| 摘要 |
A hydraulic system for applying tension to musical drum heads (2). It consists of one or more master cylinders (166) applying pressure to a hydraulic fluid (106) in a sealed circuit. The master cylinders (166) may be hand-activated, foot-activated, controlled by an external source (167), or a combination thereof. The hydraulic fluid is then forced through tubing (32) to any number of reacting slave cylinders (50). The slave cylinders may be either single action (one moving piston and seal) or dual action (two moving pistons and seals moving in opposite directions), depending on the size and configuration of the drum (2). The pistons (50) activate a mechanical lever (68) or combination linkage that in turn pulls on a typical tension screw (10) and rim (4) configuration found on most common musical drums. The system allows for immediate pitch changes through the complete range of the drum while always maintaining uniform tension around the perimeter of each head. It also allows a fixed preset ratio between the tensions of the top and bottom heads on a twoheaded drum. The system includes a procedure for rapid change of heads with immediate tension balancing. With the addition of a visual gauge to observe and repeat the fluid pressure in the hydraulic system, accurate pitches can be recalled no matter what source initiated the change.
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