TRACKED LOAD CARRYING VEHICLE

Abstract: A tracked load carrying vehicle comprises a chassis (10); an engine (11) mounted on the chassis for propelling the vehicle; an output shaft (13) driven by the engine; two tracks (14, 15) provided in parallel on either side of the chassis and each one running over a plurality of wheels (16-19, 20-23), at least one of which being adapted to be driven by the output shaft (13) of the engine for driving the track; and a control lever (60) for steering the vehicle. A clutch is connected between the output shaft (13) of the engine and each one of the tracks (14, 15), so that either one of the tracks can be disengaged. The control lever (60) is adapted to actuate one or the other of the clutches by means of a linkage, so that the clutch interrupts the transmission to the pertaining track (14, 15). These features will give the vehicle a small turning radius and good maneuverability. The vehicle can alo be provided with braking means for braking the tracks.

Description: Tracked load carrying vehicle Technical Field The present invention is related to a tracked load carrying vehicle comprising a chassis; an engine mounted on the chassis for propelling the vehicle; an output shaft driven by the engine; two tracks provided in parallel on either side of the chassis and each one running over a plu¬ rality of wheels, at least one of which being adapted to be driven by the output shaft of the engine for driving the track; and a control lever for steering the vehicle. The load carrying vehicle is primarily intended as an aid for heavy transports in woods and fields, all the year round, for example for trailing logs in the woods, for transporta¬ tion of plants in connection with new plantation on clea¬ rings, and for transportation of carcases in connection with hunting. Background Art Load carrying vehicles for the above mentioned objects are previously known. These vehicles are either of snow- scooter-type having tracks and turnable runners or wheels in front, or tracked special vehicles having particular equipment, for example a hoist. These prior art vehicles have the disadvantage in common that they are difficult to handle in wood-land where the free space is limited, becau¬ se their steering capacity is limited. Vehicles steered -by means of runners or wheels are bound to get a large turning radius, and also the prior art vehicles of other types have had a low steering capacity or no steering capacity at all, so that a change of direction must be provided by turning the vehicle, for example by forceful pulling in an opera- ting arm attached to the vehicle, and this operation is tiresome and time-consuming. It is previously known to steer tracked vehicles, par¬ ticularly heavy tracked vehicles and armoured cars, by dis¬ engaging and/or braking one of the tracks and continuous driving of the other track, thus providing a turning of the vehicle. This steering method requires complicated mechani¬ cal s-teering devices which normally are controlled by a person who rides in or on the vehicle. An example on this type of steering is diclosed in the United States Patent Specification No. 2 614 642. It is also previously known" to steer small load car¬ rying vehicles by means of a control lever adapted to actuate a braking device for braking one or the other of two tracks or driving wheels. Such a device is disclosed in the United States Patent Specification No. 3 444 945. The steering device disclosed in that specification, however, comprises a differential, so that braking of one track en¬ tails a faster driving of the other track. If one track skids, no driving at all is obtained from the other track. Such a_ device is not suitable for load carrying vehicles which must be operable under hard conditions in woods and fields all the year round. Disclosure of Invention The main object of the present invention is to provide a tracked load carrying vehicle which is easy to steer and therefore very easy to handle also in difficult terrain and which has a low weight and small size, so that it easily can be moved between different places. This object is obtained with a load carrying vehicle having the characte¬ rizing features set forth in the claims. Due to the fact that the load carrying vehicle is pro¬ vided with a clutch' for each track and a turnable control lever by means of which the clutches can be actuated, either one of the tracks easily and rapidly can be disenga¬ ged from the engine. Therefore, the load carrying vehicle can be turned with a very small turning radius in any direction and with a rapid change between different turning directions. The use of a cross arm attached to the control lever and simple linkage for controlling the clutches, which preferably are claw clutches, will make the construc¬ tion simple and reliable. The provision of separate track brakes for steering will further improve the maneuverabili¬ ty of the vehicle. Due to the fact that one of the