GB1110107A - Improvements in centrifugal pumps - Google Patents

Abstract

1,110,107. Centrifugal pumps. HAYWARD TYLER & CO. Ltd. (A. Ivanoff). July 28, 1965 [July 28, 1964], No.29985/64. Heading F1C. In a centrifugal pump and motor combination, the pump has one or more impellers 9 mounted on a pump shaft 3 coupled to the motor shaft 4 by a flexible coupling 6, the stiffness of the coupling (which, as shown, may be of spherical bonded rubber type) being such that the primary critical speed of the system including the pump shaft the impeller or impellers and the coupling is substantially below the running speed of the motor 1 and the stiffness of the pump shaft being such that any secondary critical speeds are substantially above the running speed. Despite unbalance caused by uneven wear due to the abrasive material contained in the sandy water being pumped, the axis of rotation coincides (or very nearly coincides) with the centre of gravity of the shaft 3 and its impeller or impellers. Lateral deflection of the shaft 3 occurring during acceleration through the primary critical speed is limited by a steady bush 7 having a large radial clearance about the shaft. A porous bush 8 allows the escape of air as the bush fills with water but prevents the entry of downwardly dropping sand when the pump is stopped. To allow the lateral deflection, a gap is left between the lower face of the impeller (preferably faced with hard metal) and the co-operating surface of the pump casing (preferably faced with a rubberlike plastics material 11 to allow passage of sand through the gap without serious impeller wear).