Abstract:
The invention relates to a telescopic steering arm assembly for a vehicle-implement coupling mechanism. There is a need for a steering arm assembly housing which is simple and inexpensive to manufacture. A steering arm assembly includes a steering arm, a housing, a detent mechanism and a cover. The housing has a detent channel and forms a rim surrounding an opening of the detent channel. An attaching groove is formed in the rim. The detent mechanism is movable in the detent channel to releasably holding the steering arm in the housing. The cover is mountable on the rim to cover the detent mechanism. The cover has a mounting bead which engages the attaching groove of the rim.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a telescopic steering arm assembly for attaching to an agricultural implement.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is known to use telescopic steering arms in coupling mechanisms, such three-point coupling mechanisms or hitches, to couple a towed agricultural implements to a tractor. With such steering arms the operator of the tractor need not steer precisely at the connecting points of the attached implement and can extend or telescope the steering arm by releasing it from the detent mechanism and connect it with the implement. Subsequently, the operator need only move the tractor towards the implement so that the steering arms are retracted into the housing and are again immobilized by the detent mechanism.  
         [0003]     Such steering arms have a housing which has a cavity with an elongated rectangular cross section which slidably receives an extendable arm. The housing is formed by two generally symmetrical forged halves which are welded to each other to form a housing with a pair of wider sides and a pair of narrower sides. The wider sides are parallel to the long dimension of the rectangular cross section. The housing includes a cavity closure wall in a connecting region which connects the housing to a rigid guide steering arm of the attachment mechanism. In such known steering arms, the weld seam which connects the two halves to each other extends along the wider sides, and along the closure wall. Because of the elongated shape of the housing cross section, the two forging require a highly accurate set up during the forging process. This results in an expensive forging process, high maintenance costs for the forging tools and correspondingly necessary rework by milling, in order to attain reasonable tolerances. Moreover, the detent mechanisms provided on the housing require costly additional manufacturing steps for their installation. In addition, the detent mechanisms are connected to the housing by additional fastening devices, for example, screw connections, that result in a large number of parts.  
       SUMMARY OF THE INVENTION  
       [0004]     Accordingly, an object of this invention is to provide a housing for a telescopic steering arm which is simple and inexpensive, and which has fewer parts.  
         [0005]     This and other objects are achieved by the present invention, wherein a housing for a telescopic steering arm which overcomes the aforementioned problems.  
         [0006]     According to the invention, a telescopic steering arm assembly is provided for a vehicle-implement coupling mechanism. The assembly includes a steering arm, a housing, a detent mechanism and a cover. The housing receives an end of the steering arm. The housing has a detent channel which extends inwardly from an opening. The housing forms a rim surrounding the opening, and the housing has an attaching groove formed in the rim. The detent mechanism is movable in the detent channel and engagable with the steering arm for releasably holding the steering arm in the housing. The cover covers the detent mechanism. The cover is mountable to the rim and has a mounting bead which engages the attaching groove.  
         [0007]     The housing includes a first housing part and a second housing part. The first and second housing parts being welded together to form a cavity which slidably receives the steering arm. The housing has an open end which receives the steering arm and has a closed end. The detent channel has a longitudinal axis which is perpendicular to a longitudinal axis of the steering arm.  
         [0008]     The first second housing parts are joined together along parting surfaces. A portion of the parting surfaces define a first parting plane which extends through the housing from the open end to a side of the detent channel, and this first parting plane is parallel to the longitudinal axis of the detent channel and is parallel to the longitudinal axis of the steering arm.  
         [0009]     A further portion of the parting surfaces define a second parting plane which extends through the housing from a second side of the detent channel to an outer side surface of the housing. The second parting plane is parallel to the longitudinal axis of the detent channel and is at an angle with respect to the longitudinal axis of the steering arm. The housing has a rectangular cross-sectional shape with a pair of longer sides on opposite sides of the first parting plane, and with a pair of shorter sides which inter-connect the longer sides with each other.  
         [0010]     The first housing part has a connecting region which forms an end or closure wall of the cavity, so that the two housing parts are asymmetrical and the weld seam does not extend through the closure wall. This has the advantage that weld seam in the connecting region of the housing is not exposed to connecting forces. As a result, the housing parts can be manufactured as forging with a very low degree of forming, so that the forging or the housing parts are provided with a relatively flat profile. This makes it possible to apply forging processes with low maintenance cost for the forging tools and the attainment of closer tolerances, so that rework processes can be reduced or even omitted.  
