Skid steer vehicle.

This invention relates to a skid steer vehicle, hereinafter referred to as "of the kind specified" comprising a body having a front end and a rear end and ground engageable propulsion wheels disposed on opposite sides of the body, each propulsion wheel being carried on an outer end of a stub axle which is housed, so as to be rotatable about an axis of rotation, in a stub axle housing member mounted on the body.

An inner end of each stub axle may have a driven wheel thereon which is driven by a flexible loop from a driving wheel driven by a motor or the inner end of each stub axle may be driven by other means such as a separate motor for each stub axle.

An object of the invention is to provide a new and improved skid steer vehicle of the kind specified.

According to the present invention, we provide a skid steer vehicle comprising a body having a front end and a rear end and ground engageable propulsion wheels disposed on opposite sides of the body, each propulsion wheel being carried on an outer end of a stub axle which is housed, so as to be rotatable about an axis of rotation, in a stub axle housing member mounted on the body, wherein each stub axle housing member is provided with a carrier member, the carrier member and the body being provided with cooperating guide means lying on a circle to guide the carrier member for rotation about a reference axis at the centre of said circle and means to mount each carrier member on the body in a selected one of a plurality of any angular positions about said reference axis, the stub axle housing member being positioned relative to the carrier member so that said axis of rotation is disposed within said circle and eccentrically relative to said reference axis.

Preferably, clamping means are provided to clamp the carrier member in said selected position relative to the body.

By virtue of said eccentric disposition of the axis of rotation, the distance between the driven wheel and the driving wheel may be adjusted thereby permitting adjustment of the wheel base, the ground clearance and the height of the centre of gravity of the machine; where the stub axles are driven by flexible loops, a flexible loop of appropriate length is provided. In addition, a flexible loop of a given length may be tensioned.

The body may be provided with an engine, two pairs of ground engageable propulsion wheels disposed on opposite sides of the body, a hydraulic drive means including first and second variable displacement pumps driven by the engine and operatively connected to first and second hydraulic motors disposed on opposite sides of the body, each motor being drivably connected to two ground engageable propulsion wheels of an associated one of said pairs of wheels on the associated side of the body by first and second flexible loops each of which is engaged with a driving wheel driven by the motor and with a driven wheel connected to an associated one of the ground engageable wheels of said pair and propulsion control means whereby the hydraulic drive means can drive the pair of wheels on one side of the vehicle at the same or a different speed and/direction from the pair of wheels on the other side of the vehicle to propel and steer the vehicle.

The body may be provided with a longitudinally extending loop case compartment on each side of the vehicle, each loop case compartment having a transversely inner wall and a transversely outer wall joined by top and bottom walls and end walls, said stub axle housing member or members being mounted on the outer wall with said driven wheel or wheels disposed within said compartment.

Preferably, two stub axle housing members are provided on each side of the vehicle and each of said housing members are mounted on said outer wall with said driven wheels disposed within the compartment with said driving wheels disposed within the compartment therebetween with said loops engaged with respective driving and driven wheels.

The outer wall may be provided with a circular opening for the or each housing member to provide one of said co-operating guide means.

Each motor may be mounted on the inner or the outer wall of an associated loop case compartment with the driving wheel or wheels disposed within the associated loop case compartment.

The driving wheel or wheels are preferably carried on an output shaft of the associated motor and are unsupported by the other wall of the associated compartment.

The output shaft of each motor may be supported at an outer part thereof by an outer bearing carried by a bracket fastened to the respective motor body.

The bracket may be provided with openings to permit of passage of said loop or loops.

The driving wheel or wheels may be provided on a sleeve member which receives the output shaft of the associated motor therein at one end, an inner bearing being provided between the sleeve and the body of the motor.

Preferably, the outer bearing is provided between the bracket and said sleeve member.

A brake member may be carried by the output shaft outwardly of said sleeve member.

The outer wall of each loop case compartment may be provided with an opening in way of the motor and driving wheel or wheels to permit of manipulation of a loop into driving relationship with a driving wheel and driven wheel.

