EP2331446A1

EP2331446A1 - Gantry crane

Info

Publication number: EP2331446A1
Application number: EP09740248A
Authority: EP
Inventors: Peter Lerchenmüller
Original assignee: Hans Kuenz GmbH
Current assignee: HANZ KUENZ GMBH
Priority date: 2008-10-09
Filing date: 2009-09-08
Publication date: 2011-06-15
Anticipated expiration: 2029-09-08
Also published as: WO2010040157A1; US20110180506A1; AT507333A1; EP2331446B1; AT507333B1; PL2331446T3

Abstract

On a gantry crane comprising a carriage which is used to displace the gantry crane along a straight track formed by parallel rails (1) and which comprises a plurality of carriage groups (11), which each have at least two wheels (12) mounted rotatably on a subframe (16) and disposed at a distance from each other in the longitudinal direction of the respective rail (1) and of which at least two, preferably all, are connected rotatably about a vertical axis (23) to an end carriage (10) of the gantry crane, at least one measuring device (26) is present for at least one carriage group (11) connected rotatably about the vertical axis (23) to the associated end carriage (10), wherein said measuring device can detect the track position of at least one of the wheels (12) of the carriage group (11) with respect to the rail (1) on which it rolls and can output a track position (a) that corresponds to the respective track position. An actuator (28) acting between the carriage group (11) and the associated end carriage (10) is controlled by a regulating device (48, 49), to which the track position value (a) output by the measuring device (26) is fed. The carriage group (11) can be subjected by the actuator (28) with a torque (m) determined by said control about the vertical axis (23).

Description

gantry crane

The invention relates to a gantry crane, which has a serving for moving the gantry crane along a rectilinear, formed by parallel rails roadway, which comprises a plurality of chassis groups, each having at least two spaced apart in the longitudinal direction of the respective rail on a subframe rotatably mounted wheels and of which at least two, preferably all, are rotatably connected to a head support of the gantry about a vertical axis, wherein for at least one of the associated head carrier about the vertical axis rotatably connected chassis group, preferably for all with the respectively associated head support to the respective vertical Axle rotatably connected chassis groups, at least one measuring device from which the tracking of at least one of the wheels of the chassis group with respect to the rail on which it rolls, can be detected and a respective track position corresponding track position value can be output ,

Trolleys of rail cranes movable on rails comprise landing gear groups for a respective leg of the gantry crane. The chassis groups have wheels for moving the crane, some or all of which are equipped with drive motors.

Another genre than the gantry cranes are the overhead cranes (= overhead cranes or

"Overhead cranes"), which have elevated lanes and in which the support structure and the chassis of the crane are in one plane.

In a conventional embodiment of a gantry crane, the individual chassis groups are connected to a head support of the steel structure of the crane with only one degree of freedom, namely a pivotability about a horizontal axis transverse to the rails. In practice, this results in more or less large inclinations of the axes with respect to their exact alignments perpendicular to the longitudinal extent of the rail, due to tolerances and deformations of the components. The resulting horizontal forces and their unfavorable distribution on the individual wheels lead to suspension restrictions and thus to an increased wear of the wheel flanges of the wheels and also the wheel treads and the rails. To reduce wear, constructions are known in which an additional degree of freedom is provided for the articulation of the chassis group on the head support, namely a rotation about a vertical axis. Such a gantry crane is known from EP 1 911 716 A2. For a pivotable connection of a respective chassis group on the associated head support both about a horizontal, transverse to the rails axis and about a vertical axis are a central joint, which is designed as a floating bearing in the vertical direction, and with respect to the direction perpendicular to the longitudinal extent of a each rail on opposite sides of the central joint arranged handlebars, which are each connected on the one hand with the landing gear group, on the other hand with the head support by superimposed joints, of which both compressive and tensile forces are transferable. The central joint may in particular be designed in the manner of a ball joint.

In addition, other constructions for the pivotable connection of a chassis group to the head carrier are known both about a horizontal axis lying transversely to the rails and about a vertical axis. For example, such constructions envisage the use of a ball or roller slewing ring, a sliding bearing with an additional counter support, an axial ball bearing with additional counter bearing or a central joint in the form of a spherical thrust bearing with tie rods arranged on both sides of the central joint between head carrier and chassis group. These constructions are sometimes quite expensive.

