EP3470362B1 - Method and device for monitoring the stability of a loading crane mounted on a vehicle - Google Patents

Description

The invention relates to a method and a device for monitoring at least one stability parameter of a loading crane mounted on a vehicle, the vehicle being supported or capable of being supported on the ground via wheels and via support elements separate from the wheels during crane operation.

The support elements are usually support legs that can be extended in the vertical direction and are mounted on a support widening that can be extended laterally in the horizontal direction. The ability to extend the support legs and the widening of the support is made possible by a telescopic construction. The vehicles relevant in connection with the invention usually have either one or two such support widenings, each with two support legs.

According to EN 12999, overload protection is required for loading cranes with a load capacity of more than 1000 kg. According to this standard, the corresponding stability test is carried out with a test load that corresponds to 125% of the specified load-bearing capacity. It is important that at least one wheel that is braked by means of a (usually manually operated) parking brake must remain on the ground. In this case, the loading crane is in a so-called partially raised state. The at least one wheel braked by means of a parking brake, which must remain on the ground, acts as an additional friction point and serves to absorb horizontal forces.

It is known that the load moment limitation for the overload protection according to EN 12999 is solved by adjusting the lifting force in the crane hydraulics. For crane work with laterally incompletely extended support elements and/or jib positions above the driver's cab, additional lifting capacity limitations must be implemented. Map-based lifting force adjustments are state-of-the-art.

With such system solutions, however, the high adjustment and testing effort is rated as disadvantageous. There is a risk of incorrect settings. Also become no payloads considered. In order to avoid these disadvantages, the effects of the crane work on the entire machine should preferably be detected by sensors.

There are solutions for truck-mounted concrete pumps that aim in this direction. The patent specification is an example in this context DE 103 49 234 A1 called. Here, to monitor the stability, the supporting forces in the support legs are determined and offset to form a stability number. However, truck-mounted concrete pumps are in a fully raised state during operation, ie none of the wheels touch the ground. The solutions used for truck-mounted concrete pumps are therefore not suitable for the loading cranes which are relevant in connection with the present invention and which must comply with EN 12999. Other approaches to monitoring the stability of a crane mounted on a vehicle are from EP 2 298 689 A2 , the EP 1 757 739 A2 and the EP 0 864 473 A2 known. EN 12999 cannot be satisfied with any of these approaches.

The object of the invention is therefore to avoid the disadvantages described above and to specify a solution for monitoring the stability of a loading crane mounted on a vehicle that is improved compared to the prior art.

According to the invention, this object is achieved by the features of the two independent claims 1 and 9 .

One of the basic ideas of the invention is that not only the contributions of the support elements, but also the contributions of the wheels to the size of at least one stability parameter are recorded and this size is compared with at least one predetermined limit value.

Depending on whether the at least one predetermined limit value is an upper or a lower critical limit, at least one warning signal is advantageously output (to the operating personnel of the crane) and/or at least a measure to Re-compliance with the limit value carried out. These include, in particular, correction movements of the boom system.

Since the stability that can be achieved with the support elements that are usually used is not the same in every part of the theoretically conceivable working space of the boom system and the support elements cannot be fully extended under certain working conditions, e.g. on cramped construction sites, it is also advantageous if a rotation angle α of the Loading crane is detected about a vertical axis and / or an extended state of the supporting elements. In this case it is possible to monitor the at least one stability parameter as a function of the angle of rotation α and/or the extended state of the support elements. The relative position of the supporting elements in relation to the vehicle is known by detecting the extended state of the supporting elements. If the support elements - as described above - are support legs that can be extended in the vertical direction and are mounted on a support extension that can be extended laterally in the horizontal direction, then the detection of the extended state of the support elements includes both the detection of the distance by which the Outrigger extension is extended, as well as the detection of the distances by which the support legs are extended.