         [0011]     The cover includes an edge with a bead which engages the fastening groove in the rim so as to immobilize the detent mechanism at the projection. The cover may be configured in the form of a housing cover, a head or a hood and is preferably formed of sheet metal. The cover has a size and shape so that the cover can be slid over the projection in a positive lock. By beading the edge of the cover in the area of the fastening groove at the projection the cover can be immobilized when the cover is slid over the projection. The beading is preferably formed on the opposite edges of the cover, where corresponding fastening grooves are formed in the rim. This eliminates costly fastening devices such as screws which would require an additional step during the manufacture of the housing.  
         [0012]     The detent mechanism includes a spring loaded detent pin that slidably supported in the cover. The detent pin is guided by a rod that extends through the cover and permits the release of the detent pin, and a tension spring is arranged on the rod to pre-load the detent pin in the detent position.  
         [0013]     The detent pin slides in guide grooves in the housing sides which extend therein from the opening in the rim. The guide grooves can be forged with the necessary so that a costly milling operation can be omitted.  
         [0014]     The opening for the detent mechanism could be provided on any side wall, but is preferably formed, for operator convenience, in the upper side wall of the housing and the guide grooves are formed in the left and right side walls.  
         [0015]     Other configurations are also possible. For examples the weld seam could extend along the edges of a lateral side of the housing.  
         [0016]     The closed end of housing is welded in a butt joint to a coupling link of the attachment mechanism. The closed end of the housing is preferably large enough to prevent deformation during welding, that could lead to errors in the tolerances of the guides for the detent pin. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a perspective view of a telescopic steering arm according to the invention.  
         [0018]      FIG. 2  is a perspective view from below of a telescopic steering arm according to the invention.  
         [0019]      FIG. 3  is a sectional view along lines  3 - 3  of  FIG. 1 .  
         [0020]      FIG. 4  is a perspective view of the interior of a first housing part.  
         [0021]      FIG. 5  is a perspective view of the interior of a second housing part.  
         [0022]      FIG. 6  is a sectional view along lines  6 - 6  of  FIG. 1 .  
         [0023]      FIG. 7  is a perspective view of the telescopic steering arm with a partial sectional view of the detent mechanism of  FIG. 6 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]      FIGS. 1 through 7  show a housing  10  for a telescopic steering arm  12 . Such telescopic steering arms housings  10  are used in attachment mechanisms for agricultural implements (not shown), for example, in a three-point coupling mechanism for an agricultural tractor (not shown).  
         [0025]     The housing  10  includes a first housing part  14  and a second housing part  16  that are connected to each other along a weld seam  18 . The housing  10  encloses a cavity  20  (best seen in  FIG. 6 ) which slidably receives the arm  12 .  
         [0026]     As best seen in  FIG. 1 , the cavity  20  includes an opening  22  into which the arm  12  is inserted. The cavity  20  is surrounded by a first side wall  24  (see  FIG. 4 ), a second side wall  26  (see  FIG. 5 ), a third side wall  28 , a fourth side wall  30  as well as a closure or end wall  32  (see  FIGS. 3-5 ). Walls  24  and  28 , and walls  26  and  30 , respectively, are arranged opposite each other. Closure wall  22  is arranged opposite opening  22 .  
         [0027]     The housing parts  14  and  16  are configured as flat profile forgings, where alternative manufacturing techniques are also possible and the housing parts  14 ,  16  could also be configured, for example, as castings.  
         [0028]     As can be seen in  FIG. 4 , an end part of the first housing part  14  forms part of the opening  22 . The first housing part  14  also forms part of walls  24  and  28 , and forms the entire wall  30  and the entire closure wall  32 . The closure wall  32  is configured as the interior of a massive connecting region  34  formed onto the housing part  14 , that is used for the connection to a coupling link  36  of a coupling mechanism (not shown). The connection to the link  36  of the coupling mechanism is established by a welded connection  37 .  
         [0029]     As can be seen in  FIG. 5 , an end part of the second housing part  16  forms the other part of opening  22 . The second housing part  14  also forms a portion of walls  24  and  28 , and forms the entire second side wall  26 . The opening  22 , wall  24  and wall  28  are completed by the aforementioned parts of the housing parts  14  and  16 .  
