| 摘要 |
The invention relates to a one piece molded plastic knob (296), which includes a planar circular section having a conformation (378) extending from the upper surface thereof adapted to be grasped to rotate the knob (296). A recess (390) is formed on the other side of the knob (296) which extends in the conformation (378) and has a pair of common substantially parallel walls defining the recess (390). Positioned centrally in the recess (390) is a shaft receiving structure (396) which defines a D-shaped opening (398). The opening is separated into two spaced apart sections (404, 406) by a vertically extending slot (400). The separate sections are integrally formed with opposing side walls. The D-shaped opening (398) is molded with a negative draft angle having a cross-sectional area at the opening smaller than that of the lower end thereof. The D-shaped control shaft (228) is sized such that as it enters the D-shaped opening (398), it causes the separate sections (404, 406) to flex outwardly to thereby firmly engage the shaft (228).
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