The present invention relates to an axle assembly of a device movable on ground or a corresponding base and ^■ being of the type described in the preamble portion of Claim 1.

The devices of such type nowadays in use, such as vehicles used as work vehicles and used in terrain are associated with the drawback that their field of use is very largely dependent of the construction of the rolling means, such as wheels, which allow the device to be moved on the ground, and it is also dependent of the distance between the axles (the wheelbase) of the device. For example, the same vehicle used for a specific operation can not be used in a versatile manner for different works. If there is a need to convert the vehicle into a vehicle suitable for another type of operation, the changes in the axle assembly of the vehicle would involve substantial expenditure of time and expenses. Therefore, the solution to this problem is to use a specific work vehicle for each specific operation, depending on the conditions in terrain and the operations to be carried out. However, the purchase costs of such vehicles are high.

On the other hand, if a vehicle already in use shall be converted to be suitable for another kind of operation, as far as its wheel system and distance between the axles is concerned, time-consuming and expensive changes, which are not economically feasible, must be carried out.

The object of the invention is to eliminate the drawbacks discussed above and to provide a vehicle for use in particularly as an off-the-road vehicle, being easily convertible according to the field of use by means of changes made mainly at the location of its driving wheels. It is an object to provide a vehicle being applicable either as a combined machine or by virtue of certain technical arrangement as three separate types differing considerably from each other, that is as a light tractor, a light loading vehicle capable of lifting loads to a high level and an off-the-road vehicle with track chain drive.

A further object of the invention is to disclose a common principle which is applicable to devices different from those mentioned in the preceding paragraph, e.g. to devices which do not travel by means of own source of power, such as trailers and other accessories which can be connected to a vehicle.

In accordance with the invention, the object is realised with the aid of a device comprising the features disclosed by the characterising portion of claim 1. By means of the pivotable arm of the invention, the distance between the axles of the device can be changed with a little converting work involved, and a possibility to adjust the position of the rolling means in vertical direction is provided simultaneously.

The appended subclaims show some advantageous embodiments of the device of the invention. The change in the distance between ^' the axles (wheelbase) is maximised when both axles of the device are arranged each on its respective pivotable arm. There

is also a preferable supplemental feature of the invention,- that is, the arm can be provided with adapters, to which either a normal wheel or a sprocket wheel of a track chain vehicle can be secured for the purpose of converting a vehicle having wheel drive to a vehicle having track chain drive.

The invention is further explained in the following by reference to its application in connection with a vehicle and by reference to drawings illustrating such an application. In the drawings

Fig. 1 is a schematic illustration of the operational principle of the axle assembly in accordance with the invention, shown in side elevation view of a chassis of- a vehicle.

Fig. 2 shows an arm of the axle assembly in accordance with the invention in a front view, as viewed in the direction of the vehicle.

Fig. 3 shows the axle of the axle assembly in accordance with the invention in its other position in perspective view, as viewed in an oblique direction from below, and

Fig. 4 is a schematic illustration of the principle that can be put into practice by means of the invention in order to convert the same vehicle into three types of work vehicles differing considerably from each other, the principle being shown in side elevation view of the vehicle.

A vehicle using the axle assembly of the invention is a vehicle which is operated in particular in terrain and as a work vehicle. The axle assembly of the vehicle comprises two axles arranged successively in the travelling direction, forming the wheelbase (the distance between the axles) therebetween in the direction of the vehicle. In the following, the invention is described mainly by reference to its use in connection with a tractor, which serves as the basic vehicle for various operations, has the weight of ca. 1000 kg, and has four wheels provided with 2-wheel or 4-wheel drive, is articulated at the body for steering the vehicle and is driven by means of a hydraulically operated power transmission system. The wheelbase of such a tractor is relatively short, ca. 1,3 to 2,0 metres and the turning radius is ca. 2,5 metres. Such a basic vehicle is designated by reference numeral 1 in Fig. 4 and its axles are designated by reference numerals 10" and 10".

The chassis 4 of the basic vehicle is provided with two points of support 2' and 2", being arranged in succession and spaced apart in the direction of the vehicle. To said points of support there are fixed arms 3, being pivotable about their respective points of support. The functional principle of said arm becomes more apparent in Figs. 1 and 2.

