AN ASSEMBLY ON A TERRAIN-TRAVELLING MOTOR VEHICLE

Abstract: A terrain-travelling motor vehicle (1) having a pair of caterpillar bogies (2) pivotably attached to the frame (3) of the vehicle and comprising a rear pair of drive wheels (5) mounted on the frame (3) of the vehicle and a front pair of wheels (7), wherein each said wheel (7a) is supported on a pivotable belt tensioning arm (9) on the forward end of a bogie arm (8) provided in each bogie (2), which bogie arm is supported at the rear end thereof by means of shaft journals (4) proximate to and in front of the center axis of the rear pair of wheels (5). The bogie arms (8) with belt tensioning arms (9) are movable in the vertical plane by means of hydraulic pressure cylinders (6) for independent upward and downward pivoting of the bogies. The belt tensioning arms (9) are movable by means of respective hydraulic pressure cylinders (10) the ends of which are connected to the belt tensioning arm (9) and the bogie arm (8) for maintenance of the desired tautness in the bogie belt during the pivoting movement of the bogie arm (8), as well as during the continual changes in configuration of the lower part of the bogie belt. A belt supporting wheel (11) for the lower part of the belt is provided between the front and rear wheels (7a and 5a) of each bogie (2). An auxiliary bogie arm (8a) is pivotably mounted (15) at the center section thereof on the forward end of the bogie arm (8). The belt tensioning arm (9) with the front wheel (7a) and the belt supporting wheel (11), respectively, are provided at the forward and rearward end of the auxiliary bogie arm (8a). The one end of the pressure cylinder (10) opposite the belt tensioning arm (9) is supported on the auxiliary bogie arm (8a).

Description: AN ASSEMBLY ON A TERRAIN-TRAVELLING MOTOR VEHICLE The present invention relates to an assembly on a terrain- travelling motor vehicle having a pair of caterpillar bogies pivotably attached to the frame of the vehicle, as recited in the preamble of the appurtenant independent claim 1. A terrain-travelling motor vehicle of the type mentioned above is known from the applicant's own Norwegian Patent No. 148,219. According to said patent, a terrain-travelling vehicle is provided wherein the body of the vehicle is raised and lowered, optionally the bogie arms are raised and lowered independently of one another, to maintain a desired position of the vehicle body when driving over uneven ground, without this affecting the tautness of the belt. The maintenance of uniform tautness of the belt while driving over uneven ground is achieved in said patent by means of the pressure cylinder described in the introduction of the patent, which acts upon the belt-tensioning arm, being pressurized at a specific desired pressure. The tautness of the belt may at any time be decreased or increased by regulating said pressure depending on land conditions and independently of the up-and-down pivoting movements of the bogie, which take place with the aid of the pressure cylinder provided for the raising and lowering thereof. Despite the aforementioned possibilities for maintaining a desired belt tautness and the fact that the caterpillar bogie is capεble of altering position or being raised and lowered depending on the conditions of the land, the vehicle will assume a bumpy or rolling movement when driven over rugged terrain. This is due primarily to the fact that when one, or both of the caterpillar bogies drives into an obstacle in the form of a rock or stump, the forward wheel of the caterpillar bogie will climb the obstacle and thereby pivot the caterpillar bogie upward, with a corresponding transfer of movement to the vehicle frame. The purpose of the present invention is to provide a caterpillar bogie wherein said movement associated with collision with and climbing over an upwardly projecting obstacle is substantially moderated by virtue of the fact that the forward wheel of the caterpillar bogie is permitted to pivot upward at the same time as the center belt support¬ ing wheel between the forward and rear bogie wheels is pivoted downward. This enables the forward wheel of the caterpillar bogie to climb up over the obstacle at the same time as the belt supporting wheel is pressed downward and raises or turns the caterpillar bogie upward with less movement than in the known construction. This is achieved according to the present invention by means of the characterizing features disclosed in the characteri¬ zing clause of the appurtenant independent claim 1 and by the subsequent