Patent Publication Number: US-7721857-B2

Title: Arrangement related to a swing damper

Description:
The present invention relates to an arrangement pertaining to a swing damper according to the preamble of Claim  1 . The invention also relates to a method. 
   In conjunction with the use of swing dampers for supporting different types of tools suspended from a crane arm for example, it is endeavoured to achieve effective and reliable braking or damping of the pendulating/swinging movement that normally occurs when, for instance, manoeuvring the crane arm in carrying out different tasks. 
   Swing dampers can be used in connection with all conceivable types of tool that hang from the tip of a crane arm or jib, for example in respect of forest harvesters, forwarders, forest processors, timber cranes, excavating or digging machines, specialty machines, and so on. The swing damper may have a single and/or a double action, i.e. it can dampen/retard movement in one or two pendulous/swinging planes. 
   One object of the present invention is to provide a highly beneficial braking arrangement in respect of swing dampers, and also to provide a braking method. These objects are fulfilled by means of the arrangement and the method having the characteristic features set forth in respective accompanying Claims. 
   The following advantages are examples of the many advantages afforded by the present invention. 
   A swing damper that includes an inventive arrangement has a compact form. 
   There is achieved a smooth braking action and uniform wear of the wear-subjected components of the braking arrangement, and also highly beneficial bearing mounts from the aspect of load support among other things. 
   The brake arrangement has a long useful life and long adjustment intervals are made possible. The braking arrangement can be readily serviced. 
   Basic setting of desired braking moments can be readily achieved, as can also any required subsequent adjustment to the braking arrangement. 
   Braking elements can be replaced without needing to dismantle the tool from the tip of the crane arm. 
   Tensioning means/braking means and bearings are independent of each other. Replacement of disc brake units is effected quickly and effectively from the side, resulting in short service stoppages. 
   Inventive arrangements can be used in connection with both single-type and double-type swing dampers. 
   The position in which the disc brake unit is placed means that the unit will be protected against mechanical damage. The brake arrangement can be readily fitted in a subsequent process. 
   The inventive arrangement affords both technical and economical advantages. 

   
     Exemplifying embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which 
       FIG. 1  is a perspective view of an inventive arrangement fitted to the tip of a crane arm and supporting a gripping tool, 
       FIG. 2  is an exploded perspective view showing a first embodiment of a swing damper that includes an inventive arrangement, 
       FIG. 3  is a vertical sectional view of a pivot joint according to  FIG. 2 , 
       FIG. 4  is a vertical sectional view of the arrangement shown in  FIG. 2 , 
       FIG. 5  is a vertical sectional view of the brake arrangement shown in  FIGS. 2 and 4 , 
       FIG. 6  is an exploded perspective view of a second embodiment of a swing damper that includes an inventive arrangement, 
       FIG. 7  is a vertical sectional view of the brake arrangement shown in  FIG. 6 , and 
       FIG. 8  is a vertical sectional view of a third embodiment of the brake arrangement. 
   

     FIG. 1  shows an inventive swing damper  1  that is pivotally mounted on the tip of a crane arm  2  through the medium of a pivot joint/bearing  3 . The swing damper  1  carries at its lower end a rotator  4 , which, in turn, carries a tool in the form of a gripping device  5 . 
   The pivot joint/bearing  3  permits free pendulous movement/pivotal movement about a shaft  6  and the rotator  4  enables the gripping device  5  to be maneuvered rotatably, said rotator being driven hydraulically in the illustrated embodiment. Hydraulic hoses connected to the rotator and the gripping device have not been shown for the sake of clarity. 
   The swing damper  1  includes an upper part  11 , which is connected to the crane arm  2  for free pivotal movement relative thereto, via the pivot joint  3 . The swing damper  1  also includes a bottom part  12 , which carries the tool  5 , via the rotator  4  for instance. The upper part  11  includes an attachment lug  15 , which co-acts with the pivot joint  3 . The bottom part  12  includes an attachment  16  for attachment of the rotator  4  or, alternatively, for direct connection to the tool  5 . 