         [0030]     As best seen in  FIG. 6 , the cavity  20  has a generally rectangular cross section with a long dimension which extends substantially vertically and which lies in a separation or parting plane  44  which lies between portions of the housing parts  14  and  16 . The cavity  20  is enclosed by walls  24 ,  28 ,  26  and  30 . Because of the parting plane, it is possible to configure the housing parts  14 ,  16  with a generally flat profile, so that these housing parts  14 ,  16  represent relatively flat forging that can be manufactured in a relatively simpler forging process.  
         [0031]     The housing  10  has a rectangular cross-sectional shape with a pair of longer sides on opposite sides of the first parting plane, and with a pair of shorter sides which inter-connect the longer sides with each other.  
         [0032]     Referring now to  FIGS. 2 and 7 , the weld seam  18  is arranged along a first parting plane  19  which extends through the middle of walls  24  and  28  from the opening  22  and through the detent channel  60 . The weld seam  18  is arranged along a second parting plane  21  which from the opening  22  and through the connecting region  34  to an outer surface of side  26 . The first parting plane  19  is parallel to the longitudinal axis of the detent channel  60  and is parallel to the longitudinal axis of the steering arm  12 . The second parting plane  21  is parallel to the longitudinal axis of the detent channel  60  and at an angle with respect to the longitudinal axis of the steering arm  12 . As best seen in  FIG. 7 , a portion of the weld seam  18  joins an edge of the connecting region  34  to an edge of wall  26 . This prevents dynamic forces in the housing  10  in the connecting region  34  from extending into the weld seam.  
         [0033]     As is shown in  FIGS. 1 through 3 , as well as  6  and  7 , the housing  10  includes a detent mechanism  46 . The detent mechanism  46  includes a handgrip  48 , a cover  50  and a detent pin  52 . The detent pin  52  includes a guide rod  54  and a detent block  56 . A preload spring  58  is supported on the guide rod  54  between the cover  50  and the detent block  56 , and it forces the detent pin  52  into the housing  10  where the guide rod  54  is guided into a bore  59  that is provided in the cover  50  and is connected with the handgrip  48 .  
         [0034]     The housing parts  14  and  16  have guide grooves  60  formed therein, which together form a detent channel which extends in an upper portion of the housing  10  near closure wall  32 . The detent channel extends parallel to and along a vertical axis which lies in the plane  44 . The detent channel extends from cavity  20  to an opening  62  in the upper surface of the housing  10 . The detent channel conforms to the shape of the detent block  56  so that the detent block  56  is slidable in the detent channel.  
         [0035]     The opening  62  is surrounded by a projection or rim  64  on the upper side of the first side wall  24 . The rim  64  forms a fastening flange for the cover  50 . Attaching grooves  66  are formed on the side of the rim  64  adjacent to side walls  26  and  30  for use in fastening a cover  50 .  
         [0036]     The cover or hood  50  has a pot-shape and is preferably formed as a deep drawn sheet metal part. The location and length of the cover  50  corresponds approximately to the distance through which the detent block  56  must be slid in the detent channel in order to release the telescopic steering arm  12  and allow it to be retracted from the interior of the housing  10 . The opening of the cover  50  is dimensioned so that it encloses the rim  64 , and the edge of the opening of the cover  50  includes beads  68  that engage the attaching grooves  66 . By pressing the cover  50  over the rim  64 , the beads  68  engage the fastening grooves  66  in a detent manner and immobilize the entire detent mechanism  46 . The combination of beads  68  and fastening grooves  66  makes it possible to immobilize the detent mechanism  46  without the use of screw threads. The configurations of all the connection necessary for the mechanism and the fastening of the detent mechanism  46  on the housing parts  14 ,  16  such as, for example, the guide grooves  60 , the fastening grooves  66 , the opening  62  and the rim  64  can be incorporated into the forging process, so that costly subsequent rework processes such as, for example, milling, can be omitted.  
         [0037]     Spring  58  urges detent block  56  into a notch or depression  70  which is formed in the steering arm  12 . The inner end  72  of the steering arm  12  includes a slanted surface which engages and raises the detent pin  52  as the steering arm  12  is inserted into housing  10 . When depression  70  is aligned with groove  60  then spring  58  moves detent block  56  into depression  70  and the steering arm  12  is immobilized with respect to the housing  10 . By pulling the handgrip  48  or by applying a force opposed to the spring  58 , the detent block  56  can be moved out of the depression  70  so as to release the detent and allow steering arm  12  to be withdrawn or moved out of the housing  10 .  
         [0038]     While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.