EP0626336A1 - Procedure and assembly for adjusting the direction of a rail wheel - Google Patents

Abstract

The invention relates to a procedure for adjusting the inclination and direction of travel of a rail wheel (1) of a crane. The bearing surfaces (8a and 8b) guiding the eccentric bearing bushes (2a and 2b) are so placed that they have the same eccentricity relative to the centre line of the shaft (6) as the journal boxes 3a and 3b, and the eccentricity has to be so chosen that the desired direction adjustment can be accomplished with a sufficiently small angle of rotation.

Description

• A procedure for adjusting the inclination relative to the vertical direction and the direction of travel of a rail wheel of a crane.
• After the assembly welding work on a crane has been completed, it is often necessary to correct the alignment of a rail wheel. This need generally arises from deformations and inaccuracies in the steel structures of the crane. As is known, each end of the shaft of the rail wheel is provided with an eccentric bearing bush held by its outer surface in the frame of the end carriage. By turning the eccentric bearing bush, it is possible to change the direction of travel of the rail wheel and its inclination relative to the vertical direction. In the starting situation, both bearing bushes lie with their eccentricity in the same direction, generally straight upwards. Therefore, when the bearing bush is rotated, the horizontal motion of the centre of the rail wheel journal box (adjustment of the direction of travel) is given by $\text{sin α x E}$

  

  , where α = angle of rotation and E = eccentricity. The vertical motion of the centre of the journal box is $\text{(1 - cos α) x E}$

  

  . When the angle of rotation is 20° or less (the situation in practice), the horizontal motion of the centre of the journal box is considerably larger than the vertical motion, so the adjustment of the direction of travel is relatively easy to carry out. After this, it is often necessary to change the inclination as well by turning the other eccentric bearing bush. This has a greater effect on the direction of travel than on the inclination. Whereupon you have to correct the direction of travel by turning the first bearing bush, as explained above. These adjustments have to be repeated several times. A further drawback is that finding the position of the bearing bushes requires considerable precision, experience and care.
• To provide a solution to the problems referred to above, a new procedure for adjusting the direction of a rail wheel of a crane is presented as an invention. The procedure of the invention for adjusting the direction of a rail wheel of a crane is characterized by what is presented in the characterization part of claim 1. Other embodiments of the invention are characterized by the features presented in the other claims. In the solution of the invention, the eccentric bearing bush on one side of the wheel is used to adjust the direction of travel while the one on the other side is used to adjust the vertical direction of the wheel.
• The advantages achieved by the invention include the following:
• The installer need not have a long experience to be able to carry out the adjustment.
• The adjustment is simple to carry out.
• No extensive adjustment instructions are needed.
• The costs of adjusting the wheel direction are reduced.
• Considerably less time is consumed.
• Enables easy readjustment.
• The angle of rotation can be seen directly in a table.
• In the following, the invention is described in detail by the aid of some of its embodiments by referring to the attached drawings, in which

Fig. 1

presents a rail wheel 1 as mounted in the frame of an end carriage, seen in front view 1a, lateral view 1b and top view 1c.

Fig. 2

illustrates the effect of direction adjustment in diagrammatic form as seen from each side of the rail wheel 1.

Fig. 3

presents a diagram of the eccentric surfaces on one side of the wheel.

Fig. 4

presents the bearing bush of Fig. 3 assembled and partially sectioned.

