Abstract: A device for collecting and distributing material into a receptacle having a receptacle curvature includes: a tapered wall; and a tamping flange adjoining the tapered wall. The tapered wall has a tapered wall curvature that approximates the receptacle curvature. The tamping flange is configured to compact the material into the receptacle.

Abstract: A loudspeaker comprising a horn waveguide having a throat and a waveguide surface; an acoustic radiator assembly, located at the throat of the waveguide, comprising a diaphragm having a rigid acoustically radiating surface shaped as a section from a toroidal surface for generating acoustic wavefronts, the waveguide surface being adapted to match the shape of the wavefronts coming from the assembly.

Abstract: An electro-acoustic transducer with a front part having an acoustically radiating surface, a supporting part that supports the front part and that extends from a peripheral region of the front part in a direction away from the acoustically radiating surface, and a reinforcing part that provides rigidity to the transducer. The reinforcing part extends from the supporting part to the front part such that a portion of the reinforcing part is spaced from the front part and/or the supporting part.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of slots constituting entrances for the channels, each slot being arranged in a substantially radial orientation on the input surface about a central axis extending through the input surface. Substantially the entire input surface situated between the slots is concave and substantially part of a sphere or an ellipsoid in shape.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of openings constituting entrances for the channels, the input surface being substantially part of a sphere or an ellipsoid in shape. The areas of the openings vary with radial position on the input surface, the radial position being measured in a direction extending perpendicularly from a central axis extending through the input surface. The variation in the areas is a function of the cosine of an angle subtended at the centre of the sphere or a focus of the ellipsoid between the central axis and the radial position.

Abstract: A loudspeaker comprises a horn waveguide having a waveguide surface, and a transducer located in, or adjacent to, a throat of the horn waveguide. The transducer has a substantially rigid convex dome-shaped acoustically radiating surface. A horn angle subtended between a longitudinal axis of the horn waveguide and the waveguide surface at the throat of the horn, is in the range 20 to 60 degrees. An intersection angle subtended between a plane tangential to the dome shape of the acoustically radiating surface and a plane tangential to the waveguide surface at a point where the dome shape or an extrapolation of the dome shape meets the waveguide surface or an extrapolation of the waveguide surface, is in the range 85 to 110 degrees.

Abstract: A loudspeaker comprising a horn waveguide having a throat and a waveguide surface; an acoustic radiator assembly, located at the throat of the waveguide, comprising a diaphragm having a rigid acoustically radiating surface shaped as a section from a toroidal surface for generating acoustic wavefronts, the waveguide surface being adapted to match the shape of the wavefronts coming from the assembly.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of slots constituting entrances for the channels, each slot being arranged in a substantially radial orientation on the input surface about a central axis extending through the input surface. Substantially the entire input surface situated between the slots is concave and substantially part of a sphere or an ellipsoid in shape.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of openings constituting entrances for the channels, the input surface being substantially part of a sphere or an ellipsoid in shape. The areas of the openings vary with radial position on the input surface, the radial position being measured in a direction extending perpendicularly from a central axis extending through the input surface. The variation in the areas is a function of the cosine of an angle subtended at the centre of the sphere or a focus of the ellipsoid between the central axis and the radial position.

Abstract: A loudspeaker comprises a horn waveguide having a waveguide surface, and a transducer located in, or adjacent to, a throat of the horn waveguide. The transducer has a substantially rigid convex dome-shaped acoustically radiating surface. A horn angle subtended between a longitudinal axis of the horn waveguide and the waveguide surface at the throat of the horn, is in the range 20 to 60 degrees. An intersection angle subtended between a plane tangential to the dome shape of the acoustically radiating surface and a plane tangential to the waveguide surface at a point where the dome shape or an extrapolation of the dome shape meets the waveguide surface or an extrapolation of the waveguide surface, is in the range 85 to 110 degrees.

Abstract: An electro-acoustic transducer comprises a front part having an acoustically radiating surface, a supporting part that supports the front part and that extends from a peripheral region of the front part in a direction away from the acoustically radiating surface, and a reinforcing part that provides rigidity to the transducer. The reinforcing part extends from the supporting part to the front part such that a portion of the reinforcing part is spaced from the front part and/or the supporting part.

Abstract: A protective guard for reducing injury to a shin of a person is provided. The protective guard includes an elastomeric substrate having a pocket disposed therein. A central core is carried by the pocket of the elastomeric substrate. The central core includes a plurality of rigid plates, a first of which is joined by at least one hinge to a second of the plates.

