SE459571B - TRACING VEHICLES - Google Patents

Description

459 571 10 15 20 2 with the closest characteristic of the invention in that a double-acting hydraulic cylinder is arranged diagonally between an inner joint of one parallel arm and an outer joint of the other parallel arm which, by changing its stroke, provides for the lowering and raising of the individual wheel relative to the vehicle framework.

Because the hydraulic cylinders are double-acting and placed diagonally between the two parallel arms, a variety of advantages are obtained. Thus, the cylinders are effectively protected against mechanical breakage and impact damage as well as against wear. Because the cylinders are double-acting, the wheels can be removed at high speed, as an active hydraulic pressure can affect the wheels' movements both upwards and downwards. Furthermore, the required stroke of the cylinders is minimal, which results in low piston speeds, low heat generation, small friction losses, low wear, fast obstacle removal properties and small risks of crack damage to the piston rod- The double-acting cylinders can further by individual maneuvering individual wheels from the ground, for example for service, wheel replacement, fitting of anti-slip protection, etc. Finally, it should be pointed out that the placement of the cylinders 25 does not result in any requirements for increasing the vehicle width.

Brief description of the accompanying drawings In the drawings, Fig. 1 is a partially transparent perspective view of the vehicle according to the invention in the form of a harvester during work in the forest, Fig. 2 a perspective view showing only the vehicle chassis and associated wheels and wheel suspensions, Fig. 3 a side view of the vehicle Fig. 4 is a schematic plan view of the vehicle, Fig. 5 is an end view from behind, i.e. from the left in Fig. 3, of the vehicle, Fig. 6 is an enlarged end view showing only the rear wheels of the vehicle, Fig. 7 is a diagram illustrating a hydraulic system included in the vehicle for automatically adjusting the height adjustment of the wheels, Fig. 8 an enlarged section through a leveling device included in the hydraulic system according to Fig. 7, Fig. 9 illustrates different situations in which the vehicle is used, and Fig. 10 a diagram showing different possible inclination angles of the ground on which the vehicle can operate.

Detailed description of a preferred embodiment of the invention Figures 1 and 2 illustrate an off-road vehicle made in accordance with the invention, which in the example has the shape of a harvester and which in a manner known per se comprises a chassis designated in its entirety by 1 or framework supported by in this case four wheels 2,3,4,5 which are mounted on a corresponding number of substantially identical wheel suspensions generally designated 6. The chassis 1 in turn supports a cab designated in its entirety by 7, a drive source 8 'šbm in practice advantageously consists of a diesel engine and a hood or box 9 which can be used to accommodate parts of the vehicle's electrical and hydraulic system. In this case, a crane generally designated 10 is also mounted on the cab 7.

In the example shown, the chassis or framework 1 is divided into two parts 11, 12 which are interconnected via a vertically extending pivot pin 13 which in a manner known per se allows waist control of the vehicle.

Pivoting of the two frame parts 11, 12 relative to each other is provided by two hydraulic cylinders 14, 14 '. In the following description, the frame parts l1 and l2 are called front and rear, respectively, meaning that the two wheels 2,3 are called front wheels and the wheels 4,5 rear wheels. From what has been said, it also appears that the cab 7 and the hood 9 are located 459 571 10 15 20 25 30 35 4 4 at the front and the engine 8 at the rear of the vehicle. In this context, however, it should be noted that the wheels 2-S are drivable in a hydrostatic manner by means of hub motors 15 which can cause the wheels to rotate in a uniform manner in either direction of rotation, so that the vehicle can be driven as comfortably backwards as forwards.

In Fig. 2, 16 is indicated by a gear for driving a rotating ring 17 (see Fig. 1) on which the driver's cab 7 is mounted. By means of this rotating ring, the cab can be rotated 360 ° to any turning angle position relative to the front frame part 11.

The two frame parts 11,12 can in practice advantageously consist of half-profiles, for example cross-sectional rectangular profiles, which completely or partially house liquid tanks. For example, the rear frame portion 12 may include a fuel tank for the engine 8, while the front frame portion houses a hydraulic oil tank for the vehicle hydraulic system (which will be described later).