tracks can be disen¬ gaged from the engine, a heavy load, for example when trai- ling logs of wood, can be started by running first one track, which is then supplied with the full power from the engine, and then engage the other track, thus creating a powerful jerk. Also comparatively heavy loads can be star¬ ted with a comparatively weak engine, so that the weight as well as the manufacturing cost of the vehicle can be kept low. The load carrying vehicle is intended to be steered by means of a control lever which is handled by a person wal¬ king in front of or beside the vehicle, and the mentioned combination of control lever and clutches will then give the special advantage that an automatic correction will be obtained in case the vehicle is skidding or is pulling dia¬ gonally, for example due to icy spots or mud. In case the vehicle unintentionally is turning diagonally to the desi- red direction, the track causing the diagonal position by a more powerful propulsion of the vehicle will be disengaged, so that the engine power can be fully used by the other track for returning the vehicle to the desired direction. As soon as the vehicle has recovered the desired direction, the first track will again be engaged, so that both tracks again propel with the same force. Due to this automatic correction of direction the use of the vehicle on bad and rough roads is highly facilitated, particularly in the win¬ ter and in heavy rainfall and snowfall. At the same time, the risk of diagonal pushing due to a heavy load pushing from behind in downhill slopes is considerably reduced. Brief Description of Drawings The vehicle according to the invention will now be described more in detail with reference to the attached drawings. Figure 1 shows in a perspective view a tracked load carrying vehicle according to the invention. Figure 2 shows in a larger scale the steeering means and the clutches for the vehicle shown in Figure 1. Figure 3 shows the operation of the steering means and the clutches when the vehicle is turned. Figure 4 shows a modified embodiment of the steering means and the clutches according to Figures 2 and 3 com¬ prising steering brakes for the tracks. Best Mode for Carrying Out the Invention The tracked load carrying vehicle shown in Figure 1 comprises a chassis 10 and an engine 11, mounted on the chassis, for propelling the vehicle. The shaft of the engi¬ ne is connected to a gear box 12 having an output shaft 13 for transmission of the propelling power from the engine. The chassis is further provided with two tracks 14,15 positioned in parallel with each other on either side of the chassis. Each track is running over a plurality of wheel pairs 16-19 and 20-23, respectively, and the shafts of these wheel pairs are mounted in bearings in the chassis 10. The wheel pairs 17,18 and 21,22 are mounted in bearings at opposite ends of a tiltable arm 24 and 25, respectively, the arm being mounted in bearings in a bracket 26 and 27 projecting from the chassis. The tiltable arms 24,25 are spring loaded by means of springs (not shown) , so that the tracks always are stretched. The wheels of the front wheel pair 16 and 20 for each track are adapted to be driven by the output shaft 13 from the gear box 12 for driving the tracks 14,15. The wheels are provided with projecting teeth (not shown) , and the tracks are provided with corresponding apertures or perforations (not shown) in a conventional way. In the front the vehicle is provided with a control lever 60, the operation of which will be described in detail below. The chassis is also provided with a rotatably mounted clamp 29 for use in trailing timber logs or for attaching a trailer table, and with a protection net 30 for the engine 11. The transmission from the output shaft 13 of the gear box 12 to the wheel pairs 16,20 is shown in Figure 2. The output shaft 13 is at each end provided with a claw clutch 31 and 32, respectively, one portion 33 and 34 of each clutch being rigidly connected to the output shaft 13 and the other portion 35 and 36 being movably connected to a rotatable intermediate shaft 37 and 38, respectively. The intermediate shaft is connected to the track driving pair of wheels 16 and 20, respectively. The movable portion 35 and 36 of each claw slutch is spring loaded by means of a spring 39 and 40, respectively, to mesh with the fixed * por¬ tion on the output shaft 13 and can be brought out of mesh by means of an angular arm 41 and 42, respectively. The angular arm is pivoting on a bracket 43 and 44, respective- ly, projecting from the gear box. One end of the angular arm is forked and provided with two pins 45 and 46, respec¬ tively, of which only one is shown i Figures 2 and 3, as the other pin is on the opposite side of the shaft 37 and 38. The pins engage with a groove 47 and 48, respectively, in the movable portion of the claw clutch. The other end of the angular arm is provided with an aperture 49 and 50 for engagement with