The brake member may be disposed outwardly of the part of the outer wall of the loop case compartment at locations spaced from said motor and a removable extension housing may be provided to enclose the brake member.

The or each flexible loop may comprise a chain such as a roller chain and the driving and driven wheels may comprise sprockets for engagement with the chain.

Alternatively, the or each flexible loop may comprise a toothed or untoothed belt and the driving and driven wheels appropriate pulleys.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings wherein: <ul id="ul0001" list-style="none"><li>FIGURE 1 is a perspective view of a skid steer vehicle embodying the invention,</li><li>FIGURE 1<u style="single">a</u> is an enlarged fragmentary view of part of Figure 1 to an enlarged scale,</li><li>FIGURE 2 is a side elevation of the vehicle of Figure 1 but showing the opposite side thereof to that shown in Figure 1,</li><li>FIGURE 3 is a section on the line 3-3 of Figure 2,</li><li>FIGURE 4 is a section on the line 4-4 of Figure 2,</li><li>FIGURE 5 is a front elevation of the vehicle of Figure 1 with part omitted for clarity,</li><li>FIGURE 6 is a fragmentary transverse cross-section, to an enlarged scale, to the vehicle of Figure 1 showing a stub axle housing assembly, and</li><li>FIGURE 7 is a fragmentary transverse cross-sectional view, to an enlarge scale, to the vehicle of Figure 1 showing a motor assembly,</li></ul>

General Layout

Referring now to the drawings, a skid steer loader vehicle 10 comprises a body 11 having a front end 12 and a rear end 13. The body 11 is provided with ground engageable propulsion means 14 comprising a pair of front wheels 15 disposed forwardly of a pair of rear wheels 16. The vehicle 10 is propelled in a straight line forwardly or rearwardly by driving all four wheels or, to steer the vehicle, by driving the wheels 15 and 16 on one side at a different speed and/or direction than those on the other side. Such skid steer loaders have a high degree of manoeuvrability and to facilitate skid steering and in particular, for example, the ability of the vehicle to turn about a central axis of the ground engageable propulsion means the wheel base is made, in the present example, slightly shorter than the track of the vehicle although, if desired, the wheel base may be the same or longer than the track if desired.

The wheels 15, 16 are carried on stub axles 17 which project outwardly from a pair of transversely spaced side members 18, 19 of the body 10 and which extend fore and aft of the vehicle. Between the side members 18, 19 is a transmission compartment 20 which houses a transmission 21, hereinafter to be described in more detail, whilst above and forwardly of the transmission compartment 20 is an operator's compartment 22 in which is provided an operator's seat 23, manually operable propulsion controls 24 for controlling the speed, selecting forward and reverse movement, and steering the vehicle and manually operable loader controls 25 for controlling a loader arm and material handling implement as hereinafter to be described.

The operator's compartment 22 is also defined by a pair of upstanding members 26, 27 which extend upwardly from the side members, 18, 19 on opposite sides of the vehicle and by a roof 28 which extends forwardly and adjacent its forward end is supported by posts 29.

A wire mesh screen 30 is provided on one side 31, of the operator's compartment 22 for protection of an operator, whilst the other side, 32 of the operator's compartment is unobstructed and provides an access opening 33 whereby an operator can enter and leave the operator's compartment 22.

Behind the transmission compartment 20 and operator's compartment 22 is provided an engine compartment 34 in which an engine 35 of any suitable type is housed. In the present example the engine is an air-cooled diesel engine but any other suitable engine may be provided.

Loader Boom Assembly

The vehicle is provided with a loader arm boom assembly 40 which is disposed adjacent the one side 31 of the operator's compartment 22. The loader arm assembly 40 comprises a lift arm assembly 41 which has a pivot member 42 projecting from an inner end 43 of the lift arm assembly 41 and extends transversely of the body and is pivotally mounted on the body by pivotal mounting means 44, 45 provided on the upstanding members 26, 27 respectively. The lifting arm assembly 41 has an implement carrying member 46 which projects from an outer end 47 of the lifting arm assembly and extends transversely across the front end of the body and has a material handling implement 48 carried thereby so as to be disposed forward of the front end 12 of the body 11. In the present example the implement 48 is an earth moving bucket 49 although if desired other material handling implements may be provided, such as forks.

