Abstract: The bearing of a machine tool spindle is sealed by a pair of wiping seals mounted on the shaft and resiliently urged into contact with opposite faces of a stationary ring through which the shaft extends. The very small clearance between the ring and the shaft is fed with gas for example air at low pressure. When there is no gas supply and for example when the shaft is stationary the seals contact the ring and the resilience ensures good contact and prevents seepage of for example lubricant along the shaft from one side of the seals to the other. When the shaft is to be driven, low pressure gas is supplied and this pressure deflects the seals to lift them from the face of the ring so that there is no frictional engagement and either power loss or heat generation, and any liquid which does go past the seals is thrown outwardly by centrifugal force and driven by the escaping gas.

Abstract: A gerotor pump set passages 32 extending parallel to the axis of rotation through the female lobed annulus, and similar passages through the male lobed rotor. These passages enable flow from the fluid inlet to pass into the working chamber such as 43 either directly at the inlet end, or after flow through those passages and through the transfer passage 43 at the opposite axial end to the inlet, without requiring a transfer passage externally of the annulus. the result is better axial filling of the working chambers, in a particularly compact design.

Abstract: A reversible unidirectional flow gerotor pump (FIG. 1) has an externally cylindrical internally lobed rotor (36) internally meshed with an eccentrically located externally lobed male rotor having a smaller number of lobes (40) and the annulus runs in a cylindrical cavity in carrier ring 22 pivoted on pin 20 via slot 24. The carrier ring is located in a cylindrical cavity in the body of the pump and is free to translate along the line 18, with accompanied movement along the line 44, this movement occurring automatically when the direction of rotation of the driven rotor 40 is reversed, and resulting in continued pumping flow in the same direction through the pump.

Abstract: The invention provides a variable output pump of the gerotor type in which one rotor meshes in two side by side annulii which can be aligned for maximum output and turned in opposite directions to be non-aligned for minimum output. The movement is effected by a gear train displaced by a rack which is hydraulically operated by pump pressure. Hence high pressure displaces the rack to result in lower output against lower pressure. A variation is described in which a control spool diverts fluid to either side of the piston according to need and this is displaced in one direction by the derived fluid pressure and in the other direction additionally by spring pressure transferred from the piston position by a lever system. This can give desired pump output/speed results at reduced power consumption.

Abstract: A variable output gerotor oil pump of the kind having a common rotor with n teeth meshed with two axially juxtaposed internally lobed annuli with n+1 teeth has the annuli individually located in eccentrics formed with gear teeth to be turned in opposite directions by a gear drive. The teeth are straight cut, not bevel, and the drive includes an intermediate pinion so that a single shaft turns the eccentrics in opposite directions.

Abstract: A cooling system for an I.C. engine includes a gerotor pump coupling a drive shaft 10 to the fan blades 20. The pump is arranged to self-prime when a by-pass passage 26 connecting the pump with the reservoir is closed by initial movement of the thermostat 34 displacing a tube 36 to close port 38. When primed, the gerotor set will drive the fan at an intermediate speed. Further movement of the thermostat displaces a spool valve 26 to take waist 24 out of register with transfer path 22 so that the pump locks up and the fan is driven at a higher speed.

Abstract: A gerotor pump is arranged for unidirectional flow irrespective of direction of rotation of the pump by arranging for displacement of the axis of eccentricity of the annulus and rotor upon drive reversal, the annulus being mounted in a carrier 14, FIG. 1, with freedom for movement in a first direction within the carrier, while the carrier itself is pivoted (24) in an outer housing 15, the carrier being free for movement in a second direction within the housing. The effect of normal drive of the rotor is to hold the parts in the FIG. 1 position while pumping continues, but in the event of drive reversal a pressure fluctuation causes the annulus to be displaced within the carrier and then the carrier to be displaced within the housing so as to bring the parts to substantially the mirror image of the FIG. 1 position allowing continued pumping in the same direction from inlet to outlet under reversed drive.

Abstract: A gerotor pump of n and n+1 type has the annulus and rotor located in a chamber with one wall provided by a floating coverplate held in place by a spring so that in the event of excess internal pressure the cover can lift to allow cross leakage between the inlet and outlet sides of the pump. FIG. 2 illustrates a typical embodiment.