WO2015150640A1

WO2015150640A1 - Method for crane turning drive

Info

Publication number: WO2015150640A1
Application number: PCT/FI2015/050235
Authority: WO
Inventors: Esa Ojapalo; Juha Santala
Original assignee: Konecranes Plc
Priority date: 2014-04-04
Filing date: 2015-04-02
Publication date: 2015-10-08
Also published as: FI126632B; FI20145326A; CN107074507A

Abstract

The invention relates to a method for turning drive of a crane, a rubber-tyred crane in particular, comprising a frame which has a main support structure in its upper part and lower beam structures transverse to the main support structure in the lower part of the frame, on opposite sides of the lower part of the frame; at least one rubber-tyred wheel or rubber-tyred wheel arrangement (6, 7) rotatable about a vertical axis at both ends of the lower beam structures, i.e. in each lower corner of the crane, whereby in turning drive the wheels or wheel arrangements (6, 7) of one lower beam structure are locked to a longitudinal drive position of the crane, i.e. parallel to the lower beam structure, the wheels or wheel arrangements (6, 7) of the other lower beam structure are turned and locked to a transverse drive position of the crane, i.e. transverse to the lower beam structure, and drive wheels or wheel arrangements (6) are driven at a speed proportional to their turning radius, the centre point (X) of the turning radius being at the centre point between the transverse wheels or wheel arrangements of the other lower beam structure.

Description

Method for crane turning drive

Field of the invention

[0001] The invention relates to a method for turning drive of a crane, a rubber-tyred crane in particular, comprising a frame which has a main support structure in its upper part and lower beam structures transverse to the main support structure in the lower part of the frame, on opposite sides of the lower part of the frame; a trolley arranged to move along the main support structure; at least one rubber-tyred wheel or a rubber-tyred wheel arrangement turnable about a vertical axis at both ends of the lower beam structures, i.e. in each lower corner of the crane.

[0002] Rubber-tyred gantry cranes are used in container storage fields for arranging and handling cranes. Cranes come in a variety of types and sizes; most commonly they are grouped according to the number of wheels in the crane, i.e. 4-, 8- or 16-wheeled cranes. They move on rubber tyres along a straight path parallel to a container row, with the wheels or wheel arrangements direction-locked in a longitudinal drive position parallel to the container rows. Since the path is straight, the crane may be controlled by adjusting the difference in speed between the wheel ends. During driving, the wheels or wheel arrangements are kept direction-locked so that they are perpendicular to the main support arrangement of the crane and parallel to the lower beam structures.

[0003] One crane may be used for a plural number of container rows by moving the crane in a transverse direction to a new container row. The crane may be moved by driving it to an end of a container row, where the direction-locking of the wheels or wheel arrangements is disengaged and the wheels or wheel arrangements are turned 90 degrees, to the transverse drive direction, and locked. Next, the crane is driven in the transverse direction on the transverse path to the proper container row, where the wheels or wheel arrangements are turned and locked to the longitudinal drive position on the path along the container row.

[0004] In some cases the paths and the container rows of the storage field are in different areas which are not necessarily parallel to one another, and hence it must be possible to change the driving direction of the crane. For this purpose the wheels or wheel arrangements of rubber-tyred gantry cranes may be locked to an intermediate locking position that enables turning drive of the crane about its centre point. The intermediate position locking point differs from one crane to another depending on the crane span, which means that for every different span length, a span-specific part is required in the crane. Although a locking piece may be standardized to cover a predetermined span range, various locking pieces are unavoidable.

[0005] There are various wheel turning arrangements and two basic principles apply in the most commonly used ones. In an arrangement in accordance with the first basic principle, crane wheels are turned with a separate turning mechanism, typically a hydraulic cylinder or a separate turning apparatus. The wheels may be placed in a centralized manner or off- centre with respect to the turning centre of the wheel, and the wheel is turned on the spot. According to the second basic principle, the driving mechanism of the crane is used for turning the wheels, in which case the drive wheel used for the turning is offset from the turning centre and the wheel turns rolling.

