An apparatus and a testing method for testing the lifespan of a drum

Abstract

The present invention discloses a device and a testing method for testing the lifespan of a drum. The device includes a striking mechanism, a coordinated adjustment mechanism, and a power mechanism. The power mechanism is used to drive the coordinated adjustment mechanism to perform a periodic state switch between compression and reset. The coordinated adjustment mechanism includes an elastic adjustment part, and the elastic adjustment part is configured to adjust the compression stroke of the coordinated adjustment mechanism within one state switch cycle. The coordinated adjustment mechanism is linked with the striking mechanism and controls the striking mechanism to periodically strike the drum surface along with the state switch between its compression and reset. By adjusting the elastic adjustment part, the compression stroke of the coordinated adjustment mechanism is changed. The smaller the compression stroke is, the greater the pressing force applied by the coordinated adjustment mechanism to the striking mechanism is, and different intensities of drum surface strikes can be simulated. Therefore, the drum surface can be subjected to strike tests in a cyclic manner, and the striking intensity can be changed to simulate the foot stepping action of a performer, so as to accurately measure the service life of the bass drum.

Description

Technical Field

[0001] The present invention relates to the technical field of musical instrument testing, and in particular to a device and method for testing the life of a drum. Background Art

[0002] Among musical instruments, drums are a very important branch, including real drums, electronic drums or other simulated drums. One way of playing is for the player to control the hammer to hit the drumhead of the bass drum by stepping on a pedal. However, since the human body has stronger control over the hands than the feet, it is easy to use too much force or too little force during the playing process. Therefore, for bass drums played by stepping on the pedal, the life of the drumhead will be higher, and the drumhead needs to adapt to a wider range of playing intensities and situations.

[0003] However, there is currently no instrument specifically designed for testing the life of bass drum heads. It is unable to simulate the impact of different pedaling forces on the drum, nor can it estimate the service life of the drum, and cannot provide effective and reliable data and theoretical support for subsequent research and development and improvements. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention aims to provide a device and method for testing drum life, so as to solve the problem that the prior art cannot simulate the drum life test under different striking forces.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a device for testing the life of a drum, which is used to strike the drumhead of a bass drum to perform a simulated performance test, and includes a striking mechanism, a joint adjustment mechanism, and a power mechanism. The power mechanism is used to drive the joint adjustment mechanism to perform periodic state switching between compression and reset. The joint adjustment mechanism includes an elastic adjustment part, and the elastic adjustment part is configured to adjust the compression stroke of the joint adjustment mechanism within a state switching cycle. The joint adjustment mechanism is linked with the striking mechanism and controls the striking mechanism to periodically strike the drumhead as its compression and reset states switch.

[0007] In some embodiments, the linkage mechanism also includes a guide rail seat, a linkage shaft, a spring and a slider baffle, one end of the spring abuts against the vertical wall of the guide rail seat, and the other end abuts against the slider baffle, the linkage shaft passes through the vertical wall of the guide rail seat and the slider baffle, and is clamped with the slider baffle through the elastic adjustment part movably fixed at one end thereof, the other end of the linkage shaft is transmission-connected to the power mechanism, and the linkage shaft is used to drive the slider baffle to slide on the slide rail of the guide rail seat.

[0008] In some embodiments, a rotatable drive wheel is fixed to the guide rail base, and the linkage shaft is connected to the power mechanism through a drive chain. During one state switching cycle of the joint adjustment mechanism, at least a part of the drive chain and the linkage shaft are on the same drive axis line, and the drive axis always maintains an acute angle with the reference plane on which the striking mechanism is placed.

[0009] In some embodiments, during one compression stroke of the joint adjustment mechanism, there are at least two stroke nodes, which are respectively used to link the striking mechanism to just contact the drum surface and compress the drum surface to the maximum stroke.