wobei a_ges die Gesamtanzahl der Räder und Abstützelemente, a_min eine vorbestimmte Mindestanzahl an Rädern und Abstützelementen, über welche das Fahrzeug wenigstens am Untergrund abgestützt sein muss, und F _i,max die (a_min -1) größten Abstützkräfte angeben. Bei S_F handelt es sich um eine dimensionslose Größe, die folgenden Effekt hat: Angenommen, das Fahrzeug sei über zwei Vorder- und zwei Hinterräder sowie eine seitlich ausgefahrene Abstützverbreiterung mit zwei Abstützelementen am Untergrund abstützbar, d.h. es würde a_ges =6 gelten. Sei weiterhin angenommen, dass ein labiler Zustand, in dem das Fahrzeug umzukippen droht, dann vorliegt, wenn das Fahrzeug nur noch auf einem Vorder- und einem Hinterrad sowie einem Abstützelement steht, wobei sich das Vorder- und das Hinterrad sowie das Abstützelement auf der gleichen Fahrzeugseite befinden, so müsste man fordern, dass im Betriebszustand zu keiner Zeit der Grenzwert a_min =4 unterschritten wird, um nicht diesen labilen Zustand zu erreichen. Der Vorteil des Kraft-Standsicherheitsbeiwert S_F besteht nun darin, dass man mit seiner Hilfe sehr leicht die Einhaltung dieses vorgegebenen Grenzwertes überwachen kann, indem man darauf achtet, dass der Wert von S_F - nach obiger Formel berechnet - immer größer als eins ist. Im Falle des labilen Zustands, d.h. im Falle von nur noch drei Abstützpunkten, würde nämlich die Kräftesumme im Nenner den gleichen Wert annehmen, wie die Kräftesumme im Zähler, da es sich dann bei den drei größten Abstützkräften um die drei einzigen von Null verschiedenen Abstützkräfte handelt.According to the invention, the number a of wheels and supporting elements, via which the vehicle is supported on the ground, and the force stability coefficient S _F are monitored as stability parameters, with S _F being calculated from the supporting forces F _i provided via the wheels and the supporting elements. S _F is preferably calculated using the following formula: $$S_f=\frac{{\displaystyle \sum _{i=1}^{a_{\mathit{total}}}{f}_i}}{{\displaystyle \sum _{i=1}^{a_{\mathrm{at\; least}}-1}{f}_{i,\mathrm{Max}}}},$$

where a _tot is the total number of wheels and supporting elements, a _min is a predetermined minimum number of wheels and supporting elements by which the vehicle must be supported at least on the ground, and F _{i ,max} indicates the ( a _min -1) greatest supporting forces. S _F is a dimensionless quantity that has the following effect: Assuming that the vehicle can be supported on the ground via two front and two rear wheels as well as a laterally extended outrigger extension with two outrigger elements, ie _a tot =6 would apply. It is also assumed that an unstable state in which the vehicle threatens to tip over is present when the vehicle is only standing on a front and a rear wheel and a support element, with the front and rear wheel and the support element being on the same level side of the vehicle, one would have to demand that the operating condition never falls below the limit value a _min =4 in order not to reach this unstable condition. The advantage of the force stability coefficient _SF is that it can be used to monitor compliance with this specified limit value very easily by making sure that the value of _SF - calculated using the above formula - is always greater than one. In the case of the unstable state, ie in the case of only three support points, the sum of forces in the denominator would assume the same value as the sum of forces in the numerator, since the three largest supporting forces are then the only three supporting forces different from zero .

In the event that the vehicle can be supported on the ground via two front wheels and two rear wheels, in particular designed as twin wheels, as well as two laterally extendable support extensions, each with two support elements, and the angle of rotation α of the loading crane about a vertical axis and the extended state of the support elements are recorded, it is advantageous if a _min = 6 or a _min = 5 is selected depending on the angle of rotation α of the loading crane when the support extensions are fully extended at the side and a _min = 6 is selected for the support extensions that are not fully extended at the side.

In the event that the vehicle can be supported on the ground via two front wheels and two rear wheels, in particular designed as twin wheels, as well as a laterally extendable support extension with two support elements and the angle of rotation α of the loading crane about a vertical axis and the extended state of the support elements is recorded it is advantageous if a _min =6 or a _min =4 is selected with the laterally fully extended outrigger extension, depending on the angle of rotation α of the loading crane, and with the laterally not fully extended outrigger extension a _min =6.