The arm 3 shown in Figs. 1 and 2 is at its one end pivotably journalled between two lugs 5 projecting downwards from the chassis 4, the pivoting taking place in a vertical plane extending in the direction of the vehicle. In the position A shown in Fig. 1, the arm 3 is in horizontal position directed away from the point of support 2 towards the articulation

of the vehicle body, which articulation is in Fig. 4 designated by reference numeral 6. The arm lies in this position against the chassis 4 and its longitudinal direction is parallel with the horisontal plane H. Fig. 1 shows also a position B, wherein the same arm is pivoted about the supporting point 2 from the position A beyond a vertical plane V extending perpendicularly to the direction of the vehicle, ^' and the arm is directed slantingly downwards from the chassis 4 in this position. The direction of the vehicle signifies in this context a line of the vehicle being parallel with the travelling direction of the vehicle when the vehicle is travelling straight forwards. The holding of the arm in position B is ensured by means of struts 7, which at their one ends are fastened to the end of the arm (point 8) and at their opposite ends they are secured to the chassis 4 by holding brackets 9, which are arranged in the chassis for the struts. The strut 7 prevents the arm 3 from pivoting upwards due to the weight of the vehicle. The free end of the arm comprises an axle tube 14 mounted transversely thereon and being adjustable in length. The number of struts can be e.g. two, in which event they can be fixed to the axle tube 14 at the points where the tube projects laterally from the end of the arm using e.g. clamps shown in Fig. 1. The operations of this tube will be described further on.

Fig. 3 shows the arm 3 in perspective view in the position A, where it is supported on the chassis 4. The arm has a perpendicular cross-section having the shape of a rectangle, the shape being such, that the dimension of the arm in the direction of its pivoting is smaller than that in the transverse direction of

the vehicle, i.e. the arm has the configuration of a flat, slab-like body, and it is made of metal. The free end of the arm 3 comprises a metallic axle tube 14 extending perpendicularly to the plane of pivoting of the arm and being attached rigidly at its middle portion 15 to the end of the arm 3 e.g. by welding. As it is evident from the Figure, the arm end carrying the pivoting arrangements is of sufficient width so as to afford a sufficient rigidity and stability in lateral direction to the construction in all positions in course of operation. The middle portion 15 of the axle tube extends at its both ends outwardly beyond the lateral side of the arm and at the same time beyond the outer edge of the chassis 4. At both ends of the middle portion 15 there is arranged a tube 16, which is telescopically movable in the middle portion. At the end of the tube 16 there is mounted a hydraulic motor 13 on which a vehicle wheel or a corresponding rolling means will be fixed. The hydraulic motor 13 can be placed at a suitable distance from the edge of the chassis 4 by moving the tube 16 within the middle tube 15 and by securing it immovably therein by means of a locking means 17, which can be e.g. a bolt which can be screwed into the holes provided in the tube 16.

Further, Fig. 3 shows a fixing plate 18 located in the axle tube 16 and ensuring the holding of the arm 3 in the position A, as the fixing plate is fixed e.g. by means of bolts to the body of the vehicle.

The construction of the arm 3 is symmetrical and it comprises means arranged in a similar fashion on its opposite side as well. The location of said means is symmetrical to the means on the opposite side of the

arm in a mirror image fashion in respect of the longitudinal center line of the arm.

In Fig. 2 the broken lines denote conduits 19 for pressure medium. The conduits are placed inside the arm 3 and they are further passed to the inside of the axle tube 14 and into the hydraulic motors 13. The construction of the arm has the configuration of a housing, thus making the accommodation of the conduits possible. From the arm 3, the conduits are led through the opening 22 located at the journalled end of the arm into the chassis 4 and they are in this way well protected in every position of the arm.