[0010] In some embodiments, the striking mechanism includes a striking hammer, a pedal, a placement base, a fixing frame, and an elastic reset part. The pedal is hinged to the placement base, the joint adjustment mechanism is fixed to the pedal, the fixing frame is fixed to the placement base, one end of the striking hammer is connected to the fixing frame through a hinge shaft and the other end is used to strike the drum surface, one end of the elastic reset part is connected to the fixing frame and the other end is connected to the hinge shaft of the striking hammer, and the striking hammer is also connected to the pedal through a linkage member.

[0011] In some embodiments, the power mechanism includes a motor and a connecting rod assembly. One end of the connecting rod assembly is connected to the motor and the other end is connected to the joint adjustment mechanism through a drive chain.

[0012] In some embodiments, the power mechanism further includes a controller, which is used to send an operation instruction to the motor, and the operation instruction is configured to adjust and control the rotation speed and / or the rate of change of the rotation speed of the motor.

[0013] In a second aspect, an embodiment of the present application provides a test method applied to the device for testing the life of a drum as described above, including the following steps:

[0014] Adjust the position of the elastic adjustment part to adjust the compression stroke of the joint adjustment mechanism;

[0015] Control the operation of the power mechanism to drive the joint adjustment mechanism into the compression stroke. During one compression stroke, make the striking mechanism move from being separated from the drum surface to contacting the drum surface, and then compress the drum surface to the maximum stroke;

[0016] The power mechanism continues to operate to drive the joint adjustment mechanism into the reset stroke, so that the striking mechanism is separated from the drum surface.

[0017] In some embodiments, adjust the position of the elastic adjustment part so that when the spring in the joint adjustment mechanism is at the minimum compression state point during one compression stroke, the striking mechanism can compress the drum surface to the maximum stroke.

[0018] In some embodiments, when switching from the compression stroke to the reset stroke, the striking mechanism is subjected to a reset force that causes the hammer in the striking mechanism to leave the drum surface.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The device and method for testing the life of a drum provided by the embodiments of the present application can change the compression stroke of the joint debugging mechanism by adjusting the elastic adjustment part. The smaller the compression stroke, the greater the pressing force exerted by the joint debugging mechanism on the striking mechanism, and different intensities of drum surface strikes can be simulated. Therefore, it is possible to cyclically perform drum surface strike tests, change the strike intensity, simulate the foot stepping action of a performer, and accurately measure the service life of a bass drum.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further illustrated by the accompanying drawings, but the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the following drawings.

[0023] Figure 1 FIG. 1 is a schematic structural diagram of a device for testing the life of a drum and a bass drum in an assembled state according to an embodiment.

[0024] Figure 2 FIG. 2 is a schematic internal structural diagram of a device for testing the life of a drum according to an embodiment.

[0025] Figure 3 FIG. 3 is a schematic structural diagram of a device for testing the life of a drum at the start of the compression stroke according to an embodiment.

[0026] Figure 4 FIG. 4 is a schematic structural diagram of a device for testing the life of a drum when the hammer just touches the drum surface during the compression stroke according to an embodiment.

[0027] Figure 5 FIG. 5 is a schematic structural diagram of a device for testing the life of a drum when the hammer compresses the drum surface to the maximum stroke during the compression stroke according to an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0030] In the description of the present invention, when it is described that a specific device is located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device. When it is described that a specific device is connected to other devices, the specific device may be directly connected to the other devices without an intermediate device, or may not be directly connected to the other devices but have an intermediate device.

[0031] Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the said technologies, methods, and devices should be regarded as part of the specification.

