Abstract: In an aspirating unit for dental workstations the blower impeller of a vacuum pump (32), a propeller (84) and a pump impeller (68) sit on a common drive shaft (66). The drive shaft (66) is enclosed by a cyclone air extractor (34), the propeller (84) keeping foam components contained in the incoming air and fluid mixture clear of the air discharge connection of the cyclone fluid extractor (34). The pump impeller (68) conveys the fluid discharged at the bottom end of the cyclone fluid extractor (34) forcibly to the fluid outlet connection (28) of the aspirator.

Abstract: A device for separating fine particles of solid matter from waste fluid has a water ring pump (16, 44), an air separator (18, 60) and a solid bowl centrifuge (24, 30) which are arranged axially one behind the other in the aforementioned sequence and are driven by the motor shaft (28) of a common drive motor (12).

Abstract: A separator for incorporation into dental suction apparatus for separating from the suction stream liquid and solid materials coming from the mouth of a patient comprises a housing, a separation chamber in the housing, an inlet for the suction stream into the separation chamber and an outlet for cleaned suction air from the separation chamber. Below the separation chamber there is a smaller collecting chamber below which is a drainage chamber provided with a liquid-solid discharge opening. In the separation chamber there is a cyclone device into which the suction stream enters tangentially so as to provide a swirling movement. The suction air then passes up through a central opening defined by the cyclone means. Also in the separation chamber there is a rotating element in the form of a rotatable float having a stem extending up from the float and provided with vanes associated with the cyclone device so as to rotate the float.

Abstract: An oil-less gas compressor comprises at least one cylinder block mounted on a crankcase, the outer end of the cylinder block being closed by a cylinder head. A piston in the cylinder block bore is reciprocated by a motor-driven crankshaft in the crankcase. The cylinder blocks and cylinder heads are generally square in cross section. On all four sides of the cylinder block and cylinder head there are spaced cooling fins which extend in an axial direction. Axially extending cooling air passages between the fins communicated at their lower ends with the interior of the crankcase. Air drawn into the crankcase by a fan on the crank shaft flows into and through these cooling air passages to cool the cylinder block and head. In one corner portion of the cylinder block and head there is an integral axially extending suction bore containing a filter. In an adjacent corner portion of the cylinder block there is an axially extending compressed air bore.

Abstract: In a torque transmitting coupling between a cylindrical shaft and a female member having a bore to receive the shaft, the shaft has a secant face and the female member has a connecting bolt bore which intersects the shaft bore and faces the secant face of the shaft. A connecting bolt in the bolt bore of the female member has a secant face which tightly engages the secant face of the shaft. In one embodiment, the shaft axis, secant faces of the shaft and bolt and the bolt bore are all parallel. In another embodiment the axis of the bolt bore is inclined at a small angle to the secant face, the bolt being of wedge form. A screw extending through a hole in the female member and screwed into a tapped hole in the bolt is rotatable to move the bolt axially and thereby wedge the secant face of the bolt against the secant face of the shaft. The secant faces of the shaft and bolt may have intermeshing longitudinally extending serrations.

Abstract: Dental suction apparatus is a modular construction, made up of a plurality of modules joined fluid-tight side-by side. A main suction duct extends through all of the modules. At least two of the modules have connection for suction hoses each having a suction nozzle, holders being provided on the modules for holding the suction nozzles when not in use. At least one module has a filter chamber connected between a suction tube and the main suction duct. A removable filter unit in the filter chamber has a basket-shaped filter on a stem by means of which the filter can be removed through on opening closed by a hinged cover. A cap on the stem provides a seal for the filter chamber. Flow of air from the suction tube of each suction tube module to the main suction duct is controlled by a valve in the form of a bellows provided with a telescopic guide and with a control valve for controlling the expansion and contraction of the bellows by differential pressure.

Abstract: The invention relates to an ink capable of producing writing or marking on a non-absorbent or impermeable surface, which can easily be wiped off. The disadvantages inherent in the known inks are overcome by adding ester compounds of a certain composition to the ink.

Abstract: Apparatus for producing dry compressed air comprises a compressor which delivers air to a dry air storage tank through a cooling coil, a liquid separator comprising a housing having a cavity with a valve controlled tap opening at the bottom thereof, a screening filter and an adsorption filter connected in sequence. A pressure sensitive switch turns off the compressor when a predetermined pressure has built up in the storage tank. When delivery of air ceases, a valve control system opens the tap opening of the separator and second valve control system opens a valve to permit back flow of air from the dry air storage tank back through the adsorption filter to regenerate it and out of the tap opening if the moisture content of air in the dry air storage tank is above a predetermined level.

Abstract: Apparatus for producing dry compressed air comprises a compressor, a separator to remove condensates, an adsorption filter to filter and dry the air and a storage tank. A valve for controlling reverse flow of air from the storage tank through the filter to the atmosphere to regenerate the adsorption filter when the compressor stops is controlled by a moisture sensitive device so that reverse flow is permitted only if the moisture control of the compressed air is above a predetermined value. The opening of a tap to discharge collected liquid from the separator is controlled by a pneumatically operated valve system so that no electrical control is required.