Drag type wheel finishing machine

Abstract

A drag type wheel finishing machine. A spindle is connected to an output shaft of a drive motor secured to an upper platform of a frame structure. Arms are mounted adjacent to a lower end of the spindle. Upright members are joined to distal ends of the arms. Wheel mounting parts are mounted to lower ends of the upright members, and an abrasive polishing media bath is placed in the frame structure to be raised and lowered by a lift mechanism. The lift mechanism is configured such that the media bath can be guided by four columns and supported by four wires. One ends of the wires are connected to a distal end of a piston rod of a drag type hydraulic cylinder installed on the media bath such that, when the wires are simultaneously pulled via the piston rod, the media bath is raised.

Description

TECHNICAL FIELD

[0001] The present invention relates, in general, to a drag type wheel finishing machine which polishes the surfaces of automobile wheels, almost perfectly and, more particularly, to a drag type wheel finishing machine which polishes and finishes surfaces of automobile wheels using friction between the surfaces and abrasive polishing media by revolving and rotating the automobile wheels, with a plurality of wheels fully or partially submerged in the abrasive polishing media accommodated in a media bath, thereby rendering a smooth and aesthetically impressive appearance.

BACKGROUND ART

[0002] The popularity of stylized automobile wheels has been largely attributable to their aesthetic enhancement of automobiles, with chrome wheels in particular providing a more stylish, sporty, and expensive look. In order to provide such an aesthetically pleasing appearance, the surface of a wheel must be as smooth as possible before it is coated or plated with a layer of chrome. If the surface is not smooth, the chrome layer applied thereto acts to enhance and magnify any grooves or imperfections remaining on the wheel surface. In the case that the plated chrome layer is exfoliated around a groove, the general appearance of the wheel is significantly detracted.

[0003] Thus, there is a need for a device which may quickly and efficiently remove substantially all grooves and roughness on the surface of a wheel to provide the surface with the desired degree of smoothness.

[0004] A wheel finishing machine related with this technique is disclosed in U.S. Pat. No. 6,406,356. In this conventional wheel finishing machine, an abrasive polishing media bath is installed on columns of a frame in a manner such that it can be raised and lowered by two hydraulic cylinders. A plurality of arms are mounted to a lower end of a vertical spindle which receives power from a drive motor secured to an upper platform of the frame. Upright members, which have wheel mounting shafts at lower ends of them, extend downward from the distal ends of the arms, respectively. The upright members are structured so that they can be rotated with respect to the arms in the range of a predetermined angle.

[0005] The conventional wheel finishing machine constructed as mentioned above suffers from defects as described below.

[0006] First, due to the fact that the media bath is raised and lowered by the two hydraulic cylinders while being guided by the four columns of the frame, it is technically difficult to stably maintain the balance of the media bath, and therefore, the probability of the media bath being tilted to one side is increased.

[0007] Second, while the wheel mounting shafts of the. upright members extending downward from the distal ends of the arms rotated integrally with the spindle can be rotated to less than ninety degrees to thereby be adjusted in its angle with respect to the arms, since the angle adjustment can be implemented only on a horizontal plane, friction between the abrasive polishing media and the wheels cannot be effectively increased as desired.

[0008] Third, because a hinged door is installed on the media bath to allow the wheels to be easily submerged in the media bath and a separate arrangement for preventing leakage of water is not provided, in a state wherein the wheels are mounted to the wheel mounting shafts coupled to the lower ends of the upright members, when the media bath is raised and the spindle is rotated to polish and finish the wheels, a problem is caused in that water leaks between the media bath and the hinged door.

[0009] Fourth, in the conventional wheel finishing machine, any means for mounting the wheels moved adjacent to the frame structure to the wheel mounting shafts coupled to the lower ends of the upright members is not provided. Thus, notwithstanding each of the wheels has a relatively heavy weight, the wheels cannot but be manually mounted to the wheel mounting shafts, and hence, the wheel mounting procedure has proved to be quite tedious, time-consuming, laborious, and thus, very costly.

DISCLOSURE OF THE INVENTION

[0010] Accordingly, an object of the present invention is to solve the above-described problems occurring in the prior art.

