Measurement system for determining support force

Abstract

A support force measurement apparatus for determining a support force on a support element of a support structure of a movable working machine. The measurement apparatus has at least one measurement element and a support leg. The measurement element is connected to a deformation body capable of being deformed with an effect of the support force, so as to form a sensor and send a signal proportional to the support force. The support leg has the sensor and is movably connected to the support element. The support element comprises a cable connection, and the cable connection is constructed in a manner of guiding electrical energy and is used for sending the signal proportional to the support force to an analysis apparatus in a machine. The support element in the support leg and the sensor are provided with electromagnetic interfaces.

Claims

1. A support force measurement apparatus for measuring a support force on a support element of a support structure of a movable working machine, the apparatus comprising: at least one measurement element, which is connected to a deformation body deformable with an effect of the support force, so as to form a sensor and send a signal proportional to the support force; and a support leg, which comprises the sensor and is movably connected to the support element, the support element comprising a cable connection, the cable connection guiding electrical energy and being used for sending the signal proportional to the support force to an analysis apparatus in the machine, wherein the support element in the support leg and the sensor are provided with electromagnetic interfaces, wherein the measurement element is supplied via electromagnetic induction with electrical energy from the machine through the electromagnetic interfaces, and wherein the signal proportional to the support force is transmitted via electromagnetic induction from the measurement element to the cable connection of the support element, wherein the support leg comprises a spherical plate supported on the sensor, wherein the support element comprises a link ball which is accommodated in the spherical plate, wherein the portion of the electromagnetic interface at the support leg side is mounted in a depressed manner in a recessed portion of the spherical plate, and wherein the portion of the electromagnetic interface at the support element side is mounted in a depressed manner in a recessed portion of the link ball, so that the two portions are arranged opposite to each other in a non-contact manner.

2. The support force measurement apparatus according to claim 1, wherein the measurement element is connected to a circuit which comprises a rechargeable buffer storage device for storing electrical energy, and wherein the buffer storage device is used for the measurement of the support force and the transmission of the signal proportional to the support force.

3. The support force measurement apparatus according to claim 2, wherein the analysis apparatus in the machine is matched up, so as to be used to switch, following the transmission of the signal proportional to the support force with a shift over time, between a charging operation for charging the buffer storage device and a measurement operation for measuring the support force, and wherein the switching cycle is time-controlled or in relation to the charge state of the buffer storage device or to the measured value of the support force.

4. The support force measurement apparatus according to claim 2, wherein the transmission of the energy and of the signal proportional to the support force are performed substantially simultaneously via a transmission of a modulated AC voltage as a signal carrier through the electromagnetic interfaces.

5. The support force measurement apparatus according to claim 1, wherein the sensor is mounted in a replaceable manner in the support leg.

6. The support force measurement apparatus according to claim 1, wherein the support element comprises sections which are adjustable relative to each other.

7. The support force measurement apparatus according to claim 6, wherein the support element is in the form of a hydraulic piston/cylinder block apparatus, a cable is arranged to pass through the piston/cylinder block apparatus, and the cable has its length changed with the adjustment of the relative position of the piston and the cylinder block and automatically returns to its initial length.

8. The support force measurement apparatus according to claim 1, wherein a cable has an initial shape, and the cable automatically returns to the initial shape following a relaxed strain, wherein the initial shape is in a spiral shape, a coiled shape, a corrugated shape, a jagged shape or a ring shape, or a combination thereof.

9. The support force measurement apparatus according to claim 1, wherein, a cable is wound around an automatic winder, and the winder winds up the cable from both sides under a spring force.

10. The support force measurement apparatus according to claim 9, wherein the winder winds up the cable from both sides under the spring force starting from the middle section.

11. The support force measurement apparatus according to claim 1, wherein the sensor is formed by the deformation body, the deformation body is used as the measurement element to form a resistance strain gauge, or is formed as a coupling membrane element together with a resistance strain gauge, or wherein the sensor, as a hydraulic force sensor, is formed by a measurement piston which functions in a cylinder block chamber, and the pressure in the cylinder block chamber is output as a measured value of the support force, or wherein the sensor is used as a force measurement shaft to analyze the support force applied by a bracket of the movable machine and analyzes herein the bending of the shaft or an axial force on a support portion of the shaft.

12. The support force measurement apparatus according to claim 1, wherein the at least one measurement element is configured to counteract the effect of a transverse interferential force.