Reference is now also made to Figs. 3-6. As best seen in Fig. 6, the individual wheel suspension 6 comprises, for example, the suspension for the wheel 4, and two mutually spaced, substantially parallel arms 18, 19 which are each at opposite ends pivotally connected via joints 20, 21 and 22, 23, respectively. on one side the frame and on the other hand a mounting plate or part 24 to which the hub or hydraulic motor 15 is attached, a rim 26 to the wheel 4 being bolted to the rotatable periphery 25 of the motor. A third arm 27 extends between the two parallel arms 18, 19 , more precisely diagonally between an inner link 20 of one parallel arm 18 and an outer link 23 of the second parallel arm 19. This third arm 27 is in the form of a double-acting hydraulic cylinder which, when changing in length, provides a lowering or raising of the wheel. 4 relative to the framework.

More specifically, an extension of the active length of the cylinder 27 causes a lowering movement of the wheel 4, while a shortening of the cylinder length causes the wheel to be raised relative to the frame. The two parallel arms 18, 19 can in practice advantageously consist of rigid, suitably rather wide plates which always have immutable length. As can best be seen from Fig. 2, the joints 20,22 can be constituted by shaft pins which extend between two separate brackets 28,28 'arranged on the outside of the rear frame part 12. The outer joints 21,23 can also advantageously be constituted by such shaft pins arranged between separate brackets 28 "on the inside ° of the mounting plate 24.

As can be seen most clearly from Fig. 4, the arms of each of the wheel suspensions 6 extend substantially perpendicular to the longitudinal axis L of the frame, the aforementioned pivot or shaft pins 20, 21, 22, 23 being directed parallel to the longitudinal axis L.

Figures 3 and 5 show the wheels 2-5 with solid lines in a normal or initial position N in which the wheel suspension arms 18, 19 extend substantially horizontally from the frame 1. In this normal position the wheels are maximally spaced from the central vertical plane intersecting the vehicle. and which in Fig. 5 is denoted V, 'in addition to the clearance height of the framework, ie the distance from the underside of the framework to the ground or the underside of the wheels, in practice can be about 0.5 m. From this normal position N the wheels can be raised and lowered to upper and lower end positions , U by pivoting the parallel arms 18,19 upwards and downwards, respectively, by means of the diagonal arm or the hydraulic cylinder 27. In the example shown, the arms 18,19 can be pivoted about 45 ° upwards and about 60 ° downwards. In the first case, the framework will be lowered to the ground while reducing the clearance height to approximately 0.1 m, while in the second case the framework will be raised to a maximum position in which the clearance height amounts to 0.9 m or more. When raising and lowering the wheels, these will move along arcuate, unequivocally 459 571 10 15 20 6 semi-circular paths of movement and in both cases approach the vertical plane V as illustrated by dash-dotted lines in Figs. 5 and 6. Where it is assumed that the vehicle in the normal position N has a total width of 2.0 m calculated from outside to outside of a pair of opposing wheels (corresponding to the clearance height 0.5 m), the vehicle width or track width can be reduced to 1.8 m by raising or lowering the wheels (position 0 ) or 1.5 m (position U). By this reduction of the track gauge, the vehicle can be advanced through passages which are considerably narrower than the normal, maximum track gauge of the vehicle. The high clearance height is of course also advantageous when crossing ground obstacles, such as rocks and stumps, when driving over land with newly planted forest.

IÉESP As described above, the arms 18 can be pivoted up about 45 ° from the substantially horizontal normal position.

To allow this and at the same time enable an advantageously low placement of the motor 8 (in order to obtain the lowest possible center of gravity), the motor is formed on its underside with inclined limiting surfaces 29 which both extend from the area of the upper longitudinal side edges of the frame profile 12 in direction obliquely upwards towards the vertical boundary walls of the engine. The hood or box 9 is similarly provided with inclined, lower boundary walls. Downwards the arms 18,19 can be swung about 60 °. In other words, the total angular deflection of the arms is about 105 °. In practice, this total angular deflection should amount to at least 90 ° and is advantageously in the range 100-110 °.

As can be seen from Figs. 3 and 4, the guide joint 13 is located substantially midway between the front and rear wheel pairs 2,3 and 4,5, respectively. Furthermore, it should be noted that the engine 8 is located with its center of gravity located substantially vertically above an imaginary axis between the centers of rotation of the two rear wheels 4,5, whereby the entire weight of the engine loads only the rear wheels. Fig. 4 shows in broken lines how the rear part of the vehicle 10 15 20 25 30 35 459. 571 7 can be swung out not less than 50 ° from the central longitudinal axis L of the vehicle. This large steering angle in combination with the moderate wheelbase gives in practice a very limited internal turning radius, which of course entails great advantages when driving, especially in young forest stands, in that the vehicle is extremely easy to maneuver. At maximum steering angle, the basic stability of the vehicle is reduced by only about 10% despite the extremely large steering angle.

