Patent Publication Number: US-6992244-B2

Title: Hold down clamp

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to clamping of drum rims, and more particularly to an improved, easily adjustable, clamping device, positively connectible to a drum rim so as not to inadvertently loosen or disconnect. 
   There is need for improvements in drum associated clamping devices of rugged construction, to provide the advantages as referred to, as well as other advantages, as will be seen. 
   SUMMARY OF THE INVENTION 
   It is a major object of the invention to provide an improved drum rim clamping apparatus, as may be incorporated on a pedal unit that drives a drum beater. Basically, the invention is embodied in a combination that includes: 
   a) a base 
   b) a wedging device to exert clamping force, that device carried by the base, 
   c) means to displace said device to move a surface or surfaces of the device relatively toward one side of a base drum rim, and 
   d) a clamp part to which clamping force is transmitted at the opposite side of the drum rim. 
   As will be seen, that device may advantageously include two wedges carried for adjustable relative movement toward one another, or away from one another. The wedges easily support drum rims of different curvature, as at spaced surface locations on the wedges. The wedges typically have substantially flat surfaces that extend in tangential contact relation with the arcuate rim, for stable support of the rim. 
   It is another object of the invention to provide for carriage of both wedges for simultaneous relative movement toward one another, or away from one another. 
   Such movement may be effected by a displacer having screw thread operative connection to the device. The displacer may advantageously comprise an adjustably rotatable displacer having screw thread operative connection to the wedges. In this regard, the displacer may have differential screw thread operative connection to the wedges, whereby, as the displacer is rotated in one rotary direction the wedges are relatively displaced toward one another, and as the displacer is rotated in the opposite rotary direction, the wedges are relatively displaced away from one another. Also, the wedges may have aligned bores which are threaded to receive differential threading on the displacer, whereby both wedges are moved, to clamp the drum rim in response to simple rotation of the displacer in one direction, and with mechanical advantage. The threaded bores and the displacer threading define worm gearing, which prevents unclamping of the rim during drum beating. 
   A further object is to provide a guide channel on the base, extending in generally perpendicular relation to a base plate of a pedal unit carrying the channel, that unit including a pedal pivotally carried by the base plate, a drum beater pivotally carried by the base plate, and a drive connected between the pedal and the drum beater. The clamp unit of the invention is also useful in other environments, as will be seen. 
   These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 

   
     DRAWING DESCRIPTION 
     Fig. is a side elevation of a pedal unit carrying base drum rim clamping structure; 
       FIG. 2  is a frontal elevation taken on lines  2 — 2  of  FIG. 1 ; 
       FIG. 3  is a top plan view taken on lines  3 — 3  of  FIG. 1 ; 
       FIG. 4  is an enlarged fragmentary end view taken on lines  4 — 4  of  FIG. 3 ; 
       FIG. 5  is an enlarged frontal view taken on lines  5 — 5  of  FIG. 3 ; 
       FIG. 6  is a top plan view taken on lines  6 — 6  of  FIG. 5 ; 
       FIG. 7  is a frontal view of a modification, in which the wedge clamping device is employed between a drum hoop and structure including a support rod and an auxiliary clamp; and 
       FIG. 8  is an elevation taken on lines  8 — 8  of  FIG. 7 . 
   

