Mobile crane, mobile crane dolly and mobile crane system

Abstract

A mobile crane has an undercarriage, a superstructure arranged on the undercarriage, a slewing gear by which the superstructure may be rotated relative to the undercarriage, a slewing gear brake that acts on the slewing gear to brake a rotation of the superstructure, and a jib mounted on the superstructure as to be adjustable in luffing angle and/or in length. The mobile crane additionally contains a dolly coupling arranged on the jib and by which the jib is coupled to a mobile crane dolly during dolly travel with the superstructure in an extended position. The mobile crane further has a sensor interface for connecting a dolly coupling sensor, and a controller that is adapted to ascertain during dolly travel, in dependence on a signal received from the dolly coupling sensor, whether the jib rests on the mobile crane doll, and to activate the slewing gear brake if it does not.

Claims

1. A mobile crane, comprising: one undercarriage; a superstructure disposed on said undercarriage; a slewing gear, by means of said slewing gear said superstructure may be rotated relative to said undercarriage; a slewing gear brake acting on said slewing gear to brake a rotation of said superstructure; a jib mounted on said superstructure so as to be adjustable at a luffing angle and/or in length; a dolly coupling disposed on said jib and by means of said dolly coupling said jib is coupled to a mobile crane dolly during dolly travel with said superstructure in an extended position; a dolly coupling sensor; a sensor interface connecting to said dolly coupling sensor; and a controller configured to ascertain, during the dolly travel, whether said jib is resting on the mobile crane dolly, as a function of a signal relating to said dolly coupling sensor, and to activate said slewing gear brake if said jib is not resting on the mobile crane dolly.

2. The mobile crane according to claim 1, wherein said controller is configured to ascertain, as a function of the signal, whether the mobile crane dolly is freely suspended from said jib, or said jib has been detached from the mobile crane dolly.

3. The mobile crane according to claim 1, wherein said controller is configured to activate said slewing gear brake so as to brake to a different extent in dependence on a travel speed and/or cornering speed of the mobile crane.

4. The mobile crane according to claim 1, further comprising only one drive motor disposed on said undercarriage, both for travel operation and for crane operation; further comprising a hydraulic line leading to said slewing gear brake; further comprising at least one hydraulic valve; wherein said slewing gear brake is configured as a hydraulic brake; and wherein said controller is adapted to release said hydraulic line in order to activate said slewing gear brake by actuating said at least one hydraulic valve.

5. The mobile crane according to claim 4, wherein said hydraulic line leading to said slewing gear brake is disposed on said superstructure.

6. The mobile crane according to claim 1, further comprising: a drive motor exclusively for travel operation; a crane operating motor exclusively for crane operation, wherein said slewing gear brake is supplied with operating energy during crane operation by means of said crane operating motor; and an energy store for said slewing gear brake when said crane operating motor is switched off.

7. The mobile crane according to claim 1, further comprising a further sensor for detecting a block position of said jib, wherein said controller is configured to additionally take into account whether said jib is in the block position before activating said slewing gear brake.

8. The mobile crane according to claim 1, wherein said dolly coupling sensor is disposed on said jib in a region of said dolly coupling and is connected to said controller via said sensor interface.

9. The mobile crane according to claim 1, wherein said dolly coupling sensor is configured as a contact switch or a proximity switch.

10. The mobile crane according to claim 1, wherein said dolly coupling sensor is a force sensor.

11. A mobile crane system, comprising: a mobile crane according to claim 1; and a mobile crane dolly having a chassis, a jib coupling and a jib bracket on which said jib coupling is disposed for connecting to said dolly coupling of said jib of said mobile crane.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a diagrammatic, side view of a mobile crane during dolly travel according to the invention;

(2) FIG. 2 is a sectional, partial view, taken along the line II-II shown in FIG. 1, of a jib of the mobile crane and the mobile crane dolly in a proper supporting position;

(3) FIG. 3 is a sectional, partial view as in FIG. 2 of the jib in a position that has been lifted from the mobile crane dolly;

(4) FIGS. 4 and 5 are respective views as in FIG. 2, each showing another exemplary embodiment of the mobile crane; and

(5) FIGS. 6 and 7 are view as in FIG. 2, respectively, of another exemplary embodiment of the mobile crane and the mobile crane dolly.