[0006] Publication EP 771306 B1 discloses a 16-wheel crane in which each bogie is provided with two wheels side by side, one of the wheels being a drive wheel and the other an idle wheel. Each bogie has a specific drive mechanism and thus a specific turning mechanism. For turning drive, specific intermediate wheel locking positions as disclosed above are provided. The wheels are made to turn to the intermediate position by means of the driving mechanisms.

[0007] Publication GB 2362863 A discloses a 16-wheel crane with an extremely complex rod arrangement for turning and locking the wheels to a turning drive position.

[0008] Publication EP 1770049 B1 , in turn, discloses an 8-wheel crane with a rod arrangement for locking the wheels to different drive positions, including the above-mentioned intermediate position for turning drive.

[0009] Other prior art cranes are disclosed in publications EP 1820769 A1 and EP 2349905 B1 , for example.

[0010] A problem with all the above cranes is specifically the intermediate position for turning drive which renders the crane structure complex and thus causes costs both in terms of crane manufacture and servicing.

Summary of the invention

[0011] An object of the invention is thus to provide a method so as to enable the aforementioned problems to be solved. This object is achieved by a method of the invention, which is characterized in that, for the purpose of turning drive, the wheels or wheel arrangements of one lower beam structure are locked to a longitudinal drive position of the crane, i.e. to a position parallel to the lower beam structure; the wheels or wheel arrangements of the other lower beam structure are locked to a transverse drive position of the crane, i.e. to a transverse position in relation to the lower beam structure; and drive wheels or wheel arrangements are driven at a speed proportional to their turning radius, the centre point of the turning radius being at the centre point between the transverse wheels or wheel arrangements of the other lower beam structure.

[0012] Most commonly, both ends of the lower beam structure are provided with two tandem wheels or wheel arrangements, with at least the inner wheels or wheel arrangements being drive wheels. Other preferred embodiments of the invention are disclosed in the dependent claims.

[0013] In other words, a turning drive of the invention is implemented without a need for a span-specific intermediate locking position, whereby a simplified structure is obtained. This may be achieved by making use of the drift feature, or deformation, of a rolling rubber tyre. Two mutually perpendicular locking positions are used for locking the wheels or wheel arrangements at one end of the crane to a transverse drive position and the wheels at the other end to a longitudinal drive position. In turning drive of the crane, the crane is turned about the centre point between the wheels at the end where they are in the transverse drive position, whereby the wheels in the longitudinal drive position are forced to a circular motion by making use of tyre drift, i.e. its lateral deviation, when it is rolling. The turning drive is carried out by means of the crane's own drive mechanisms by proportioning wheel speeds in relation to each turning radius so that they are proportional to one another.

[0014] An essential aspect of this invention is that the centre lines of the wheels do not meet at a specific turning centre and that the wheels are turned to positions of 90 degrees, which means that they are independent of the span (on a sufficient long span) and locking positions to 90 degrees are easy to arrange so that intermediate positions between 0 to 90 degrees may be disposed of, particularly when corner support by a plural number of wheels is provided. According to the invention, the directions of the wheels are substantially the same as the selected directions parallel to the lower beam structure or to the transverse drive position of the crane. [0015] In other words, lateral grip properties of the tyre or, in particular, a low lateral grip of the tyre as described above in connection with the disclosure on the tyre drift property is made use of in a rolling motion, in fact, a core aspect of the invention is that the turning mechanics of the wheels has been simplified to the extreme between degrees from 0 to 90 so that one of the extreme positions, i.e. either 0 or 90 degrees, is only used. Consequently, wheel-specific ideal driving lines are not achieved during turning drive so that proper wheel roll, in textbook manner, would take place. In order for the crane to be turned nevertheless, this non-ideal solution must be compensated for in some way. In practice this is handled by loading the tyre also in the lateral direction during the turn.

[0016] An advantage of the solution is that the steel constructions, their mechanics and actuators are plain and simplified, thus leading to costs savings. Proper tyre selection will allow the tyres to be loaded in a non- textbook manner and, consequently, their deformations that are within an acceptable range may compensate for imperfections in path geometry.

