Patent Publication Number: US-6903257-B2

Title: Bass drum pedal with eccentricity-adjustable cam system

Description:
CLAIMING FOREIGN PRIORITY 
   The applicant claims and requests a foreign priority, through the Paris Convention for the Protection of Industry Property, based on a patent application filed in the Republic of Korea (South Korea) with the filing date of Oct. 1, 2002, with the patent application number 10-2002-0059724, by the applicant. (see the attached declaration) 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to improvements in a foot-operated bass drum pedal and more particularly to a bass drum pedal with a cam system wherein a user may adjust the eccentricity of the cam system to thereby obtain an optimized drum pedal for a user&#39;s performance. 
   2. Description of Related Art 
   A drummer plays the bass drum by pressing down the drum pedal. Each drummer needs his own drum pedal suitable to him because each drummer has different playing style and physical condition. 
   The primary factors that determine the overall feels of the drum pedal to the drummer himself and the performance characteristics are an impact force and a restoring force. In this description, the impact force is defined as a force acted on a bass drum head by a beater when the beater strikes the drum head, and the restoring force is defined as a force applied to a foot board by a spring to return the foot board to its original up-position. 
   A strong impact force enables the drummer to play a powerful performance, and a strong restoring force enables the drummer to play a speedy performance. 
   With the same stepping force on the foot board, the impact force acted on the drum head by the beater and the restoring force applied to the foot board by the spring depend on the torque arm of the cam system. 
   When the torque arm of the cam system is long, the impact force acted on the drum head by the beater is strong. But in this case, the restoring force applied to the foot board by the spring thereby returning the foot board to its original up-position is weak. On the contrary, when the torque arm is short, the impact force is weak and the restoring force is strong. 
   Because the impact force and the restoring force suitable to each drummer might vary, conventional drum pedal companies have provided many kinds of drum pedals, each of which has different torque arm of cam system, thereby permitting the drummers to selectively purchase the suitable one to him. But when a drummer&#39;s playing style changes, a drummer must buy a new pedal. And if a drummer intends to try a variety of playing styles, he has to purchase a plurality of drum pedals with different cam features. 
   Therefore, there&#39;s been a need for a drum pedal wherein the torque arm of the cam system is adjustable. A prior art that meets the above need is U.S. Pat. No. 6,172,291. 
   Said prior art provides a plurality of interchangeable cam members with different shape and radius for selective attachment to the drum pedal sprocket. But it takes a great deal of time to remove a cam member and interchange it with another one, and it is liable to lose the cam members not in use. 
   The present invention tends to solve the above problems and permits the user to tune the bass drum pedal up more efficiently and precisely to suit the user&#39;s style and ability without any risk of missing cam members. 
   SUMMARY OF THE INVENTION 
   Torque arm of the cam system is the distance from the axis of rotation defined by the rotating shaft to the outer surface of the cam system, and depends on the eccentricity of the cam system. Therefore if the eccentricity of the cam system changes, so does the torque arm. 
   As a result, the impact force and the restoring force depend on the eccentricity of the cam system because the torque arm depends on the eccentricity of the cam system. 
   The present invention provides an enhanced bass drum pedal with an eccentricity-adjustable cam system wherein a user may easily adjust the eccentricity of the cam system thereby easily changing the impact force and the restoring force to suit his playing style and ability without interchanging cam members. 
   And with a single cam system of this invention the user can readily alter the performance characteristics, playing response and overall feels of the pedal to the user, so the user need not carry a plurality of cam members. 
   The present invention is embodied in a foot-operated bass drum pedal that includes a horizontally extending base plate, two upright posts mounted on and attached to the base plate, a rotating shaft rotatably supported by the two posts, a foot board hingedly connected to the base plate, an eccentricity-adjustable cam system mounted on the rotating shaft, a flexible drive linkage drvingly connecting the foot board with the cam system, a beater driven by the rotating shaft to strike a drum head, a crank carried by the rotating shaft, and a spring connected between the crank and the lower end of the post. 
   The flexible drive linkage, which partially overlies the outer surface of the cam system, has two opposite end portions, one of which is anchored to the front portion of the foot board and the other of which is anchored to the eccentricity-adjustable cam system. 