It should be noted that by complying with the limit values for a _min mentioned in the last two sections, the EN 12999 standard mentioned at the beginning is also automatically met, provided that all wheels can be braked with a parking brake.

If the support forces F _i provided by the wheels are recorded, it makes sense to also monitor the axle loads as part of the stability monitoring, since they can be calculated very easily from the corresponding support forces F _i (by summation). The axle load is the proportion of the total mass (dead mass and mass of the load of a vehicle) that falls on one axle (axle) of this vehicle.

wobei r_ges die Gesamtanzahl der Räder, r_min eine vorbestimmte Mindestanzahl an Rädern, über welche das Fahrzeug wenigstens am Untergrund abgestützt sein muss, L_rest,_i die Restlängen der Schwingungsdämpfer bis zum Abheben der Räder, L_grenz,_i die Grenzlängen der Schwingungsdämpfer, bei denen die Räder vom Untergrund abheben, und L_rest,i,max die (r_min-1) größten Restlängen der Schwingungsdämpfer angeben. Wie im Falle des Kraft-Standsicherheitsbeiwert S_F könnte man dann im Zuge der Standsicherheitsüberwachung darauf achten, dass der Wert von S_L immer größer als eins ist.It is particularly advantageous to determine the supporting forces F _i provided by the wheels by measuring the spring deflection distances (of the wheel spring systems). To this end, it is advantageous to determine a de-springing characteristic (de-springing path as a function of the supporting force) for each of the wheels. These characteristic curves can then be used at any time to convert the measured deflection distances into support forces. The maximum possible suspension distance corresponds to the distance in which a wheel lifts off the ground and the supporting force provided by this wheel assumes the value zero. This procedure is particularly useful for vehicles that have leaf springs with a linear spring characteristic. In the case of other types of suspension, for example, for the sake of simplicity, the measured lengths L _i of the vibration dampers of the wheels could also be converted directly into a longitudinal stability coefficient S _L and the value of _SL could be monitored. _SL is preferably calculated using the following formula: $$S_L=\frac{{\displaystyle \sum _{i=1}^{{\mathrm{right}}_{\mathit{total}}}{L}_{\mathit{rest},i}}}{{\displaystyle \sum _{i=1}^{{\mathrm{right}}_{\mathrm{at\; least}}-1}{L}_{\mathit{rest},i,\mathrm{Max}}}},\mathrm{With}{L}_{\mathit{rest},i}=L_{\mathit{limit},i}-L_i,$$

where r _tot is the total number of wheels, r _min a predetermined minimum number of wheels by which the vehicle must be supported at least on the ground, L _rest , _i the remaining lengths of the vibration dampers until the wheels are lifted, L _limit , _i the limit lengths of the vibration dampers, where the wheels lift off the ground, and L _rest,i,max the ( r _min - 1) greatest residual lengths of the vibration dampers specify. As in the case of the force-stability coefficient S _F , one could then make sure in the course of stability monitoring that the value of _SL is always greater than one.

wobei a_ges wiederum die Gesamtanzahl der Räder und Abstützelemente angibt.A further advantageous exemplary embodiment consists in the fact that the extended state of the supporting elements is detected and, based on this, the possible tipping edges K _j of the vehicle are calculated during crane operation. If one also calculates the distances l _i,Kj of the wheels and support elements to the tipping edges K _j and at the same time records the rotation angle α of the loading crane around a vertical axis and the support forces F _i provided by the wheels and the support elements, then it is possible to monitor the residual torque M _rest,Kα as a stability parameter, depending on the rotation angle α of the loading crane in relation to the currently relevant tipping edge K _α , where M _rest,Kα can be calculated using the following formula: $$M_{\mathit{rest},\mathit{K\alpha }}={\displaystyle \sum _{i=1}^{a_{\mathit{total}}}{f}_i\cdot l_{\mathit{iK\alpha }}},$$

where _a tot indicates the total number of wheels and support elements.