List of figures

[0017] Next, the invention will be explained in greater detail with reference to the accompanying drawings, in which:

Figure 1 is a diagonal top view of a crane;

Figure 2 is a schematic view of a turning drive according to the invention of the crane of Figure 1 ;

Figure 3 is a diagonal top view of another crane; and

Figure 4 is a schematic view of a turning drive according to the invention of the crane of Figure 3.

Detailed description of the invention

[0018] With reference to Figure 1 there is shown a crane with a frame 1 which, in its upper part, is provided with a main support structure 2 formed of two upper beams 2 and which, in its lower part and on opposite sides of the lower part of the frame 1 , is provided with mutually parallel lower beam structures 3 transverse to the main support structure 2. A trolley 4 is arranged to move along the main support structure 2. The ends of the lower beam structures 3 are provided with bogie structures 5, each comprising two tandem wheels 6 and 7. In other a words, a total of four bogie structures 5 are provided, one in each lower corner of the crane 1. Correspondingly, there are altogether eight wheels 6 and 7.

[0019] In this example the wheels 6 and 7 are mounted on bearings at the lower ends of tubes 8 and 9, on the sides of these tubes, extending downwardly from a bogie frame 5a. The wheels 6 and 7 turn with the tubes 8 and 9 about their vertical axes, and the wheels 6 and 7 are offset from the vertical axes. At least one wheel of the wheels in each bogie structure 5, preferably the inner wheel 6, is a drive wheel, while the other wheel 7 is preferably an idle wheel. A drive mechanism, such as an electric motor (not shown), is arranged for driving the drive wheel 6, the mechanism being coupled to the wheel 6 by a suitable gearing (not shown). Due to the "asymmetric" suspension of the wheel 6 described above, the drive wheel 6, when being driven, turns "automatically" about the vertical axis of the vertical tube 8, unless the turning is prevented by a locking device. This "asymmetric" suspension is advantageous if the drive mechanism of the crane is to be used also for turning the wheel 6 when turning is required.

[0020] As shown in Figure 2, in the method of the invention for turning drive of a crane the wheels 6 and 7 of one lower beam structure 3 are locked to a longitudinal drive position of the crane, i.e. parallel to the lower beam structure 3, while the wheels 6 and 7 of the other lower beam structure 3 are turned and locked to a transverse drive position of the crane, i.e. transverse to the lower beam structure 3, and the drive wheels 6 are driven at speeds proportional to their turning radii R1 , R2 and R3, a centre point X of a turning radius being located at the centre point between the transverse wheels 6 and 7 of the lower beam structure 3.

[0021] At least the drive wheel 6 of each bogie structure 5 may be turned by means of drive mechanisms, while the wheels 6 and 7 of the other bogie structures 5 are, at the same time, prevented from rolling and the trolley 4 is preferably driven to an opposite side of the crane with regard to the wheel 6 that is to be turned. The wheels 6 and 7 are interconnected by a connecting rod (not shown) so that the drive wheel 6 turns both wheels 6 and 7. The longitudinal and transverse drive positions are locked by means of locking pins (not shown), which are known per se, as are the connecting rods mentioned above. What is different now is that no intermediate locking positions are needed. [0022] Of the wheels 6 and 7 turned to a transverse position with regard to the lower beam structure 3, wheels 6 on opposite sides of the centre point X of the turning radius are driven in opposite directions with regard to one another, while the wheels 6 parallel to the lower beam structure are driven in the direction to which the crane is to turn.

[0023] The crane in Figure 3 differs from the one in Figure 1 in that it is a 16-wheel crane, and its bogie structures 50 comprise two tandem wheel pairs 60 and 70, each pair having an outer wheel 60a, 70a and an inner wheel 60b, 70b, one wheel in a wheel pair being typically a drive wheel, while the other is an idle wheel. The driven wheels may be on the outer sides of the bogie structures 50, although often a crosswise arrangement is used in which the outer wheel 60a of the wheel pairs 60 and 70 is the drive wheel and the inner wheel 60b is the idle wheel, and the inner wheel 70b is the drive wheel and the outer wheel 70a the idle wheel. The wheels 60a, 60b and 70a, 70b of the wheel pairs 60 and 70 are placed on both sides of the tubes 80 and 90 extending downwardly from the bogie frame 50a.