The pivotal mounting means comprise a pivot boss 44<u style="single">a</u> welded in an aperture provided in an inner plate 27<u style="single">a</u> of the upstanding member 27 and a pivot pin 45 is fixed therein. At its other end the pivot pin 45 is fixed in a further pivot boss 44<u style="single">b</u> which is welded in an aperture in an inner plate 26<u style="single">a</u> of the upright 26 and a downwardly inclined part 28<u style="single">a</u> of the roof plate 28.

At its free end the pivot member 42 has a bearing housing 42<u style="single">a</u> welded therein and the housing 42<u style="single">a</u> carries a bush to rotatably mount the pivot member 42 on the pivot pin 45. At its other end the pivot member 42 has a further bearing housing 42<u style="single">b</u> in the form of a bush welded in an opening formed in the pivot member 42 where it merges into a major part 55 of the lift arm assembly 41 and the bearing housing 42<u style="single">b</u> again houses a suitable bearing bush to pivotally mount the pivot member 42 on the pivot pin 45. The inner plate 26<u style="single">a</u> is cut away in this region, as shown at 26<u style="single">a</u>' in Figure 1<u style="single">a</u>, to accommodate the boom assembly.

The lift arm assembly 41, pivot member 42 and implement carrying member 46 are formed as a unitary member by bending a steel tube to the desired shape. It will be seen that the lift arm assembly 41 comprises a major part 55 which extends generally rectilinearly from the inner end 43 towards the outer end 47 and a minor part 56 which extends generally downwardly and forwardly relative to the main part 55 and is disposed between the main part 55 and the implement carrying member 46. As best shown in Figures 4 and 5 an intermediate part 57 is provided between the main and minor parts 55, 56 which is inclined forwardly and transversely inwardly so as to position the minor part 56 within the front wheels 15 and in front of the operator's compartment 22.

A hydraulic lift ram 58 is pivotally connected between a bracket 59 welded to the lift arm assembly 41 and the upstanding member 26 about an axis indicated at 60. The pivotal connection of the lift ram 58 to the upright 26 at the axis 60 comprises a pivot pin 60<u style="single">a</u> which is fixed in pivot bushes 60<u style="single">b</u> welded in openings provided in the inner plate 26<u style="single">a</u>, and an outer plate 26<u style="single">b</u> and a further plate 26<u style="single">c</u> of the upstanding member 26. The cylinder of the ram 58 is pivotally mounted on the pivot pin 60<u style="single">a</u>. The lift ram 58 when actuated is adapted to raise and lower the lift arm assembly 41 between a lower position shown in Figures 1 to 4 in full line and a raised position shown in chain dotted line in Figure 2.

An implement levelling link is indicated generally at 61 and comprises a first link 62 which comprises a bar 63 pivotally connected to the upstanding member 26 about an axis 64 and connected to a ram 65 from a cylinder 66 of which a piston rod 67 projects forwardly and is pivotally connected to one end of a first lever 68. The pivotal connection of the first link 61 comprises a pivot pin 64<u style="single">a</u> fixed in pivot bushes 64<u style="single">b</u> welded in apertures in the inner and outer members 26<u style="single">a</u>, 26<u style="single">b</u> respectively whilst the bar 63 is pivotally mounted on the pivot pin 64<u style="single">a</u>.

The first lever 68 is pivotally mounted on the lift arm assembly 41 by a pivot member 69 and is connected by a torque tube 70 to a second lever 71 which is pivotally connected at its outer end 72 to a second, fixed length link 73 which is pivotally connected to the bucket 49 as shown at 74.

The respective positions of the axis of pivot of the lift arm assembly 41 provided by the pivot pin 45 and the connection of the implement levelling link to the upstanding member 26 at axis 64 together with the length of the first and second levers 68, 71 and the position of pivotal connection of the second link 73 to the bucket 49 at 74 together with the position of pivotal connection of the bucket 49 to the implement carrying member 46 at 75 is arranged so as to provide a linkage which ensures that the orientation of the bucket 49 relative to the body is preserved irrespective of the angular position of the lift arm assembly 41 so long as relative movement does not occur between the piston rod 67 and cylinder 66.