   The eccentricity-adjustable cam system of this invention comprises a cam core mounted on and attached to the rotating shaft, a cam member rotatably connected to the cam core by a first pin, a positioning member rotatably connected to the cam member by a second pin, and a set screw fastening the positioning member onto the cam core. 
   The positioning member is adjustably positioned onto the cam core by the set screw to thereby adjust the eccentricity of the cam system and accordingly torque arm. As a result, the impact force acted on a drum head and the restoring force applied to the footboard may be readily altered according to the user&#39;s intention. And a user may have a drum pedal suitable to his playing style and ability by adjusting the eccentricity-adjustable cam system. 
   These and other objects and advantages of the invention, as well as the details of the illustrative embodiments will be more fully understood from the following specification and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of bass drum pedal; 
       FIG. 2A  is a perspective view of eccentricity-adjustable cam system of this invention; 
       FIG. 2B  is an exploded view of eccentricity-adjustable cam system of this invention; 
       FIG. 3A  is a side view of the eccentricity-adjustable cam system and beater of this invention as the beater strikes a drum head with the torque arm being maximum; 
       FIG. 3B  is a side view of the eccentricity-adjustable cam system and beater of this invention as the beater strikes a drum head with the torque arm being minimum; 
       FIG. 4A  is a perspective view of another embodiment of this invention; 
       FIG. 4B  is an exploded view of another embodiment of this invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIG. 1 , basically a bass drum pedal of this invention includes an elongated horizontal base plate  1 , two upright laterally spaced posts  2  mounted on and attached to the base plate, and a shaft  3  rotatably supported by the two posts via bearings located in the upper portions of the two posts. 
   The base plate supports all the other members of the drum pedal. Instead of the base plate, a suitable wire structure adapted to support the posts, foot board, and so on may be provided. 
   The shaft  3  extends between the two posts  2  and may be polygonal to mount a cam system. 
   The eccentricity-adjustable cam system  100  is mounted on the shaft  3  and may have a corresponding polygonal bore  112  to closely fit the shaft  3 . 
   The shaft  3  carries a beater  4 , which is mounted on the shaft  3  in driven relation to strike a drum head. 
   The eccentricity-adjustable cam system  100  engages a flexible drive linkage  7  driven by the foot board  6 . The flexible drive linkage  7 , which partially overlies the outer surface of the cam system  100 , has two opposite end portions, one of which is anchored to the front portion of the foot board  6  and the other of which is anchored to the eccentricity-adjustable cam system  100 . 
   Although the drawings show a chain as the flexible drive linkage  7 , the flexible drive linkage  7  may be a chain or a strap. 
   An elongated foot board  6  extends in inclined relation above the base plate  1 . The rear portion of the foot board  6  is hingedly connected to the base plate  1 , and the front portion of the foot board is attached to the flexible drive linkage  7 . 
   A crank  8  is carried by the shaft  3 . A spring is connected between the crank  8  and the lower end of the post  2  to return the beater and the foot board to their original position for the next striking. 
   The eccentricity-adjustable cam system  100  of this invention will be described more specifically with reference to  FIG. 2 , FIG.  3  and FIG.  4 . 
   The eccentricity-adjustable cam system  100  of this invention comprises a cam core  101  mounted on and attached to the shaft  3 , a cam member  102  rotatably connected to the cam core  101 , a positioning member  103  rotatably connected to the cam member  102 , a first pin  104  rotatably connecting the cam member  102  with the cam core  101 , a second pin  105  rotatably connecting the positioning member  103  with the cam member  102 , and a set scew  106  fastening the positioning member  103  onto the cam core  101 . 
   The set scew  106  fastens the positioning member  103  onto the cam core  101  to adjustably position the positioning member  103  onto the cam core  101 , while the cam core  101  remains affixed to the rotating shaft  3 , thereby defining the eccentricity of the cam system  100 . 
   With reference to FIG.  2 A through  FIG. 4B  the eccentricity-adjustable cam system  100  of this invention will now be described in detail. 