[0024] Figure 4 shows a turning drive position of the crane of Figure 2, with the wheels 60a, 60b and 70a, 70b of the crane being in turning drive positions corresponding to those of the crane of Figure 1 in Figure 2. Since all the wheel pairs 60 and 70 have their specific drive mechanisms, the wheel pairs 60 and 70 are easy to turn. Turning drive and driving the wheels are performed according to a similar principle as shown in Figure 2.

[0025] In wheeled vehicles the properties of a rubber tyre may be made use of by means of toe angles, i.e. longitudinal displacement, adjusted in a desired manner. The ability of a rubber tyre to adapt to longitudinal displacement may be utilized, similarly as toe angles, or longitudinal displacement, in wheeled vehicles, for improving steerability. The invention makes use of this property when the rolling axis is not at a right angle to the travel direction. Another feature that is made use of at the same time is that, due to the spring characteristics of the tyre, lateral forces do not grow excessively as the tyre rolls diagonally to the direction of travel.

[0026] According to the invention, the wheels are preferably turned at a crawl speed, or generally at a non-zero drive speed. This way it is possible to reduce the stress on the tyre and, at the same time, the driving surface is not subjected to any particularly great local wear. Significant tyre elasticity in connection with turning may be obtained, and the crane may be turned about a relatively small turning radius,

[0027] The frame of the crane and its components that participate in the turning are dimensioned to be sufficiently strong to sustain without damage and repeatedly loads caused by turnings,

[0028] The above description of the invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may thus vary its details within the scope of the attached claims,

Claims

1. A method for turning drive of a crane, a rubber-tyred crane in particular, comprising:

- a frame (1 ) which has a main support structure (2) in its upper part and lower beam structures (3) transverse to the main support structure (2) in the lower part of the frame (1 ), on opposite sides of the lower part of the frame

(1 );

- a trolley (4) arranged to move along the main support structure (2); and

- at least one rubber-tyred wheel or rubber-tyred wheel arrangement (6, 7; 60a, 60b, 70a, 70b) turnable about a vertical axis at both ends of the lower beam structures (3), i.e. in each lower corner of the crane;

c h a r a c t e r i s e d in that for the purpose of turning drive, the wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b) of one lower beam structure (3) are locked to a longitudinal drive position of the crane, i.e. parallel to the lower beam structure (3);

the wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b) of the other lower beam structure (3) are turned and locked to a transverse drive position of the crane, i.e. to a transverse position in relation to the lower beam structure (3); and

drive wheels or wheel arrangements (6; 60a; 70a) are driven at a speed proportional to their turning radius, a centre point (X) of the turning radius being at the centre point between the transverse wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b) of the other lower beam structure (3).

2. A method as claimed in claim 1 , ch a racte rized in that at both ends of the lower beam structure (3) there are two tandem wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b), at least the inner wheels (6) of the tandem wheels (6, 7) being drive wheels or at least one wheel in each wheel arrangement (60a, 60b; 70a, 70b) being a drive wheel.

3. A method as claimed in claim 2, cha ra cte rized in that the wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b) are turned by means of drive mechanisms of the wheels or wheel arrangements.

4. A method as claimed in claim 1 or 2, ch a racterized in that the wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b) are turned by means of hydraulic cylinders.

5. A method as claimed in claim 1 or 2, characterized in that the wheels or wheel arrangements (6, 7; 80a, 60b, 70a, 70b) are turned by means of separate turning mechanisms.

6. A method as claimed in any one of the preceding claims, cha racterized in that for the duration of the turning of each wheel or wheel arrangement (6, 7; 60a, 60b, 70a, 70b), the trolley (4) is driven to an opposite side of the crane in relation to the wheel or wheel arrangement in question.

7. A method as claimed in any one of the preceding claims, cha racterized in that the turning of the wheels or wheel arrangements (6, 7; 60a, 60b, 70a, 70b) is carried out at a non-zero speed, preferably at a crawl speed.