The hydraulic cylinders 27 included in the vehicle's four wheel suspensions are connected to a communicating hydraulic system which can press, for example, the right wheel automatically downwards when the left wheel is lifted when passing an obstacle and vice versa, whereby the frame 1 and superstructures can be kept in a horizontal or leveled position both when crossing high obstacles and when driving on large slopes.

The vehicle has hydrostatic power transmission to the hub motors 15 in all four wheels, namely from a variable hydraulic pump directly connected to the motor 8, while the crane 10 is fed from a separate pump unit which also constitutes a pump for the automatic leveling system for the cylinders 27.

Reference is now made to Figures 7 and 8 which schematically illustrate the above-mentioned leveling system. The main circuit of the system is of conventional type and comprises a hydraulic pump 30 which feeds hydraulic medium through a number of control valves 31,32,33,34 and from there on to a tank 35. The hydraulic cylinders connected to the respective wheels are in Fig. 7 designated 272,273,724 and 275, respectively. The system also includes three hydraulically controlled leveling devices 36, 37 and 38, of which the first two have the task of providing lateral leveling, while the latter provides longitudinal leveling. A first inclination sensing sensor 39 has the task of sensing incipient lateral inclination laterally and thereby activating the leveling function of the system, more specifically by electrically actuating the control valve 32. Corresponding activation during longitudinal inclination takes place by a second sensor 40 which acts on the valve 33.

All leveling devices 36,37,38 are preferably identical. As can be seen from Fig. 8, the individual leveling device consists of a cylinder 41 comprising two mutually spaced pistons 42,43 which together with the two end walls 44, 45 of the cylinder delimit first and second end chambers 46 and 47, respectively, and which are rigidly interconnected by means of a rod or 48 which projects through a hole in a partition wall 49 suitably located in the middle of the cylinder 41 which, together with said pistons 42,43, delimits first and second intermediate chambers 50 and 51, respectively, which communicate with lines 52,53, of which a 52 allows evacuation of hydraulic medium from the first intermediate chamber S0 by displacing the piston pair 42,43 in one direction relative to the cylinder due to supply of hydraulic medium to the first end chamber 46 while the second conduit 53 allows supply of hydraulic medium to the adjacent second intermediate chamber 51 and vice versa.

The hydraulic system is in principle equally built for both pairs of wheels, but for information-simplifying reasons, the end that is marked with a directional arrow for the front is hereinafter referred to.

The function of the system is as follows: When the ground changes from a horizontal section to a sloping one, eg to the left, the vehicle frame 1 begins to deviate gradually from its horizontal position. The sensor 39 then activates the valve 32 which sends a hydraulic flow via the line 54 to the leveling devices 36 and 37. The event then becomes the same for both pairs of bellows, but for the sake of simplicity only the hydraulic function at the two front wheels 2,3 is now described. The side leveling device 37 receives hydraulic medium in the chamber 46 which is thereby enlarged, whereby the pistons 42,43 connected via the rod 48 are pressed in the direction of the end wall 45 while reducing the volume of the end chamber 47 and extruding hydraulic medium via line 55 to the valve 32 and back to the hydraulic tank 35. When the piston 42 is moved towards the partition 49, oil from the first intermediate chamber 50 is forced out via the channel or line 52 and led via line 56 to the positive connection of the cylinder 273. Via a branch line 57, approximately 15% of the flow also goes to the negative connection of the cylinder 272 (piston rod end) so that vacuum arises there, when the second intermediate chamber 51 of the leveling device 37 simultaneously increases in volume and takes over flow from the positive connection of the cylinder 272 and the negative connection of the cylinder 273 via When the cylinders 273 and 272 have increased and decreased their strokes, respectively, through the described process, the parallel arms 18, 19 of the wheel suspensions have changed angles in such a way that the frame has resumed horizontal position and thus the activation from the sensor 39 is interrupted.

