| 摘要 |
PURPOSE:To aim at simplification and miniaturization in a bearing structure in making it so as to get off without using a special bearing for receiving thrust force, by holding a timing gear of a Roots pump between a thrust plate and a housing and supporting it by this thrust plate. CONSTITUTION:A timing gear 35 is inset in a small diametral part 21a at an end of a rotor shaft 21, and it is clamped to this rotor shaft 21 so as not to cause axial and circumferential movements via a key 2, a washer ring 3 and a clamping bolt 4. This timing gear 35 is held between the thrust plate 1 fixed to a center housing 25b by a clamping bolt 6 and the center housing 25b and supported by this thrust plate 1. Therefore, thrust force acting on the rotor shaft 21 is supported by contact between the thrust plate 1 and the center housing 25b, so that a small-sized bearing structure is securable in a simple structure without using any special bearing.
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