Abstract:
A drive assembly, especially for agricultural implements with rotatingly driven masses, has a shear pin coupling ( 1 ) with a coupling hub ( 3 ) and a coupling sleeve ( 12 ) rotatable relative to the coupling hub ( 3 ). A ratchet gear ( 20 ) supported on the coupling hub ( 3 ) and rotatable relative to the coupling hub ( 3 ) and the coupling sleeve ( 12 ). All three components ( 3, 12, 20 ) are connected to one another by the head screw ( 26 ) constituting the shear pin. A ratchet (not illustrated) may engage a holding face of the ratchet gear ( 20 ). This results in the head screw ( 26 ) being sheared. As a result, the coupling sleeve ( 12 ) is disconnected from the coupling hub ( 3 ) in respect of drive.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims priority to German Patent Application No. 10145012.5 filed Sep. 12, 2001, which application is herein expressly incorporated by reference.  
         FIELD OF THE INVENTION  
         [0002]    The invention relates to a drive assembly, and especially for agricultural implements with driven rotating masses.  
         BACKGROUND OF THE INVENTION  
         [0003]    In the driveline of agricultural implements pulled by a tractor, driven by the tractor power take-off shaft or are in self-propelled agricultural implements, different functional parts of the implement are driven by a branched drive system that starts from a central drive. In order to avoid any overloading, the drive systems are provided with couplings.  
           [0004]    In some functional areas where there is a risk of clogging, it is necessary to remove the material causing the clogging. In such a case, the operative either has to reverse the drive and if such an action does not release the obstruction, the operative must manually remove the clog while the machine is still in operation. Therefore, the drive first has to be stopped.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the present invention to propose a drive assembly where the drive can be disconnected either manually or by an actuating device.  
           [0006]    In accordance with the invention, a drive assembly has a shear pin coupling defining a longitudinal axis. A coupling hub is provided with a seat face and a bearing seat. A first projection with reference to the longitudinal axis projects radially from the seat face. A first attaching means is included. The seat face is axially arranged between the first projection and the bearing seat. A coupling sleeve is supported on the bearing seat of the coupling hub and is rotatable relative thereto. A second projection extends radially relative to the longitudinal axis. A second attaching means has a ratchet gear which is supported on the seat face of the coupling hub by a bearing bore to be rotatable relative thereto. At least one holding face is present. A shear pin is received in receiving bores of the first projection, second projection and ratchet gear. The bores are aligned relative to one another. The shear pin firmly connects the projections in the direction of rotation around the longitudinal axis. The receiving bores are arranged to be radially offset relative to the longitudinal axis. A locking device with a locking element is held in an inactive position. The locking device can be displaced manually, either directly or via an actuating device, out of the inactive position into contact with the holding face of the ratchet gear. This stops the rotational movement of the ratchet gear.  
           [0007]    The solution in accordance with the invention provides a drive assembly that uses a shear pin coupling for disconnecting, by an outside external action, the drive from the functional part of the driven implement. This can be effected manually by a release cord or a lever arrangement. The locking element of the locking device is displaced from the inactive position into the active position to contact the holding face of the ratchet gear. The release cord may be a Bowden cable, for example, on the locking element. However, it is also possible to select a different actuating device which automatically releases a locking function, for example, when a cover in an agricultural implement is opened. The transmission of torque can deliberately be restored only by inserting a new shear pin. The measures in accordance with the invention make it possible to provide a prior art shear pin coupling additionally with a disconnecting function.  
           [0008]    According to a further embodiment of the invention, the bearing seat of the coupling hub includes a first running groove which receives bearing balls. The coupling sleeve, via a second running groove, is rotatably supported around the longitudinal axis relative to the coupling hub. This ensures that the relative movement between the coupling hub and the coupling sleeve is of the low-friction type.  
           [0009]    In a preferred embodiment, the holding face is formed by a projection provided on the circumference of the ratchet gear. Preferably, a plurality of holding faces are on the circumference of the ratchet gear in order to keep the reaction time as short as possible.  
