Abstract: An axial air movement fan having a plurality of variable pitch fan blades (2), extending radially from a hub (4) rotatable about a main axis (3), each blade (2) further being pivotable about its radial axis to vary the blade pitch. The blades (2) each are mounted on an associated bearing (5) mounted on said hub, the bearing comprising a ball bearing having a first radially inner race (25) fast the blade (2) and a second radially outer race (26) rotationally fast to the hub (4). The balls (14) in the bearing are separated by separators (15), each separator being generally cylindrical and having its cylindrical axis coaxial with the orbital axis (22) of the orbit of the balls (14) and being adapted to rotate about the said orbital axis (22), the side faces of the separator each having a part spherical recess (16) adapted to receive a ball (14).

Abstract: A method of detecting stall in an axial fan through acoustical measurements in air the air flow, includes measuring the sound emanating from the flow adjacent the fan, preparing a visual representation of the sound, comparing the visual representation with a library of fixed visual representations derived from a plurality of tests representative of the performance of the fan under a range of operating parameters, selecting the fixed visual representation most closely matching the visual representation of the said sound, and deriving a control signal from the selected fixed visual representation. The visual representations are formed by a symmetrised dot pattern (SDP) technique.

Abstract: An axial air movement fan having a plurality of variable pitch fan blades (2), extending radially from a hub (4) rotatable about a main axis (3), each blade (2) further being pivotable about its radial axis to vary the blade pitch. The blades (2) each are mounted on an associated bearing (5) mounted on said hub, the bearing comprising a ball bearing having a first radially inner race (25) fast the blade (2) and a second radially outer race (26) rotationally fast to the hub (4). The balls (14) in the bearing are separated by separators (15), each separator being generally cylindrical and having its cylindrical axis coaxial with the orbital axis (22) of the orbit of the balls (14) and being adapted to rotate about the said orbital axis (22), the side faces of the separator each having a part spherical recess (16) adapted to receive a ball (14).

Abstract: A method of detecting stall in an axial fan through acoustical measurements in air the air flow, includes measuring the sound emanating from the flow adjacent the fan, preparing a visual representation of the sound, comparing the visual representation with a library of fixed visual representations derived from a plurality of tests representative of the performance of the fan under a range of operating parameters, selecting the fixed visual representation most closely matching the visual representation of the said sound, and deriving a control signal from the selected fixed visual representation. The visual representations are formed by a symmetrised dot pattern (SDP) technique.

Abstract: This invention provides a device for capacitively measuring the distance to an object, which comprises an electrode that will couple capacitively with the object, a shield that surrounds the electrode and is electrically isolated from the electrode by means of insulation, and a layer of insulation that surrounds the shield, wherein the insulation between the electrode and the shield, and the insulation that surrounds the shield, are formed by deposition.This invention further provides a method for measuring the distance to a solid object, which comprises forming an electrode that will capacitively couple with the object, depositing a layer of insulation over at least part of the electrode so that the insulation surrounds the electrode, depositing a layer of metal over the insulation to form a shield, and depositing a second layer of insulation over the shield.