[0032] In a first aspect, referring to Figures 1 to 5 , this embodiment provides a device for testing the lifespan of a drum, which is used to strike the drumhead 41 of a bass drum 4 to conduct a performance test in a simulated foot-tapping manner. It includes a striking mechanism 1, a linkage adjustment mechanism 2, and a power mechanism 3. The power mechanism 3 is used to drive the linkage adjustment mechanism 2 to perform a periodic state switch between compression and reset. The power mechanism 3 provides a repetitive force to the linkage adjustment mechanism 2. The self-structure of the linkage adjustment mechanism 2 will experience a compression stroke and a reset stroke. During the periodic state switch of these two strokes, the linkage adjustment mechanism 2 is linked with the striking mechanism 1. The linkage adjustment mechanism 2 will periodically press the striking mechanism 1, simulating the action of a person stepping on, so that the striking mechanism 1 periodically strikes the drumhead 41 as its state switches between compression and reset, realizing the linkage.

[0033] The joint adjustment mechanism 2 includes an elastic adjustment portion 21, which is configured to adjust the compression stroke of the joint adjustment mechanism 2 within a state switching cycle. The overall movement of the joint adjustment mechanism 2 is linked to the striking mechanism 1, and the compression stroke and return stroke involved in the state switching within the joint adjustment mechanism 2 are controlled by the elastic adjustment portion 21. In order to change the pressing force applied by the joint adjustment mechanism 2 on the striking mechanism 1, the elastic adjustment portion 21 is adjusted to change the compression stroke of the joint adjustment mechanism 2. The smaller the compression stroke, the greater the pressing force applied by the joint adjustment mechanism 2 to the striking mechanism 1. This can simulate strikes of the drumhead 41 with different forces. Therefore, it is possible to perform a cyclical strike test on the drumhead 41, and the striking force can be changed to simulate the player's foot movement, thereby accurately measuring the service life of the bass drum 4.

[0034] Embodiment 1:

[0035] The elastic adjustment part can be electrically adjusted, and the position of the elastic adjustment part in the set linear track can be changed by electronic control to limit the compression stroke of different distances.

[0036] Example 2:

[0037] Combine Figure 2 The linkage mechanism 2 also includes a guide rail seat 22, a linkage shaft 23, a spring 24 and a slider baffle 25. The elastic adjustment portion 21 is a nut structure. One end of the spring 24 abuts against the vertical wall of the guide rail seat 22, and the other end abuts against the slider baffle 25. The guide rail seat 22 is provided with a slide rail for the slider baffle 25 to slide thereon. The vertical wall of the guide rail seat 22 is perpendicular to this slide rail. The linkage shaft 23 passes through the vertical wall of the guide rail seat 22 and the slider baffle 25, and is engaged with the slider baffle 25 through the elastic adjustment portion 21 movably fixed at one end thereof. The other end of the linkage shaft 23 is transmission-connected to the power mechanism 3. The linkage shaft 23 is used to drive the slider baffle 25 to slide on the slide rail of the guide rail seat 22. The guide rail seat 22 is connected to the striking mechanism 1.

[0038] When the power mechanism 3 pulls the linkage shaft 23 to move in the direction of compression of the spring 24, since the linkage shaft 23 passes through the through hole in the vertical wall of the guide rail seat 22, under the limiting action of the through hole, the slider baffle 25 will be pulled toward the direction of the vertical wall, and the spring 24 will be compressed at the same time. This process is the compression stroke; and when the power mechanism 3 cancels this pulling force, under the restoring force of the spring 24, the slider baffle 25 moves in the direction away from the vertical wall, pushing the elastic adjusting part 21, so that the linkage shaft 23 moves in the direction of restoring and rebounding of the spring 24. This process is the reset stroke.

[0039] The free end of the linkage shaft 23 has a threaded structure, and the elastic adjustment part 21 of the nut structure can adjust the fixed position of the elastic adjustment part 21 on the linkage shaft 23 by changing the screwing degree, thereby adjusting the initial distance between the slider baffle 25 and the vertical wall of the guide rail seat 22, which is also equivalent to adjusting the pre-tightening force of the spring 24.

[0040] Preferably, the spring 24 is sleeved outside the linkage shaft 23 and is coaxially arranged with the linkage shaft 23, which helps to improve the stability of the spring 24 during the compression and reset process.