Despite the rotatable about the vertical axis connection of the chassis groups with the associated headrests, it comes, especially in cranes with long driveways, usually to the concerns of the wheel flanges of the wheels on the rail flanks, depending on the flange clearance and the axle deviations of the wheels. In the best case, which is practically unavailable, the chassis group drives a sinusoidal curve, whereby the wheel flanges of the wheels start alternately with relatively low forces on both rail flanks. In practice, due to deviations of the axles of the wheels of a chassis group from their exact parallel orientations to each other, which are referred to as "inclinations of the wheels", to horizontal forces acting in the sense of a rotation of the landing gear group about the vertical axis to a tarnishing of one of the two wheel flanges, in particular of the front wheel of a respective chassis group for a respective direction of travel, to the respective rail flank and thus to an increased wear of this wheel flange. come flanges come. The renovation of worn flanges in practice leads to significant costs in the operation of gantry cranes.

An increase in service life can be achieved by means of tracking wheels which are rotatable about vertical axes and by means of which the wheels are guided in relation to the rails. However, original equipment costs a great deal and, due to roller wear, there are also considerable consequential costs and such equipment is not always possible, e.g. at floor level installed rails.

Also known is an attachment of lubricating pins to reduce the friction between the flanges and the rail edges. However, the effectiveness is not very high and the rapid wear of the lubricating pins leads to a high maintenance.

In addition to "straight-ahead chassis" for moving a gantry crane along rails laid in a straight line, non-generic corner bogies are also known, which serve for moving a crane along a roadway which has at least one bend.

In chassis of overhead cranes, a synchronization device is known, in which a preceding wheel is scanned and the drives associated with the two rails are controlled in such a way that the desired alignment of the crane undercarriage with the rails is achieved. Such a synchronization device is made possible by the usually rigid design of overhead cranes.

From DE 25 28 293 A1, a gantry crane of the type mentioned is apparent from one of the described embodiments, wherein the speed of the motors of the two rails associated drives are regulated for the traction control.

The object of the invention is to achieve a substantial cost reduction over the service life of the gantry crane. According to the invention, this is achieved by a gantry crane having the features of claim 1.

In a gantry crane according to the invention, an actuator is provided for at least one of the associated head carrier rotatably connected to the vertical axis group, of which the chassis group with a torque which is determined by the control of the actuator by means of a control device to the vertical Axis can be acted upon. It is therefore a force-controlled actuator, which causes a torque about the vertical axis about which the chassis group is rotatable, according to its force generated by it. Preferably, at least one force-controlled actuator acts on each of the chassis groups, which are rotatable about a vertical axis relative to the associated head carrier.

To control the actuator by the control device of the control device is supplied by a measuring device, a tracking value. In the context of the present document, the track position is the position of the wheel relative to the rail with respect to the direction at right angles to the longitudinal extent of the rail. This tracking is detected by the measuring device for at least one of the respective direction of travel in front of the vertical axis about which the chassis group relative to the head carrier is rotatable, lying wheels of this suspension group, which acts on the actuator, and one of the respective instantaneous tracking corresponding measured value (= tracking value) is output by the measuring device to the control device as a controlled variable. Depending on the track position value, which is supplied to the control device, this is set by this the moment-loading of the force acting on this chassis group actuator. The force acting on the vertical axis, caused by the actuator torque thus represents the manipulated variable of the control loop. Preferably, the track of the measuring device for the front wheel for the respective direction of travel is detected.

By applying torque according to the invention, the wheel flanges of the wheels can be kept at a distance from the rail flanks, completely or at least substantially (for example over more than 90% of the driving distance). As a result, a substantial reduction in wear is achieved, and in a very simple manner without carrying out a positive control that compulsorily sets the rotational position of a chassis group relative to the vertical axis. The torque application of a respective chassis group is effected by a control, wherein the actual value of the tracking of the detected by the measuring device for the present direction of travel wheel is used as a controlled variable.