dependent claims. Hence, the caterpillar bogie according to the invention shows a front wheel having a belt tensioning arm and a belt supporting wheel provided at respective ends of an auxiliary bogie arm pivotably supported at the center section thereof on the forward end of the bogie arm mentioned above. The pressure cylinder used to move the belt tensioning arm is journalled, with the one end thereof that is opposite the belt tensioning arm, to the bogie arm or the auxiliary bogie arm. Said one end of the pressure cylinder is preferably mounted on/at the center section of the auxiliary bogie arm. However, it is possible in practice to mount said one end of the pressure cylinder at the forward end of the bogie arm in close proximity to the support of the auxiliary bogie arm on the bogie arm. The invention will be described in the following with reference to an embodiment shown in the drawings, wherein Figure 1 shows a terrain-travelling motor vehicle as seen from the side and in partial section, Figure 2 shows the frame of the motor vehicle with a caterpillar bogie on a level, horizontal surface, Figure 2a and Figure 2b show in perspective the bogie arm and the auxiliary bogie arm of the caterpillar bogie in exploded view and in mounted state, respectively, Figures 3 - 9 show the same as Figure 2, but with the caterpillar bogie pivoted up or down depending on the ground conditions and with , ?. auxiliary bogie pivoted into various positions to illustrate how the caterpillar bogie according to the invention adapts itself to the surface while simulta¬ neously maintaining a uniform desired tautness in the belt, and Figures 10a and 10b show the previously known caterpillar vehicle according to Norwegian Patent No. 148,219, seen respectively from the side and from above, herewith to illustrate clearly the present invention and the advantages thereof in relation to said previously known terrain- travelling motor vehicle. We will first describe the known terrain-travelling motor vehicle 1 as shown in Figures 10a and 10b and thereafter the further development of the caterpillar bogies for attainment of smoother running for the terrain-travelling motor vehicle as shown in Figures 1 and 2. The terrain-travelling motor vehicle 1 known from Norwegian Patent No. 148,219 as shown in Figures 10a and 10b is equipped with a pair of caterpillar bogies 2,2 wherein each wheel 5a of the rear wheel pair 5 in the caterpillar bogie pair is supported in the frame 3 of the vehicle, while each wheel 7a in the front wheel pair 7 is supported on a respective pivotable arm 9 on the forward end of the bogie arm 8 provided on each bogie, which bogie arm is supported at the rear end thereof by means of shaft journals 4 proximate to and in front of the center of the rear wheel pair 5. Arm 9 is movable by means of a pressure cylinder 10, which is pressurized at a desired, adjustable pressure for maintaining a desired tautness in the bogie belt 2a during the pivoting movement of bogie arm 8, as well as during the continual changes in the configuration of the lower part of the bogie belt occurring during driving over uneven ground. The bogies 2 are independently and/or mutually pivotable and adjustable in relation to each other in the vertical plane by means of pressure cylinders 6, which are controllable from the cab 3b of the vehicle. Approximately midway between the front and rear wheels 7a, 5a, a belt supporting wheel 11 is mounted on bogie arm 8, which wheel 11 preferably has a smaller diameter than the front and rear wheels 7a, 5a, and which abuts with the lower part of belt 2a. This means that when bogies 2,2 are in the normal position as shown in Figure 10a, the lower portion of all the wheels will rest against a level surface, i.e., that the front and rear wheels 7a, 5a and the belt supporting wheel 11 in each bogie 2 have a common tangent. Since bogie arm 8 is eccentrically supported at 4 in relation to the center axis of rear wheel pair 5, i.e., in front of and somewhat below said center axis, bogie belt 2a will slacken when bogie arm 8 is pivoted upward by with the aid of pressure cylinder 6. This slack is taken up by belt tensioning arm 9, which pivots front wheel 7 forward due to the fact that pressure cylinder 10 is pressurized in a manner known per se, whereby the pressure cylinder connected to the extension of belt tensioning arm 9 maintains the desired tautness in the belt whether it is slackened as bogie arm 8 is pivoted upward or is tightened as bogie arm 8 is pivoted downward, or as the lower part of belt 