   The upper part  11  and the bottom part  12  are pivotally connected to each other via a pivot bearing  13 , wherewith relative pivotal movement of the upper part  11  and lower part  12  is effected about a pivot shaft  14 . The pivot shaft  14  is generally positioned at right angles to the pivot shaft  6 . This provides the mobility desired of the tool  5 . 
   The swing damper  1  includes a brake arrangement  50  which functions to dampen relatively quickly the swinging movement of the tool  5  when manoeuvring the crane arm wherewith the swinging movement about the pivot shaft  14  is retarded in the way desired. 
   The brake arrangement  50  included in the swing damper  1  has the form of a disc brake assembly, which is described in more detail hereinafter. 
   In the case of the illustrated embodiment, the upper part  11  comprises two downwardly facing attachment lugs  20 , 21  and an abutment surface, or shoulder,  22  disposed between said lugs. The attachment lugs  20 , 21  include a circular hole  23 , each of which accommodates a respective circular plain bushing or sliding bearing bushing  24 . 
   The lower part  12  includes four upwardly facing attachment lugs  30 - 33  which engage the downwardly facing lugs  20 , 21  in a forked-like fashion, as will be evident from the figures. A lower abutment surface or shoulder  34  is disposed between the upwardly facing lugs  31  and  32 . The outermost lugs  30 , 33  include a circular hole  35  and the innermost lugs  31 , 32  include a circular hole  36 . The hole  36  includes a circular countersink  37  of larger diameter than that of the hole  36 , as will be evident from the figures. 
   The upper part  11  and the lower part  12  are pivotally joined and held together by two supportive sleeves  40 , 41 . The sleeves  40 , 41  each include an outer flange  42  which lies in abutment with the outer surface of respective outer lugs  30 , 33 , wherein said sleeves  40 , 41  are fixed in position by means of a locking ring  43  received in the countersink  37  of the inner lugs  31 , 32 . The locking rings  43  are anchored to the sleeves  40 , 41  by means of a number of locking screws  44 , wherein the locking rings  43  include countersinks for receiving the heads  45  of the screws  44 . The aforesaid assembly provides a self-holding and load-supporting transfer between the upper part  11  and the lower part  12 , wherewith said parts  11 , 12  are able to pivot by virtue of a sliding bearing surface  46  located between the sliding bearing bushings  24  and the sleeves  40 , 41 . The construction of the pivot bearing  13  will be apparent from  FIG. 3 . 
   The brake arrangement  50  is, in accordance with the invention, designed to brake or retard the pivotal movement between the upper part  11  and the lower part  12 . 
   The inventive brake arrangement  50  can be fitted readily to the pivotal joint  13  shown in  FIG. 3 . 
   The brake arrangement  50  includes a brake unit  60  which comprises a central brake disc  70 , which includes a brake lining, and two outer brake discs  80 . 
   The central disc  70  includes an upper abutment surface  71  that abuts with the upper abutment surface  22  between the downwardly facing attachment lugs  20 , 21  of the upper part  11 . This ensures that the disc  70  will be locked against rotation relative to the upper part  11 . The lower portion of the disc  70  has a semi-circular rounding  72  that enables the disc  70  and the lower part  12  to swing relative to one another. The disc  70  also includes a circular centre hole  73 , which accommodates a bearing  74 , for instance a ball bearing. It is, of course, possible to use other types of bearings. The brake disc  70  carries annular brake linings  75  on its respective side surfaces, as evident from the figures. 
   The outer brake discs  80  include a lower abutment surface or shoulder  81 , which abuts with the lower abutment surface or shoulder  34  between the upwardly facing attachment lugs  31  and  32  on the lower part  12 . This ensures that the brake discs  80  will be locked against rotation relative to the lower part  12 . The upper portion of the brake discs  80  has a semi-circular rounding  82  which enables the brake discs  80  and the upper part  11  to pivot relative to one another. The brake discs  80  includes a circular centre hole  83 . 
   The brake arrangement  50  also includes a tensioning element which functions to compress the brake unit  60  when braking. 