When it is desired to pivot the bucket upwardly, i.e. cause it to rotate about the axis 75 in a clockwise direction as viewed in Figure 2, fluid is supplied to the cylinder 65 to act on the larger diameter side of the piston therein so as to force the piston rod 67 out of the cylinder 65 so that the above described linkage causes the desired clockwise movement of the bucket 49. Such movement is generally required in operation to lift or tear out earth and hence is known as "tear out" movement. Because the fluid is operative upon the whole crosssectional area of the piston a relatively high power action is provided in this direction.

When it is desired to rotate the bucket in an anti-clockwise direction as shown in Figure 2, commonly known as "dumping" then fluid is supplied to act on an annular surface of the piston surrounding the piston rod 67 so that a smaller cross-sectional area is acted upon and therefore a faster, although less powerful action, is provided.

At the front end 12 of the side member 18 there is provided an abutment surface 76 provided by a bar 77 welded to a cam plate extension 78 of the side member 18. The bar 77 is adapted to abut a flanged roller 79 rotatably mounted on a spigot 80 projecting from the free end of the implement carrying member 46. The abutment surface 76 comprises a lower, generally vertical surface part 81 and a forwardly and upwardly inclined part 82, the surface parts 81 and 82 being contoured to co-operate with the roller 79 as the lift arm assembly 41 approaches its lowermost position and to prevent rearward displacement of the free end of the implement carrying member 46 when in such a lower position, for example, when driving a vehicle forwardly to load the bucket 49. If desired the abutment surface 76 may be extended upwardly so as to support the member 46 over a greater height.

From the foregoing it will be seen that boom assembly 40 extends forwardly from a position adjacent the rear end of the body 11 alongside the one side 31 of the operator's compartment 22 whilst the other side 32 is unobstructed so that an operator can gain accesss to the compartment through the access opening 33.

By providing the axis of pivot of the lift arm assembly 41 adjacent the top rear corner of the operator's compartment the operator is provided with the ability to lift the bucket to a relatively great height and at the same time provide the bucket with good reach and the vehicle with a stability. For example, the axis of pivot of the lift arm assembly is approximately 1.5m above the ground in the example illustrated, whilst the distance between the axis of pivot of the lift arm assembly and the axis of pivot of the bucket about the axle 75 is approximately 2.5m. Hence the vehicle has a total lift of approximately 3m and over the whole of this range of lift the pivotal connection 75 to the bucket lies forwardly of the front end 12 of the vehicle.

Propulsion and Loader Controls

The transmission 21 comprises a pair of conventional swash plate hydrostatic pumps 90, 91 the output of which is sent, in conventional manner, to a conventional hydrostatic motor 92. In this example the rearmost pump 90 provides a feed to the motor 92 on the left-hand side of the vehicle whilst pump 91 provides feed to the corresponding pump, not shown, on the right-hand side of the vehicle.

The pumps 90, 91 each have an input member 93. 94 respectively which are rotatable about spaced parallel axes which extend perpendicular to a fore and aft axis of the vehicle and which lie in a substantially horizontal plane.

The input members 93, 94, in the present example, control the angle of the swash plates of their associated hydraulic pump through the intermediary of a hydraulic servo mechanism in-built into the hydraulic pump in conventional manner. If desired, however, the input members 93, 94 may directly mechanically actuate the angle of the swash plates again in conventional manner.

The vehicle is provided with a suitable linkage to connect the manually operable propulsion control means 24 to the input members 93, 94 in order to achieve a desired regime of swash plate angle control.

Motor and Stub Axle Mounting

The side members 18, 19 each comprise a loop case compartment and as best shown in Figure 4 each comprise a transversely inner wall 160 and a transversely outer wall 161 which are joined by top and bottom walls 162, 163 and end walls 164, which provide an oil tight compartment.