In an advantageous embodiment of the invention, for a central region of the tracking of the wheel detected by the measuring device, wherein in this central region the flanges are spaced from the rail flanks, for example at least 3mm, the torque exerted by the actuator on the chassis group of the control device on the Value 0 is set, ie no torque is applied to the chassis group by the actuator. exerted or the landing gear group is released with respect to a rotation about the vertical axis. If, during the process of the gantry crane, the track position of the wheel comes to lie on one side outside this middle range, a torque is exerted on the chassis group by the actuator. In this case, it can be conveniently provided that the amount of torque exerted is a constant value, regardless of how far the track position of the wheel is outside this middle range. For left and right deviations with respect to the central region, the direction of the force exerted by the actuator is reversed, ie, the direction of rotation of the torque is reversed. The amount of applied torque may be the same as or different than the left and right deviations from the middle range. In this way, a very simple control can be achieved.

Further advantages and details of the invention are explained below with reference to the accompanying drawings. In this show:

Fig. 1 and Fig. 2 is a front view and a plan view of a gantry crane according to an embodiment of the invention, highly schematic and simplified; 3 shows a side view (viewing direction A in FIG. 1) of a chassis group connected to a head carrier with the rail; Fig. 4 shows a portion of the head carrier and connected to the head carrier

Rocker in view, viewing direction B in Figure 3 (without the hinge elements for connecting the head carrier with the rocker).

5 shows a schematic enlarged representation of a section of a subframe in the region of the measuring device, in a side view corresponding to FIG. 3 (without the drive motor);

Fig. 6 is a schematic representation of the measuring device in view (corresponding to the viewing direction B in Fig. 3);

7 shows a schematic representation of a part of the front wheel for the respective direction of travel with an upper section of the rail, in a view corresponding to the viewing direction B in FIG. 3;

8 is a schematic representation of the control loop in a possible embodiment; 9 shows exemplary diagrams of the track position versus time (diagram above) and the torque exerted by the actuator versus time (diagram below) to illustrate the control. An exemplary embodiment of a gantry crane designed in accordance with the invention is shown in the figures. The gantry crane is movable on a straight roadway, which is formed by two mutually spaced, parallel rails 1. The gantry crane has four legs 2, 3, 4, 5 in the illustrated embodiment. Also constructions with three legs are known. Furthermore, two supports can be provided. The legs 2-5 and supports support the cross member 6 or 7, along which a trolley 8 is movable or which are provided with another type of movable or fixed lifting device. In the case of training with two or more cross members 6, 7 run between these connection carrier. 9

At the lower ends of the arranged on a respective side of the portal legs 2, 3; 4, 5, a connecting this head carrier 10 is attached. Such a head carrier 10 is also referred to as a "chassis carrier" or "moving beam". The head carrier 10 serve to connect the steel structure of the crane with the individual chassis groups 11 of the crane chassis. The crane chassis is a straight-ahead chassis for moving along the rectilinear rails 1.

Preferably, a landing gear group 1 is arranged directly below each of the legs 2-5. It would also be conceivable and possible, for example, to provide a separate head carrier 10 for each leg 2-5. Pro rail 1 are preferably at least two spaced apart in the longitudinal direction of the rail 1 chassis groups 11 are present. An arrangement below a respective leg 2 - 5 is preferred.

All wheels 12 of a respective chassis group 11 are arranged one behind the other on a straight line formed by the rail 1. The axes 13 of the wheels 12 are aligned approximately at right angles to the rails 1 (the deviation in all possible rotational positions of the chassis group 11 with respect to the below explained vertical axis 23, for example, less than 3 °, which value depends on the geometry of the chassis group, deviations the axial positions of the wheels 12 of a chassis group 11 with respect to their orientations parallel to one another are preferably less than 0.05 °).

In the exemplary embodiment shown, a respective chassis group 11 has eight wheels 12 which are spaced apart from one another in the longitudinal direction of the rail 1. In each case two longitudinally of the rails one behind the other wheels 12 are rotatably mounted on a subframe 16. In the exemplary embodiment shown, four subframes 16 located one behind the other in the longitudinal direction of the rails are thus present per chassis group.