     FIGS. 2 ,  4  and  5  illustrate a double-sided tensioning element  90 , which is based on the action of a spring force.  FIGS. 6 and 7  illustrate a double-sided tensioning element  110  which is based on the action of a pressurised medium.  FIG. 8  illustrates a single-sided tensioning element  130 , which is based on the action of a spring force. 
   As will be seen from  FIGS. 2 ,  4  and  5 , the tensioning element  90  is comprised of two force-transmitting circular sliding sleeves  91 , 92  disposed within the carrier sleeves  40 , 41  and within the locking rings  43 . One end of the sliding sleeves  91 , 92  abuts said outer brake discs  80  and the other end abuts a spring-force-exerting device in the form of a spring pack  93 , 94  consisting of mutually opposed cup springs  101 . A circular centre tube  95  is disposed inside the sliding sleeves  91 , 92 . The centre tube  95  has a threaded centre hole  96  and two end recesses  97 . The centre tube  95  extends through the centre hole  83  in the brake discs  80  and also through the centre hole in the bearing  74  of the central disc  70 . One purpose of the centre tube  95  is to centre the brake unit  60  relative to the pivot shaft  14  and to take-up the shear forces generated during a braking action. Desired braking torque is set by tightening screws  98 , 99  whose heads act to compress the spring pack  93 , 94 , wherewith the threaded end of respective screws engage the threaded centre hole  96  of the centre tube  95 . Maximum tightening of the screws is limited by a circular spacing sleeve  100  which surrounds the screws  98 , 99 , wherewith one end of the sleeves  100  abuts the screw head and the other end of the sleeves comes into contact with the bottom of respective end recesses  97  in the centre tube  95  when reaching maximum tightening of the screws. If desired, the spacing sleeves  100  can be formed in one piece with the screws  98 , 99 . 
   In  FIG. 4 , the screw  98  is shown in a maximum tightened state, whereas the screw  99  is shown in a state at the beginning of a tightening stage.  FIG. 5  shows both screws  98 , 99  tightened to a maximum. 
   It will be seen that a desired braking torque or braking force can be set by appropriate tightening of the screws  98 , 99 . It will be understood that by using a relatively large number of cup springs  101  in the spring packs  93 , 94 , it is possible to decrease the rate at which braking torque/braking force is reduced when the brake linings  75  become worn, which results in longer time intervals between subsequent adjustments to the braking torque required as a result of such wear. Thus, the desired braking effect can be achieved by virtue of the spring packs  93 , 94  compressing the brake unit  60  via the sliding sleeves  91 , 92 , so as to press the discs  70  and  80  together. 
   It will be understood that the described tensioning element  90  can be constructed in many different ways. For example, the spring force/pre-tensioning force can be obtained with the aid of helical springs or some other type of spring means. Moreover, the tensioning element can be comprised of different components than those described, within the concept of the invention 
   As shown in  FIGS. 6 and 7 , the tensioning element  110 , operated on the basis of a pressure medium, is comprised of a circular, sliding sleeve  111  which includes end-walls and which is disposed within the carrier sleeve  40  and its locking ring  43 . One end of the sliding sleeve  111  abuts one of the outer brake discs  80  and the sleeve  111  includes at its other end a hole-equipped end-wall  112 . A cylindrical tube  113  is disposed within the carrier sleeve  41  and its lock ring  43  and which includes two abutment surfaces or shoulders  114  and  115 . The abutment surface  114  is located within the carrier sleeve  41  and the lock ring  43 , while a further abutment surface  116  located between the shoulders  114  and  115  is in abutment with one of the outer brake discs  80 , as shown in  FIG. 7 . The abutment surface  115  extends through the centre holes  83  in said brake discs  80  and also through the centre hole in the bearing  74  of the central disc  70 . The free end of the abutment surface/shoulder  115  extends into the slide sleeve  111 . The cylindrical tube  113  includes two circular centre holes  117  and  118 . The centre hole  117  serves as a pressure-medium cylinder that houses a plunger  120 . The plunger  120  carries a pull rod  121  whose free end  122  is anchored to the end-wall  112  of the sliding sleeve  111  by means of a nut  123 . A pressure chamber  124  is located between the plunger  120  and the cylindrical tube  113 , this arrangement including, of course, the necessary seals. The supply of pressure medium to the pressure chamber  124  is effected through the means of a hydraulic line connection  125 . Thus, the braking torque can be set to a desired magnitude, by controlling the pressure of the medium delivered to the pressure chamber  124 . A desired braking effect is obtained by compression of the brake unit  60  by means of the sliding sleeve  111  and the cylindrical tube  113  through the action of said pressure medium, therewith pressing the discs  70  and  80  together. Such pressure medium control can also be achieved to enable the braking torque to be varied in accordance with requirements and to achieve a specially-adapted braking pattern, which can be automated. 
