Abstract:
A tool to facilitate removal of a pitman-arm mounted on a shaft includes a main frame member with a threaded center drive rod and radially spaced, depending retention arms pivotally suspended from the frame member. Rotation of the threaded drive rod causes a wedge section at the leading end of the drive rod to separate the legs of the pitman-arm as the retention arms hold the tool in place on the pitman-arm.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     In a principal aspect, the present invention relates to a tool especially useful for the removal of a steering gear pitman-arm from a shaft, more particularly a steering gear pitman-arm of the type having opposed slightly spaced legs wherein the legs define a shaft opening and the arm is retained on the shaft by means of a bolt which is positioned in a bore adjacent to and transverse to the shaft opening in the pitman-arm.  
         [0002]     Pitman-arms of various size and configuration are utilized in vehicles to transfer motion, for example, rotary motion to longitudinal motion. Typically the pitman-arm includes a throughbore or passage capable of receiving a shaft, for example, a driving shaft. One end of the arm is mounted on the shaft and the opposite end of the arm is attached to another element of the vehicle. Pitman-arms utilized in larger or heavy duty vehicles are massive; being not only structurally large, but quite heavy and cumbersome. Typically such pitman-arms include a shaft opening defined by a pair of opposed, slightly spaced legs. The arm is mounted on a shaft and retained thereon by means of a bolt located in a bore through the legs adjacent to and transverse to the shaft. The bolt tightens the legs on the shaft.  
         [0003]     When repairing or servicing a vehicle having a heavy duty pitman-arm, it is often desirable to remove the pitman-arm. This is initially accomplished by removing the retention bolt. However, corrosion of the component parts of the vehicle may preclude ease of removal of the pitman-arm from the shaft. Therefore additional leverage is required. For example, some mechanics will attempt to drive a hand wedge between the arms forming the shaft opening in the pitman-arm. This, however, is considered to be somewhat dangerous inasmuch as the wedge may slip from its position and is not easily guided when attempting to spread the legs. Thus, there has developed a need for a tool which will facilitate removal of a pitman-arm of a type having opposed legs defining a shaft opening.  
       SUMMARY OF THE INVENTION  
       [0004]     Briefly, the present invention comprises a tool for spreading the opposed legs of a pitman-arm wherein those legs include or define a shaft opening for attachment of the arm to a shaft. The tool includes a cross bar frame member with a center drive rod projecting axially through the frame member and lateral depending arms pivotally attached to the frame member. The arms include pin or rod sections designed to fit into the bolt bore in the end of the legs of the pitman-arm. A wedge member is provided at the end of the drive rod. The wedge member of the drive rod may then be inserted in the small opening or slot between the legs of the pitman-arm and driven or wedged between those legs by turning the threaded drive rod to spread the legs slightly so that the pitman-arm may be more easily removed from the shaft on which it is mounted.  
         [0005]     Thus it is an object of the invention to provide a tool which will facilitate removal of a pitman-arm from a shaft on which that arm is mounted.  
         [0006]     It is a further object of the invention to provide a tool which can be used in a manner considered to be safer than the prior art methodology of hand-driving a wedge between legs associated with the pitman-arm.  
         [0007]     Another object of the invention is to provide a tool that facilitates removal of a pitman-arm from a shaft which is easy to use, economical and rugged.  
         [0008]     These and other objects, advantages, and features of the invention will be set forth in greater detail in the description which follows.  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0009]     In the detailed description which follows, reference will be made to the drawing comprised of the following figures:  
         [0010]      FIG. 1  is a plan view of the tool of the invention;  
         [0011]      FIG. 2  is a plan view of a depending leg which is incorporated in the tool of  FIG. 1  as viewed from a side thereof;  
         [0012]      FIG. 3  is a plan view of the frame member of the tool of  FIG. 1  as viewed along the top end or edge of the tool;  
         [0013]      FIG. 4  is an exploded view of the drive rod or pusher bolt and wedge section or wedge member associated therewith;  
         [0014]      FIG. 5  is an isometric view of a typical pitman rod as mounted on a shaft;  
         [0015]      FIG. 6  illustrates the method of use of the tool of  FIG. 1  with respect to removal of a pitman rod of the type shown in  FIG. 5 ; and  
         [0016]      FIG. 7  is another prospective view illustrating the use of the tool of  FIG. 1 .  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     Referring to  FIGS. 1-4 , there is depicted a tool which is used to practice the method of the invention. The tool is comprised of a cross bar frame member  10  which has a first depending arm  12  pivotally attached to one side thereof and a second depending arm  14  attached to the opposite side thereof. The cross bar frame member  10  includes a threaded center throughbore  16  having a drive member or rod or pusher bolt  18  threaded therethrough and moveable along an axis  20  in response to turning bolt  18  in the threaded passage  16 . The bolt or drive rod  18  includes a polygonal or hexagonal cross section drive end  22 , a threaded rod or center section  24  and a ball-shaped forward end  26 . Attached to the ball-shaped forward end  26  is a spreader or wedge section or assembly  28  which includes a leading edge wedge  29  and a counterbore  31  to receive end  26 . A locking pin or washer  35  fits into a slot  38  to retain the wedge member  28  on the drive rod  118  ball end  26 . Thus the wedge member  28  may be freely rotated about the axis  20  and may also move a certain limited amount about the axis  20  so as to align effectively between the legs of a pitman-arm.  