   As shown in  FIG. 2B , a preferred embodiment of this invention provides a slot  109  passing through the positioning member  103  and four grooves  108   a ,  108   b ,  108   c , and  108   d  in the positioning member  103 . 
   The width of the slot  109  is wider than outer diameter of the set screw  106  and narrower than the diameter of the set screw head. The length of the slot defines the range wherein the eccentricity of the cam system  100  may vary. The four grooves are located spaced and the mid-portions of the grooves are cut by the slot  109 . The cam core  101  includes a female thread  111  for engaging the set screw  106 , and a protrusion  107  for engaging one of the four grooves in the positioning member  103 . 
   The eccentricity of the eccentricity-adjustable cam system  100  depends on which groove of the positioning member  103  engages the protrusion  107  on the cam core  101 . 
   Two representatives wherein the eccentricity of the cam system is adjusted are shown in FIG.  3 A and FIG.  3 B. In  FIG. 3A  the cam system is adjusted to have the longest torque arm R, and in  FIG. 3B  the cam system is adjusted to have the shortest torque arm R. 
   In  FIG. 3A  the fourth groove  108   d  of the positioning member  103  matingly engages the protrusion  107  of the cam core  101 , and as a result, the torque arm is maximum. In  FIG. 3B  the first groove  108   a  of the positioning member  103  matingly engages the protrusion  107  of the cam core  101 , and as a result, the torque arm is minimum. 
   The torque arm between maximum and minimum can be obtained by utilizing second or third groove. By adjusting the torque arm as described above, the impact force and the restoring force can be altered. 
   Although this preferred embodiment provides the drum pedal with four-grade-tuning system, this invention should not limited to any particular number of grooves in the positioning member  103 . The positioning member  103  may have two, three or a plurality of grooves more than four. 
   Another embodiment of this invention will be described with reference to  FIGS. 4A and 4B . 
   The cam core  101  is provided with no protrusion and the positioning member  103  is provided with no groove. As shown in  FIG. 4B , the positioning member has a slot  109  passing through the positioning member  103  and the cam core has a corresponding female thread  111  for the set screw  106 . The width of the slot  109  is wider than outer diameter of the set screw  106  and narrower than the diameter of the set screw head. The length of the slot  109  defines the range wherein the eccentricity of the cam system may vary. The eccentricity of the cam system depends on which portion of the slot  109  the positioning member  103  is fastened onto the cam core  101  at. 
   This embodiment provides more various and exquisite adjustment for the eccentricity of the cam system. 
   The operation of the bass drum pedal of the present invention will be illustrated in detail hereinafter with reference to drawings. 
   As easily understood from  FIG. 1 , when the drummer steps on the foot board  6 , the front end of the foot board is depressed and accordingly the flexible drive linkage  7  connected to the front end of the foot board is displaced downward thereby rotating the eccentricity-adjustable cam system  100 . 
   The rotation of the cam system  100  causes the rotating shaft  3  to rotate thereby driving the beater  4  to strike the drum head  10 . 
   The rotation of the rotating shaft  3  also causes the crank  8  to rotate thereby elongating the spring  9 , and accordingly the restoring force is applied to the foot board  6  for returning the foot board to the original up-position. 
   When the drummer stops depressing the foot board  6 , the foot board returns to its original up-position by the spring  9  for the next striking. 
   With the same stepping force on the foot board  6 , the impact force acted on the drum head  10  by the beater  4  and the restoring force applied to the foot board  6  by the spring  9  depends on the torque arm. 
   The user may adjust easily the bass drum pedal of this invention wherein the eccentricity of the cam system is adjustable thereby varying the impact force and the restoring force to suit the user&#39;s playing style. 
   Therefore the user need not purchase a new drum pedal but may just tune up the pedal of this invention by adjusting the eccentricity of the cam system to suit his changed playing style. 
   And with a single cam system of this invention the user can readily alter the performance characteristics, playing response and overall feels of the drum pedal to the user, so the user need not carry a plurality of cam members. 
   While the foregoing invention has been illustrated and described with reference to a number of preferred embodiments, it will be understood by those having skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of this invention.