DETAILED DESCRIPTION OF THE INVENTION

(6) Components and magnitudes that correspond to each other are always assigned the same reference signs in all drawings.

(7) Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a schematic view of a mobile crane 1. The mobile crane 1 has an undercarriage 2 with a cockpit 4, a drive motor arranged under a cover 6, a vehicle frame 8 and a plurality of driving axles 10 on which wheels 12 are arranged. In addition, the mobile crane 1 has a superstructure 14 that has a mount 16 for a jib 22 that may be luffed around a “luffing axis” 18, i.e. slewed in the height direction 20. The jib 22 is also configure to be adjustable in length—telescopic. The superstructure 14 may also be rotated or pivoted about an axis of rotation running in the height direction 20 (not shown in greater detail), relative to the undercarriage 2, by a slewing gear 24 (only schematically indicated). The mobile crane 1 also has a slewing gear brake 26, which acts on the slewing gear 24 to brake a rotation of the superstructure 14.

(8) FIG. 1 shows the mobile crane 1 during a what is referred to as dolly travel. For this purpose, the superstructure 14 is pivoted to a 180-degree position, and the jib 22 thus points to the rear. In addition, the jib 22 is mounted on a mobile crane dolly (hereinafter referred to as “dolly 30”). The dolly 30 has a chassis 32 and a jib bracket 34. A jib coupling 36 for mechanically connecting the dolly 30 with the jib 22, specifically a dolly coupling 38 of the jib 22 (see FIG. 4), is arranged in turn on the jib bracket 34. Such dolly travel is usually necessary when the axle load of the mobile crane 1 exceeds a permitted axle load of the road to be driven on. Because the jib 22 rests on the dolly 30 during dolly travel, the weight of the superstructure 14 in particular is distributed over a plurality of axles and thus the axle load of the mobile crane 1 is reduced.

(9) For example, if the mobile crane 1 passes over a bump and/or the dolly 30 traverses a dip, the jib 22 may shift into a lower block position in which the jib 22 cannot move any further toward the ground 40 (see FIG. 1), because it rests against a mechanical stop. If the height difference between the mobile crane 1 and the dolly 30 is greater than the distance that the jib 22 may travel to the lower block position due to the bump or dip, the dolly 30 may lose contact with the ground 40 when suspended from the jib 22. In this case, the superstructure 14 may rotate freely, because the power supply for the slewing gear 24 and slewing gear brake 26 is inactive, enabling free cornering with the dolly 30, which forms a kind of trailer. In addition, the slewing gear 24 and slewing gear brake 26 are always disconnected from the power supply during road travel of the mobile crane 1, because the jib 22 is usually arranged mechanically secured in a storage position.

(10) To prevent the dolly 30 of the superstructure 14 from turning out at right angles to the undercarriage 2 and thus to the direction of travel—for example during a curve—during dolly travel when the dolly is freely suspended from the jib 22, which poses a high risk of accident, the mobile crane 1 has a dolly coupling sensor 44. The sensor is connected to a control unit 46 of mobile crane 1 via an interface that is not shown in greater detail. The control unit 46 is adapted to ascertain whether the jib 22 is resting on the jib bracket 34 of the dolly 30 by means of a (sensor) signal S.sub.D transmitted from the dolly coupling sensor 44. In addition, the control unit 46 is adapted to activate the slewing gear brake 26, specifically for braking the slewing gear 24 and thus at least for slowing down or blocking a superstructure rotation, in the event that the jib 22 is not resting (anymore) on the jib bracket 34.

(11) In the exemplary embodiment shown, for both travel operation and crane operation, the mobile crane 1 has only the drive motor that is mounted on the undercarriage 2. In other words, the drive motor likewise supplies energy, specifically hydraulic pressure, to the slewing gear 24, the slewing gear brake 26, a luffing cylinder not shown in greater detail (for luffing the jib 22) as well as a cable winch for pulling in or paying out the crane cable 48. However, these drive elements are depressurized (i.e. inactive) during travel operation and thus are also inactive during dolly travel. To activate the slewing gear brake 26 during travel operation, the mobile crane 1 has a valve that the control unit 46 (not shown in greater detail) may actuate, by means of which hydraulic pressure may also be applied to the slewing gear brake 26 during travel operation. If the control unit 46 detects by the signal S.sub.D that the dolly 30 is hanging from the jib 22, the control unit 46 opens this valve, so that the slewing gear brake 26 is activated and thus blocks or brakes a rotation of the superstructure 14.