           [0010]    An advantageous embodiment includes the locking element as a locking ratchet held by a spring in the inactive position. The locking ratchet is pivoted against the force of the spring, so that, via a locking face, it comes into contact with the holding face. The locking ratchet is arranged such that the forces which are introduced into the locking ratchet, as a result of abruptly stopping of the ratchet gear, are directly introduced into the pivot bearing so that the locking ratchet cannot escape.  
           [0011]    Instead of actuating the locking ratchet manually via a suitable lever drive, Bowden cable or by cable control, it can be actuated by a power drive. The power drive can be controlled by a sensor. When an operative places his hand into the region of the machine, the power drive records such an action as a releasing criterion. In a preferred embodiment, the shear pin is a headed screw with a nut. The shear pin connects the coupling sleeve, the coupling hub and the ratchet gear firmly to one another and is radially offset and arranged parallel relative to the longitudinal axis. Depending on the type of application, the first attaching mechanism is a profiled bore in the coupling hub. The bore is centred on the longitudinal axis. Also, the first attaching mechanism may be a flange connected to the coupling hub. The bore includes teeth to enable a connection with a corresponding profiled journal. Where the drive assembly is to be integrated into a driveshaft drive system, the second attaching mechanism is a joint yoke of a universal joint or a flange.  
           [0012]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0014]    [0014]FIG. 1 is a partial section view of a shear pin coupling;  
         [0015]    [0015]FIG. 2 is a side view according to FIG. 1 with a locking device associated with the shear pin coupling;  
         [0016]    [0016]FIG. 3 is a section view along line III-III of FIG. 1; and  
         [0017]    [0017]FIG. 4 is a perspective view of the inventive drive assembly associated with a transfer box of a drive system of an agricultural implement. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0019]    The drive assembly in accordance with the invention has a shear pin coupling  1  which defines a longitudinal axis  2  which also constitutes the axis of rotation of the shear pin coupling  1 . The shear pin coupling  1  includes a coupling hub  3  with a bore  4  centred on the longitudinal axis  2 . The bone includes teeth which are shown in FIG. 3. A transverse bore  5  intersects the bore  4 . A tensioning element  6  is threaded into the transverse bore  5 . The tensioning element  6  may fix the coupling hub  3  on the shaft of a transfer box. The shaft includes corresponding outer teeth.  
         [0020]    The coupling hub  3  has a seat face  7 . A first projection  8  radially projects from the seat face  7  and has a flange-like design. The seat face  7  ends in a first running groove  9 , which constitutes a bearing seat. The first running groove  9  is an annular groove centred on the longitudinal axis  2 . A first receiving bore  10  in the coupling hub  3  is radially offset relative to the longitudinal axis  2 . The first receiving bore  10  extends parallel to the longitudinal axis and extends through the first projection  8 .  
         [0021]    The first projection  8  forms a first contact face  11  that extends towards the first running groove  9 . The shear pin coupling  1  includes a coupling sleeve  12  which, in the present embodiment, embraces the joint yoke  13  with its two yoke arms. The joint yoke  13  constitutes part of a universal joint which, in turn, forms part of a driveshaft.  
         [0022]    The coupling sleeve  12  has a bore  15 . A second running groove  14 , in the form of an annular groove, is arranged around the longitudinal axis  2 . The coupling sleeve  12 , by means of its bore  15 , extends over the portion of the coupling sleeve  3  that contains the seat face  7 . The first running groove  9  is positioned opposite the second running groove  14 . The running grooves  9  and  14  together accommodate bearing balls  16 . Thus, the coupling sleeve  12  and the coupling hub  3  are rotatable relative to one another.  
         [0023]    The coupling sleeve  12  includes a second projection  17 . The second projection  17  includes a second receiving bore  19 . The arrangement of the second receiving bore  19  corresponds to the arrangement of the first receiving bore  10  relative to the longitudinal axis  2  in the first projection  8 . The second receiving bore  19  extends parallel relative to the longitudinal axis  2 . The second projection  17  and the coupling sleeve  12  form a second contact face  18  which extends towards the first projection  8  of the coupling hub  3 .  