13. The support force measurement apparatus according to claim 1, wherein the sensor is redundantly arranged.

14. The support force measurement apparatus according to claim 1, wherein the signals from the sensor are analyzed and evaluated independently of each other.

15. A support force measurement apparatus for measuring a support force on a support element of a support structure of a movable working machine, the apparatus comprising: at least one measurement element, which is connected to a deformation body deformable with an effect of the support force, so as to form a sensor and send a signal proportional to the support force; and a support leg, which comprises the sensor and is connected to the support element in a movable manner; and a foot plate which is connected with the support leg, wherein the support leg comprises a device for storing electrical energy and a radio transmitter, the radio transmitter being connected to the sensor and transmits in a wireless mode the signal proportional to the support force detected by the sensor to a radio receiver in the machine, wherein the foot plate comprises an insertion portion connected to the force sensor, wherein the insertion portion is provided with a connection unit, and wherein the connection unit is configured as the radio transmitter and comprises an antenna.

16. The support force measurement apparatus according to claim 15, wherein the device for storing electrical energy is a rechargeable storage device, and the support leg is provided with a charging apparatus by which the storage device can be charged.

17. The support force measurement apparatus according to claim 15, wherein the radio receiver in the machine is connected to the analysis apparatus, and wherein the analysis apparatus converts the signal proportional to the support force into a support load.

18. The support force measurement apparatus according to claim 15, wherein the radio transmitter and the radio receiver are respectively configured and constructed to be a radio transmitter and a radio receiver in communication with each other.

19. The support force measurement apparatus according to claim 18, wherein the radio transmitter and the radio receiver transmit data by radio waves, are coupled with each other according to a given protocol, and check a signal source and a correct transmission to the receiver of the machine.

20. The support force measurement apparatus according to claim 15, wherein the device for storing electrical energy is connected to the charging apparatus, and the charging apparatus comprises a charging socket for connecting a current source or an interface for non-contact transmission of electrical energy by electromagnetic induction.

21. The support force measurement apparatus according to claim 15, wherein the support leg comprises an apparatus for monitoring the charge state of the device for storing electrical energy, which transmits data regarding a charge state to the radio receiver of the machine by the radio transmitter.

22. The support force measurement apparatus according to claim 15, wherein the support leg comprises an antenna of the radio transmitter, the antenna being disposed in a recessed portion.

23. The support force measurement apparatus according to claim 15, wherein the support leg carries a light-emitting apparatus on its upper side, which is controlled by the radio transmitter, so as to display working states by light symbols.

24. The support force measurement apparatus according to claim 23, wherein the light symbols are distinguishable by light colors or light-emitting intervals and display the different working states.

25. The support force measurement apparatus according to claim 15, wherein the radio receiver is disposed in a control station of a machine operator and comprises a screen, and a measured value and/or a value calculated from the measured value are shown on the screen.

26. The support force measurement apparatus according to claim 15, wherein the sensor is formed by the deformation body, and the deformation body is used as a measurement element to form a resistance strain gauge or is formed, as a coupling membrane element, together with the resistance strain gauge, or wherein the sensor is a hydraulic force sensor and is formed by a measurement piston which functions in a cylinder block chamber, and the pressure in the cylinder block chamber being output as a measured value of the support force, or wherein the sensor is used as a force measurement shaft to analyze the support force applied by a bracket of the movable machine and analyzes herein the bending of the shaft or an axial force at a support portion of the shaft.

27. The support force measurement apparatus according to claim 15, wherein the at least one measurement element is configured to counteract the effect of a transverse interferential force.

28. The support force measurement apparatus according to claim 15, wherein the sensor is redundantly arranged.

29. The support force measurement apparatus according to claim 15, wherein the signals from the sensor are analyzed and evaluated independently of each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 shows, in a front view, one of the support elements on a crane vehicle;

(3) FIG. 2A shows a bracket, which comprises a schematically illustrated deformable part and a reinforced structure;

(4) FIG. 2B shows a bracket, which may be pivoted around a vertical axis out of the vehicle;

(5) FIG. 2C shows a bracket, which may be pivoted around a horizontal axis out of the vehicle;

(6) FIG. 3 shows a bracket, which has a sensor and can hydraulically extend outwardly, and a support leg which comprises a sensor at the lower foot part;

(7) FIGS. 4A to 4G show various electrically coupling apparatuses used for the sensor and passing through the support leg;

(8) FIG. 5A shows a sectional view of the support leg which has a sensor element and a sleeve used for matching up the maximum load;

