Abstract: A linear motion actuator of the present invention is provided with a casing including slits extending axially, a carriage being axially movable along guide rails within the casing, the carriage including driven member mounting portions protruded outside through the slits for mounting a driven member, a plurality of seal bands fastened to the driven member mounting portions of the carriage for sealing openings of the slits regardless of the location of the carriage when the seal bands are moved along the slits, and a driving device for driving the carriage to move along the guide rails. The linear motion actuator with a dust-proof function has no need of passing the seal bands through the carriage, so that the carriage have a solid and simple structure of high rigidity without the abnormal shifting motion of the seal bands.

Abstract: A hydrostatic bearing system utilizing ferromagnetic fluid exclusively as working fluid including that used for sealing for preventing the ferromagnetic fluid itself from escaping outside the bearing. In order to accomplish the objects and function, the hydrostatic bearing system proposed here comprises, in addition to ordinary parts or components used in the conventional type, a fluid chamber for containing the ferromagnetic fluid as a working fluid, a circulating passage, at least a recovery groove for collecting the fluid squeezed out of the fluid chamber, a magnetic seal to prevent the fluid from escaping and at least an impelling device to forcibly deliver the ferromagnetic fluid at a predetermined pressure and flow rate. The impelling device can be constructed utilizing a shifting magnetic field, or multilayered rings fabricated of piezo-electric components, or of impelling cylinders having axially lengthenee or reduced in length.