[0041] As an implementation manner, a rotatable transmission wheel 26 is fixed at the front end of the guide rail seat 22. The transmission wheel 26 can rotate around its connecting shaft. Preferably, the transmission wheel 26 has a gear structure. The linkage shaft 23 is connected to the power mechanism 3 through a transmission chain 27. The transmission chain 27 is engaged with the transmission wheel 26. During a state switching cycle of the joint adjustment mechanism 2, at least a part of the transmission chain 27 and the linkage shaft 23 are on the same transmission axis line, and the transmission axis always maintains an acute angle with the reference plane where the striking mechanism 1 is placed. When the power mechanism 3 pulls the linkage shaft 23 through the transmission chain 27, the part of the transmission chain 27 engaged with the transmission wheel 26 will provide a downward pressing force to the transmission wheel 26. Synchronously, the transmission chain 27 moves on the transmission teeth of the transmission wheel 26, so that the linkage shaft 23 moves along the transmission axis in the direction of the force. Once the force applied by the power mechanism 3 on the transmission chain 27 decreases, under the action of the spring 24, the linkage shaft 23 rebounds, and the transmission axis remains at an acute angle with the reference plane, which can better control the force condition of the joint adjustment mechanism 2 during the periodic state switching, making the switching smoother and the force more reasonable.

[0042] Combined Figures 3 to 5 , further, during a compression stroke of the joint adjustment mechanism 2, there are at least two stroke nodes, which are respectively used for the striking mechanism 1 to just contact the drum surface 41 and compress the drum surface 41 to the maximum stroke. That is, during the compression stroke, as Figure 3 shown, the striking mechanism 1 is first not in contact with the drum surface 41; when reaching the first stroke node, as Figure 4 shown, the striking hammer 11 of the striking mechanism 1 just touches the drum surface 41, and at this time the drum surface 41 is not oppressed; during the process from the first stroke node to the second stroke node, the striking hammer 11 further oppresses the drum surface 41, and finally the drum surface 41 is compressed to the maximum stroke, as Figure 5 shown; by adjusting the position of the elastic adjustment part 21, the force between the striking mechanism 1 and the drum surface 41 can be controlled in the above two stroke node states, thereby simulating different playing intensities.

[0043] Specifically, when this device is applied to a magnetic induction bass drum, since a Hall sensor is installed under the drumhead of the magnetic induction bass drum, there is an induction distance between the drumhead and the Hall sensor, and the striking hammer is equipped with a magnet. When the striking hammer strikes the drumhead, the induction distance between the magnet and the Hall sensor will change, thereby generating a Hall voltage and forming a magnetic induction bass drum. For such a magnetic induction bass drum, it is more necessary to control the depression distance of the drumhead during the life test. Therefore, the elastic adjustment part can better control the striking force of the striking hammer and the depression distance of the drumhead.

[0044] In this embodiment, the striking mechanism 1 includes a striking hammer 11, a pedal 12, a placement base 13, a fixing frame 14, and an elastic reset part 15. The pedal 12 is hinged to the placement base 13, and the guide rail seat 22 of the joint adjustment mechanism 2 is fixed to the pedal 12. When, under the action of the power mechanism 3, the guide rail seat 22 is pressed down, the pedal 12 imitates the process of being stepped on by a human foot and rotates around its connecting shaft. The fixing frame 14 is fixed to the placement base 13. One end of the striking hammer 11 is connected to the top of the fixing frame 14 through a hinge shaft 16, and the other end is used to strike the drumhead 41. One end of the elastic reset part 15 is connected to the fixing frame 14, and the other end is connected to the hinge shaft 16 of the striking hammer 11. The striking hammer 11 is also connected to the pedal 12 through a linkage 17. When the pedal 12 is pressed down, the striking hammer 11 is driven to rotate through the linkage 17, so that one end of the striking hammer 11 strikes the drumhead 41. The elastic reset part 15 is a tension spring structure and is stretched. When the striking hammer 11 has compressed the drumhead 41 to the maximum stroke, under the action of the elastic reset part 15, the striking hammer 11 rotates in the reverse direction, controlling the striking hammer 11 to leave the drumhead 41, and through the action of the linkage 17, the pedal 12 flips up again to reset, and this process repeats under the action of the power mechanism 3.