(9) FIG. 5B shows an enlarged view of the sensor body;

(10) FIGS. 6A and 6B show support legs with a sensor insertion portion for different spherical links;

(11) FIG. 6C shows a support leg in a wireless connection with a crane control apparatus;

(12) FIG. 6D shows a support leg in a radio connection with a crane control apparatus;

(13) FIG. 7 shows a schematic sectional view of a support leg which comprises a sensor in a piston rod of a hydraulic cylinder;

(14) FIG. 8 shows a crane vehicle comprising mountable support legs, the support legs sending measured values to a crane cabin by means of radio; and

(15) FIG. 9 shows a solution, in which the force sensor is formed by a piston/cylinder block apparatus and a pressure measurement apparatus.

DETAILED DESCRIPTION

(16) According to FIG. 1, a rotatable crane 1 (the crane is a machine in the sense of the present application) comprises a basic frame or a lower structure 44 which is fixed to a horizontally movable crane jib or bracket 3. A support leg 2 is mounted on the bracket 3, and the support leg may lift up the crane structure or the entire vehicle in a restricted manner.

(17) According to a suspended load 5, the outwardly extended length of the crane bracket (column 8B), the expanded extension portion 8C, the arrangement of the self-weight of the crane and a balance weight 8A, and the outwardly extended length L of the bracket 3 with the support leg 2, the maximum load of the load 5 to be lifted before the dumping of the crane is obtained.

(18) By analyzing support forces of all the support elements, approaching or reaching the maximum load (also referred to as an overload limit) may be shown to a crane driver.

(19) To this end, a sensor is arranged in the support structure.

(20) According to FIG. 2A, the force sensor may be disposed at different points in the support structure. For example, in the support element, the force sensor may be disposed on the support leg 2 in the region of a ball 4, on the reinforcement element 5 on the bracket 3, or in a tray roller shaft 7 of the bracket 3. The present invention may be applied to these applications, preferably to the application in which the sensor and the analysis apparatus can move relative to each other.

(21) The following solution is shown in FIG. 2B, in which the bracket 3 may pivot out of the vehicle around a vertical axis. A journal 7 around which the bracket 3 pivots may be implemented as a force measurement shaft. Furthermore, other force sensors may be arranged in the region of the ball 4 of the support leg 2 or in the support plate 9 as described below and connected to the analysis apparatus of the crane in the described manner.

(22) The following solution is shown in FIG. 2C, in which the bracket 3 may be driven by a hydraulic cylinder 300 to pivot out of the vehicle around the horizontal axis. A hinge joint 7 around which the bracket 3 and the hydraulic cylinder pivot may be implemented as a force measurement shaft. Furthermore, other force sensors may be arranged in the region of the ball 4 of the support leg 2 or in the support plate 9 as described below and connected to the analysis apparatus of the crane in the described manner.

(23) FIG. 3 shows two sensors which may work redundantly with each other on the support structure 6 with the bracket 3 and the support leg 2 and therefore improve the safety of the crane.

(24) The support structure 6 is mainly composed of a horizontal bracket 3 and a vertical support leg 2. The crane vehicle, as shown in FIG. 1, is generally provided on each of the two vehicle sides with two such apparatuses, i.e., there are four support legs 2 on four brackets 3 in total.

(25) Merely described below is such a support structure, which is copied by arranging the support structures having the same structure or radial configuration on the rest vehicle points.

(26) To this end, the first force sensor 10 is arranged above the spherical link 4 on the foot, and the support plate 9 accommodates the spherical link. The support leg 2 is manufactured in two pieces as a hollow cylinder block with the movable piston 11. By guiding hydraulic oil 13 under a pressure P2, the piston rod 11 moves until the support plate 9 comes into contact with the ground 12 and lifts the crane.

(27) The force sensor 10 makes contact herein via a spiral cable 14 for example, and the spiral cable passes through, preferably centrally passes through, the piston and cylinder block unit. The measured signal is then transferred to a crane control apparatus or a crane monitoring apparatus via a sealed contact portion 15.

(28) Likewise, it is possible that the bracket 3 moves in a hydraulic manner by means of a piston and cylinder block unit 16, the piston and cylinder block unit is supported in the bracket 3, and the bracket 3 may retract or stretch on a roller 7 or a sliding support plate 7B relative to a lower structure of the crane which is not shown herein in detail.

