The disclosure relates to a rolling bearing for a medical or cosmetic instrument having a bearing inner ring revolving around an axis of rotation and a stationary bearing outer ring, which concentrically encloses the bearing inner ring; wherein in the radial direction to the axis of rotation, a bearing gap is formed between the bearing inner ring and the bearing outer ring and a plurality of rolling bodies is arranged in succession in the circumferential direction in the bearing gap, via which the bearing inner ring is mounted in the bearing outer ring; wherein the rolling bodies are arranged rolling on the bearing inner ring and the bearing outer ring and have a rolling body height in the radial direction; and the bearing gap is covered in the axial direction by a cover disk, which is fastened on the bearing outer ring or on a housing accommodating the bearing outer ring or is integrally formed with the housing or the bearing outer ring, and which jointly with the bearing inner ring forms a radial gap extending in the axial direction with a gap length, which gap has a gap height in the radial direction.

The rolling bearing according to the invention disclosure is characterized in that the gap length is at least 25% of the rolling body height.

Provided is a roller bearing in which a restraining force of a seal member is further strengthened. The roller bearing includes: an outer ring having an outer ring raceway surface on an inner peripheral surface; an inner ring having an inner ring raceway surface on an outer peripheral surface; a plurality of rolling elements rotatably arranged between the outer ring raceway surface and the inner ring raceway surface; and a seal member that is fixed to a seal attachment groove formed in an axially end portion of the outer ring by a snap ring and seals an axially end portion of a bearing internal space between the outer ring and the inner ring, in which an outer diameter of the seal member is larger than an outer diameter of the snap ring in the seal attachment groove, and in which a radially outer end portion of the seal member is sandwiched between an inner peripheral surface of the seal attachment groove and an outer peripheral surface of the snap ring.

A ball bearing includes an inner ring; an outer ring placed outside of the inner ring; a plurality of rolling bodies intervening between the inner ring and the outer ring; and an annular cage including pockets rotatably holding the rolling bodies in a circumferential direction at intervals determining a rotation axis to be a center. The cage comprises a resin composition comprising a polyetherketone-based resin, graphite, and a carbon fiber. The resin composition comprises the polyetherketone-based resin in an amount of 60% by weight or more and 80% by weight or less, the graphite in an amount of 10% by weight or more and 30% by weight or less, and the carbon fiber in an amount of 5% by weight or more and 20% by weight or less when the entire resin composition is determined to be 100% by weight.

A dental handpiece and method of turbine support therein, comprises a turbine wheel having a rotor shaft rotatably supported by a housing via ball bearings, and configured to rotationally drive a clamping chuck, at least one of the ball bearings including, an inner ring arranged on the rotor shaft, the inner ring having a raceway, an outer ring, having an outer raceway movably supported by the housing, and balls arranged between and guided by the inner and outer raceways. The raceway of the inner ring, in cross section, has a concave shape with a curvature corresponding to a radius of the balls. Optionally, the raceway of the outer ring in cross section, has, in a central area, a first curvature with a first radius and, adjoining the central area, a second curvature with a second radius, the first radius being smaller than the second. Optionally, the raceway of the outer ring has a substantially parabolic profile.

The disclosure relates to a head bearing assembly for a dental or surgical handpiece, comprising an outer sleeve, in which at least four radial bearings are arranged, which enclose an axis of rotation and each have their own bearing outer ring or a common bearing outer rings, wherein the bearing outer rings are surrounded radially on the outside by the outer sleeve in the circumferential direction about the axis of rotation, and each radial bearing has at least one or exactly one rolling element row with rolling elements which are arranged one behind the other in the circumferential direction and rolling in the respective bearing outer ring. The head bearing assembly according to the disclosure is characterized in that the at least four radial bearings have a common, integral bearing inner ring on which the rolling elements are arranged in rolling contact.

The disclosure relates to a rolling bearing for a medical or cosmetic instrument including a bearing inner ring revolving around an axis of rotation; and a stationary bearing outer ring, which concentrically encloses the bearing inner ring; wherein a bearing gap is formed between the bearing inner ring and the bearing outer ring and a plurality of rolling bodies is arranged in succession in circumferentially in the bearing gap, the bearing inner ring being mounted in the bearing outer ring; and wherein the rolling bodies are arranged rolling on the bearing inner ring and the bearing outer ring, the bearing gap being covered in the axial direction by a cover disk, which forms a radial gap with the bearing inner ring extending in the axial direction, the radial gap has a gap length and a gap height, the gap length being at least 25% of the rolling body height.

A dental hand piece or angle piece including a rotating tool, which is driven via a rotating drive element disposed in a housing, wherein the rotating drive element is mounted in the housing by a radial rolling bearing, wherein the rolling bearing comprises an axial abutment surface and the housing comprises an axial countersurface, and wherein the rolling bearing is axially preloaded with respect to the housing by a spring element 11 and has a coefficient of friction for the static friction of the abutment surface to the countersurface or the abutment surface and the countersurface to the spring element that is at least 0.16 in the lubricated state and at least 0.25 in the unlubricated state.

When the compressed air is not applied, an inclined surface, which is positioned at an upstream side with respect to the supply direction of the compressed air, of the lip part is in contact with the inclined surface of the inner ring. When the compressed air is applied, a contact area between the inclined surface, which is positioned at the upstream side with respect to the supply direction of the compressed air, of the lip part and the inclined surface of the inner ring becomes smaller, as compared to when the compressed air is not applied.

A two-part ball bearing cage includes two, in particular at least substantially identical, cage parts forming an even-numbered plurality of ball pockets for receiving a corresponding number of balls having a predeterminable ball diameter. Each cage part has an annular body on which substantially evenly distributed webs are disposed in the circumferential direction to form the ball pockets. A distance in the circumferential direction between two webs that are adjacent in the circumferential direction approximately corresponds to the sum of twice the ball diameter and a width of the web in the circumferential direction. A ball bearing having the ball bearing cage and a method for assembly of the ball bearing are also provided.

Provided is a handpiece in which a predetermined section of a rotational power transmission shaft includes a plurality of flexible rods. The single rotational power transmission shaft is able to change the direction of the rotation center axis of a rotational power source in order to overcome problems, such as rotational power loss, noise, fine vibration, reduced durability, or an increase in volume, caused by a complicated gear connecting structure of a rotational power transmission shaft for changing the direction of the rotation center axis of the rotational power transmission shaft of a related-art rotational power source.