[0045] In this embodiment, the power mechanism 3 includes a motor 31 and a connecting rod assembly 32. One end of the connecting rod assembly 32 is connected to the motor 31, and the other end is connected to the joint adjustment mechanism 2 through a transmission chain 27. The connecting rod assembly 32 includes at least two hinged connecting rods. One connecting rod is connected to a non - central position of the motor 31, and one connecting rod has a fixed fulcrum that remains stationary. When the motor 31 rotates, the transmission chain 27 is periodically pulled through the connecting rod assembly 32.

[0046] Preferably, the power mechanism 3 further includes a controller. The operator can write relevant programs into the controller, and the controller sends operation instructions to the motor 31 according to the logic of the program. Among them, the operation instructions are configured to adjust and control the rotation speed and / or the rate of change of the rotation speed of the motor 31. The rotation speed and / or the rate of change of the rotation speed of the motor 31 are used to restore the different striking forces of the drum beats of certain songs. That is, in an automatic control manner, the operation parameters of the motor 31 are parameterized, so that the striking force and the stroke distance of the striking hammer 11 are more controllable.

[0047] In a second aspect, this embodiment provides a testing method for the apparatus for testing drum life as described in the above embodiment, comprising the following steps:

[0048] Adjust the position of the elastic adjustment part 21 to adjust the compression stroke of the joint adjustment mechanism 2;

[0049] The power mechanism 3 is controlled to operate, driving the joint adjustment mechanism 2 to enter the compression stroke. During this process, the pedal 12 is pressed down, and the striking hammer 11 moves toward the drum surface 41. In one compression stroke, the striking mechanism 1 moves from separation from the drum surface 41 to contact with the drum surface 41, and then to compress the drum surface 41 to the maximum stroke.

[0050] The power mechanism 3 continues to run, reducing the force applied to the joint adjustment mechanism 2, driving the joint adjustment mechanism 2 into the reset stroke. This process mainly relies on the elastic reset part 15 to provide force to the striking hammer 11, so that the striking mechanism 1 is separated from the drum surface 41. At the same time, the pedal 12 flips up, and the elastic adjustment part 21 also completes the reset stroke to complete a test cycle.

[0051] As an embodiment, the position of the elastic adjustment part 21 is adjusted so that when the spring 24 in the joint adjustment mechanism 2 is at the minimum compression state point in a compression stroke, the striking mechanism 1 can compress the drum surface 41 to the maximum stroke. Due to the physical properties of the spring 24, its maximum compression stroke is L1, but at the minimum compression state point required to be reached in the compression stroke, the spring 24 can be in a compression state with a stroke less than L1, thereby controlling the force applied by the striking hammer 11 to the drum surface 41 when it is at this minimum compression state point.

[0052] As an embodiment, when switching from the compression stroke to the reset stroke, the striking mechanism 1 is subjected to a reset force, that is, the force applied to the striking hammer 11 by the elastic reset portion 15 as a tension spring structure. The reset force causes the striking hammer 11 in the striking mechanism 1 to leave the drum surface 41, and at the same time allows the striking hammer 11 to drive the pedal 12 to flip up and reset through the linkage 17.

[0053] Compared with the prior art, the above embodiment provides a device and method for testing the life of a drum. By adjusting the elastic adjustment portion 21, the compression stroke of the joint adjustment mechanism 2 can be changed. The smaller the compression stroke, the greater the pressing force applied by the joint adjustment mechanism 2 to the striking mechanism 1, which can simulate strikes of the drumhead 41 with different forces. Therefore, the drumhead 41 can be tested cyclically, and the striking force can be changed to simulate the player's foot-stepping action, thereby accurately measuring the service life of the bass drum 4.