In each case two in the longitudinal direction of the rails one behind the other subframe 16 are connected to a common rocker 17. In the embodiment shown thus two spaced apart in the longitudinal direction of the rails 1 wings 17 are present. The subframe 16 are pivotally connected to the wings 17 about horizontal, parallel to the axes 13 of the wheels 12 axes 18.

The two rockers 17 are connected to a common rocker 19, wherein they are each pivotable relative to the rocker 19 about a horizontal, parallel to the axes 13 of the wheels 12 axis 20.

To move the crane along the rails 1 are drive motors 21, which drive the respective wheels 12. Depending on the application, more or fewer such drive motors 21 may be present.

The respective head carrier 10 is connected to the respective chassis group 11 in such a manner that the chassis group 11 is pivotable relative to the head carrier 10 about a horizontal, perpendicular to the respective rail 1 axis 24 and about a vertical axis 23 is rotatable. For this purpose, a connecting device 25 is provided, which can be designed according to the aforementioned prior art. Particularly preferred is an embodiment, as known from EP 1 911 716 A2, wherein a central, preferably designed in the form of a ball joint, joint 22 is present and further between the respective head carrier 10 and the respective chassis group 11 two arms 29, 30th are arranged, which are seen in the direction perpendicular to the rail 1 on both sides of the central joint 22. Each of the two links 29, 30 is hinged to both the head carrier 10 and the rocker 19. These superimposed joints 31, 32 of the links 29, 30 are in this case designed such that both pressure and tensile forces between the respective head support 10 and the respective chassis group 11 can be transmitted via the links 29, 30. In this case, these joints 31, 32 each have a degree of freedom for pivoting the respective link 29, 30 relative to the head carrier 10 or against the rocker 19th about a plane parallel to the axes 13 of the wheels 12 axis 33 and a degree of freedom for pivoting the respective link 29, 30 relative to the head support 10 and with respect to the chassis group 11 about a perpendicular to the axes 13 of the wheels 12 standing horizontal axis 34. The central joint 22 is designed as a loose bearing in the vertical direction, ie has a clearance in this direction in the mounted state.

A chassis group 11 of a gantry crane constructed in accordance with the invention may also comprise more or less than eight wheels 12 spaced apart in the direction of travel, wherein at least two wheels 12, spaced apart from one another in the longitudinal direction of the respective rail 1, are rotatably mounted on a common subframe 16. In the case of the formation of the chassis group 1 1 with only one subframe 16, the connecting device 25 can be arranged directly between this subframe 16 and the head carrier 10. For example, in a chassis with four consecutively arranged in the direction of travel wheels 12 two wheels on a respective subframe 16 may be rotatably mounted and the subframe 16 about horizontal parallel to the axes 13 of the wheels 12 axes pivotally connected to a rocker 17. The connecting device 25 could be arranged directly between the head carrier 10 and this rocker 17 in this case.

The wheels 12 are rigid within the chassis groups 11 with respect to rotations about vertical axes, i. apart from the rotatability of the chassis group 1 1 as a whole about the vertical axis 23 are no rotations about vertical axes, e.g. of individual wheels 12, given.

At least in the one direction of travel and in the opposite direction of travel foremost wheel 12, that is the in Fig. 3 far left and rightmost wheel of a respective about a vertical axis 23 rotatable suspension group 1 1, are preferably with flanges 14, 15th equipped, as can be seen in Fig. 7. The intermediate wheels 12 may be equipped with flanges 14, 15. Instead, trackless wheels could be used for the intermediate wheels 12. In this case, a derailment protection (which may be formed by stops arranged on the subframe which cooperate with the rail flanks, as is known) is advantageously provided, whereby cost savings can be achieved in comparison to wheels with flanges. In principle, trackless wagons with derailment protection could also be used for the foremost wheels in relation to the two directions of travel, although wheels with flanges are preferred for safety reasons. are awarded. Instead of wheels 12 with flanges 14, 15 and wheels 12 could be used with tracking rollers, which are also known. However, the initial equipment costs and the maintenance costs are higher.

