| 摘要 |
PURPOSE: To provide a variable resistor superior in sealing characteristics by surely engaging an O-ring with a rotor for preventing dismounting or dislocation of the O-ring during assembly. CONSTITUTION: At least two sliding pieces 9-11 fixed on the bottom surface of a recessed part 3 of a case 2, rotator 18 comprising an engagement part 19 for engaging with a tool at the upper end part and housed in the recessed part 3 of the case 2 for rotation, a resistance board 24, which is fitted to the lower end surface of the rotor 18 and comprises a resistor and an electrode to slide/contact the sliding piece on its lower surface, a cover 30 attached to a recessed part opening part of the case 2 for regulating rising of the rotor for holding while rotation is allowed, and an O-ring 28, which seals between the recessed part inner peripheral surface of the case 2 and the outer peripheral surface of the rotor 18, are provided. A step part 23 whose lower side is to be small in diameter is formed on the outer peripheral surface at the lower end part of the rotor 18, and the resistance board 24 is so formed into a disc which is larger in diameter than the small-diameter part of the step part of the rotor, by fixing the resistance board 24 to the lower end surface of the rotor 18 for preventing the O-ring 28 from dropping out.
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