Protection is also sought for a device for monitoring at least one stability parameter of a loading crane mounted on a vehicle, the vehicle being able to be supported on the ground during crane operation via wheels and via support elements separate from the wheels according to claim 9. The at least one stability parameter is again - exactly the same as described in connection with the method according to the invention - by the number a of the wheels and supporting elements, over which the vehicle on Ground is supported and the force-stability coefficient S _F It can also be the residual torque M _rest,Kα as a function of the rotation angle α of the loading crane in relation to the momentarily relevant tipping edge K _α .

Advantageously, the control and regulation unit can generate at least one warning signal and/or control at least one measure for maintaining the at least one predetermined limit value when the at least one predetermined limit value is exceeded or not reached. The warning signal can be generated by the control and regulation unit, e.g. in the form of an electrical pulse sequence, and then converted into an optical and/or acoustic signal by means of warning lights and/or loudspeakers. The at least one measure for maintaining the at least one predetermined limit value again can be stored, for example, as a programmed course of action in the control and regulation unit. In the simplest case, the course of action is a stopping process that stops the crane operation.

It is also advantageous if the device has a rotation angle measuring device for detecting a rotation angle α of the loading crane about a vertical axis and/or an extended status measuring device for detecting an extended status of the support elements, the measurement signals of the rotational angle and/or the extended status Measuring device (eg via appropriate signal lines or by wireless transmission) of the control and regulation unit can be fed. In the event that the support elements are support legs that are mounted on a laterally extendable support extension and that all non-variable parameters (such as the installation position of the support extension on the vehicle frame) are known and stored in the control and regulation unit , in order to determine the position of the support elements relative to the vehicle, it is only necessary to use the extended state measuring device to record the extended lengths of the support widening and the support legs.

In the event that the support elements are arranged on at least one laterally extendable support extension and the loading crane rests on a crane base which is connected to the at least one support extension, it is advantageous to use the support element measuring devices in the support elements and/or to be arranged at the connection of the support elements with the support widening and/or at the connection of the support widening with the crane base.

In a preferred embodiment, the wheel and support element measuring devices can detect the support forces F _i provided via the wheels and the support elements. In the case of the supporting forces F _i provided by the supporting elements, this is possible, for example, by the supporting element measuring devices being designed as load cells. In the case of the wheels, the measurement of the supporting forces F _i can be carried out, for example, by measuring the despringing distances (of the wheel spring systems) or the lengths L _i of the vibration dampers (eg using cable length sensors) or by measuring the internal tire pressures. It is also conceivable to measure the wheel force using strain gauges near the ends of the axle. If the support forces F _i provided via the wheels are recorded, then it makes sense (as already described above) to also monitor the axle loads as part of the stability monitoring—with the aid of the control and regulation unit—because they are very simple can be calculated from the corresponding support forces (by summation).

Further exemplary embodiments are characterized in that (when the position of the supporting elements relative to the vehicle is known) the tilting edges _Kj of the vehicle during crane operation and, in addition, the distances l _i,Kj of the wheels and supporting elements from the tilting edges K _j are computable. Under this condition, the residual stability torque M _rest,Kα can then be monitored (as described further above) as a stability parameter.

Fig. 1

eine schematische Darstellung eines Ausführungsbeispiels eines Fahrzeugs, auf dem ein Ladekran montiert ist und das für die vorliegende Erfindung relevant ist,

Fig. 2

ein Modell des in Fig. 1 dargestellten Fahrzeugs, in dem einige der für die Standsicherheitsüberwachung relevanten Parameter eingezeichnet sind,

Fig. 3a, 3b, 4a, 4b

Grenzwertdarstellungen für die Mindestanzahl an Rädern und Abstützelementen, über welche das Fahrzeug in unterschiedlichen Ausführungsformen wenigstens am Untergrund abgestützt sein muss, in Abhängigkeit von dem Drehwinkel α des Ladekrans und dem Ausfahrzustand der Abstützelemente,

Fig. 5

einen beispielhaften Verlauf des Kraft-Standsicherheitsbeiwerts SF in Abhängigkeit von dem Drehwinkel α des Ladekrans und

Fig. 6

eine schematische Darstellung eines möglichen Schwingungsdämpfers eines Rads.