For each of the rotatable about the vertical axes 23 chassis groups 11 two measuring devices 26 are available. Of these, the positions of the front wheels 12 with respect to the two directions of travel are detected with respect to their orientations in the direction perpendicular to the rail 1. The orientation of a wheel 11 with respect to the rail 1 with respect to its position perpendicular to the longitudinal extent of the rail 1 is referred to as tracking in the context of this document. The tracking value a indicates the offset of the wheel from the central orientation on the rail 1. In the case of a wheel with flanges 14, 15, as is preferred for the front wheels 12 with respect to the two directions of travel, the distance between one of the wheel flanges 14, 15 with respect to the adjacent rail flank 27 could also be used as the track position value a.

The tracking of the foremost wheel 12 of a drive group 11 relative to the respective direction of travel is largely determinative of the positions of the wheels 12 of the chassis group 11 relative to the rails and of the forces with which wheel flanges of the wheels 12 start on the rail flanks. Instead of detecting the front wheel with respect to the present direction of travel, the measuring device could in principle also detect the tracking position of another of the wheels lying in front of the vertical axis 23 about which the chassis group 11 is rotatable. Which are relative to the respective direction of travel in front of the vertical axis 23 about which the chassis group 11 is rotatable, lying wheels are the respective "leading" wheels.

An example of a possible embodiment of a measuring device 26 can be seen in particular from FIGS. 5 and 6. A yoke 35 slidably bears with sliding linings 36 on the two rail flanks 27. The yoke 35 is pivotally mounted on first and second pivot arms 37, 38 about horizontal axes perpendicular to the axes 13 of the wheels 12, 39, 40. The pivot arms 37, 38 are further pivotally mounted above the axes 39, 40 about horizontal, perpendicular to the axes 13 of the wheels 12 stationary axes 41, 42 which are fixedly mounted on the subframe 16, preferably in the region of the end of the subframe sixteenth The distance of the yoke 35 from the axis 13 of the frontmost wheel 12 with respect to the direction of travel in question is relatively small, preferably smaller than the diameter of this wheel 12. The first pivot arm 37 has an extension arm 43 which projects upwards relative to the axle 41. is formed by a two-armed lever. In a displacement of the wheel 12 relative to the rail 1 in the direction perpendicular to the rail 1, there is a rectified shift of lying in the region of this wheel 12 portion of the subframe 16 relative to the rail 1 and thus to a pivoting of the first and second pivot arms 37, 38th and the extension arm 43. The position of the extension arm 43 corresponding to the center position of the track of the wheel 12 is shown in solid lines in FIG. 6; two positions of the extension arm 43 for track positions displaced in the two transverse directions are indicated in FIG. 6 by dashed lines.

The pivoting position of the extension arm 43 is detected by, for example, inductive measuring sensors 44, 45. In the simplest case, it would be conceivable and possible to design the two measuring sensors 44, 45 as switches which can be actuated mechanically by the extension arm 43.

Conceivable and possible would be e.g. Also, the respective measuring device 26 on the subframe 16 on the vertical axis 23, about which the chassis group 11 is rotatable, facing side.

Between the landing gear group 1 1 and the associated head carrier 10 acts an actuator 28, which is for example formed as shown in the form of a piston-cylinder unit. This is arranged between a connection bracket 46 attached to the head carrier 10 and a connection tab 47 attached to the rocker 19. By a force exerted by the actuator 28, a force acting around the vertical axis 23 torque m is exerted on the chassis group 11.

The actuator 28 is controlled by a control device 48, 49 in response to the output by the measuring device 26 tracking position value. In this case, a force variable is set as the controlled variable on the actuator 28. An exemplary embodiment of the entire control loop is shown schematically in FIG. 8. The control device has a control unit 48, which is supplied to the tracking position value detected by the measuring device 26, and an actuator drive device 49. The actuator drive means 49 is formed in the illustrated embodiment of hydraulic elements. A feed pump 50 in this case conveys hydraulic oil from a reservoir 51. By means of a pressure relief valve 52, the maximum, prevailing in the hydraulic line 53 pressure is set. A 4/3

Directional valve 54 is controlled by the control unit 48. Depending on the position of the 4/3-way valve 54, the actuator 28 is released or by the actuator 28, a force is exerted in one or the other direction, ie on the chassis group 11, a force acting in one or the other direction of rotation torque m is exercised. This torque m represents the manipulated variable of the control loop. The controlled system, as shown schematically in FIG. 8, is formed by the running gear group 1 1 running on the rail 1.