Fig. 4 is a schematic illustration of the possibility to convert a vehicle used as a work machine or in off-the-road conditions to be suited for a specific operation. This conversion can be effected by using the arms 3 pivotable in accordance with the invention. The successive body sections 1' and 1", which are able to turn relative to each other by virtue of the articulation 6 in the body of the vehicle, comprise each a point of support 2 for the arm '3. In the front body section 1', the point of support 2' is situated as close to its front edge as possible, and in the rear body-section 1", the point of support 2" is situated correspondingly as close to the rear edge as possible. When the vehicle is used with a 4-wheel or a 2-wheel drive (wheels 11), the arms 3 are in a position where they are directed towards each other, i.e. in the position A shown by Fig. 1 where their longitudinal directions coincide with the horisontal plane H. In this event the axle tubes 14 in the ends of the arms and thus the wheels 11 fixed on the hydraulic motors 13 in the ends of

the axle tubes are as close to each other as possible and the wheelbase L, (the distance of the connecting line 10' between the center points of two parallel wheels from the corresponding connecting line 10" between the two wheels that follow in the direction of the vehicle) is shortest. The vehicle can now be used e.g. as a work vehicle in difficult terrain or it can move in areas of limited space, such as in parks and in real-estate maintenance works.

In the other position shown in Fig. 4, the arms 3 have been pivoted to a position corresponding to the position B in Fig. 1. The arms are directed in this position slightly away from each other and slantingly downwards. The wheelbase has now increased by a distance 2R+Rsin α +RsinB, wherein R denotes the length of the arm from point of support to the center of rotation of the hydraulic motor 13, α denotes the angle which the front arm 3* forms with the vertical plane V extending perpendicularly to the direction of the vehicle and the β denotes the acute angle formed by the rear arm 3" with regard to the same vertical plane V. As it can be well seen, the axis 10' and 10" extending at the location of the axle tubes 15 have assumed a position where they are situated lower than in the position A, and the ground clearance of the vehicle has increased consequently. In this position it is also possible to replace the wheels 11 with sprocket wheels 12 of a track chain, which wheels act as guiding rollers at the ends of a track chain 20. Because the axle tubes 14 are in a lower position, a space extending along the direction of the vehicle is formed on both sides of the arm 3. This space is limited at the location of the axis 10 and 10" upwards by the lower surface of the chassis 4, in

lateral direction by the lateral side of the arm 3 and downwards by the axle tube 14 at the end of the arm (Fig. 2). Because the track chains are usually of a considerable width, this space can be well utilised for accommodation of the track chain 20 and its inner edge will be in this case very close to the arm 3. As the wheels are replaced with sprocket wheels, the total length of the axle tube 14 can be simultaneously adjusted by means of the telescopic axle tubes 16. The roller frame of the track chain can be supported on the axle tube 16 e.g. at a point designated by reference numeral 23 in Fig. 2.

From the foregoing it will be evident that the total length of the device in the track chain mode can be minimised as well. Further, due to the increased wheelbase, the surface pressure exerted-- onto the ground by the rollers is decreased.

A position, where.the rear arm 3 of the axle assembly is in a horizontal position opposite to the position A, thus directed away from the body articulation 6 after pivoting about the supporting point 2, is designated by arrow C in Fig. 4. The wheel base is thereby increased and the centre of gravity can in this way be shifted slightly backwards, while the front arm 3 remains in its position where it is directed towards the body articulation 6. A maximum increase in the wheelbase L is effected by pivoting both arms 3' and 3" into a horisontal position where they are directed away from each other, in which event the wheel baseis increased by the distance of 2R.

The vehicle can be converted to track chain mode in course of conversion operations which take approximately 2 hours. The wheels 11 are detached and the arms 3 are pivoted to be at a greater distance from each other in position B. The vehicle can not be steered at the body articulation in the track chain mode, and the body is therefore stiffened by disposing footboards above the track chains. The footboards extend in the longitudinal direction of the vehicle and they are fastened to both the front body section 1' and rear body section 1". The footboards serve simultaneously as decks for transport when the vehicle is uses in terrain. Guiding sprockets 12 are fixed on the hydraulic motors 13 located at the ends of the axle tubes 14. The sprockets constitute the wheelbase L_ therebetween in the direction of the vehicle and the track chain 20 is entrained thereabout, changing its direction of travel to a substantially opposite direction at the location of each respective guiding sprocket 12.