Further details and advantages of the present invention are explained in more detail on the basis of the description of the figures with reference to the exemplary embodiments illustrated in the drawings. It shows:

1

a schematic representation of an embodiment of a vehicle on which a loading crane is mounted and which is relevant to the present invention,

2

a model of the in 1 vehicle shown, in which some of the parameters relevant for the stability monitoring are marked,

Figures 3a, 3b, 4a, 4b

Representations of limit values for the minimum number of wheels and supporting elements, via which the vehicle must be supported at least on the ground in different embodiments, depending on the rotation angle α of the loading crane and the extended state of the supporting elements,

figure 5

an exemplary course of the force stability coefficient SF as a function of the rotation angle α of the loading crane and

6

a schematic representation of a possible vibration damper of a wheel.

In the 1 one of the examples of a vehicle 1 is shown schematically, on which a loading crane 2 is mounted and whose stability can be monitored using the method according to the invention or the device according to the invention. In this case, the vehicle 1 can be supported on the ground via two front wheels 3a and four rear wheels 3b designed as twin wheels, as well as a laterally extendable support widening 5 with two support elements 4 . One of the axles 6 of the vehicle 1, part of the vehicle frame 9, a control and regulation unit 7 and the crane base 8 of the loading crane 2 can also be seen. since these are partially integrated into certain vehicle components--such as, for example, in the case of the supporting element measuring devices in the supporting feet 4--or are covered by other vehicle components.

the 2 shows a model of the in 1 illustrated vehicle 1 in plan view. In this model, the support points on the ground (black and white circles), the position of the crane base 8, which at the same time also defines the intersection of the vertical axis around which the loading crane 2 can be rotated, with the horizontal vehicle plane, are one of the in this state possible tipping edges K _α and the distances l _i , _Kα of the support points (wheels 3a and 3b and support elements 4) to the Tilting edges K _α located. The model also includes a definition of the angle of rotation α of the loading crane 2 about the vertical axis. It should be noted that the wheels 3a and 3b are of course not support points but support surfaces. In a first approximation, however, support points were assumed here.

The Figures 3a, 3b, 4a and 4b Preferred limit values for the minimum number of wheels 3a and 3b and supporting elements 4, via which the vehicle 1 must be supported at least on the ground in different embodiments, are shown as a function of the rotation angle α of the loading crane 2 and the extended state of the supporting elements 4. The reference numbers are representative of this group of figures only in the Figure 3a specified. the Figures 3a and 3b refer to the case in which the vehicle 1 can be supported on the ground at most via two front wheels 3a and two rear wheels 3b designed as twin wheels and two laterally extendable support widenings 5 each with two support elements 4 . In this case it is advantageous if, with the laterally fully extended outrigger extensions 5 ( Figure 3b ) with a rotation angle α of the loading crane 2 between approx. 225° and 315° a _min =6 or a _min =5 and with laterally not fully extended outriggers 5 ( Figure 3a ) always a _min =6 is chosen to ensure the stability of the vehicle 1 in crane operation. If, on the other hand, the vehicle has only one laterally extendable support extension 5 with two support elements 4, it is advantageous, with the laterally fully extended support extensions 5 ( Figure 4b ) with a rotation angle α of the loading crane 2 between approx. 225° and 315° a _min =6 or a _min =4 and with laterally not fully extended outriggers 5 ( Figure 4a ) to choose a _min =6.

In the figure 5 an exemplary course of the force stability coefficient S _F as a function of the rotation angle α of the loading crane 2 is shown. This course results approximately for the in Figure 3b depicted situation. It can be seen very clearly that the value of S _F assumes an absolute minimum between approx. 225° and 315°. Here the loading crane 2 or the boom system is located above the driver's cab. To ensure stability, it is therefore advantageous to require a _min =6 for this angular range.

6 shows a schematic representation of a possible vibration damper 10 of the wheels 3a and 3b. The position of the vibration damper 10 at which the wheel would lift off the ground is shown in dashed lines. Furthermore, the values L _i and L _limit , _i relevant for the calculation of the length stability coefficient S _L are shown.