   DETAILED DESCRIPTION 
   In  FIG. 1 , a pedal  10  is pivoted at  11  to a heel support  12 , attached to base plate  13 . A flexible coupling, such as a chain  14  is connected at  15  to the forward end of the pedal  10 , and extends upwardly at  14   a  to mesh with and/or wrap on a sprocket or drum  16 . The latter is fixedly mounted to an axle  17 , whereby, as the pedal is pushed down by the user&#39;s shoe or foot, the sprocket and axle are rotated; the beater  19  then rotates forwardly so that head  20  strikes the bass drum surface or head indicated at  21 . 
   Yieldable means, such as tension spring  22  is operatively connected between a rotor  23  on the axle, and the frame, such as the lower end of pedestal  24 , to yieldably resist axle rotation, and return the beater to  FIG. 1  position. Rotor  23  defines an effective crank arm  23   a  to which a spring support  25  is connected. A spring tension adjustment means is shown at  27 . Two pedestals  24  and  24   a  support the axle  17 , for rotation, and are carried by the base plate  13 . 
   In accordance with an important aspect of the invention, a clamp device, for attachment to a base drum rim  30 , is indicated generally at  31 . That device preferably includes: 
   a) a base  32 , 
   b) a wedging device, such as two wedges  33  and  34  to exert clamping force, the device or wedges carried by the base, 
   c) means to displace that device to move a device surface or surfaces relatively toward one side of base drum rim  30 , and 
   d) a clamp part  32   a  to which clamping force is transmitted at the opposite side of the drum rim. 
   The two wedges are carried for adjustable relative movement, of at least one wedge and preferably both wedges, toward one another, or away from one another. Typically, the two wedges are slidably carried by the base  32  for simultaneous relative movement toward one another, or away from one another. In this regard, the drum rim, which may be metallic, is arcuate, for example circular, and stably supported on wedge oppositely angled surfaces, at spaced contact locations. For example such locations  36  and  37  are at approximately equal spacings from a vertical plane  38  normal to the plane of  FIG. 2 . The wedges are also typically metallic, and their angled surfaces are flat and extend in tangential contact with the outer side of the drum rim, which they support, enabling sliding of the wedges under the rim. 
   Means is provided to displace the device  31  to move a surface or surfaces of the device relatively toward one side (typically the outer side) of the drum rim; and a clamp part is provided to which clamping force exerted by device  31  is transmitted, via the rim, at the opposite side of the rim. As shown, such means may take the form of a displacer  40  having screw thread operative connection to device  31 , as for example to the wedges  33  and  34 . The illustrated displacer  40  extends lengthwise transversely through aligned bores  41  in the two wedges and has screw thread  40   a  operative connected to that threading at such bores. That threading connection is differential as respects the two wedges, as for example in turnbuckle relation, whereby, as the displacer is rotated in one rotary direction the wedges are relatively displaced toward one another, to tighten the wedge connections to the drum rim, and as the displacer is rotated in the opposite rotary direction, the wedges are relatively displaced away from one another, to loosen that connection. 
   Accordingly, as the elongated displacer is rotated in one direction, the drum rim is clamped between the wedges and fixed part  32   a , and with high mechanical advantage, such as to prevent undesired unclamping of the clamped rim during drum beating impacts, transmitted to the device  10 . Part  32   a  is shown in the form of a tongue extending upwardly at  32   b  from the base, and projecting at  32   a  over the drum rim inner side. See  FIG. 1 . The end  40   c  of the displacer may have wrench flats  40   b  enabling clamping rotary tightening of the displacer by use of a wrench. Wedges  33  and  34  may slide or travel in a channel  50  defined by the base  32 . See in  FIG. 4 , for example channel lips  51  and  52  in  FIG. 4 , over hanging wedge sideward extensions  53  and  54 . A T-slot arrangement is thereby defined. 
   Base  32  may be attached, as by fasteners  56 , to the plate  13  of the drum beater device, for supply at the time of manufacture and sale of the drum beater device; or the clamp device  31  may be separately produced and sold, and it may have other clamping uses, as enabled by fastener attachment to other devices. 
     FIGS. 7 and 8  show fastener  60  attachment of base  32  and plate  113  to an auxiliary clamp structure  61  attached to a rod  62 . When wing nut  63  is loosened, clamp structure  61  is loosened and may be adjustably shifted along the rod. The wedges  33  and  34  are shown clamped to a drum rim  30 , as before. 
   Additional advantage include:
         The single point hold-down method distorts the bass drum hoop under tension. This distributes uneven amount of pressure applied to the drumhead. Therefore, evenness in tuning is not achieved, resulting in the reduction of vibration (resonance) and degradation of fundamental pitch development of the bass drum sound. Conversely, the 3-point/prism clamp establishes equal contact with minimal pressure placed along the bass drum hoop. The technique alleviates inherent problems in the single point clamping technique allowing accurate tuning of the bass drumhead.   Finally, the 3-point clamping technique offers positive contact between the pedal and the hoop, insuring the pedal or percussion instrument from loosening up due to the extreme forces of rigorous performance.