| 摘要 |
1,195,368. Rotary positive-displacement pumps. W.C. HOLMES & CO. Ltd. Oct. 12, 1967 [Oct. 19, 1966; July 14, 1967], Nos.46707 and 32531/67. Heading F1F. In rotary positive-displacement pumping apparatus of the Roots'-blower type a probe 36 in each of several units 34 upon a casing 18 for a pair of pumping rotors (10, 12), (Figs. 1 and 2 (not shown), completes a low-voltage electric circuit including the casing and the rotors whenever axial or radial clearance between the rotor and the part of the casing adjacent the probe reach a predetermined minimum owing to thermal expansion. Completion of the circuit aforesaid by contact between any of the probes and the adjacent rotor produces a warning signal. As an alternative the probes may be arranged in pairs, the circuit being completed when the adjacent rotor touches both of the probes in any pair. Each probe is mounted in an electrically-insulating bush 38 supported by a screw-threaded outer-bush 40, and may be furnished with adjusting means of micrometer type to facilitate measurement of the clearance in its vacinity. The aforementioned warning signal may actuate means for stopping the rotors. |