Claims (15)

1. A method for monitoring at least one stability parameter of a loading crane (2) mounted on a vehicle (1) by means of a device, wherein during crane operation the vehicle (1) is supported on the ground by means of wheels (3a, 3b) and by means of support elements (4) separate from the wheels (3a, 3b), characterized in that both contributions of the wheels (3a, 3b) and contributions of the support elements (4) to a magnitude of the stability parameter are detected and said magnitude is compared to at least one predetermined limit value, wherein the device comprises wheel and support element measuring devices, by which both contributions of the wheels (3a, 3b) and contributions of the support elements (4) to the magnitude of the at least one stability parameter can be detected, wherein the device comprises a control and regulating unit (7), to which measuring signals of the wheel and support element measuring devices can be fed, wherein a magnitude of the at least one stability parameter can be detected and can be compared to at least one predetermined limit value by the control and regulating unit (7), and in that a number (a) of the wheels (3a, 3b) and support elements (4), by means of which the vehicle (1) is supported on the ground, is monitored as stability parameter, and in that a force-stability coefficient (S_F) is monitored as stability parameter, wherein the force-stability coefficient (S_F) is calculated from support forces (F_i ) provided by means of the wheels (3a, 3b) and the support elements (4), wherein the force stability coefficient (S_F) is calculated in accordance with the following formula: $$S_F=\frac{{\displaystyle \sum _{i=1}^{a_{\mathit{ges}}}{F}_i}}{{\displaystyle \sum _{i=1}^{a_{\min }-1}{F}_{i,\max }}},$$

   

   wherein (a_ges) specifies a total number of the wheels (3a, 3b) and support elements (4), (a_min) specifies a predetermined minimum number of wheels (3a, 3b) and support elements (4), by means of which the vehicle (1) must be supported at least on the ground, and (F_i,max) specifies the (a_min-1) greatest support forces.
2. The method as set forth in claim 1, characterized in that

   - when said magnitude exceeds or falls below the at least one predetermined limit value, at least one warning signal is output and/or at least one measure for return to compliance with the at least one predetermined limit value is implemented and/or

   - a rotational angle (a) of the loading crane (2) about a vertical axis and/or an extension condition of the support elements (4) is detected, wherein preferably the at least one stability parameter is monitored in dependence on the rotational angle (a) of the loading crane (2) and/or the extension condition of the support elements (4).
3. The method as set forth in claim 1 or 2, wherein the wheels (3a, 3b) of the vehicle (1) are arranged on axles (6), characterized in that axle loads are monitored, wherein the axle loads are calculated from the support forces (F_i ) provided by means of the wheels (3a, 3b).
4. The method as set forth in one of the claims 1 through 3, characterized in that the support forces (F_i) provided by means of the wheels (3a, 3b) are detected by measurement of spring relief travel.
5. The method as set forth in one of the claims 1 through 4, characterized in that lengths (L_i) of vibration dampers (10) of the wheels (3a, 3b) are detected and that a length-stability coefficient (S_L) is monitored, wherein the length-stability coefficient (S_L) is calculated from the detected lengths (L_i), and wherein preferably the length-stability coefficient (S_L) is calculated in accordance with the following formula: $$S_L=\frac{{\displaystyle \sum _{i=1}^{r_{\mathit{ges}}}{L}_{\mathit{rest},i}}}{{\displaystyle \sum _{i=1}^{r_{\min }-1}{L}_{\mathit{rest},i,\max }}},\mathrm{with}{L}_{\mathit{rest},i}=L_{\mathit{grenz},i}-L_i,$$