In the illustrated embodiment, the manipulated variable can take only three values, namely, a torque 0, a torque acting in the one direction of rotation with an amount m _x or in the other direction of rotation acting torque with the amount m _y exerted. The amount m _x or m _{y of} the torque is preset here, in the illustrated embodiment by adjusting the pressure value of the pressure relief valve 52.

The default can be done after the gantry crane is completed, according to the horizontal forces caused by the deviations of the axles 13 of the wheels 12 of a chassis group 11 with respect to their mutually parallel orientations.

In a predetermined central region of the track position value, the torque value 0 is set by means of the control device, ie in the embodiment shown by setting the corresponding position of the 4/3-way valve 54 by the control unit 48. This middle region corresponds to a tracking value a which is between a value a , and a ₂ lies. In the region of the tracking value a between a, and a ₂ , the flanges 14, 15 are spaced from the rail flanks 27. If, for example, in the center position of the wheel 12 with respect to the rail 1 (= tracking value a ₀ ), the distances of the flanges 14, 15 of the rail flanks are each 20mm, so the distance of the flange 14 of the rail flange 27 in tracking position a, eg 5mm and when tracking value a _2, for example 35mm.

When the middle region S ₁ to a _{2 is} left, the 4/3-way valve 54 is correspondingly adjusted by the control unit 48, so that one of the further approach or removal of the flange 14 to the rail edge 27 and of the rail edge 27th counteracting torque ιm _x or -m _{y is} exerted on the chassis group 11. In order to determine whether the tracking position value a corresponding to the current track position lies within the range a, to a ₂ or above or below this range, the control unit 48 has a comparator part. For controlling the 4/3-way valve 54, the control unit 48 has a control part.

A control process is explained below by way of example with reference to FIG. 9. The front wheel 12 of the chassis group 11, which is the front wheel in relation to the direction of travel, has, for example, the mean track position a ₀ at the beginning of the method of the gantry crane. As a result of occurring horizontal forces and / or tolerances in the rail position, a change in the track position occurs in the method of the crane, in the exemplary embodiment shown in the direction of the value a. Factors for the horizontal force occurring are in particular the total non-compensating deviations of the axial positions of the wheels 12 of a respective chassis group 11 with respect to their orientations parallel to each other, and wind loads occurring. If the tracking value a, is reached, then the chassis group 11 is acted upon by the torque m _x . The distance a from the rail edge 27 thereby increases again. If an intended tracking value a is reached, for example, when the center position a ₀ is reached again, the Fahrwersgruppe 11 is again unlocked. The described control process is repeated in the sequence.

If the horizontal forces in conjunction with the orientation of the rail position so affect that the tracking value a _{2 is} reached, so acting in the reverse direction torque -m _{y is} applied to the chassis group 11.

Instead of adjusting the size of the applied torque by a pressure relief valve 52, for example, a feed pump 50 could be used for this purpose, the delivery pressure is adjustable.

Instead of hydraulically acting actuators 28 and other actuators could be used, for example, mechanically or electromechanically acting actuators. For example, in the case of an electrically controllable actuator, this could be controlled directly by the control part of the control unit 48.

Instead of only three different values for the manipulated variable (0, m _x , -m _y , wherein the amounts m _x and m _{y may be the} same or different), more than three values for the manipulated variable could also be provided, for example in addition to 0. Value two different strengths for the torque that are exerted in the two directions of rotation you can. These can be activated at given actual values of the controlled variable a. Also, a continuous control of the torque could be provided.

Per chassis group 11, more than one actuator 28 could be provided.

The measuring device 26 could also be designed in another way as shown. For example, a cooperating only with a rail edge 27, rotatably mounted relative to the subframe 16 part could be present.

