Patent Publication Number: US-7213317-B2

Title: Shaft pushing device

Description:
FIELD OF THE INVENTION 
   The present invention relates to a shaft pushing device with a driving mechanism for adjusting pawls of the pushing device. 
   BACKGROUND OF THE INVENTION 
   For a conventional transmission mechanism including a shaft and a gear for example, the gear is securely mounted to the shaft so as to transfer torque via the gear. A conventional shaft pushing device is used to separate the shaft from the gear when in maintenance. Due to the secured connection between the gear and the shaft, the shaft pushing device has to hold the gear while pushing the shaft from the gear. The convention shaft pushing device generally includes an operation portion and a plurality of pawls which are pivotably connected to the operation portion. A push rod is connected to the operation portion which is extended by operating the operation portion and pushes against an end of the shaft. The user then carefully rotates a nut of the operation portion to control the pivotal movement of the pawls to grasp the gear. During the operation of the nut, the user has to frequently check the pawls to make sure that the pawls are positioned at desired positions on the shaft. The pawls often move off from the shaft when the user operates the nut. This takes a lot of time and could damage the shaft. 
   The present invention intends to provide a shaft pushing device that includes an adjusting mechanism which is movably mounted to the threaded tube of the shaft pushing device and easily controls the movement of the pawls to grasp the gear. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a shaft pushing device that comprises a driving mechanism having a threaded tube with a threaded outer periphery and a push rod movably extends through the threaded tube. A distal end of the push rod extends out from an end of the threaded tube and is used to push against a shaft. A grasp mechanism has a first ring threadedly mounted to the threaded tube and a plurality of pawls are pivotably connected to the first ring. Each pawl has a hook end so as to grasp a gear. An adjusting mechanism has an adjusting nut threadedly mounted to the threaded tube and located between the first ring and the distal end of the push rod. A second ring is mounted to the adjusting nut and a plurality of stretch rods are pivotably connected between the pawls and the second ring. 
   The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view to show the shaft pushing device of the present invention; 
       FIG. 2  is a cross sectional view to show the shaft pushing device of the present invention; 
       FIG. 3  is an enlarged cross sectional view to show the connection of the adjusting mechanism and the threaded tube of the shaft pushing device of the present invention; 
       FIG. 4  shows that the pawls grasp the gear and the push rod pushes the shaft from the gear; 
       FIG. 5  is a perspective view to show another embodiment of the shaft pushing device of the present invention, and 
       FIG. 6  is a cross sectional view to show the shaft pushing device in  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 to 4 , the shaft pushing device of the present invention comprises a driving mechanism  2 , a grasp mechanism  3  and an adjusting mechanism  6 . The driving mechanism  2  includes a threaded tube  21  with a threaded outer periphery and a central passage  22 . A driving device  4  is connected to an end of the threaded tube  21  and can be a hydraulic or pneumatic cylinder which includes a piston rod  41  movably extending into the threaded tube  21 . A push rod  1  has one end in contact with the piston rod  41  and received in the threaded tube  21 , and a distal end  11  of the push rod  1  extends out from the other end of the threaded tube  21 . 
   The grasp mechanism  3  includes a first ring  31  threadedly mounted to the threaded tube  21  and a plurality of first extensions  311  extend radially from the first ring  31 . A plurality of pawls  5  are pivotably connected to the first extensions  311  and each pawl  5  has a hook end  51 . 
   The adjusting mechanism  6  includes an adjusting nut  61  threadedly mounted to the threaded tube  21  and located between the first ring  31  and the distal end  11  of the push rod  1 . A second ring  62  includes a recess  622  defined in an underside thereof with which the adjusting nut  61  is engaged. The second ring  62  includes a first groove  621  defined in an inner periphery thereof and the adjusting nut  61  includes a second groove  611  defined in an outer periphery thereof. A C-clamp  6  is engaged with the first groove  621  and the second groove  611  which is located in alignment with the first groove  621  such that the adjusting nut  61  and the second ring  62  are connected with each other. The second ring  62  includes a plurality of second extensions  63  extending radially therefrom and a plurality of stretch rods  64  are pivotably connected between the second extensions  63  and respective middle portions of the pawls  5 . 
   As shown in  FIG. 4 , when operating the shaft pushing device, the adjusting nut  61  is rotated to move the second ring  62  along the threaded tube  21 , and the pawls  5  are then pivoted by the stretch rods  64  to grasp a gear  8  by the hook ends  51 . The user then activates the driving device  4  to push the push rod  1  to push an end of the shaft  81  which is then disengaged from the gear  8 . During the operation, the user simply focuses on the grasp of the pawls  5  to the gear  8  and needs not to check the action of the driving device  4 . The procedures of operation of the shaft pushing device is simplified. 
     FIGS. 5 and 6  show another embodiment of the present invention, wherein the threaded tube  21  includes a threaded inner periphery and the push rod  1  is threadedly connected to the threaded inner periphery of the threaded tube  21 . A driving device  9  is connected to the push rod  1  and can be a motor for rotating the push rod  1 . The push rod  1  can also be rotated manually. 
   While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.