(29) The bracket sensor 17 is then preferably, as a constituent part of the plate 5, disposed on the bracket 3 by welding, for example. A recess surrounding the bracket sensor 17 surrounds the lines of force or concentrates same at the support leg sensor and improves the measured signal.

(30) Similar to the implementation for the support leg 2, a cable 14B of the bracket sensor 17 is guided to pass through a hydraulic oil and pass through the piston and cylinder block unit to the crane control apparatus. It is further possible that the cable 14 is electrically connected to the cable 14B of the support leg 2, so that the cable 14B guides the measured value of the force sensor 10 and the measured value of the support leg sensor 17 to the analysis apparatus (not shown) of the crane 1.

(31) According to FIG. 4, to this end, the cable may be in different configurations:

(32) FIG. 4A shows a cable connection, in which the cable is spirally formed and is coated with a material so as to elastically spring back, and is predefined in the initial shape thereof, so as to always try to return to its initial shape from the length when the load is reduced.

(33) An enveloping shape herein, e.g., a tube (which may also be implemented as an extension tube (not shown, see FIG. 7)) takes assisting and guiding effects, in which each end section of the extension tube is fixed onto the cylinder block or the piston rod, and a variable-length protection cover is formed surrounding the elastically deformable (i.e., capable of automatically returning to the initial shape thereof) cable.

(34) FIG. 4B shows a cable connection, in which the cable is coiled by an apparatus not shown when the load is reduced. This may be an elastically pre-tensioned roll-up device.

(35) FIG. 4C shows a cable connection, in which the cable is wound in zigzag fashion by an apparatus not shown.

(36) FIG. 4D shows a cable connection, in which the cable flexibly matches the change in length in the form of a simple (spiral) spring. The cable is reinforced herein by means of a metal or fibrous liner or wrapper, so that the spiral shape thereof, such as a spring, symmetrically matches the extension portion.

(37) FIG. 4E shows a cable connection, in which the cable predefines a film conductor or a ribbon conductor in an accordion form. To this end, an insulated printed conductor may also be used as a film to connect with a spring elastic carrier material, for example, by lamination method, to connect with a printed circuit board material.

(38) FIG. 4F shows a cable connection, in which the cable has elastic spring folding elements, and once the connection load is reduced, the spring folding elements roll up inwards by pre-tensioning.

(39) According to FIG. 5, the force cell or the force sensor is configured to be a spherical link or a section of the spherical link 4, is mainly formed of a rustproof iron deformation body, and performs detection by the strain induced by the force to be measured by means of a resistance strain gauge adhered to the deformation body or by means of a strain-sensitive resistor fabricated by the thin-layer technique.

(40) To this end, the resistor may be directly arranged on the ball link or disposed on the sensor body 20, and is connected to the deformation body, preferably by welding. When guiding the support force F to a connecting plate 21, the sensor region or a sensor body 20 deforms similar to the load F, the resistor deforms, and the measured signal for the load on the spherical link may be analyzed by the crane control apparatus.

(41) The sensor device and the matching between the arisen strain and the desired force may be achieved by the configuration of a hole 22. The sensor device further matches the maximum load or the support geometrical structure of the crane in that the connecting diameter 22 of the spherical link section of different sleeves 23A, 23B is connected to the connecting plates 21A, 21B which are matched in strength.

(42) By selecting the sleeve and the plate, the stiffness of connection may be changed, so that the strain level in the sensor region may be matched up according to the load.

(43) In order to achieve a higher functional safety, regarding the wiring of the resistor arranged on the sensor body 20, there are two or more Huygens bridges connected in the same way on the sensor body, and the signals thereof are separately analyzed and evaluated in an electronic comparison circuit.

(44) Furthermore, the resistor related to temperature is directly located on the sensor body, by which the influence of the temperature on the measured value may be compensated.

(45) If the spherical link 4 is cooperatively configured, for example, as shown in FIG. 5B, when a measuring resistor 24 is located on a measurement film 25 (which is a constituent part of the sensor body 20) which is connected to the spherical link, the horizontal force guided by the support leg to the sensor body 20 results in a deformation of the sensor region or the sensor body, which is analyzable in the measurement technology. Therefore, the force cell for detecting the support force transferred by a support element for carrying a load may be configured to compensate for the transverse interferential force. Thus, it will be achieved particularly by the way of appropriately (for example, crosswise) arranging the resistor on the sensor body 20.

