Patent Publication Number: US-8533923-B2

Title: Method and device for chain wheel change

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a National Phase entry of PCT Application No. PCT/NO2009/000147, filed 16 Apr. 2009 which claims priority to Norwegian Application No. 20081890, filed 21 Apr. 2008, both of which are incorporated herein by reference. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     A method for a chain wheel change is provided. More particularly it relates to the change of a chain wheel which is on an axle. There is also provided a device for practising the method. 
     A chain wheel which is used to handle an anchor chain on board a vessel often needs to be changed to work together with a chain of a different dimension. A chain wheel is subjected to considerable wear and thereby constitutes a wear part which must be replaced from time to time or be brought to a workshop for repair. Chain wheels of this kind are relatively big and heavy. 
     According to the prior art, chain wheels are removed and fitted by means of lifting tools and manually operated equipment, which may be fraught with danger, especially when the vessel is subjected to heavy sea. Thus, it is usual to go to shore, where chain wheels may be handled in a safe way within the relatively limited space available. 
     An interruption to change a chain wheel entails considerable costs. 
     The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art. 
     The object is achieved according to the invention through the features which are specified in the description below and in the claims that follow. 
     SUMMARY OF THE PREFERRED EMBODIMENTS 
     A method for a chain wheel change is provided, a first chain wheel being on an axle, and the method being characterized by including:
         arranging a hydraulic cylinder at the axle;   moving the first chain wheel off the axle by means of the cylinder;   connecting the first chain wheel to a conveying device while it is held in position by the cylinder;   connecting a second chain wheel to the cylinder while it is held in position by the conveying device; and   moving the second chain wheel onto the axle by means of the cylinder.       

     It is possible to let the cylinder constitute a guide for the respective chain wheels during their movement to and from the axle. 
     The method may include placing the first chain wheel in a suitable storage place after disconnection from the cylinder. 
     For the method to be practised, a device is provided which is characterized by the hydraulic cylinder being fixed to the axle while the cylinder is being connected to the first chain wheel by means of an adapter. 
     The cylinder may be placed, at least partially, in the axle, which contributes to a relatively compact construction. 
     The cylinder may constitute a guide for the chain wheel. This may help the chain wheel to be moved steadily. 
     The cylinder may cooperate with a conveying device, the first chain wheel being connected to the cylinder during connection to the conveying device. There is thereby insignificant risk of the chain wheel moving during this part of the operation. 
     The adapter may complementarily fit the cylinder and the conveying device, the conveying device possibly being constituted by a carriage running on rails. 
     It is advantageous, but no condition, for the entire cylinder to be inside the bore of the axle. However, the cylinder should be constructed in such a way that it can absorb the bending moments arising because of the weight of the chain wheel. 
     The method and device provided make it possible for a chain wheel replacement to be carried out while the chain wheel is connected to either the cylinder or the conveying device. The replacement may thereby be carried out in a controlled manner without the risk of the chain wheel moving unintendedly. This reduces to a substantial extent the risk of injuries and also provides for the replacement of chain wheels while the vessel is in the open sea. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In what follows is described an example of a preferred embodiment which is visualized in the accompanying drawings, in which: 
         FIG. 1  shows, in perspective, a chain wheel which is on an axle; 
         FIG. 2  shows an axial section of the chain wheel and axle; 
         FIG. 3  shows the same as  FIG. 2  but after the chain wheel has been moved somewhat outwards on the axle; 
         FIG. 4  shows the same as  FIG. 2  but after the chain wheel has been moved completely off the axle; and 
         FIG. 5  shows the same as  FIG. 2  but after the chain wheel has been released from the axle and is ready to be carried away. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the drawings the reference numeral  1  indicates a chain wheel which is on a flanged axle  2  in  FIG. 1 . A driving portion  4  of the bore  6  of the chain wheel  1  is given a cornered shape which complementarily fits the axle  2 . The axle  2  forms part of an anchor winch  8 . 
     Normally, a first chain wheel  1   a  is replaced with a second chain wheel  1   b . In this detailed description both chain wheels  1   a ,  1   b  are indicated by “chain wheel  1 ”. 
     A hydraulic cylinder  10  is positioned in an axial bore  12  in the axle  2 . The bore  12  is open at the free end portion  14  of the axle  2 . The cylinder  10 , which is, with advantage, removed from the axle  2  during normal operation, is connected to the axle  2  by means of a first bolt connection  16  which may include several bolts. 
     The cylinder  10  comprises a cylinder housing  18  with a first guide sleeve  20  and a piston rod  22  which is movable in the guide sleeve  20  and which is connected to a piston  24 . The piston  24  is movable in the cylinder housing  18 . Necessary seals in the guide sleeve  20  and piston  24  are not shown. The piston  24  divides the cylinder housing, in a known manner, into a plus chamber  26  and a minus chamber  28 . The guide sleeve  20  and piston  24  constitute slide bearings against their respective abutments. 
     A first liquid bore  30  extends axially through the piston rod  22  and ends in the plus chamber  26  whereas a second liquid bore  32  in the piston rod  22  ends in the minus chamber  28 . 
     The liquid bores  30 ,  32  are connected, in a manner known per se, to a hydraulic aggregate not shown. 
     The piston rod  22  is connected by means of a second bolt connection  34  to an adapter  36 , the adapter  36  being connected to the chain wheel  1  by means of a threaded connection not shown. 
     The adapter  36  also fits a conveying device  38  in the form of a carriage and can be connected to the conveying device  38  by means of a third bolt connection  40 , see  FIG. 4 . 
     The conveying device  38  is provided with castors  42  running in horizontal rails  44  on an adjacent structure  46 . 
     In  FIG. 2  is shown a guide mandrel  48 . This is used when the chain wheel  1  is to be steered onto the axle  2 , to ensure that the chain wheel  1  will be in the desired rotational position relative to the axle  2 . 
     When a chain wheel  1  is to be changed after securing means, not shown, between the chain wheel  1  and axle  2  have been removed, the cylinder  10  is positioned in the bore  12  of the axle  2  and fixed to the axle  2  by means of the first bolt connection  16 . 
     Subsequently, the adapter  36  is fitted to the chain wheel  1  and to the piston rod  22  by means of the second bolt connection  34 , see  FIG. 2 . 
     Pressure fluid is then carried via the first liquid bore  30  to the plus chamber  26 , whereby the piston  24  moves the piston rod  22 , adapter  36  and thereby the chain wheel  1  outwards on the axle  2 , see  FIG. 3 . 
     On further movement, the adapter  36  hits the conveying device  38  and is secured to the conveying device  38  by means of the third bolt connection  40 , see  FIG. 4 , in which the chain wheel  1  has been moved off the axle  2 . 
     The piston rod  22  is disconnected from the adapter  36  by removal of the second bolt connection  34 . By applying pressure fluid to the minus chamber  28  via the second liquid bore  32  while the chamber  26  is simultaneously being drained via the first liquid bore  30 , the piston rod  22  is moved into the cylinder housing  18 . The chain wheel  1  may then be moved along the rails  44  transversally to the axle  2 , see  FIG. 5 . 
     When a chain wheel  1  is to be fitted on the axle  2 , the operation is carried out as described above, but in the reverse order. As mentioned, the guide mandrel  48  is used to simplify the assembly work.