(12) In the exemplary embodiment shown in FIGS. 1-3, the dolly coupling sensor 44 is a proximity switch formed by a contactless proximity sensor installed in the jib 22. The dolly coupling sensor 44 and control unit 46 are configured in such a way that when the jib 22 is in the proper position on the dolly 30 (also referred to as the proper contact position), the signal S.sub.D exceeds a predetermined switching value and thus an “active switching state” is indicated.

(13) In order to provide “switching play” for the dolly coupling sensor 44, a range of play is configured between the dolly coupling 38 and the jib coupling 36, specifically between a safety pin 50 and the jib 22, in such a way that in the event that the dolly 30 is hanging from the jib 22, a distance between the dolly 30 and the jib 22 is increased. In this case, the value of the signal S.sub.D changes to in such a way that it specifically falls below the predetermined switching value. The signal S.sub.D thus no longer indicates the active switching state. In this case, the control unit 46 activates the slewing gear brake 26.

(14) FIG. 4 shows an alternative exemplary embodiment of the arrangement of the dolly coupling sensor 44 in the form of a proximity switch (alternatively a contact switch). In this case, the dolly coupling sensor 44 is arranged in the area of the dolly coupling 38, and specifically is arranged in such a way that the predetermined switching value is exceeded when the dolly 30 is hanging from the jib 22. For this purpose, the dolly coupling sensor 44 is arranged on the underside of a receptacle 52 in the dolly coupling 38 for the safety bolt 50. If the dolly 30 is hanging from the jib 22, the safety bolt 50 in this receptacle 52 is displaced toward the underside and “triggers” the dolly coupling sensor 44.

(15) FIG. 5 shows another alternative exemplary embodiment. Here, the dolly coupling sensor 44 is a force sensor. In this case, the receptacle 52 may be designed free of play—at least approximately. In this case, the control unit 46 is adapted to ascertain from the signal S.sub.D the amount of the force with which the jib 22, specifically the dolly coupling 38, is loaded. If this force value exceeds a predetermined threshold value or if this force value corresponds to the weight force of the dolly 30, the control unit 46 activates the slewing gear brake 26 for braking.

(16) FIGS. 6 and 7 show two more alternative exemplary embodiments. The dolly coupling sensor 44 in this case is not a part of the mobile crane 1 but instead is part of the dolly 30. The dolly coupling sensor 44 is connected to the control unit 46 by means of the signal interface described above, which is not shown in greater detail. By way of example, the signal interface is a plug connection to the wired connection. Alternatively, the signal interface is designed as a wireless interface.

(17) In FIG. 6, the dolly coupling sensor is designed as a proximity switch or contact switch, the function of which corresponds to the exemplary embodiment shown in FIGS. 1-3. FIG. 6 shows the state in which the dolly 30 hangs freely (without ground contact) from the jib 20.

(18) In FIG. 7 the dolly coupling sensor 44 is configured as a force sensor and is adapted to ascertain the amount of force acting on the jib coupling 36. Otherwise, the function corresponds to the exemplary embodiment shown in FIG. 5.

(19) In an exemplary embodiment not shown in greater detail, the mobile crane 1 has an additional sensor that indicates the lower block position of the jib 22. In this case, the control unit 46 is adapted to use the signal S.sub.D from the dolly coupling sensor 44 and the jib 22 block position sensor described above, to ascertain whether the jib 22 is resting on the dolly 30. This may increase reliability.

(20) The subject matter of the invention is not limited to the exemplary embodiments described above. Rather, a skilled person may derive additional embodiments of the invention from the claims and the above description. In particular, the individual features of the invention and its variant configurations that have been described with reference to the various exemplary embodiments may also be combined in other ways.

LIST OF REFERENCE SIGNS

(21) 1 Mobile crane 2 Undercarriage 4 Cockpit 6 Cover 8 Vehicle frame 10 Driving axle 12 Wheel 14 Superstructure 16 Mount 18 Tilt axis 20 Height direction 22 Jib 24 Slewing gear 26 Slewing gear brake 30 Dolly 32 Chassis 34 Jib bracket 36 Jib coupling 38 Dolly coupling 40 Ground 44 Dolly coupling sensor 46 Control unit 48 Crane rope 50 Safety bolts 52 Receptacle S.sub.D Signal