   

   wherein (r_ges ) specifies a total number of the wheels (3a, 3b), (r_min) specifies a predetermined minimum number of wheels (3a, 3b), by means of which the vehicle (1) must be supported at least on the ground, (L_rest,i) specifies remaining lengths of the vibration dampers (10) until the wheels (3a, 3b) lift off, (L_grenz,i) specifies limit lengths of the vibration dampers (10), at which the wheels (3a, 3b) lift off the ground, and (L_rest,i,max) specifies the (r_min-1) greatest remaining lengths of the oscillation dampers (10).
6. The method as set forth in claims 1 through 5, characterized in that during crane operation a condition S_F >1 and/or a condition S_L>1 is met.
7. The method as set forth in one of the claims 1 through 6, characterized in that tipping lines (K_j) of the vehicle (1) are calculated during crane operation and that preferably distances (l_i,Kj ) of the wheels (3a, 3b) and the support elements (4) relative to the tipping lines (K_j) are calculated.
8. The method as set forth in claim 7, wherein the rotational angle (a) of the loading crane (2) about a vertical axis is detected and the support forces (F_i) provided by means of the wheels (3a, 3b) and the support elements (4) are detected, characterized in that in dependence on the rotational angle (a) of the loading crane (2) in relation to a current tipping line (K_α) as stability parameter a remaining stability moment (M_rest,Kα) is monitored, wherein the remaining stability moment (M_rest,Kα) is calculated in accordance with the following formula: $$M_{\mathit{rest},\mathit{K\alpha }}={\displaystyle \sum _{i=1}^{a_{\mathit{ges}}}{F}_i\cdot l_{\mathit{iK\alpha }}}$$

   

   wherein (a_ges) specifies the total number of wheels (3a, 3b) and support elements (4).
9. A device for monitoring at least one stability parameter of a loading crane (2) mounted on a vehicle (1), wherein during crane operation the vehicle (1) can be supported on the ground by means of wheels (3a, 3b) and at the same time by means of support elements (4) separate from the wheels (3a, 3b), characterized in that the device has:

   - wheel and support element measuring devices, by which both contributions of the wheels (3a, 3b) and contributions of the support elements (4) to the magnitude of the at least one stability parameter can be detected, and

   - a control and regulating unit (7), to which measuring signals of the wheel and support element measuring devices can be fed,

   wherein a magnitude of the at least one stability parameter can be detected and can be compared to at least one predetermined limit value by the control and regulating unit (7), wherein the device is configured for performing a method as set forth in one of claims 1 through 8.
10. The device as set forth in claim 9, characterized in that

    - when the magnitude exceeds or falls below the at least one predetermined limit value, at least one warning signal can be generated and/or at least one measure for returning to compliance of the at least one predetermined limit value is controllable by the control and regulating unit (7), and/or

    - the device has a rotational angle measuring device for detecting a rotational angle (a) of the loading crane (2) about a vertical axis and/or an extension condition measuring device for detecting an extension condition of the support elements (4), wherein measuring signals of the rotational angle and/or extension condition measuring device can be fed to the control and regulating unit (7).
11. The device as set forth in claim 9 or 10, wherein the support elements (4) are arranged on at least one laterally extendable support extension (5) and the loading crane (2) rests on a crane base (8) connected to the at least one support extension (5), characterized in that the support element measuring devices are arranged in the support elements (4) and/or at a connection of the support elements (4) to the support extension (5) and/or at a connection of the support extension (5) to the crane base (8).
12. The device as set forth in one of claims 9 through 11, characterized in that the support forces (F_i) provided by means of the wheels (3a, 3b) and the support elements (4) can be detected by the wheel and support element measuring devices, wherein preferably the support forces (F_i) provided by means of the wheels (3a, 3b) can be detected by means of a measurement of spring relief travels.
13. The device as set forth in one of the claims 9 through 12, characterized in that lengths (L_i) of vibration dampers (10) of the wheels (3a, 3b) can be detected by the wheel measuring devices.
14. The device as set forth in one of the claims 9 through 13, characterized in that tipping lines (K_j) of the vehicle (1) can be calculated during crane operation by the control and regulating unit (7), and that preferably distances (l_i,Kj) of the wheels (3a, 3b) and support elements (4) relative to the tipping lines (K_j) can be calculated by the control and regulating unit (7).
15. A vehicle (1) on which a loading crane (2) is mounted, and which has wheels (3a, 3b) and extendable support elements (4), characterized in that the vehicle (1) has a device as set forth in one of the claims 9 through 14.

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