         [0018]     The depending arms  12 ,  14  are mounted respectively equally from and on opposite sides of the centerline axis  20  in the frame member  10 . Thus, the frame member  10  includes a first pair of generally radially extending arms  30 ,  32  defining a first yoke and a second pair of generally radially extending arms  34 ,  36 . The arms  34 ,  36  extend in opposite directions respectively from the arms  30 ,  32 . As depicted in  FIG. 3 , the arms  30 ,  32 ,  34 ,  36  are symmetrical with respect to the axis  20 . The arms  30 ,  32  as well as the arms  34 ,  36  are spaced one from the other so that the depending arms  12 ,  14  and, more particularly, the attachment ends  40  of the depending arms  12 ,  14  may be fitted between the legs  30 ,  32  or  34 ,  36  as the case may be. Thus referring to  FIG. 2 , the depending arms  12 ,  14  each include an end  40  having a through passage  42  for receipt of a bolt or a fastener  44  to retain the depending arm  12  or  14  on the frame member  10 . The opposite or distal end of the depending arms  12 ,  14  include a rod section  48  which is adapted to fit into a fastener bore associated with the pitman-arm as described hereinafter. The rod sections  48  are opposed one to the other as depicted in  FIG. 1 . Thus, the arms  12 ,  14  pivot freely about the respective bolts  44  so that the rod sections  48  may be inserted into bores of the pitman-arm. Note that the rod sections  48  are generally in the same plane as the axis  20 . Thus, all of the component elements are aligned and symmetrical.  
         [0019]      FIGS. 5, 6  and  7  illustrate the manner of operation of the tool depicted in  FIGS. 1-4 . Thus, a pitman-arm  50  includes first and second legs  52 ,  54  which are spaced one from the other and include a slot  56  therebetween with a bolt  58  mounted in bores  59 ,  61  defined in the rod legs  52 ,  54  to retain the pitman-arm  50  on a shaft  60 . The shaft  60  is typically a splined shaft and the passage for the shaft in the pitman-arm  50  is likewise splined to enable the shaft  60  to be fixed to the pitman-arm and move in a manner which will rotatably drive the pitman-arm  50  or alternatively, the pitman-arm  50  will rotatably drive the shaft  60 .  
         [0020]     To remove the pitman-arm  50  from the shaft  60  is often difficult inasmuch as the arm  50  may become somewhat corroded on the shaft  60 . Thus by using the tool of the invention, the legs  52 ,  54  of arm  50  may be slightly spread or at least disengaged from shaft  60  in a manner which will permit the shaft  60  and the arm  50  to be easily disengaged. As depicted in  FIG. 6 , the rod sections  48  are inserted through the bore  59 ,  61  associated with the bolt  58  that has been removed from the pitman-arm  50 . The wedge section  28  may then be driven into the space  56  between the legs  52 ,  54  by axial movement of the drive rod  18 . Note that the orientation of the tool depicted in  FIG. 6  is not limiting. In  FIG. 6  the orientation is such that the axis of the drive rod  18  aligned with the axis of the shaft  60 . It is possible, however, that the axis of the shaft  18 ; namely, axis  20  may be transverse to the axis of the shaft  60 . This alternative alignment is depicted in  FIG. 7  wherein the pitman-arm  50  has been removed from a shaft  60  and is in the process of being replaced. Thus, the tool of the invention may be used to spread the legs  52 ,  54  so as to effect a slight opening thereof for ease of replacement of the pitman-arm  50  on a shaft  60 .  
         [0021]     While there has been set forth a preferred embodiment of the invention, various alternative constructions are possible within the spirit and scope of the invention. For example, the configuration and shape of the depending arms  12 ,  14  may be altered. The construction of the frame  10  may be altered. The construction of the wedge member  26  as well as the means for driving the wedge member, including the drive rod may be altered using other drive means