• Fig. 1 presents three different views of a rail wheel 1. The figure shows the eccentric bearing bushes 2a and 2b on either side of the rail wheel 1, which in the structure of the invention consist of journal boxes 3a and 3b and shields 4a and 4b having an eccentricity with respect to their outside diameter. The shields match the inside diameter of the journal boxes 3a and 3b and are attached to each other by means of bolts 5. The eccentricity has to be so chosen that the necessary adjustments can be achieved with an angle of rotation below 20°. The bearing surfaces 8a and 8b are the contact surfaces between the supporting plates 7a and 7b and the bearing bushes 2a and 2b. For example, in the solution of the invention, the bearing surface 8a for the bearing bush 2a on one side of the wheel is made equally eccentric as the bearing bush 2a. The direction of eccentricity of the bearing surface 8a of the supporting plate 7a is selected e.g. on the basis of the desired directional effect. If the eccentricity of the bearing surface 8a is in the direction of the vertical axis and the bearing bush 2a is eccentrically installed so that it compensates the eccentricity of the bearing surface 8a (the journal box 3a lies on the centre line of the shaft), then the horizontal motion of the centre of the journal box 3a will be considerably larger than the vertical motion. On the other hand, if the bearing surface 8a has a horizontal eccentricity relative to the centre, then rotating the eccentric bearing bush 2a will cause a change in the vertical position of the journal box 3a but hardly any change in its horizontal position. Fig. 1 also shows the shaft 6 by means of which the rail wheel 1 is mounted in the bearing bushes 2a and 2b, as well as the above-mentioned supporting plates 7a and 7b whose bearing surfaces 8a and 8b guide the bearing bushes 2a and 2b and which are mounted on the frame of the end carriage so that they have the same eccentricity in the same direction as the corresponding outer diameters of the bearing bushes 2a and 2b. Supporting plate 7a has a horizontal eccentricity and supporting plate 7b on the opposite side a vertical eccentricity. The end carriage steel structure is manufactured to as high a precision as possible so as to minimize the need for adjusting the direction of the rail wheels 1. Because of the precision requirement regarding the direction adjustment, there is generally always a need for adjusting the direction of the rail wheel. The adjustment is performed as follows: The inclination relative to the vertical direction is adjusted by rotating bearing bush 2a, and the direction of travel is adjusted by turning bearing bush 2b. In the solution of the invention, bearing bush 2a is rotated if the centre of journal box 3a is to be moved in the vertical direction. When the direction of travel of the rail wheel 1 is to be corrected, bearing bush 2b is rotated either clockwise or anticlockwise, depending on the direction of the desired correction. This produces a horizontal displacement of the centre of journal box 3a. As an aid for the installer, the bearing bushes 2a and 2b and supporting plates 7a and 7b are provided with markings indicating the position of the eccentric. When the adjustment is started, these markings must be aligned with each other. Thus, the markings allow the installer to see how much the bearing bushes 2a and 2b have been rotated during the adjustment.
• The diagrams in Fig. 2 illustrate the effect of the direction adjustment, diagram A showing a view from the side of supporting plate 7a and the corresponding bearing bush 2a and diagram B from the side of supporting plate 7b and bearing bush 2b. In the solution of the invention, when bearing bush 2a is rotated by an amount less than 20° according to diagram A, the vertical displacement of the centre of journal box 3a is considerably larger than its horizontal displacement. If the eccentricity = E, then the (vertical) displacement of the centre of journal box 3a corresponding to a rotational angle of 20° in the desired direction of correction will be = $\text{sin 20° x E = 0.34 x E}$

  

  , whereas the displacement in the unwanted direction, in this case the horizontal direction, will be $\text{(1-cos α) x E = 0.06 x E}$

  

  . Thus, the effect of the adjustment in the wanted direction of correction is 5.6 times as large as the effect in the unwanted direction. If the angle of rotation α is smaller than in the example, then the effect in the unwanted direction will be considerably smaller. In this way, adjustment of the inclination of the rail wheel 1 is achieved. Diagram B in Fig. 2 illustrates the effect of the direction adjustment when bearing bush 2b is turned, causing the centre of journal box 3b to be displaced in the desired horizontal direction in the manner described above. In this way, adjustment of the direction of travel of the rail wheel 1 is achieved.
• Figures 3 and 4 present a diagrammatic illustration of the eccentric surfaces 9 forming part of the bearing bushes 2a and 2b. The bearing surfaces 8a and 8b have the same eccentricity as the corresponding eccentric bearing bushes 2a and 2b. The bearing bushes 2a and 2b are composed of parts 3a+4a+5 or 3b+4b+5 respectively, number 5 indicating a screw used to fix the parts together. In Fig. 1, numbers 2a and 4a point to the same part, because these parts consist of the same component.
• It is obvious to a person skilled in the art that different embodiments of the invention are not restricted to the examples described above, but that they may instead be varied within the scope of the claims presented below. The design of the eccentric bearing bush may be varied by placing the eccentric surface either on the inside or outside of the bush, and the bush may be manufactured as a single part or as consisting of several parts. On the framework side of the structure, the bearing surface guiding the bearing bush can be produced by casting or machining it in the framework or a separate part attached to it, and so on. The solution of the invention can also be applied for the adjustment of fulcrum pins and the shafts of rope pulleys.

Claims (3)

1. Procedure for adjusting the inclination relative to the vertical direction and the direction of travel of a rail wheel (1) of a crane, characterized in that

   - the bearing surfaces (8a and 8b) guiding the eccentric bearing bushes (2a and 2b) are so placed that they have the same eccentricity relative to the centre line of the shaft (6) as the eccentricity of the journal boxes 3a and 3b, and

   - the eccentricity has to be so chosen that the desired direction adjustment can be accomplished with a sufficiently small angle of rotation.
2. Procedure according to claim 1, characterized in that one of the bearing bushes (2a and 2b) is for the adjustment of the direction of travel and the other for the adjustment of the inclination relative to the vertical direction.
3. Assembly for adjusting the inclination relative to the vertical direction and the direction of travel of a rail wheel (l) of a crane, comprising eccentric installations of bearing bushes on either side of the rail wheel, characterized in that the eccentric bearing bush (2a) on one side of the wheel is used to adjust the direction of travel while the one on the other side is used to adjust the vertical direction of the wheel.

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