An electric motor is described comprising a rotor, a shaft integral with the rotor to transfer torque to a load, a stator coaxially crossed by the shaft. To improve the thermal resistance, a plain bearing placed between the stator and the shaft, and a lubricating fluid circuit configured to transport lubricating fluid and wet a contact surface between the stator and the shaft with the fluid.

A bearing unit provided with a radially outer ring, a radially inner ring, a plurality of rolling bodies interposed between the radially outer ring and the radially inner ring, and a retention device for keeping in position the plurality of rolling bodies, having a circular base rib, a plurality of fingers circumferentially spaced and defining a plurality of cavities for holding respective rolling bodies of the plurality of rolling bodies which are in contact with the retention device by means of a contact surface, and a plurality of discontinuity elements which reduce the extent of the area of contact with the rolling bodies.

A ball bearing is provided which includes a cage made of a resin, and having pockets open to the side surface of the cage on its one axial side. The ball bearing includes an outer bearing ring including a radially protruding engagement portion on the other axial side of the raceway surface. The cage includes engagement portions disposed on the other axial side of the pockets so as to be engageable with the engagement portion of the outer bearing ring in the other axial direction. The relationship between the axial depth H of each pocket and the diameter d of the ball is set at 0.15d≤H≤0.65d. By setting the above relationship in this way, it is possible to reduce the deformation of the cage due to a centrifugal force, and to reduce the shear resistance of lubricating oil between the pockets and the balls.

The bearing structure includes an insertion member, which is inserted through a pin hole (insertion hole) of a bearing housing (housing) in a direction intersecting an axial direction of a shaft, has one end side inserted between a pair of radial bearing surfaces of a main body portion and another end side inserted through the insertion hole, and has a through hole passing from one end to another end.

A cage for a tapered roller bearing includes a large-diameter-side annular portion circumferentially extending along large end surfaces of a plurality of tapered rollers; a small-diameter-side annular portion circumferentially extending along small end surfaces of the tapered rollers; and a plurality of pillars coupling together the large-diameter-side annular portion and the small-diameter-side annular portion. The large-diameter-side annular portion has large-diameter-side pocket surfaces opposed to the large end surfaces of the respective tapered rollers. The large-diameter-side pocket surfaces include oil retaining holes including blind holes, and being configured to receive and retain lubricating oil by capillary action.

A tapered roller bearing includes an inner ring, an outer ring, a plurality of tapered rollers, and an annular cage having a plurality of cage pockets. Each of the cage pockets has a retainer configured to permit displacement of the tapered roller in a direction with a component in a radial direction, and restrict detachment of the tapered roller to an outer side in the radial direction by bringing the retainer into contact with a part of an outer peripheral surface of the tapered roller. The cage pockets include a first cage pocket having a first retainer with which a permissible amount of the displacement is a first displacement amount, and a second cage pocket having a second retainer with which the permissible amount of the displacement is a second displacement amount smaller than the first displacement amount.

A rolling bearing unit provided with a radially outer ring having an assembly groove, two radially inner rings, two series of rolling elements interposed between the radially outer ring and the radially inner rings and defining between them a first internal grease reservoir. The groove is arranged in an axially intermediate position with respect to the two radially inner rings and a grease dispensing device is housed inside the groove of the radially outer ring and is in turn provided with a second grease reservoir formed inside the radially outer ring and communicating with the first reservoir via the groove. A permeable retaining wall housed is inside the groove so as to retain the grease inside the second reservoir and allow it to flow out towards the first reservoir during operation of the bearing unit, dispensing it in a controlled manner.

An inner ring for a bearing assembly comprises an inner circumferential surface disposed between a first axial end and a second axial end. A circumferential slot is disposed in the inner circumferential surface adjacent the second axial end. At least one radial passage is disposed within the inner ring and is in fluid communication with the circumferential slot. At least one axial slot extends axially along the inner circumferential surface from a respective opening in the first axial end to the circumferential slot. At least one of the radial passage is circumferentially offset from each at least one axial slot.

A roller and cage assembly (1) includes a roller (2) and a cage (3). The cage has a plurality of annular portions (30), a plurality of pillars (31) that couple the plurality of annular portions, and a pocket (40) formed between adjacent pillars. The pillars include a protrusion (35) that protrudes from a side wall surface towards the pocket and contacts the roller, which side wall surface configures the pocket, and within the protrusion, a plane facing the roller in a circumferential direction has a first plane (36), and a second plane (37) connecting to the first plane, the first plane being a flat plane, and the second plane being a curved plane, or a flat plane inclined against the first plane.

A refrigeration apparatus includes a compressor connected to a refrigerant circuit, and a bearing monitor. The compressor includes a compression mechanism, an electric motor, a drive shaft, and a plain bearing that supports a journal portion of the drive shaft. The bearing monitor performs an abnormal-state operation to cope with poor lubrication on the plain bearing if an abnormal state condition is satisfied. The abnormal state condition is a condition indicating that a rate of change of current exceeds a first reference value. The rate of change of current is an amount of change in a driving current usable to drive the compressor per unit time. The journal portion of the drive shaft has a surface roughness of at least 0.05 μm.