[0011] In order to achieve the above object, according to one aspect of the present invention, there is provided a drag type wheel finishing machine in which a spindle extending downward is connected to and rotated integrally with a velocity-reduced output shaft of a drive motor secured to an upper platform of a frame structure, a plurality of arms horizontally extending in respective four directions are mounted adjacent to a lower end of the spindle, upright members are joined to respective distal ends of the arms to extend downward, wheel mounting parts for mounting wheels are mounted to respective lower ends of the upright members, and an abrasive polishing media bath is placed in the frame structure to be raised and lowered by a lift mechanism, wherein the lift mechanism of the abrasive polishing media bath is configured in a manner such that the abrasive polishing media bath can be raised and lowered while being guided by four columns and supported by four wires extending downward from upper ends of the respective columns, and wherein one ends of the wires are connected to a distal end of a piston rod of a drag type hydraulic cylinder installed on the abrasive polishing media bath in a manner such that, when the wires are simultaneously pulled via the piston rod, the abrasive polishing media bath is raised.

[0012] According to another aspect of the present invention, the arms and the upright members are connected with each other by pins in a manner such that the upright members can be pivoted relative to the arms, and upright hydraulic cylinders connect the upright members to the arms in a manner such that the upright members can be adjusted in their respective angular positions.

[0013] According to another aspect of the present invention, a sliding door is installed on the abrasive polishing media bath to be guided in a circumferential direction while being opened and closed, upper and lower guide walls are formed on the abrasive polishing media bath to receive upper and lower ends of the sliding door, respectively, the lower guide wall has a Y-shaped section which has a hole for allowing water that has overflowed onto the lower guide wall to be returned into the abrasive polishing media bath, and a flexible seal strip to be brought into contact with the sliding door is affixed to an inner surface of the abrasive polishing media bath to reduce an amount of water overflowing onto the lower guide wall.

[0014] According to another aspect of the present invention, rotation wings are formed on the lower end of the spindle and extend downward to reach the same level as the lower ends of the upright members, in a manner such that, when the wheels mounted to the wheel mounting parts of the upright members are rotated, abrasive polishing media collected toward a center of the abrasive polishing media bath can be re-distributed in all directions.

[0015] According to still another aspect of the present invention, the upper platform of the frame structure is provided with a wheel mounting crane for mounting and dismounting the respective wheels to and from the wheel mounting parts; and the wheel mounting crane comprises a first rotation shaft installed on the upper platform to be capable of being horizontally rotated in both directions, a first horizontal lever fastened at one end thereof to the first rotation shaft to extend in a horizontal direction, a second rotation shaft installed on the other end of the first horizontal lever to be capable of being horizontally rotated in both directions, a second horizontal lever fastened at one end thereof to the second rotation shaft and provided with a cylinder, a pulley connected to a distal end of a piston rod of the cylinder adjacent to the other end of the second horizontal lever, and a wheel dragging wire having one end which is secured to the second horizontal lever and the other end which is connected to a wheel hanger, the wheel dragging wire wound on the pulley and extending downward from the other end of the second horizontal lever.

[0016] According to yet still another aspect of the present invention, the upper platform of the frame structure is provided with a wheel mounting crane for mounting and dismounting the respective wheels to and from the wheel mounting parts; and the wheel mounting crane comprises a crane body arranged on the upper platform to be capable of being horizontally rotated in both directions, a quadric wheel moving lever installed on the crane body to be pivoted in upward and downward directions, a crane cylinder secured to the crane body to pivot the wheel moving lever in the upward and downward directions, and a wheel gripper provided to a distal end of the wheel moving lever to selectively grip the wheels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

[0018] FIG. 1 is a front view illustrating a drag type wheel finishing machine in accordance with an embodiment of the present invention;

[0019] FIG. 2 is a side view of the drag type wheel finishing machine shown in FIG. 1;

[0020] FIG. 3 is a transverse sectional view of the drag type wheel finishing machine according to the present invention;

[0021] FIG. 4 is a perspective view independently illustrating a lift mechanism for raising and lowering a media bath, which serves as one main component element of the drag type wheel finishing machine according to the present invention;

[0022] FIG. 5 is a partial enlarged view illustrating a lower part of a spindle;

[0023] FIG. 6 is a partial enlarged view illustrating a wheel mounting crane in the drag type wheel finishing machine according to the present invention;

[0024] FIG. 7 is a partial enlarged view illustrating a door part in the drag type wheel finishing machine according to the present invention; and

[0025] FIG. 8 is a partial enlarge view illustrating a variation of the wheel mounting crane in the drag type wheel finishing machine according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts.