Since the vehicle shown in Figs 1 to 4 has a hydraulic motor at each of its four wheels or sprocket wheels, no problems are encountered in steering of the vehicle, irrespective of whether the vehicle is in wheel mode or in track chain mode. Due to the enormous versatility of possibilities afforded by the hydraulic drive system, the actuating of the hydraulic motors 12 can be arranged so, that the motors can be e.g. pairwise actuated, each pair independently of the other, e.g. by utilising two hydraulic pumps. The connections and control means between the pumps and the motors 12 can be designed so, that the wheels which are to be actuated by the

common hydraulic pump can be selected by actuating the control means of conventional construction which control the flow of the hydraulic fluid between the pumps and the hydraulic motors. The motors actuated by the common hydraulic pump can be selectively of two motors on the same side of the vehicle, two parallel motors in the same section of the vehicle, or two motors in a diagonal relationship to each other, depending on the position of the control means and the operational mode of the vehicle. As the present invention is mainly concerned with the mechanical arrangement of the axles of the vehicle, the various possibilities of the hydraulic control systems are not described in more detail, and it is understood that the variety of such hydraulic systems of the prior art can be used in connection of this type of vehicles. The same applies to a common construction of track chain assemblies known as such, and reference is made eg. to US-patent 3 710 886, which disclosure is incorporated herein by reference.

As far as the body articulation 6 is concerned, any conventional means can be used for steering the vehicle, such as a pair of double-acting hydraulic jacks which are connected between the front and rear body sections. The construction of the articulation 6 and the steering means can be e.g. of the type disclosed by US-patent 3 435 908, incorporated herein by reference.

The hydraulic motor 13 may be of conventional construction, and the same applies for the fixing means for fixing the wheel 11 onto or the sprocket wheel 12 around the rotating portion of the hydraulic

motor 13. The fixing means can be e.g. of nut-bolt-type or of any type enabling a firm attachment of the rolling means to the hydraulic motor. The sprocket wheel 12 is preferably of cylindrical configuration, as shown schematically in Fig. 2, so that the end of the axletube 14 together with the hydraulic motor 13 can be well fitted inside the sprocket wheel 12. A part of the frame of the track-chain assembly can be led via the inner end of the cylindrical sprocket wheel 12 for fastening to the point 23 on the tube 16.

The axle assembly of the invention is in particular suited for use in connection with light weight operating vehicles having a weight of ca. 1000 kg. For example, the distance between the supporting points 2 in the chassis may be ca. 3,2 m and the length of the arms 3 may be ca. 0,3 m. The wheelbase L, in the position A of Fig. 4 would be ca. 1,7 m in the abovementioned case and after shifting the arms into the positions B, the wheelbase L_ would be ca. 2,7 m, in other words the wheel base is increased by approximately one meter. In the wheel mode the total width of the device is ca. 1,5 m and in the track chain mode, due to the construction of the axle assembly, the track chains with associated frame, sprockets and rollers can be disposed partly beneath the chassis 4 and the total width of the device is thus not ingreased and remains at the value not exceeding 1,6 m. Consequently, the vehicle is able to pass through very narrow openings and is thus very well suited for making ski-tracks, for transport of wood, for resque operations and as a general rule it is well suited for places, where the sizes of the devices of prior art have prevented their use. The

surface pressure of the device in the track chain mode would be in the abovementioned case only ca. 25 g/cm ² .

The invention is by no way limited to only the embodiment described above, but the device can be altered within the scope of the inventional . idea represented by the appended claims. The axle assembly can be used e.g. in trailers and in other accessories which can be connected to a driving vehicle or in connection with accessories which can be steered in other ways and which are moved on a supporting base by means of rolling means. Claw cranes can be mentioned as one example of the latter devices.

The configuration of various parts can be altered, and e.g. arm 3 in this context signifies an assembly by means of which the axle of a vehicle can be turned from one position to an other supported by the supporting point 2 located in the chassis 4. Likeways the term "axle" shall be understood to be a designation of a imaginary connecting ^' line or axis between the parallel rolling means of the vehicle

(conventional wheels or sprocket wheels of the track chain vehicle), and it is not necessary that at this location there is a member exactly intermediate of the vehicle wheels, as is the case in the embodiment shown by the figures where said member is constituted of the elongate axle tube 15.