[0054] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A device for testing the lifespan of a drum, which is used to strike the drumhead of a bass drum to conduct a simulated performance test, characterized in that, The drum comprises a striking mechanism, a joint adjustment mechanism, and a power mechanism, wherein the power mechanism is used to drive the joint adjustment mechanism to periodically switch between compression and reset states. The joint adjustment mechanism includes an elastic adjustment portion, which is configured to adjust the compression stroke of the joint adjustment mechanism within a state switching cycle. The joint adjustment mechanism is linked to the striking mechanism and controls the striking mechanism to periodically strike the drumhead as the striking mechanism switches between compression and reset states. The linkage mechanism further includes a guide rail seat, a linkage shaft, a spring and a slider baffle, one end of the spring abuts against the vertical wall of the guide rail seat, and the other end abuts against the slider baffle, the linkage shaft passes through the vertical wall of the guide rail seat and the slider baffle, and is clamped with the slider baffle through the elastic adjustment portion movably fixed at one end thereof, the other end of the linkage shaft is transmission-connected to the power mechanism, and the linkage shaft is used to drive the slider baffle to slide on the slide rail of the guide rail seat; A rotatable transmission wheel is fixed to the guide rail seat, and the linkage shaft is connected to the power mechanism via a transmission chain. During a state switching cycle of the linkage mechanism, at least a portion of the transmission chain and the linkage shaft are located on a transmission axis, and the transmission axis always maintains an acute angle with the reference plane on which the striking mechanism is placed. In a compression stroke of the joint adjustment mechanism, there are at least two stroke nodes, and the two stroke nodes are respectively used to link the striking mechanism to just contact the drum surface and compress the drum surface to the maximum stroke.

2. The device for testing the life of a drum according to claim 1, characterized in that The striking mechanism includes a striking hammer, a pedal, a placement base, a fixing frame and an elastic reset part. The pedal is hinged to the placement base, the joint adjustment mechanism is fixed on the pedal, and the fixing frame is fixed to the placement base. One end of the striking hammer is connected to the fixing frame through a hinge shaft, and the other end is used to strike the drum surface. One end of the elastic reset part is connected to the fixing frame, and the other end is connected to the hinge shaft of the striking hammer. The striking hammer is also connected to the pedal through a linkage.

3. The device for testing the lifespan of a drum according to claim 2, wherein The power mechanism includes a motor and a connecting rod assembly, one end of the connecting rod assembly is connected to the motor, and the other end is connected to the joint adjustment mechanism through a transmission chain.

4. The device for testing the life of a drum according to claim 3, wherein The power mechanism further includes a controller, which is configured to send an operating instruction to the motor, wherein the operating instruction is configured to adjust and control the rotation rate and / or speed change rate of the motor.

5. A test method for an apparatus for testing the drum life as described in any one of claims 1 to 4, characterized in that, The following steps are involved: Adjust the position of the elastic adjustment part and adjust the compression stroke of the joint adjustment mechanism; Controlling the operation of the power mechanism to drive the joint adjustment mechanism to enter a compression stroke, wherein in one of the compression strokes, the striking mechanism moves from being separated from the drum surface to being in contact with the drum surface, and then compressing the drum surface to a maximum stroke; The power mechanism continues to operate, driving the joint adjustment mechanism to enter the reset stroke, so that the striking mechanism is separated from the drum surface.

6. The test method according to claim 5, wherein The position of the elastic adjustment portion is adjusted so that when the spring in the joint adjustment mechanism is at the minimum compression state point in a compression stroke, the striking mechanism can compress the drumhead to the maximum stroke.

7. The test method according to claim 6, wherein, When switching from the compression stroke to the reset stroke, the striking mechanism is subjected to a reset force that causes the hammer in the striking mechanism to move away from the drum surface.

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