[0027] FIGS. 1 through 7 are views illustrating a drag type wheel finishing machine in accordance with a preferred embodiment of the present invention.

[0028] As shown in the drawings, the drag type wheel finishing machine includes a frame structure 10. The frame structure 10 possesses substantially a quadrangular box-shaped configuration. The frame structure 10 has four columns 12 which are erected at four corners, respectively, of the frame structure 10. An upper platform 13 is provided to upper ends of the columns 12. A drive motor 20 having a reduction gear box 21 is secured to the upper platform 13. The drive motor 20 and the reduction gear box 21 constitute one unit. A spindle 22 is coupled to a velocity-reduced output shaft of the reduction gear box 21 to extend downward.

[0029] Below the upper platform 13, four arms 23 are mounted adjacent to a lower end of the spindle 22 to extend in a horizontal direction. Upright members 24 are connected to distal ends of the arms 23 by means of pins 25 to extend downward. Upright hydraulic cylinders 26 also connect the arms 23 and the upright members 24 with each other to allow for angular adjustments of the upright members 24. Wheel mounting parts 27 for mounting wheels designated by the reference character ‘w’ are mounted to respective lower ends of the upright members 24.

[0030] An extended portion 22a is formed on the lower end of the spindle 22 and extends downward to reach the same level as the lower ends of the upright members 24. Rotation wings 22b are formed on the extended portion 22a in a manner such that, when the wheels ‘w’ mounted to the wheel mounting parts 27 of the upright members 24 are rotated, abrasive polishing media collected toward a center of an abrasive polishing media bath 30 can be re-distributed in all directions.

[0031] A lift plate 31 is installed in the frame structure 10 in a manner such that the lift plate 31 can be raised and lowered by a lift mechanism while being guided along the columns 12. The abrasive polishing media bath 30 is securely inserted through the lift plate 31. The abrasive polishing media bath 30 has a bottom end which is convexed downward and a top end which is opened.

[0032] As can be readily seen from FIG. 7, a pair of arc-shaped sliding doors 32 are provided at one side of the top end of the abrasive polishing media bath 30 in a manner such that they can be opened and closed in a circumferential direction of the abrasive polishing media bath 30. Upper and lower guide walls 33a and 33b are formed on the abrasive polishing media bath 30 to receive upper and lower ends of the sliding doors 32, respectively. The lower guide wall 33b has a Y-shaped section which has a hole 34 for allowing water overflowed onto the lower guide wall 33b to be returned into the abrasive polishing media bath 30. A flexible seal strip 35 to be brought into contact with the sliding doors 32 is affixed to an inner surface of the abrasive polishing media bath 30 by means of a fastener strip 36 to reduce an amount of water overflowing onto the lower guide wall 33b.

[0033] As shown in FIG. 4, in the lift mechanism of the abrasive polishing media bath 30, a drag type hydraulic cylinder 37 having a piston rod 37a is installed on the lift plate 31 in a horizontal direction. Four wires 38a through 38d are connected at one ends thereof to a distal end of the piston rod 37a of the drag type hydraulic cylinder 37 and at the other. ends thereof to the upper ends of the columns 12. At this time, the lift plate 31 must be appropriately supported in a manner such that the abrasive polishing media bath 30 can be raised and lowered when the piston rod 37a of the drag type hydraulic cylinder 37 is operated to simultaneously pull and release the one ends of the respective wires 38a through 38d.

[0034] A wheel mounting crane 40 is provided on the upper platform 13 at one side of the frame structure 10, in a manner such that the wheels ‘w’ moved adjacent to the frame structure 10 can be easily mounted to the wheel mounting parts 27 coupled to the lower ends of the upright members 24, and the wheels ‘w’ having undergone a polishing and finishing operation can be easily dismounted form the wheel mounting parts 27.