         [0024]    The shear pin coupling  1  includes a ratchet gear  20 . The ratchet gear includes a bearing bore  21  centered on the longitudinal axis  2 . Additionally, the ratchet gear  20  has a first end face  22  and a second end face  23 . The ratchet gear  20 , via the bearing bore  21 , is rotatably supported on the seat face  7  of the coupling hub  3 . In the direction of the longitudinal axis  2 , the ratchet gear  20  is held by its first end face  22  against the second contact face  18  and by its second end face  23  against the first contact face  11  of the coupling hub  3 . The ratchet gear  20 , on its circumference, includes plurality of projecting cams with holding faces  25 . The holding faces  25  extend radially relative to the longitudinal axis  2 .  
         [0025]    A third receiving bore  24  is arranged at a radial distance from the longitudinal axis  2 . The receiving bore  24  extends parallel relative to the longitudinal axis  2 . The longitudinal axis of the receiving bore  24  is collinear to the first receiving bore  10  and the second receiving bore  19 .  
         [0026]    A shear pin, in the form of a head screw  26 , is guided through the receiving bores  10 ,  19 ,  24 . Additionally, the shear pin, by a nut  27 , tensions the coupling hub  3 , the ratchet gear  2  and the coupling sleeve  12 . The head screw  26  is preferably received in a play-free way in the receiving bores  10 ,  19 ,  24 . As a result, the coupling hub  3 , the coupling sleeve  12  and the ratchet gear  20  are connected to one another in a rotationally fast way. Thus, when rotatingly driven by the joint yoke  13 , the hub  3 , sleeve  12  and gear  20  have to rotate together around the longitudinal axis  2 .  
         [0027]    The drive assembly in accordance with the invention, includes a locking device  28  in addition to comprising the above-described shear pin coupling  1 . The locking device  28  is best seen in FIG. 2. The locking device  28  includes a locking element in the form of a locking ratchet  29 . The locking ratchet  29  is arranged at a stationary bearing and is pivotable around the pivot axis  30 . The locking ratchet  29  is held by a spring  32  in an inactive position. The locking face  31  is disengaged from the holding faces  25  of the ratchet gear  20 . The ratchet gear  20  is pivoted around the pivot axis  30  by an actuating mechanism (not shown). The locking face  31  moves into the path of movement of the holding face  25  of the rotating ratchet gear  20  when the gear  20  is driven in the rotational direction N. Thus, the ratchet gear  20  is abruptly stopped. As a result, the head screw  26  shears at least one of the two shear faces formed in the region of contact between the ratchet gear  20  and the first projection  8  or the second projection  17 . Thus, the transmission of torque is interrupted between the coupling hub  3  and the coupling sleeve  12  and, respectively, between the coupling sleeve  12  and the coupling hub  3 .  
         [0028]    [0028]FIG. 4 shows the drive assembly associated with a transfer box of a drive system for an agricultural implement. The transfer box has been given the reference number  33 . It is attached to a machine frame (not shown), for example. The drive is effected via the driveshaft  34  and the shear pin coupling  1 . The torque introduced into the transfer box  33  is distributed to the two output shafts  36 ,  38 . In FIG. 4, the shear pin coupling  1  is disconnected from the driveshaft  34  in order not to obstruct the view of the shear pin coupling  1  and, in particular, of the locking device  28 . The transfer box  33  is associated with a bracket  37  which pivotably supports the locking ratchet  29  of the locking device  28 . FIG. 4 also shows how the locking ratchet  29 , by its locking face  31 , is associated with the holding face  25  of the ratchet gear  20 . The head screw  26  acting as the shear pin can also be seen.  
         [0029]    The actuating device  38  includes a setting element which directly acts on the locking ratchet  29  ends at the bracket  37 . The setting element itself can be activated by a Bowden cable, an actuating lever or a release cord. Alternatively, the setting element may be an electrically, pneumatically or hydraulically operated power drive. The power drive is connected, by lines, to an actuating switch, an actuating valve or a sensor to release the actuating function.  
         [0030]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.