2a is subjected to changes in configuration as the belt passes over irregularities such as roots and rocks on the ground terrain. The front and rear wheels 7a and 5a of each bogie 2 have preferably the same diameter, whereby the vehicle on a less irregular surface is able to move equally well forward and backwards. When driven in very rough terrain, the bogies 2,2 are pivotable upward and downward independently of each other, and can thereby compensate for traverse driving in sloping terrain so that the frame and the cab of the vehicle are held approximately level, and bogies 2,2 may also be raised and lowered in connection with passing over depres¬ sions and elevations on one side or the other of vehicle 1. The drive member or pressure cylinder 10 for the pivoting of belt tensioning arm 9 and for the maintenance thereby of desired tautness of the belt consists of a hydraulic cylinder 10' with a piston 10''arranged on the top side of bogie arm 8, the end of cylinder 10' being supported at 12 on the forward part 8' of the bogie arm, and the piston/piston rod 10' being supported at 13 on an extension of belt tensioning arm 9 which extends upwardly from the arm support 14 on bogie arm 8. When passing obstacles such as rocks or roots with this known motor vehicle, one or the other of the bogies 2 will, on hitting a root or rock, climb up thereon as bogie 2 pivots upward about support 4 for bogie arm 8 in frame 3. On continued driving over said obstacle, bogie 2 with belt 2a will raise itself up over the obstacle and simultaneously also raise frame 1, as belt 2a will not adapt its form to that of the obstacle due to supporting wheel 11, which contributes toward maintaining an approximately straight line in the lower part of belt 2a. To achieve a smoother passage over said obstacle the caterpillar bogie 2 according to the present invention and as shown in Figures 1 - 9 has been reconstructed such that the front wheel 7a with belt tensioning arm 9 and belt supporting wheel 11 are each arranged at their respective ends of an auxiliary bogie arm 8a pivotably mounted 15 at the center section thereof on the forward end of bogie arm 8. The one end of pressure cylinder 10 opposite its support 13 on belt tensioning arm 9 is now supported at 12' on auxiliary bogie arm 8a (Figure 2a and Figure 2b). By this means pressure cylinder 10 will continue to exercise its belt tensioning effect without the exertion of any torque on the auxiliary bogie arm 8a. Pressure cylinder 2 may, of course, also be mounted with said end thereof on the bogie arm 8 itself at the forward end thereof and close to the support 15 (not shown) for auxiliary bogie arm 8a. What is achieved hereby when passing over an obstacle such as a rock or root is that during the climb up over the obstacle, the forward wheel 7a of bogie 2 yields, while at the same time the following supporting wheel 11 is pivoted downward, due to auxiliary bogie arm 8a, and presses bogie arm 8 upward about its support 4 at the rear bogie wheel 5a. In contrast to the direct raising or upward pivoting of bogie 8 described above, there is now achieved a reduction of this pivotal movement due to the fact that auxiliary bogie arm 8a with front wheel 7a and auxiliary wheel 11 climbs up over and passes the obstacle in the course of a simultaneous decreased upward pivoting of bogie arm 8 and, therewith, an upward movement of frame 3. Of course, the rear bogie wheel 5a must, in the same manner as with the known construction, climb all the way over and pass the obstacle, thereby raising frame 3. The difference is that the initial climbing motion of the bogie and the passage over irregularities are rendered smoother by means of the described auxiliary bogie arm 8a, compared with the known caterpillar bogie described above, wherein said upward pivoting of bogie 8 takes place at the same instant as the front bogie wheel 7a climbs/enters the obstacle/elevation. A further advantage with the new caterpillar bogie is that it is capable of climbing up over and passing higher obstacles in relation to what the known caterpillar bogie is capable of. This is achieved by virtue of the fact that the front bogie wheel 7a due to auxiliary bogie arm 8a is capable of yielding and pivoting upward as shown in Figure 5, simultaneously as supporting wheel 11 is pressed downward and pivots bogie arm 8 upward. The caterpillar bogie can hereby pass over substantially higher obstacles than the known caterpillar bogie described in the introduction above. Due to the fact that auxiliary bogie arm 8a with front