Drum and head diaphragm adjustor for drum

1. A head diaphragm adjustor for a drum for adjusting tension applied to an upper head diaphragm and a lower head diaphragm of the drum, wherein the head diaphragm adjustor is one of a plurality of head diaphragm adjustors attachable to an outer surface of a shell of the drum, the head diaphragm adjustor comprising:

a first bolt operated to adjust the tension applied to the upper head diaphragm;

a second bolt operated to adjust the tension applied to the lower head diaphragm;

a first meshed portion meshed with the first bolt and fixable to the outer surface of the shell of the drum;

a second meshed portion meshed with the second bolt and fixable to the outer surface of the shell of the drum;

a rod including an upper portion, a lower portion, and a cylindrical portion, the upper portion of the rod being inserted in the first bolt in a manner independently rotatable relative to the first bolt, the lower portion of the rod being connected to the second bolt in a manner slidable relative to the second bolt and rotated integrally with the second bolt, and the cylindrical portion of the rod having a diameter greater than that of the upper portion of the rod, the first bolt having a lower end surface abutting against an upper end surface of the cylindrical portion.

2. The head diaphragm adjustor according to claim 1 , wherein the rod includes:

an upper rod;

a pipe connected to the upper rod and functioning as the cylindrical portion; and

a lower rod connected to the pipe,

wherein the upper rod has a lower end portion extending through the first bolt and inserted in the pipe, and the lower rod is fitted to the second bolt and has an upper end portion inserted in the pipe.

3. The head diaphragm adjustor according to claim 2 , wherein the lower end surface of the first bolt and the upper end surface of the pipe abut against each other by way of a washer.

4. The head diaphragm adjustor according to claim 2 , wherein the upper rod has a head having a diameter greater than that at a portion lower than the head, and a washer formed by an elastic member is arranged between a lower end surface of the head and an upper end surface of the first bolt.

5. The head diaphragm adjustor according to claim 2 , further comprising:

a tubular member having an upper portion that includes the first meshed portion and a lower portion that includes the second meshed portion;

a fastener fixed to an outer surface of the tubular member to fasten the tubular member to the shell of the drum, the fastener including a stopper extending through a wall of the tubular member and projecting into the tubular member to abut against an outer surface of at least one of the first bolt and the second bolt.

6. The head diaphragm adjustor according to claim 5 , wherein the stopper is an elastic member.

7. A drum comprising a shell, an upper head diaphragm, a lower head diaphragm, and an adjustor for adjusting tension applied to both head diaphragms, the adjustor including:

a first bolt operated to adjust the tension applied to the upper head diaphragm;

a second bolt operated to adjust the tension applied to the lower head diaphragm;

a first meshed portion meshed with the first bolt and fixed to the outer surface of the shell of the drum;

a second meshed portion meshed with the second bolt and fixed to the outer surface of the shell of the drum;

a rod including an upper portion, a lower portion and a cylindrical portion, the upper portion of the rod being inserted in the first bolt in a manner independently rotatable relative to the first bolt, the lower portion of the rod being connected to the second bolt in a manner slidable relative to the second bolt and rotated integrally with the second bolt, and the cylindrical portion of the rod having a diameter greater than that of the upper portion of the rod, the first bolt having a lower end surface abutting against an upper end surface of the cylindrical portion.

8. The drum according to claim 7 , wherein the rod includes:

an upper rod;

a pipe connected to the upper rod and functioning as the cylindrical portion; and

a lower rod connected to the pipe,

wherein the upper rod has a lower end portion extending through the first bolt and inserted in the pipe, and the lower rod is fitted into the second bolt and has an upper end portion inserted in the pipe.

9. The drum according to claim 8 , wherein the lower end surface of the first bolt and the upper end surface of the pipe abut against each other by way of a washer.

10. The drum according to claim 8 , wherein the upper rod has a head having a diameter greater than that at a portion lower than the head, and a washer formed by an elastic member is arranged between a lower end surface of the head and an upper end surface of the first bolt.

11. The drum according to claim 8 , further comprising:

a tubular member having an upper portion that includes the first meshed portion and a lower portion that includes the second meshed portion;

a fastener fixed to an outer surface of the tubular member to fasten the tubular member to the shell of the drum, the fastener including a stopper extending through a wall of the tubular member and projecting into the tubular member to abut against an outer surface of at least one of the first bolt and the second bolt.

12. The drum according to claim 11 , wherein the stopper is an elastic member.