a pin 51 and 52 on an arm 53 and 54, res¬ pectively, pivoting on a cross arm 55. The cross arm is pivoting on a shaft 56 on a bracket 57 rigidly attached to the gear box 12. The arms 53,54 are mounted in bearings at opposite ends of the cross arm 55. The cross arm is at its centre provided with a projecting portion 58 carrying a pivot 59. The pivot 59 is intented for positioning a control lever 60, so that the lever can be swivelled in a plane perpendi¬ cular to the plane of the cross arm 55. In the modified embodiment shown in Figure 4 the chas- si 10 of the vehicle is provided with two brackets 61,63 on either side of the gear box 12. Each one of these brackets carry a replaceable brake cone 62 and 64, respectively, mounted in such a way that it cannot rotate in the same di¬ rection as the intermediate shaft 37 and 38. The clutch .OM portions 35 and 36 have a conical shape at its outer ends, i. e. the ends turned away from the gear box 12, and the ends are adapted to engage with the fixed brake cones 62 and 64, so that the cones can operate as steering brakes, as shown in the left portion of Figure 4. The operation of the steering means will now be de¬ scribed with reference to Figures 2 and 3. When the control lever 60 is pointed straight forward, i. e. in parallel with the longitudinal central line of the vehicle, both claw clutches 31,32 are in engagement, so that the power from the engine is transmitted to both tracks in parallel. The vehicle is then propelled straight ahead, when the vehicle has to be turned, the control lever is moved in the direction of the desired turn, for example to the left, as shown in Figure 3. This-will cause the cross arm 55 to be turned, so that the arms 53 and 54 are moved. The arm 53 will then be pushed towards the angular arm 41, so that this arm is turned (clockwise in Figure 3), thus moving the movable portion 35 of the claw clutch 31 against the force of the spring 39, so that the clutch portions 33 and 35 are disengaged. The transmission from the output shaft 13 to the intermediate shaft 37 and the wheel pair 16 for the track 14 is thus interrupted, so that the track stops or only moves due to the movement of the vehicle. The other -.claw clutch 32 is not actuated by the changed direction of the control lever, as the pin 52 of the arm 54 only is lif¬ ted a small distance in the aperture 50 of the angular arm 42. Thus, the propelling of the other track 15 is continued and this track can then use the full pcw-r from the engine. The vehicle will then turn around its vertical central axis with a very small turning radius. The vehicle can be turned to the right by moving the control lever to the right in a corresponding way. In the case when the vehicle is provided with separate steering brakes 35,64,63 and 36,62,61, respectively, accor¬ ding to Figure 4, the transmission to the track will be interrupted and the track will also be braked, when the control lever 60 is turned to its end position, i. e. when the movable portion 35 or 36 of the claw clutch is in en¬ gagement with the brake cone 64 or 62, respectively. The brake cones are over the brackets 63 and 61 rigidly attac- hed to the chassis 10 of the vehicle. The control lever 60 is pivoting around the shaft 56, which is substantially vertical in normal use of the vehic¬ le, so that a change of turning direction can be made ra¬ pidly, as well as around the substantially horizontal pivot 59, so that the control lever can be kept at a comfortable level for the work. The control lever 60 is provided with a control for adjusting the rotation speed of the engine. Due to the design of the steering means with two clutches for interrupting the transmission to one or the other of the tracks a comparatively weak engine can be used, for example a gasoline engine of about 5 Hp. The en¬ gine is preferably provided with a centrifugal clutch, so that the shaft of the engine is connected to the gear box, when the rotation speed of the engine is increased over a ' : certain limit by controlling the supply of gasoline by means of the control 61 attached to the control lever. This will avoid a separate clutch control. While only two embodiments of the tracked load car¬ rying vehicle according to the invention have been descri- bed and shown, it is evident that many modifications and variations are possible within the scope of the invention. In stead of claw clutches, for example friction clutches can be used, and in stead of the shown wheel pairs, for example driving rolls can be used. As an alternative, the wheels can be provided in a bogie, and the bogie can then be attached to the chassis or form the chassis. The control lever can also be arranged so that the vehicle can be stee¬ red from beside the vehicle, which may be an advantage, for example when heavy loads have to be transported down steep hills. The steering brakes can alternatively be designed for direct, firm locking, for example by means of teeth or jaws.

