| 摘要 |
A dump valve assembly for opening and fluid-tightly sealing the drain outlet of a waste tank, the assembly comprisng a rotatable elongated shaft having a handle at its upper end and a first or lower compression plate adjustably secured to its lower end. Disposed concentrically about the shaft are a first and second tubular member, the former having a length less than that of the shaft, and the latter having a length less than that of the first tubular member. Fixedly secured to the lower end of the first tubular member is a second or upper compression plate spaced from the lower plate. Sandwiched and pre-loaded between the upper and lower compression plates is a valve plug made of an expandable material. The shaft is provided with a double-thrust ball bearing which abuttingly engages the upper end of the first tubular member to permit independent rotation of the shaft relative to the former member. The threaded lower end of the shaft meshes with the inner threading of a hub formed integrally with the lower compression plate, in upright orientation relative thereto. Typically, the lower end portion of the shaft extends beyond the undersurface of the lower compression plate and a roll pin extends through the projecting lower shaft portion to retain the lower compression plate on the shaft during rotation of the latter. As a result of the pre-load of the plug, the lower compression plate will ride upwardly on the shaft threaded lower end thereby to expand the plug when the shaft is rotated in clockwise direction. Conversely, when the shaft is rotated in counterclockwise direction, the plug, on account of its expanded condition will urge the lower compression plate downwardly due to contraction of the plug to its normal size. The outer periphery of the plug is provided with a plurality of ribs which effect a positive seal with the drain outlet in expanded condition of the plug. The upper end of the first tubular member is formed with a narrow sleeve, the latter having a downwardly oriented finger which, during operation of the valve assembly, is received and accommodated in a downwardly extending, open-ended slot in the upper end of the second tubular member. This arrangement prevents rotation of the first tubular member relative to the second one. Secured to the second tubular member is a mounting plate for securing the assembly to the waste tank. Hence, during operation, both the first and second tubular members are stationary while rotation of the shaft causes expansion or contraction of the plug depending upon the rotation direction of the shaft.
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