L e g e to the reference numbers:

1 rail 31 joint

2 leg 32 joint

3 leg 33 horizontal axis

4 leg 34 horizontal axis

5 leg 35 yoke

6 cross member 36 sliding coating

7 cross member 37 first pivot arm

8 Trolley 38 second arm

9 connection carrier 39 axis

10 head support 40 axis

11 Chassis group 41 Axle

12 wheel 42 axle

13 Axis 43 extension arm

14 Flange 44 Sensor

15 wheel flange 45 sensors

16 Subframe 46 Connecting link

17 rocker 47 connecting link

18 axis 48 control unit

19 rocker 49 actuator drive means

20 axis 50 feed pump

21 Drive motor 51 Reservoir

22 central joint 52 pressure relief valve

23 vertical axis 53 hydraulic line

24 horizontal axis 54 4/3-way valve

25 connection device

26 measuring equipment

27 rail flank

28 actuator

29 handlebars

30 handlebars

Claims

claims

1. gantry crane, which has a for moving the gantry crane along a straight, of parallel rails (1) formed roadway comprising several chassis groups (11), each spaced at least two in the longitudinal direction of the respective rail (1) from each other on a subframe (16) rotatably mounted wheels (12) and of which at least two, preferably all, with a head support (10) of the gantry about a vertical axis (23) are rotatably connected, for at least one with the associated head carrier ( 10) about the vertical axis (23) rotatably connected chassis group (11), preferably for all with the respective associated head support (10) about the respective vertical axis (23) rotatably connected chassis groups (11), at least one measuring device (26) the track position of at least one of the wheels (12) of the chassis group (11) with respect to the rail (1) on which it rolls, can be detected and one of the respective Track position corresponding to the track position value (a) can be output, characterized in that between the landing gear group (11) and the associated head carrier (10) acting actuator (28) are provided, which of a control device (48, 49), the the tracking device (a) is fed to the measuring device (26), is driven and from which the chassis group (11) can be acted upon by a predetermined by this control torque (m) about the vertical axis (23).

2. gantry crane according to claim 1, characterized in that for each of the two directions of travel of the gantry crane at least one measuring device (26) for detecting the tracking of a relative to the respective direction of travel of the gantry crane in front of the vertical axis (23) to which the chassis group (11) is rotatable, lying wheel (12) of the

Chassis group (11) is present.

3. gantry crane according to claim 1 or 2, characterized in that for a central region (a _r a ₂ ) of the tracking of the measuring device (26) detected wheel (12) exerted by the actuator (28) on the chassis group (11) Torque (m) from the

Control device (48, 49) is set to the value 0.

4. gantry crane according to claim 3, characterized in that for a tracking of the wheel (12), which lies on one side outside the central region (a, -a ₂ ) exerted by the actuator (28) on the chassis group (11) Torque (m) is set to a constant, presettable amount (m _x , m _y ), wherein the direction of rotation of the torque (m), depending on the side on which the tracking is outside the central region (a _r a ₂ ), different is.

5. gantry crane according to one of claims 1 to 4, characterized in that the actuator (28) between the landing gear group (11) and the associated head carrier (10) acting piston-cylinder unit.

6. gantry crane according to one of claims 1 to 5, characterized in that the measuring device (26) has a pivotally mounted on the subframe (16) on which the wheel to be detected (12) is rotatably mounted part (35), which at least with a rail edge (27) cooperates.

7. gantry crane according to claim 6, characterized in that the measuring device has a two rail flanks (27) cooperating yoke (35) which is pivotally mounted on the subframe (16) pivotally mounted pivot arms (37, 38).

8. gantry crane according to one of claims 1 to 7, characterized in that a respective chassis group (11) two or more subframe (16) each with at least two in the longitudinal direction of the respective rail (1) spaced from each other, on the driving stool (16) has rotatably mounted wheels (12) and the respective chassis group (11) as a whole about a single vertical axis (23) rotatably connected to the head support (10).

9. gantry crane according to one of claims 1 to 8, characterized in that the chassis groups (11) are each arranged directly below a respective leg (2-5) of the gantry crane.