(46) The force cell or the force sensor comprises a measurement section (which is the measurement film 25 herein) or a deformation body which deforms under the support force and the transverse force in a direction deviating from the support force, and the force cell or the force sensor forms a part of the support element together with the measurement section or the deformation body. Furthermore, a plurality of resistors arranged on the measurement section (measurement film 25) are firmly connected to the measurement section, and the measurement section displays a response proportional to the strain and preferably counteracts the response proportional to the transverse force.

(47) The elimination of the response may be achieved by appropriately arranging the measurement element (which is a film resistor herein) on the measurement section and/or by correspondingly processing the measured signals.

(48) FIGS. 6(A, B, C, D) show a foot plate 9 for the support structure of the crane, which may be implemented, for example, as described with reference to the above figures.

(49) In the expanded solution according to FIG. 6, the accommodation region 30 for the spherical link 4 is configured in a replaceable manner. Particularly, to this end, the sensor insertion portion 31 is provided with a sectioned spherical surface 32, and guides the support force of the spherical link 4 with a diameter D1 to the force sensor 33 in the support leg 9.

(50) According to FIG. 6B, such a sensor insertion portion 31 may be locked with a fixing apparatus 34 in the support leg 9, and has an interface which will be described later and only shown similar to a connection unit 35, and the measured data may be sent to the crane control apparatus or an analysis unit through the interface.

(51) To this end, the first force sensor 10 is arranged above the spherical link 4 on the foot, and the support plate 9 accommodates the spherical link.

(52) According to FIG. 6C, the sensor insertion portion 31 connected to the force sensor 10 is provided with a connection unit 35, and the connection unit is configured as a radio transmitter and sends the measured data to the analysis unit or the crane control apparatus by means of radio, preferably via an antenna 37. The required energy supply may be wirelessly transferred via a receiving unit 36, for example, via an inductive interface.

(53) The apparatus 34 is used to fix the sensing insertion portion 31 into the support leg 9, and the apparatus 38 herein is in the form of an upper hemispherical shell for fixing the support leg 9 onto the spherical link 4.

(54) According to an embodiment of FIG. 6D, such a sensor insertion portion 31 transfers the support force to a double redundant force sensor 10, and the force sensor transfers the measured data thereof to a sensor analysis apparatus SA. The sensor analysis apparatus SA further wirelessly provides the measured data from a transceiver 50 to a transceiver 51, and the transceiver 51 operates as a receiver in the inductive interface and is disposed in the spherical link 4. The transceivers 50, 51 together form inductive interfaces.

(55) In the scope of connection, it is integrated with coil systems 52A, 52B, and also transmits electrical energy for supplying power to the force sensor 10. In the embodiment, the force sensors do not need to be present in double, which may also be only a single force sensor 10, and is connected to the corresponding circuit SA, so as to transmit the measured data thereof through the inductive interfaces 50, 51.

(56) The circuit SA connected to the coil system 52B and the force sensor 10 also comprises a device for storing electrical energy, which is in the form of a storage battery or a capacitor. The electrical energy may be transmitted through the inductive interfaces 50, 51, so as to subsequently drive the force sensor 10 to perform measurement and process the measured signal into an appropriate signal to be transmitted to the analysis apparatus of the machine or coupled and output into the interfaces 50, 51. Hence, the interfaces 50, 51, for example, may be alternately used for transmitting energy or for transmitting the measured value. Hence, a simple double-core cable and/or a simplified signal transmission form may be used to work.

(57) Another embodiment is shown in FIG. 7, in which the support leg 2 is integrated with a force sensor 10. According to FIG. 7, the force sensor 10 is integrated into the support leg 2 or mounted on an upper end portion inside the piston rod. A section of the piston rod 11 forms a deformation body, and a sensor (not shown) is disposed on the deformation body. The sensor may, for example, have the form as shown in FIGS. 5A and 5B.

(58) The cable connection 14 is accommodated and guided in a retractable protection tube 67, and therefore is specially protected from damage. It is ensured by the tube that the cable, as an electric signal connection, is always orderly loosely folded or disposed in a tube system without being held or squeezed.

(59) The cable to the force sensor 10 may be implemented as shown in FIGS. 4A to 4G.

(60) The expanded solution according to FIG. 7 may also change, so that the force sensor 10 is fixed onto a section of the piston rod 10 connected to the interior of the cylinder block. The arrangement has the advantage as follows: the electric connection to the force sensor 10 is in the interior of the cylinder block, and no cable has to pass through the piston.