[0035] As best shown in FIG. 6, in the wheel mounting crane 40, a first rotation shaft 41 is installed on the upper platform 13 to be capable of being horizontally rotated in both directions, and a first horizontal lever 42 is fastened at one end thereof to the first rotation shaft 41 to extend in a horizontal direction. A second rotation shaft 43 is installed on the other end of the first horizontal lever 42 to be capable of being horizontally rotated in both directions; and a second horizontal lever 45 provided with a cylinder 44 is fastened at one end thereof to the second rotation shaft 43. A pulley 46 is connected to a distal end of a piston rod 44a of the cylinder 44 adjacent to the other end of the second horizontal lever 45. A wheel dragging wire 47 is secured at one end thereof to the second horizontal lever 45 and connected at the other end thereof to a wheel hanger 48. The wheel dragging wire 47 is partially wound on the pulley 46 and extends downward from the other end of the second horizontal lever 45.

[0036] The unexplained reference numeral 49 designates a control box unit for synthetically controlling the drive motor 20 and the respective cylinders.

[0037] In the drag type wheel finishing machine according to the present invention, constructed as mentioned above, if power is applied to start the polishing and finishing operation, a predetermined amount of abrasive polishing media is supplied into the abrasive polishing media bath 30 placed on the lift plate 31, and then, wheels ‘w’ are mounted to the respective wheel mounting parts 27 which are anchored to the lower ends of the upright members 24.

[0038] Describing a procedure for mounting the wheels ‘w’ to the wheel mounting parts 27 with reference to FIG. 1, the control box unit 49 is manipulated to extend the piston rod 44a out of the cylinder 44 to thereby lower the wheel hanger 48 connected to the other end of the wheel dragging wire 47 to the ground. Next, in a state wherein the wheel hanger 48 is hooked on the wheel ‘w’ which is moved adjacent to the frame structure 10, the cylinder 44 is operated to raise the wheel ‘w’. At this time, a worker grasps the wheel hanger 48 on which the raised wheel ‘w’ is hung and moves the wheel hanger 48 to a position which is close to the wheel mounting parts 27 by rotating the first and second horizontal levers 42 and 44 about the first and second rotation shafts 41 and 43. Thereupon, by fitting the wheel ‘w’ around one of the wheel mounting parts 27, the wheel ‘w’ is mounted to the wheel mounting parts 27.

[0039] If the wheels ‘w’ are mounted to the wheel mounting parts 27 in the above-described way, the drag type hydraulic cylinder 37 constituting the lift mechanism for the abrasive polishing media bath 30 is operated. By this fact, as the piston rod 37a of the drag type hydraulic cylinder 37 pulls the four wires 38a through 38d, the abrasive polishing media bath 30 is raised along with the lift plate 31. At this time, if the abrasive polishing media bath 30 is fully raised by the drag type hydraulic cylinder 37, the wheels ‘w’ which are mounted to the wheel mounting parts 27 coupled to the lower ends of the upright members 24 are held partially submerged into the abrasive polishing media.

[0040] In this state wherein the wheels ‘w’ are held partially submerged into the abrasive polishing media accommodated in the abrasive polishing media bath 30, as the drive motor 20 is actuated, the spindle 22 is rotated by way of the reduction gear box 21 of the drive motor 20. With this, the arms 23, the upright members 24 and the extended portion 22a which are integrated with the spindle 22 are also rotated.

[0041] Accordingly, as the wheels ‘w’ are revolved: along with the upright members 24, the wheels ‘w’ are polished through friction between the wheels ‘w’ and the abrasive polishing media. Due to this friction between the wheels ‘w’ and the abrasive polishing media, the wheels ‘w’ are rotated about their respective wheel mounting parts 27. In other words, since the wheels ‘w’ are polished while being simultaneously revolved and rotated, the entire surfaces of the wheels ‘w’ can be uniformly polished.

[0042] While the wheels ‘w’ are polished in this way, as the arms 23, the upright members 24 and the extended portion 22a are rotated by the spindle 22, water which serves as one constituent of the abrasive polishing media accommodated in the abrasive polishing media bath 30 is primarily prevented from leaking by the presence of the flexible seal strip 35 which are disposed between the abrasive polishing media bath 30 and the doors 32. In spite of the sealing function rendered by the flexible seal strip 35, water overflowed onto the lower guide wall 33b is returned into the abrasive polishing-media bath 30 through the hole 34 which is defined in the lower guide wall 33b. Therefore, leakage of water out of the abrasive polishing media bath 30 is avoided.

