Abstract: A combination of two angular type ball bearings provided in a face-to-face arrangement to form a ball bearing unit in which the diameter of the balls of the second ball bearing is less than the diameter of the balls of the first ball bearing. This ball bearing unit is used at high speed to support a substantially unidirectional axial load. When this axial load is applied to the ball bearing unit, only the first ball bearing supports the axial load. The product of the pitch circle diameter of the row of balls in the ball bearing unit and the rotating speed of the inner ring of the ball bearing unit is in the range of 800,000 to 3,000,000 mm.rpm, while the radial load is up to one fifth the axial load.

Abstract: A combination of two angular type ball bearings provided in a face-to-face arrangement for use at high speed to support a substantially unidirectional axial load, such that e.g. when a loading in a leftward direction is applied to the rotating shaft during rotation, the contact angle of the left side bearing which supports this load is made larger, while the contact angle of the right side bearing which does not support this load is made smaller to avoid a drop in fatigue life and improve the endurance of a rolling bearing unit, wherein the product of the pitch circle diameter of the raw of balls and the rotating speed of the inner ring of the bearing is in the range of 700,000 to 2,000,000 mm.rpm, and the radial load is up to twice the axial load.

Abstract: A system for crushing and discharging a powder and granular material that has become caked in a storage tank has a device for supplying compressed air that is used to activate machines as well as to blow up and deliver crushed material, a drilling machine which has drilling rotary blades that rotate at the distal end of a casing to drill a guide hole in the caked material for discharging crushed material by applying impact and rotation to the rotary blades by means of compressed air, and a crusher which has crushing blades to cut the opening edge of the drilled guide hole and to crush the periphery of the guide hole. A guide hole for discharging crushed grain is drilled in the caked grain by applying impact and rotation to the rotary blades of the drilling machine by use of compressed air, and after the guide hole has been drilled, crushing is carried out with the crusher. Since not electricity but compressed air is employed, it is possible to eliminate the fear of a spark being generated.

Abstract: An annular ball retainer for a ball bearing having a plurality of balls disposed in an annular space between an inner race and an outer race comprises radially extending cylindrical wall portions defining holes for retaining the balls therein, and restraining portions extending into the holes in circumferentially opposed relationship with each other in the radial end portions of the cylindrical wall portion and supporting the circumferentially fore and rear portions of the balls. A ball bearing has a plurality of balls retained between the inner race and the outer race by the ball retainer.