to a caliper assembly 232 of the service brake 203. The connection provides hydraulic fluid to a pair of fluid chambers 233 and 234 formed on the opposite legs of the
caliper assembly 232. Hydraulic pistons in these chambers 233 and 234 act upon brake pads 235 and 236, respectively, which are slidably supported on pins 237 that span the legs of the caliper assembly 232. When these brake pads 235 and 236 are
actuated, they will be forced in opposite directions into engagement with the brake disc 202 to brake its rotation.
The caliper assembly 232 is fixed relative to the vehicle frame by fasteners 238 which bolt the caliper assembly 232 to the transmission housing 146 and, accordingly, to the snowmobile frame 32.
As may be best seen in FIGS. 14 and 18, the area adjacent the transmission case 146 is formed with a ledge 239 that supports a battery carrier 241. A storage battery 242 is retained in the battery carrier 241 by a strap 243 that is connected at
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