If the ground instead tends to slope to the right, the described function takes place in reverse order, which is achieved by the valve 32 transmitting the hydraulic flow in the reverse direction, ie through line 55 instead of through line 54. By the hydraulic system of the front and rear wheels communicating with each other via the lines 54.55, all four wheels can move individually on uneven sections of land or over terrain obstacles. Because the vehicle frame is torsionally rigid along its entire length, the front and rear wheel cylinders continuously cooperate with four-wheel stability in every situation. To the extent that the driver wishes to influence the inclination control laterally by manual means, the sensor 39 is temporarily switched off, after which the valve 32 can be operated by hand.

When the longitudinal slope sensing sensor 40 detects deviation from the horizontal position, for example in the middle slope, it activates the valve 33, which via the line 459 571 10 15 20 25 30 35 10 58 activates the leveling device 38 to send slope compensating hydraulic medium to the leveling device 37. At the same time the device takes 38 at the same time as this volume flow is in progress, the means 36 and 37 automatically regulate the changed volume so that the hydraulic medium is directed out to the cylinders 272-275 with function-adapted volumes. This is done by control from the sensor 39, which monitors that the volume is distributed while maintaining the horizontal position laterally. if the grounding instead gave way - a counter-slope, the function is the reverse, whereby the valve 33 sends a pressure flow through the line 59 instead of through the line 58. In cases where the driver wishes to influence the slope regulation manually, both longitudinally and laterally, sensors 39 and 40 are switched off and the communicating function of the lines 54 and 55 is blocked by means of the three-way valve 60. The valve 32 is then in functional connection only with the leveling device 37, while the now connected valve 34 is in separate connection with the leveling device 36.

Since the leveling devices 36,37,38 together with the cylinders 272-275 have a function-adapted flow volume for the automatic leveling, this volume must be increased for a higher clearance height or decreased for a lower clearance height. This is done manually by filling the hydraulic medium via the control valve 311 through the line 61 and draining hydraulic medium by means of the back pressure in this line.

The hydraulic cylinders 272-275 are dimensioned with a good margin to cope with the hydraulic pressures to which they may be exposed through external loads, for example during crane work. The basic principle of the described hydraulic system is based on the pressure to a lesser extent building up - a function-controlled back pressure. This is done by the pressure lines of one vehicle side to the positive connection of one cylinder also branching off to the negative connection of the cylinder of the other vehicle side. It should be noted here that 159 251 4.59 571 ll that the piston rods of the cylinders are dimensioned with such a large diameter that the negative end has only about 15% pressure surface in comparison with the positive side. This system means that at the same time as the positive end provides the vehicle's carrying capacity, the system relinquishes a smaller force share to the negative end of the cylinder on the other side of the vehicle. This should help to press over flow from the positive end of the cylinder to the expansion chamber of the leveling device at the same time as the high pressure compression chamber presses out the corresponding volume to the positive positive end of the second cylinder. In this way, the system gets a calm, soft, shock-free and powerful movement function. In manual control, this system also means that the operator can leave the machine standing on three wheels in maximum clearance and lift the fourth wheel level with the underside of the frame, for example for service access or to allow climbing, eg for climbing on a trailer or such. The maximum wheel lift in such a position can be significantly higher than the wheel diameter.

Reference is now made to Fig. 1 which illustrates how the circumferential driver's cab 7, in addition to two opposite, substantially planar side walls 62, comprises front and rear walls 63, 64 which both have arched or cross-sectional semi-circular shapes to provide extremely high rigidity of the cab. in its entirety. All of these walls are based on a strong floor construction mounted on the rotating ring 17. On one side wall 62 is a cab door, while the opposite wall is extraordinarily strongly designed so that it can absorb forces from a crane attachment in the form of a stable, horizontal joint pin 65.

The main arm of the crane is pivotally movable about the pivot pin 65 by means of a hydraulic cylinder 66, which is likewise mounted on the side wall 62. By mounting the crane in this way on the cab, separate bracket and turning devices are eliminated, in that the crane is pivoted relative to the vehicle chassis itself. the cabin. 459 571 10 15 20 25 30 35 12 Because the front and rear cab walls are made with a curved shape without protruding corners, the space between the hood 9 and the engine 8 can be reduced to a minimum without interfering with the possibilities of turning the cab. Furthermore, it should be noted that the center of rotation of the cab is located a short distance in front of the guide joint 13, whereby the crane and the driver obtain a central location on the machine; which in turn provides good visibility and an efficient working position. d The crane 10 consists of a folding arm crane with a telescopic extension of the folding arm 67 and with a main arm 68 which is substantially L-shaped to locate the arm behind and under the window 69 located on the cab side wall 62 when the crane is placed in a parking position.