Claims: Claims 1. Tracked load carrying vehicle, comprising a chassis (10); an engine (11) mounted on the chassis for propelling the vehicle; an output shaft (13) driven by the engine; two tracks (14,15) provided in parallel on either side of the chassis and each one running over a plurality of wheels (16-19,20-23), at least one of which being adapted to be driven by the output shaft (13) of the engine for driving the track; and a control lever (60) for steering the vehic¬ le; characterized in that the control lever (60) is adapted to be turned around a substantially vertical shaft (56) and in that a clutch (31,32) is connected between the output shaft (13) of the engine and each one of the tracks (14,15), so that either one of the tracks can be disengaged from the output shaft of the -engine, the control lever (60) being adapted to actuate one or the other of the clutches (31,32), when turned around the vertical shaft (56) from a neutral position to one or the other side, so that the clutch interrupts the driving of the pertaining track (14,15). 2. Vehicle according to claim 1, characterized in that the control lever (60) is provided with a cross arm (55), each end of which being connected to a linkage (41,53;42,54) adapted to transmit the turning motion to the clutch (31,32) for disengagement of the clutch, when the control lever is turned to the side on which the linkage is posi¬ tioned. 3. Vehicle according to claim 2, characterized in that each linkage (41,53;42,54) consists of a link arm (53,54), one end of which being pivoting on the cross arm (55) and the other end of which being provided with a projecting pin (51,52) engaged with an aperture (49,50) in one end of a pivoting angular arm (41,42), the other end of which (45,46) being adapted to engage with a movable portion (35,36) of the clutch (31,32). 4. Vehicle according to claim 3, characterized in that the " B URE _ OMP angular arms (41,42) are pivoting on brackets (43,44) rigidly attached to the chassis. 5. Vehicle according to claim 2, characterized in that the cross arm (55) of the control lever (60) is pivoting on a substantially vertical shaft (56) forming the vertical pivot for the control lever, and in that the control lever is pivoting on a horizontal shaft (59) on the cross arm. 6. Vehicle according to any of the preceding claims, cha¬ racterized in that the two clutches (31,32) consist of claw clutches, one portion (33,34) of the claw clutch being rigidly attached to the output shaft (13) of the engine and the other portion (35,36) being movable on an intermediate shaft (37,38), provided to transmit the power from the out¬ put shaft of the engine to the track (14,15). 7. Vehicle according to claim 1, characterized in that the chassis (10) is provided with a rotatably mounted clamp (29), provided for transportation of timber logs or for attaching a trailer table. 8. Vehicle according to claim 3, characterized in that the movable portion (35,36) of the clutches (31,32) is adapted to cooperate with a brake means (64,62), rigidly attached to the chassis (10) for braking the track (14,15). 9. Vehicle according to claim 8, characterized in that the movable portion (35,36) is provided with a conical end, and in that a brake cone (64,62) is attached to the chassis (10) of the vehicle and adapted to cooperate with the mo¬ vable portion for braking the track (14,15), when the cont¬ rol lever (60) is positioned in one or the other of its end positions. _ OMPI W1PO

Inventors: BERGQUIST ERIK ARNE, BERGQUIST, ERIK, ARNE
Applicants: GRAENGES METALLVERKEN AB
Application year: 1984
Main classification: B65G7
IPC codes: B62D11, B62D51