   It will also be understood that the design of the tensioning element  110  described above can also be varied in many ways within the scope of the inventive concept. 
   The tensioning element  130  illustrated in  FIG. 8  is constructed in accordance with the same basic concept as that applied with regard to the tensioning element  90 . In the case of the  FIG. 8  embodiment, the centre tube  131  of the tensioning element  130  includes an end flange  132  which lies in abutment with one of the outer brake discs  80 . The single-sided tensioning element  130  enables a side space  201  in the brake unit  60  to be used for location of a cable and/or a hose for instance, or for some other purpose. A pressure-medium-based tensioning element  110  can be made single-sided in a corresponding manner, if so desired. The presence of a side space  201  is indicated in chain lines in  FIG. 8 . 
   Thus, the brake unit  60  can fill the space  200  between the lugs  31  and  32 , either completely or partially, see  FIG. 3 . 
   It will be understood from the aforegoing that the outer brake discs  80  accompany the movement of the lower part  12  and that the central disc  70  accompanies the movement of the upper part  11 , wherewith compression of the brake discs results in braking of the swinging movement between the upper part  11  and the lower part  12 . When wishing to increase the braking effect, the brake unit  60  of the brake arrangement  50  may, of course, be provided with several inventive brake disc assemblies, etc. 
   It will be noted that worn brake discs can be replaced very readily, since it is only necessary to dismantle and remove the tensioning devices concerned, therewith enabling the brake unit  60  to be removed sideways, as illustrated in  FIGS. 2 and 6 . A new brake unit  60  is then fitted from one side and the tensioning element concerned is then mounted in place, and so on. Thus, brake discs can be replaced without needing to remove the carrier sleeves  40 , 41  and the locking rings  43 . The pivot bearing  13  is thus not affected by a brake unit change. This is highly beneficial from a servicing aspect. 
   In the illustrated embodiments, the disc  70  carrying said brake lining has been secured against rotation relative to the upper part  11  and the brake discs  80  have been secured against rotation relative to the lower part  12 . It will be understood, however, that it lies within the framework of the inventive concept to secure the disc  70  against rotation relative to the lower part  12  and to secure the brake discs  80  against rotation relative to the upper part  11 , even though this structural solution is less beneficial. It will also be understood that the number of discs or the number of brake units can be varied as required and desired, as can also the positioning of the brake linings within the brake unit. 
   In the case of a simplified embodiment, there can be used a brake unit that includes one single brake disc  80  and one single disc  70  which includes a brake lining, wherewith the brake lining  75  is disposed in this case only on that side of the disc  70  which faces towards the brake disc  80 . The tensioning element is designed to press the brake disc  80  against the disc  70  in conjunction with a braking operation. 
   It will be noted that many structural variations can be made within the scope of the present invention. 
   Although the swing damper of the illustrated embodiment is a single-type damper, it will be understood that the inventive arrangement can also be used in a double-type damper, wherewith swinging movement about the pivot bearing  3  and the pivot bearing  13  can be dampened by means of inventive arrangements. 
   It will also be understood that the described components of the swing damping arrangement can be replaced with functionally equivalent components within the framework of the inventive concept. It is, of course, possible to vary the choice of material. 
   It will also be noted that the lower part  11  can be integrated with, e.g., an underlying rotator  4 , which will then also include certain rotator components. 
   Thus, the invention is not restricted to the illustrated and described embodiment, since changes and modifications are possible within the scope of the accompanying Claims.