Due to the angular shape of the main arm 68, the mounting of the hydraulic cylinder 66 also becomes simple and smooth. In the example shown, a processing unit 70, for example a harvester unit, is mounted at the crown tip or the free end of the folding arm 67. According to a preferred embodiment, this assembly is eccentrically placed relative to the folding arm 67, more specifically offset to the left relative to the arm 67; whereby the driver sitting in the cab 7 always has the unit under good supervision without obstruction of the arms 67.68.

Fig. 9a shows the vehicle according to the invention in side view in the normal position N. Figs. 9b and c illustrate the vehicle when driving in the middle slope and the opposite slope, respectively. Fig. 9d is an end view of the vehicle in the normal position according to Fig. 9a.

Fig. 9e shows the vehicle with the chassis maximally submerged in relation to the wheels, while Fig. 9f illustrates the same with the chassis raised to a maximum position remote from the ground. Fig. 9g shows the vehicle under obstacle, while Fig. 9h illustrates how the vehicle as a whole can be tilted by raising the two wheels on one side of the vehicle relative to the frame, while lowering the wheels on the opposite side. In particular, it should be noted here that the center of gravity of the vehicle is still located within the wheelbase despite the relatively large inclination of the vehicle. Fig. 9i shows the vehicle in the same inclined position, but with one of the wheels raised to a highest position, the vehicle still being stable despite only a three-point abutment against the ground.

Fig. 10 schematically illustrates the different inclination conditions under which the vehicle can operate without risk of overturning. As shown in the diagram, the vehicle can automatically assume a horizontal position at sloping conditions up to 36% (approx. 20 °) longitudinally and 60% (approx. 30 °) laterally; all while maintaining continuous four-wheel stability. Other advantages of the vehicle according to the invention are that the risk of accidents when getting on and off is reduced by the fact that the machine can be lowered to a level where the cab floor is only 0.5 m above the ground. Only when the driver has installed himself in the cab does the chassis and cab drive up to normal working height again. The all-round cab facilitates the driver's work and prevents wear and tear in the neck column due to otherwise required head twists. The attachment of the crane to one side wall of the cab means that it always follows the rotational movements of the cab and that the crane arm movements in and out always take place in the driver's line of sight. This is de-stressing and provides increased precision in crane work. In thinning stands with difficult visibility conditions due to the abundance of twigs, the driver can raise or lower the cab to an optimal line of sight between obscuring twigs.

Since the machine can be raised to a high clearance height and contracted to a narrow overall width or driven out to a large and stable overall width or go in exceptional cornering, a flexible and quickly adaptable work vehicle is obtained.

The following is a compilation of technical data of a work vehicle 459 571: 14 made in accordance with the invention for practical use. § Total length 3.3 m I Width (stepless variable) 1.5-2.0 m E Total satisfaction (stepless variable) 2.3-3.1 m: 5 Clearance height (stepless variable) 0.1-0.9 m É Wheelbase 2.2 m Wheel dimension (four pcs) 400x22.5 mm Total weight (including crane but excluding work tools) 3,500 kg 10 engine power 45 kw Traction (four hydrostatically driven hub motors) 4,000 kp Power transmission, hydrostatic.

Hydraulic pressure 350 kp / cm2 15 Brakes, mechanical in the hub motors.

Braking force 6,400 kp Speed in terrain, four-wheel drive 0-13 km / h Speed on the road, two-wheel drive 0-26 km / h Steering principle waist steering 20 Max steering angle 1 50 ° Leveling longitudinally, automatic up to 36% inclination lateral tilting, automatic up to 60% inclination 25 Maximum lateral inclination to overturned edge 120% inclination Obstacle height, horizontal 0.8 m Cab, rotating on turntable 360 ° 30 Crane, folding arm type with telescopic extension, range 5 m Possible modifications of the invention _ It is a given that the invention does not is limited only to the embodiment described above and shown in the drawings. Thus, the principle of the invention is applicable o c _. of v i - also on other off-road vehicles and just work machines 10 15 459 571 15 for forestry purposes. It should also be emphasized that the minimum and maximum values (0.1 and 0.9 m) above for the clearance height stated above are not limited. Thus, these limit positions - depending on vehicle size and needs - can vary both upwards and downwards. For example, it is conceivable to lower the vehicle frame all the way to the ground so that the frame carries the vehicle at the same time as all wheels are lifted, eg for fitting anti-slip protection, service, etc. The machine can be supplemented with various tools, which are attached at its front. The implements can be, for example, a clamping bank, harvester head, shaft or plow equipment or various loader implements.