[0043] Further, since the rotation wings 22b which are formed on the extended portion 22a of the spindle 22 are also rotated, while the wheels ‘w’ mounted to the wheel mounting parts 27 coupled to the lower ends of the upright members 24 are rotated at a predetermined separation from the spindle 22, the abrasive polishing media collected toward the center of the abrasive polishing media bath 30 can be re-distributed in all directions, as a result of which uniform polishing of the wheels ‘w’ can be ensured and a polishing time can be shortened.

[0044] In the course of polishing the wheels ‘w’, if the control box unit 49 is manipulated to operate the upright hydraulic cylinders 26, as piston rods of the upright hydraulic cylinders 26 are extended and retracted out of and into the upright hydraulic cylinders 26, the upright members 24 are rotated about the pins 25. Due to this fact, because the wheels ‘w’ mounted to the wheel mounting parts 27 coupled to the lower ends of the upright members 24 are also rotated, it is possible to rotate the wheels ‘w’ to an optimal angle with respect to the arms 23. Therefore, since the friction between the wheels ‘w’ and the abrasive polishing media bath 30 is effectively promoted, polishing efficiency of the wheels ‘w’ is improved, and due to this fact, it is possible to complete the polishing and finishing operation within a short period of time.

[0045] If the polishing and finishing operation for the wheels ‘w’ is completed, the control box unit 49 is manipulated so that the piston rod 37a of the drag type hydraulic cylinder 37 installed on the lift plate 31 is extended out of the drag type hydraulic cylinder 37, by which the lift plate 31 is lowered along with the abrasive polishing media bath 30. Thereafter, the wheels ‘w’ are dismounted using the wheel mounting crane 40 from the wheel mounting parts 27 coupled to the lower ends of the upright members 24. A procedure for dismounting the wheels ‘w’ from the wheel mounting parts 27 using the wheel mounting crane 40 is performed in a reverse order to the above-described wheel mounting procedure.

[0046] FIG. 8 is a partial enlarge view illustrating a variation of the wheel mounting crane in the drag type wheel finishing-machine according to the present invention. In the wheel mounting crane, a crane body 50 is arranged on the upper platform 13 of the frame structure 10 to be capable of being horizontally rotated in both directions. A quadric wheel moving lever 51 is installed on the crane body 50 to be pivoted in upward and downward directions. A crane cylinder 52 is secured to the crane body 50 to pivot the wheel moving lever 51 in the upward and downward directions, and a wheel gripper 53 is provided to a distal end of the wheel moving lever 51 to selectively grip the wheels ‘w’.

[0047] In the wheel mounting crane constructed as mentioned above, first, by operating the crane cylinder 52, the wheel gripper 53 is raised or lowered to hold the wheel ‘w’. Then, by operating again the crane cylinder 52, the wheel ‘w’ is raised. Next, as a worker pushes the wheel ‘w’ to a desired position, the crane body 50 is rotated, and thereby, it is possible to mount and dismount the wheels ‘w’ to and from the wheel mounting parts 27 of the upright members 24.

[0048] Industrial Applicability

[0049] As apparent from the above description, the drag type wheel finishing machine according to the present invention, constructed as mentioned above, provides advantages in that a media bath along with a lift structure is guided by four columns and supported by four wires which extend downward from upper ends of the respective columns, and one ends of the four wires are connected to a distal end of a piston rod of a drag type hydraulic cylinder. Therefore, it is possible to stably maintain the balance of the media bath.

[0050] Further, due to the fact that a sliding door is installed on the media bath, space occupation can be diminished when opening and closing the door. Therefore, a sufficient work space can be secured, and leakage of water between the media bath and the door is effectively prevented. Also, in the present invention, because upright members are connected to arms by means of pins and hydraulic cylinders connect the upright members to distal ends of the arms, a wheel mounting angle, that is, a wheel polishing angle can be adjusted, whereby it is possible to conduct a polishing operation under a condition where friction between abrasive polishing media and the wheels is maximized and an optimal polishing angle is maintained.