bogie wheel 7a and supporting wheel 11 is capable of adapting to the various ground configurations, there is achieved under all conditions a smoother running of the caterpillar bogie 2, as shown in Figures 3 - 9. During terrain driving each of the caterpillar bogies may be controlled individually, as mentioned above, from the cab 3b of the motor vehicle. This pertains particularly to driving in very rugged terrain where, as mentioned in connection with the discussion of. the known construction, it is practical to pivot the bogies upward or downward relative to each other in order thereby to compensate for traverse driving in sloping terrain, so that the vehicle frame and cab are held approxi¬ mately level. The same applies to passing over depressions or elevations on one or the other side of the vehicle, where frame 3 is held in the approximately desired position, while the bogie is pivoted with the front part thereof down into the hole and supports frame 3, and thereafter on continued driving is gradually pivoted upward again on the other side of the hole while simultaneously maintaining the position of frame 3. With this type of individual maneuvering of the caterpillar bogies 2, the present terrain-travelling motor vehicle is capable of moving forward in a surprisingly smooth manner over extremely rugged terrain. The tautness of the belt is maintained, as mentioned previously, by means of pressure cylinders 10, which are pressurized at a desired and appropriate pressure and which thereby permit the lower part of belt 2a to adapt to the surface below it, as is clearly shown in Figures 4, 5, 6, 8 and 9 in the drawings.

Claims: P a t e n t C l a i m s 1. An assembly on a terrain-travelling motor vehicle (1) having a pair of caterpillar bogies (2) pivotably attached to the frame (3) of the vehicle and comprising a rear pair of drive wheels (5) mounted on the frame (3) of the vehicle and a front pair of wheels (7), wherein each said wheel (7a) is supported on a pivotable belt tensioning arm (9) on the forward end of a bogie arm (8) provided in each bogie (2), which bogie arm is supported at the rear end thereof by means of shaft journals (4) proximate to and in front of the center axis of the rear pair of wheels (5), said bogie arms (8) with belt tensioning arms (9) being movable in the vertical plane by means of hydraulic pressure cylinders (6) control¬ lable from the cab of the vehicle, for pivoting the bogies upward and downward simultaneously or independently of each other, and wherein the belt tensioning arms (9) are movable independently of the bogie arms (S) by means of respective hydraulic pressure cylinders (10) the ends of which are connected to the belt tensioning arm (9) and the bogie arm (8), and which are pressurized at a desired adjustable pressure for maintaining a desired tautness in the bogie belt during the pivoting movement of the bogie arm (8), as well as during the continual changes in configuration of the lower part of bogie belt which occur during driving over uneven ground, and a belt supporting wheel (11) for the lower part of the belt provided between the front and rear wheels (7a and 5a) of each bogie (2), c h a r a c t e r i z e d by an auxiliary bogie arm (8a) pivotably mounted (15) at the center section thereof on the forward end of the bogie arm (8), and at the forward and rearward end of which the belt tensioning arm (9) with the front wheel (7a) and the belt supporting wheel (11), respectively, are provided, and wherein the one end of the pressure cylinder (10) opposite the belt tensioning arm (9) is supported on the auxiliary bogie arm (8a). 2. The assembly according to claim 1, c h a r a c t e r i z e d i n that the auxiliary bogie arm (8a) is supported in a downwardly projecting shank (16) on the bogie arm (8). 3. The assembly according to claim 1, c h a r a c t e r i z e d i n that said one end of the pressure cylinder (10) is supported proximate to the support of the auxiliary bogie arm (8a) on the bogie arm (8). 4. The assembly according to one of the claims 1 - 3, c h a r a c t e r i z e d i n that the distance (A) from the support (15) for the auxiliary bogie arm (8a) to the support for the front wheel (7) is equal to or greater than the distance (B) from the support for the auxiliary bogie arm (8a) to the support for the belt supporting wheel.

Inventors: BRAATHEN THOR REIDAR FROLICH, BRAATHEN, THOR, REIDAR, FROELICH
Applicants: BRAATHEN THOR REIDAR FROLICH, BRAATHEN, THOR, REIDAR, FROELICH
Application year: 1993
Main classification: B62D55
IPC codes: B62D55