It will be seen that the outer walls 161 provide main chassis members of the vehicle body and that at the rear of the vehicle extensions of the outer walls provide the inner side plate of the upstanding members 26, 27. In addition, a transversely extending member 165 interconnects the main chassis members 161 together and provides a floor to the body.

The loop case compartments 18, 19 have mounted thereon, at the positions shown in Figure 2 and Figure 1 respectively, the ground engageable propulsion wheels 15, 16 and the motors 92.

Referring now particularly to Figure 6 there is illustrated the mounting of one of the ground propulsion wheels 16 on the loop case compartment 18 although it should be appreciated that each of the four wheels is mounted on its associated loop case compartment in exactly the same manner and do not require separate description.

At the location of the wheel 16 the outer wall 161 is provided with a circular opening 166 which provides a first guide means which cooperates with a second guide means provided by a shoulder 167 of a carrier member 168 of generally frusto-conical configuration and formed integrally with a stub axle housing member 169. The stub axle housing member 169 carries taper roller bearings 170 so that a stub axle 171 is housed by the member 169 so as to be rotatable about an axis of rotation 172.

The wheel 16 is bolted to one end of the stub axle 171 in conventional manner by bolts 173 whilst a driven wheel in the form of a sprocket 174 is bolted to the other end of the stub axle 171 by bolts 175.

The stub axle and its housing, together with the carrier member 168 are configured so that the sprocket 174 is disposed within the loop case compartment 18. The teeth of the sprocket 174 are offset from a central mounting part of the sprocket so that the sprocket can be fastened to the stub axle 171 in a reverse orientation, shown in chain-dotted line in Figure 6, when attached to the stub axle for the other wheel on the same side of the vehicle.

The carrier member 168 is formed so that the axis of rotation 172 of the stub axle 171 is eccentrically disposed relative to the central axis of the rebate 167 and hence relative to a reference axis 176 about which the carrier member 168 is guided to rotate by co-operation between the hereinbefore mentioned guide surfaces 166, 167.

Clamping means, such as an annular ring 177, are provided to enable the carrier member 168 to be clamped to the outer wall 161 in any desired angular orientation around the reference axis 176.

By the above described eccentric disposition of the axis 172 relative to the axis 176, the position of the axis 172 both longitudinally and vertically of the vehicle can be adjusted thereby permitting of adjustment of the wheel base of the vehicle, in association with driving chains L of appropriate lengths, as well as permitting of adjustment of the ground clearance of the vehicle together with providing a facility for tensioning a chain of a given length.

It will be seen that the stub axle 171 is supported solely from the side wall 161 without any support being afforded by the inner wall 160 thereby avoiding the need to effect any machining operations on the wall 160 which would otherwise be necessary if the stub axle were additionally supported thereby.

In addition, a clearance is provided between the sprocket member 174 and the wall 160 to permit of manipulation of a chain L through the space and hence into driving relationship with the teeth of the sprocket 174.

Referring now to Figure 7, there is shown the mounting of a motor 92 on the loop case compartment 18.

The motor 92 is a conventional commercially available high torque motor and has a conventional output shaft 180. The motor 92 has a mounting flange 181 by which it is bolted to a mounting plate 182 welded to the inner wall 160 of the compartment 18. The mounting plate 182 has a rebate 183 which is received within a circular aperture 184 formed in the wall 160 to aid location of the ring 182.

A sleeve 185 is machined to provide a pair of driving wheels in the form of sprockets 186, 187 and an inner part 188 of the central passage of the sleeve 185 has the output shaft 180 received therein with a splined connection 189 provided therebetween.

A seal 186<u style="single">a</u> is provided in the central passage and a shaft seal 186<u style="single">b</u> is also provided so that lubricating oil for the splined connection 189 supplied from the motor 92 is caused to flow via bore 186<u style="single">c</u> to lubricate the bearing 190 before returning to the motor.

A taper roller bearing 190 is provided between the external surface of the sleeve 188 and a seat 191 provided by the body 192 of the motor 92.

