Patent GB-268197-A (GB)
Title: Improvement in centrifugal pumping apparatus
IPC: F04D29/16
Filed: 1926-07-05
Abstract: 268,197. Jennings, I. C. July 5, 1926. Pumping machines and apparatus; driving- gear; leakage-preventing devices; starting, facilitating.-A centrifugal pumping apparatus P has a driving motor M mounted on a base 20; the impeller shaft forms an extension of the motor shaft and the sealing means provided between the impeller shaft and the casing or impeller chamber, are adapted to slight variations in the position and alignment of the axes of the shafts relative to the pump casing. The motor shaft 25 is carried in bearings supported by the motor casing and its end enters a recess 35, Fig. 1<b>, in the end of the impeller shaft 34. A longitudinal key 36 prevents relative rotary movement of the shafts and a screw 37 holds them in the desired axial relationship. The impeller 33 is shown of the double entry type and rotates in a chamber 28, the whole being enclosed in a two-part casing 26, 27, so that water spaces 29, 32 are formed. A cock is provided at the top of the casing to permit removal of air from the water spaces. A stuffing box 41 is fixed at the left hand side of the casing and contains soft annular packing 42; it may also contain lantern packing 45 connected to a water supply pipe 46 to form a water seal. The inward extension 49 of the stuffing box is smaller than the opening in the casing, and the box is held by bolts 47 passing through radial slots in the flange 48. This construction enables the box to be adjusted radially. The spaces on each side of the impeller, between the hub and the walls of the chamber 28 are sealed by self-adjusting and centring devices. Each device consists of a ring 52 on a cylindrical surface on the hub and a ring 53 in a recess in the chamber wall. The rings are movable relatively in a radial direction and are held together yieldingly by springs 55. When assembling the machines the motor is secured to the base and the pump is moved axially for the shafts to engage and be secured by the screw 37. The stuffing box is then secured in radially adjusted position by the bolts 47 and the sealing devices 52, 53 adapt themselves to the position assumed by the pump shaft 34. The pump shown in Fig. 2 has an air pump 60 attached for priming purposes. This pump withdraws air from the water-space surrounding the impeller chamber and it has a rotor 64 mounted on a shaft 65 carried in bearings in a casing extension 68. An annular space 69 retains priming water for the air pump. A member 71 forms a self-aligning connection between the rotor shaft 65 and the impeller shaft; pins 75, 77 secure the member to the impeller shaft and at the other end a cross plate 78 fits loosely in a slotted recess in the rotor 64 and transmits rotary motion thereto. A sealing member 80 on the impeller shaft is pressed by a spring against a finished surface 81 on the pump wall and is self-centring like the rings 52 shown in Fig. 1. In another modification provision is made for accurately positioning the air pump rotor within the pump chamber. A sleeve 96, Fig. 3, has an internal thread to engage a thread on the rotor shaft, and an external thread to engage another in a recess in the rotor. The internal and external threads are of the same hand but different pitches so that a fine axial adjustment can be obtained. The parts are secured by a cross pin 98.