[0051] Moreover, in the present invention, by the fact that rotation wings are formed on a lower end of a spindle which is positioned centrally of the plurality of upright members, while the wheels mounted to wheel mounting parts coupled to lower ends of the upright members are revolved and rotated, the abrasive polishing media collected toward a center of the media bath can be re-distributed in all directions, whereby the wheel polishing and finishing operation can be uniformly implemented.

[0052] Furthermore, since a crane which employs a cylinder is installed at a side of a frame structure, it is possible to simply and conveniently mount and dismount the wheels to and from wheel mounting shafts of the wheel mounting parts.

[0053] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A drag type wheel finishing machine in which a spindle extending downward is connected to and rotated integrally with a velocity-reduced output shaft of a drive motor secured to an upper platform of a frame structure, a plurality of arms horizontally extending in respective four directions are mounted adjacent to a lower end of the spindle, upright members are joined to respective distal ends of the arms to extend downward, wheel mounting parts for mounting wheels are mounted to respective lower ends of the upright members, and an abrasive polishing media bath is placed in the frame structure to be raised and lowered by a lift mechanism, wherein the lift mechanism of the abrasive polishing media bath is configured in a manner such that the abrasive polishing media bath can be raised and lowered while being guided by four columns and supported by four wires extending downward from upper ends of the respective columns, and wherein one ends of the wires are connected to a distal end of a piston rod of a drag-type hydraulic cylinder installed on the abrasive polishing media bath in a manner such that, when the wires are simultaneously pulled via the piston rod, the abrasive polishing media bath is raised.

2. The machine as set forth in claim 1, wherein the arms and the upright members are connected with each other by pins in a manner such that the upright members can be pivoted relative to the arms, and upright hydraulic cylinders connect the upright members to the arms in a manner such that the upright members can be adjusted in their respective angular positions.

3. The machine as set forth in claim 1, wherein a sliding door is installed on the abrasive polishing media bath to be guided in a circumferential direction while being opened and closed, upper and lower guide walls are formed on the abrasive polishing media bath to receive upper and lower ends of the sliding door, respectively, the lower guide wall has a Y-shaped section which has a hole for allowing water that has overflowed onto the lower guide wall to be returned into the abrasive polishing media bath, and a flexible seal strip to be brought into contact with the sliding door is affixed to an inner surface of the abrasive polishing media bath to reduce an amount of water overflowing onto the lower guide wall.

4. The machine as set forth in claim 1, wherein rotation wings are formed on the lower end of the spindle and extend downward to reach the same level as the lower ends of the upright members, in a manner such that, when the wheels mounted to the wheel mounting parts of the upright members are rotated, abrasive polishing media collected toward a center of the abrasive polishing media bath can be redistributed in all directions.

5. The machine as set forth in claim 1, wherein the upper platform of the frame structure is provided with a wheel mounting crane for mounting and dismounting the respective wheels to and from the wheel mounting parts; and wherein the wheel mounting crane comprises a first rotation shaft installed on the upper platform to be capable of being horizontally rotated in both directions, a first horizontal lever fastened at one end thereof to the first rotation shaft to extend in a horizontal direction, a second rotation shaft installed on the other end of the first horizontal lever to be capable of being horizontally rotated in both directions, a second horizontal lever fastened at one end thereof to the second rotation shaft and provided with a cylinder, a pulley connected to a distal end of a piston rod of the cylinder adjacent to the other end of the second horizontal lever, and a wheel dragging wire having one end which is secured to the second horizontal lever and the other end which is connected to a wheel hanger, the wheel dragging wire wound on the pulley, and extending downward from the other end of the second horizontal lever.

6. The machine as set forth in claim 1, wherein the upper platform of the frame structure is provided with a wheel mounting crane for mounting and dismounting the respective wheels to and from the wheel mounting parts; and wherein the wheel mounting crane comprises a crane body arranged on the upper platform to be capable of being horizontally rotated in both directions, a quadric wheel moving lever installed on the crane body to be pivoted in upward and downward directions, a crane cylinder secured to the crane body to pivot the wheel moving lever in the upward and downward directions, and a wheel gripper provided to a distal end of the wheel moving lever to selectively grip the wheels.