A bracket member 193 in the form of a three-legged spider is bolted to the pump body 192 by bolts 194, only one leg 195 and one bolt 194 being shown in Figure 7, the other two legs and bolts being equally angularly disposed around the axis of rotation of the output shaft 180.A further taper roller bearing 196 is provided between the bracket 193 and an outer surface part of the sleeve 185.

A brake drum 197 is formed with a boss 198 which is received within an outer part 199 of the central passage of the sleeve 185 and is retained in splined engagement therewith, as shown at 200 by a bolt 201. The sleeve is provided with a transversely extending passage 202 to receive a locking pin for the bolt 201.

Chains, such as roller chains L (see Fig. 2) each comprise a flexible loop and are looped around the respective sprockets 186, 187 and the respective driven sprockets 174 and the sprocket, not shown, of the other wheel.

To assemble the sprocket and chain drive, initially the chains are manoeuvred into the compartment 18 through an opening 203 provided in the outer wall 161 and are passed between the inner wall 160 of the compartment 18 and the respective driven sprocket such as the sprocket 174. At this stage, although the motor 92 is bolted in position, the sleeve 185 and bracket 195 are absent.

The sleeve 185 is then offered up the output shaft 180 and the chains are then manoeuvred over the outer end of the sleeve 185 and into position on their associated sprockets 186, 187. The hereinbefore described eccentric mounting of the stub axles permits the stub axle axes 172 to be moved towards the motor 92 to provide sufficient slack in the chain L for the above manipulation to occur.

The bracket member 195 is then bolted in position with the chains L passing through the spaces between the legs 195 thereof. Thereafter the brake drum 197 is bolted in position and finally an extension housing enclosure member 204 is bolted in fluid tight relationship to the outer wall 161.

In the assembly described with reference to Figure 7, the output shaft 180 and the associated driving sprockets 186, 187 and brake drum 197 are supported entirely from the motor through the bracket 195 and receive no support from any component which is independent of the motor and in particular do not receive any support from the outer member 161. It is therefore unnecessary to perform any machining operation on the member 161 other than the simple formation of the clearance opening 203 which may be made, for example, by flame cutting.

If desired, the motor described above may be mounted on the outer wall 161 instead of the inner wall.

Instead of driving the stub axles from a shaft motor through loops L, if desired, the stub axles may be driven by other means such as, by providing a separate motor which may drive each stub axle directly. In this case, if desired the above described eccentric mounting may also be provided with the motor similarly moving eccentrically with the stub axle.

Operator's Compartment

The operator's compartment 22 is defined in part by the inner plates 26<u style="single">a</u>, 27<u style="single">a</u> of the upstanding members 26, 27, the roof 28 and the posts 29 which together provide the enclosure with one side, 31 and a top and rear wall which include means for preventing access therethrough. In the case of the one side 31 this is by virtue of the presence of the boom assembly and also the wire mesh protective screen 30. At the rear, the operator's compartment is defined in part by the front wall 34<u style="single">b</u> of the engine compartment 34. The space between the top wall 34<u style="single">b</u> and the underside of the pivot member 42 whilst preventing access to the operator's compartment does permit the operator to look out of the compartment to the rear beneath the pivot member 42.

The inner plates 26<u style="single">a</u>, 27<u style="single">a</u> which in substance define part of the operator's compartment are themselves integral continuations of the outer walls 161 of the hereinbefore described side members 18, 19. In the present example the inner plates 26<u style="single">a</u>, 27<u style="single">a</u>, and a contoured base 28<u style="single">a</u> are made by bending a single plate to the profile shown in Figure 4. The roof 28 is welded to the plates 26<u style="single">a</u>, 27<u style="single">a</u>. If desired the operator's compartment may be integrated with other structural members of the body by welding instead of being formed from a single plate.

Thus it will be seen that the main structural parts of the operator's compartment which provide the wall thereof are formed integrally with other structural elements of the vehicle and in particular the side members 18, 19 which provide the loop cases and the upstanding members 26, 27 which carry the boom assembly pivots and thus the operator's compartment is integrated with the remainder of the machine and hence has a high ability to withstand forces exerted thereon during roll-over conditions.