(61) FIG. 8 shows another embodiment. The crane 1 comprises a bracket 3 and a support leg 2. The support plate 9 is arranged on the support leg 2 and comprises a measurement insertion portion 31, which sends the measured value of a support force to an analysis unit 38 to an operation cabin 40 of the crane 1 by means of an antenna 37 which is flush with and integrated into the support plate 9.

(62) Since the measured data is transmitted wirelessly by means of radio, particularly in the case of a rotatable crane structure, other electric rotation connection is not required in the region 60 where the crane is rotatably connected to the frame 44.

(63) The radio transmission system between the support legs may be particularly designed so that the signal transmission is checked bidirectionally for many times, so that the signal transmission of the transmitted signal is particularly safe.

(64) Furthermore, high accuracy can be achieved by encrypting, for example, a Hamming distance H=4. In the wireless system, each of the transmitting and receiving units has a definite address, so as to not only always associate the correct measured value with the correct support leg, but also automatically identify, by means of an appropriate apparatus, whether the corresponding correct support plate 9 is mounted on the correct support leg 2.

(65) If all the support legs use the same support plate, a programming function is set, and used to determine the association between the support leg and the corresponding bracket in the analysis apparatus. When no prescribed association occurs, the corresponding safety query can prevent/delay/limit the operation of the crane. It is also possible that the support leg is provided with a RFID chip as a support leg mark, which comprises a mark for the corresponding support leg. After arranging the support plate 9, the measurement insertion portion 31 wirelessly detects the support leg mark and registers, as the support plate of the corresponding bracket, at the analysis apparatus of the machine. The RFID chip and the apparatus for detecting same may, for example, be mounted on the spherical link 4 or the measurement insertion portion 31, as shown in FIG. 6D.

(66) Preferably, the whole system can be modified, the system is composed of the support leg plate 9 and an analyzing and warning unit 70 which may be disposed in the field of view of the operator in the operation cabin 40, and the analyzing and warning unit comprises an analysis apparatus and a radio connection system. Particularly, the support leg plate 9 comprises a special current supply apparatus composed of two energy storage devices, the energy storage devices can be charged by a charging terminal 41, and the charging terminal may also be implemented as a waterproof inductive interface. The analyzing and warning unit merely needs an on-board current, which is generally already provided in the operation cabin 40 (on-board socket).

(67) Optionally, the disposed measurement system or foot plate 9 comprises a light-emitting apparatus 39, which is displayed in an optical mode when correctly operating, arranging and protecting radio transmission, and the system is ready for operation. An optical display of the light-emitting apparatus 39 comprises light symbols, which can be distinguished by light colors or light-emitting intervals, particularly continuous lights and flash lights having different frequencies, and preferably show the different working states, e.g., particularly the ready-to-work, failure, interruption of radio contact, and the charge state of the storage device.

(68) Once the foot plate 9 is correctly mounted and/or or locked in a transport and charging notch 40 of the crane, a charging terminal 41 on the foot plate 9 is connected to a charging unit 42 on the crane. It may also be possible that the in situ recharging for the foot plate is in the insertion portion, which may be achieved particularly by a portable recharging unit, which is connected to the charging terminal of the support leg to be recharged. The waterproof and contaminant-proof connection herein, such as an inductive connection, is advantageous.

(69) FIG. 9 shows a solution, which uses a force sensor 200 to measure the support load, and the force sensor measures the pressure of a liquid in a cylinder block chamber 202 and deduces therefrom the support force applied, by a piston rod 11, to a measurement piston 201 which works together with the cylinder block chamber 202. For measuring the pressure, a pressure sensor 91 is used, which is connected to an analysis apparatus 93, and the analysis apparatus comprises an antenna 92. The measured value of the pressure or the calculated force value may be sent by the analysis apparatus 93 to the display or the analysis apparatus (70 in FIG. 8) in the operation cabin of the machine by means of radio signals. Preferably, the sensor structure form is provided with a temperature measurement apparatus (not shown), which determines the liquid temperature so as to consider the temperature when determining the support force.

(70) Preferably, the measurement apparatus may send an optical signal regarding the correct installation or regarding the forthcoming overloading or a warning flash light as a warning for collision by means of a semitransparent cover plate 33.

(71) The structure form of the support leg is different from the other embodiments merely in the structure form of the force sensor. Therefore, these implementations may also be equipped with an inductive interface or a cable connection and the force sensor 200 of such fluid dynamics.

(72) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.