Claims (4)

459 571 10 15 20 25 30 35 16 PATENT REQUIREMENTS 1. All-terrain vehicle comprising a chassis or framework (1) carried by at least two pairs of wheels (2,3; 4,5), which in turn carries a driver's cab (7) and a motor or drive source (8 ), wherein at least a pair of cooperating wheels are mounted on movable wheel suspensions (6) which allow the individual wheel to be raised and lowered relative to the chassis and which are separate. comprises two mutually spaced, substantially parallel arms (18, 19), each of which at opposite ends is pivotally connected via joints (20,2l; 22,23) to on one side the frame (1) and on the other hand a mounting plate or part (24) on which the wheel (2,3,4,5) is rotatably arranged, characterized in that diagonally between an inner joint (20) of the one-parallel arm (18) and an outer joint ( 23) of the second parallel arm (19) is arranged a double-acting hydraulic cylinder (27) which, by changing its stroke, takes care of the lowering and raising of the wheel relative to the frame. Off-road vehicle according to claim 1, characterized in that all wheels t É (2,3,4,5) included in the vehicle are individually connected to the framework (1) via = each suspension (6) comprising said double-acting hydraulic cylinder (27), whereby the frame is adjustable in a horizontal position independent of varying ground inclination conditions by not only lateral leveling, namely by raising or lowering at least one of the wheels in a cooperating pair of wheels (2,3 and 4,5 respectively) without also length leveling, namely by raising or lowering one or both wheels in a front wheel pair (2,3) relative to the wheels in a rear wheel pair (4,5). Off-road vehicle according to claim 1 or 2, characterized in that four hydraulic cylinders (272,273 10 15 20 25 30 35 459 571 17 274.275) each form diagonal alarms of variable length in four wheel suspensions (6), namely a pair of front wheels (2,3) and a pair of rear wheels (4,5) are part of a hydraulic system which, in addition to a pump (30) and a tank (35), includes three leveling devices (36,37,38) , more specifically a longitudinal leveling device (38) and two side leveling devices (36,37) for the two pairs of wheels, first and second inclination sensing sensors (39,40) for sensing the inclination of the ground laterally or longitudinally and of these sensors activatable control valves (32, 33) one of which (33) is activatable by one of the inclination sensors (40) and connected to the length leveling device (38) which, when supplying hydraulic medium, provides a transfer of hydraulic medium from the front side leveling device (37) to the rear (36) or vice versa while raising the front wheels simultaneously me d a lowering of the rear wheels or vice versa, and of which the other is activatable by the second, side inclination sensing sensor (39) and connected to the two side leveling devices (36, 37) which, when supplying hydraulic medium from the control valve (32), each provide a supply of hydraulic medium 'to the positive chamber of one of the two hydraulic cylinders (272,273) in a pair of front and rear wheel suspensions, respectively, during lowering of associated wheels relative to the frame while hydraulic medium is evacuated from the negative chamber of the other cylinder while raising associated wheels, all while achieving a horizontal position or leveling of the framework. Off-road vehicle according to claim 3, characterized in that the individual leveling device consists of a cylinder (41) comprising two mutually separated pistons (42,43) which together with the end walls (44,45) of the cylinder delimit the first and other end chambers (46,47) and which are rigidly interconnected by means of a rod or the like, which projects through a heel in a partition wall (49) 459 571 10 18 which is conveniently located in the middle of the cylinder (41), which together with said = pistons ( 42,43) delimit first and second intermediate chambers (50,51), which communicate with conduits (52,53) of which one allows evacuation of hydraulic medium from the first intermediate chamber (50) by displacing the piston pair in one direction relative to the cylinder as a result of hydraulic medium supply to the first end chamber at the same time as the second line allows supply of hydraulic medium to the adjacent second intermediate chamber (51), and vice versa. "-