Abstract: A loudspeaker or other enclosure 10 constituting a humidity sensitive region the moisture of which is to be reduced contains a heater 18A. The tube 12 having a bore narrow enough to prevent diffusion of gases therethrough leads from the enclosure 10. The heater is operated cyclically by a switching circuit 19 to heat the interior of the enclosure to expel moist air through the tube 12 and thereby control the humidity of the air in the enclosure. A dessicant 16 may be provided in the tube 12. A heater 18B may be provided in the tube instead of in the enclosure.

Abstract: A drive assembly for a loudspeaker comprises a permanent magnet (42) and pole pieces (44a, 44b, 44c, 44d, 4e, 44f, 44g, 44h, 46a, 46b, 46c, 46d) of ferromagnetic material. The pole pieces define an air gap (43) in which a coil formed from windings (40a, 40b) on a former (41) is movable. The shaping of the pole pieces to form air-filled recesses extending to the air gap has the result that the path of the magnetic flux of the permanent magnet is split in the region of the gap and the magnetic permeability of the path of the magnetic flux of the secondary magnetic field induced in the coil upon energisation thereof is reduced. The effect of the secondary field is thereby also reduced and a particularly linear response and a reduction in harmonic distortion can thereby be achieved.

Abstract: A hydraulic valve assembly for selectably delivering hydraulic fluid from a supply of hydraulic fluid to one of a first hydraulic operator and a second hydraulic operator is disclosed. The assembly includes first and second supply ports which communicate with the supply and four operator ports. First and third ports communicate with the first hydraulic operator. Second and fourth ports communicate with the fourth hydraulic operator. First and second chambers are provided. The first chamber communicates with the first supply port and first and second operator ports. The second chamber communicates with the second supply port and third and fourth operator ports. Two selection valves operating in unison are each located in each chamber. The selection valves operate between a first position at a first hydraulic fluid pressure and a second position at a second hydraulic fluid pressure.

Abstract: A loudspeaker unit has, in combination, a pistonically driven diaphragm loudspeaker and a generally planar resonant panel loudspeaker, in which the plane of the resonant panel lies in the same orientation as an axis along which the diaphragm is pistonically driven. The resonant panel loudspeaker may be located behind the diaphragm loudspeaker, with the resonant panel loudspeaker functioning as a diffuse dipole, e.g. to generate surround sound reproduction, and the diaphragm loudspeaker located in the null of the dipole and functioning as an acoustic monopole, e.g. to generate imaged stereophonic sound reproduction.

Abstract: A hydraulic valve assembly for selectably delivering hydraulic fluid from a supply of hydraulic fluid to one of a first hydraulic operator and a second hydraulic operator is disclosed. The assembly includes first and second supply ports which communicate with the supply and four operator ports. First and third ports communicate with the first hydraulic operator. Second and fourth ports communicate with the fourth hydraulic operator. First and second chambers are provided. The first chamber communicates with the first supply port and first and second operator ports. The second chamber communicates with the second supply port and third and fourth operator ports. Two selection valves operating in unison are each located in each chamber. The selection valves operate between a first position at a first hydraulic fluid pressure and a second position at a second hydraulic fluid pressure.

Abstract: A side shifting and fork positioning assembly for a lift truck is disclosed. The assembly includes a carriage which moves in a lift truck mast. The carriage includes a pair of horizontally spaced apart vertical members and a frame support member secured transversely to the vertical members. A side shift frame slides on the carriage. An upper cross member of the side shift frame supports two forks along their hook portion. Hydraulically actuated cylinders located in the frame support member move the side shift frame. The assembly also includes first and second fork shoes movably secured to the side shift frame. Each of the fork shoes define a contact surface to engage the forks. The contact surface of the fork shoes is located no further forward than a front face of the upper cross member. The assembly includes a fork positioner which moves the first fork shoe relative to the second fork shoe, where the fork shoes are maintained at an equal distance from the center of the side shift frame.

Abstract: An improved acoustic horn for loudspeakers is provided. The acoustic horn of the referred embodiment of the present invention includes a one piece body that incorporates damping material within the body. Preferably, the one piece body is slotted and vibration damping material is provided within the slots. The horn is fabricated by casting from suitable metals and metal alloys. In the preferred embodiment, the body comprises four outwardly curved and flared side walls and is generally rectangular. Each wall of a pair of the opposed side walls is cast with a slot. Vibration damping material is provided in each slot to substantially reduce the structural resonances of the one piece body, so that the acoustic horn has enhanced vibration damping. Various vibration damping materials that are flexible relative to the body and have a high loss tangent are used. Suitable materials include hot melt adhesives, epoxy resins, and commercially available elastomeric materials.