Abstract: A ball bearing includes an inner ring having a raceway surface, an outer ring having a raceway surface, a plurality of rolling elements rollably disposed between the raceway surface of the inner ring and the raceway surfaces of the outer ring, and a resin cage configured to retain the plurality of rolling elements between the inner ring and the outer ring. The cage is a crown type cage having an annular base portion and a plurality of pockets formed in an axial end face of the annular base portion, in which the pockets retain the rolling elements. An axial distance between an axial position of a center of gravity of the cage and a curvature center of a spherical or cylindrical inner surface of each of the pockets is 0.6 or more times a radius of curvature of the inner surface. A hybrid vehicle transmission has this ball bearing.

Abstract: A rolling bearing includes: an inner ring; an outer ring; a plurality of rolling elements; a retainer; and a sealing member. First to third lubricant reservoir portions that store the lubricant are respectively formed on the radially inner side of the retainer, on the inner side of the sealing member, and in an inner peripheral surface of the outer ring at a position near a raceway. An inclined first guide surface that guides the lubricant from the second lubricant reservoir portion toward the raceway is formed in an inner surface of the sealing member. An inclined second guide surface contiguous with the first guide surface and guiding the lubricant toward the raceway is formed in the inner peripheral surface of the outer ring. The first lubricant reservoir portion of the retainer is in communication with pockets of the retainer, which accommodate the rolling elements.

Abstract: It is an object of the present invention to provide a rolling bearing which can be used in conditions in which a DN value is not less than 1,500,000 and an operating temperature is not less than 200° C. and which can be securely operated for a sufficiently long period of time without seizing, even though the rolling bearing is used in a dry run state and a cage for the rolling bearing. A cage (1) is formed by molding a carbon fiber composite material composed of a matrix consisting of a high-molecular compound reinforced with a carbon fiber material. The carbon fiber material consists of a bundle of 1000 to 5000 monofilaments, a woven cloth or a unidirectional material consisting of the bundle of the monofilaments. The high-molecular compound is polyimide resin or the like whose glass transition temperature is not less than 200° C. after the high-molecular compound thermally hardens.

Abstract: A cage has a ring portion, and a plurality of column portions that protrude from the ring portion, that are arranged in the circumference direction. Each column portion has a column portion radially inward section that forms a bearing-radial-direction inward side portion, and a column portion radially outward section that is connected to the radially inward section at its radially outer end position, so as to protrude on both sides in the circumferential direction from the radially inward section. A connection position at which the radially outward section is connected to the radially inward section is adjusted to a position radially outward of a pitch circle position of the plurality of the balls that are held in the respective pockets. Thus, the thickness of the radially inward section at the connection position is larger than the thickness of the radially inward section at the pitch circle position.

Abstract: Provided are a retainer for a ball bearing, and a ball bearing which are capable of obtaining an effect of reducing torque even in grease lubrication. The retainer for a ball bearing comprises a retainer body (35) which has an annular shape and comprises: recesses (37) formed in one axial end surface (36) of the retainer body (35) along a peripheral direction at predetermined pitches; and a pair of claw portions (38, 38) provided to protrude from opening ends of each of the recesses (37), the opening ends being opposed to each other in the peripheral direction, the each of the recesses (37) and the pair of claw portions (38, 38) forming a pocket (38) in which a ball (24) is received. A pocket (39) has a PCD which is set smaller than a PCD of the ball (24) to be received in the pocket (39).

Abstract: Provided is a rolling bearing, comprising: an inner race (2) and an outer race (3), which rotate relative to each other; a plurality of balls (4), which are interposed between the inner race (2) and the outer race (3); a retainer (5), which is arranged between the inner race (2) and the outer race (3), for retaining the plurality of balls (4) equiangularly, the retainer (5) comprising two annular members (10) which face each other in an axial direction and have opposing surfaces each including hemispherical pockets (12) formed in a plurality of circumferential positions, for receiving the plurality of balls (4), the two annular members (10) being coupled together so that the opposing surfaces are brought into abutment on each other; a flange portion (18), which extends radially and is provided on a radially inner side or a radially outer side of an axial end portion of each of the two annular members (10); and a recessed groove (20, 21), which is formed in a region of the inner race (2) corresponding to the f

Abstract: A shaft may have functional elements arranged thereon and at least one bearing point. At least one rolling bearing with rolling bodies may be arranged between the shaft and the at least one bearing point, the bearing having at least one rolling body cage configured to accommodate the rolling bodies and an outer ring. The rolling body cage may be fixed at least one of directly and indirectly to the shaft by a carrier ring and the outer ring may be fixed in the bearing point. The carrier ring may include the rolling body cage fixed thereon, the cage having a greater radial extent than the functional elements.

Abstract: A cage for a ball bearing comprising a body of generally annular shape and clamps, the body comprising a heel of substantially annular shape and a substantially axial portion being connected to the heel and wherein recesses are arranged for the balls, the substantially axial portion supporting said clamps on the side axially opposite to the heel, the cage comprising an axial partition placed between the recesses and extending axially from the end of the heel opposite to the clamps toward the clamps while radially delimiting external free spaces and internal free spaces situated radially on either side of said partition.

Abstract: In a grease filled bearing for a machine such as a turbo molecular pump that rotates at high speed, objects are to prevent grease retained in an inner circumferential part of a ball retainer from being forced out to the outside of the bearing due to centrifugal force, thereby achieving extension of the operational life of the bearing, and preventing occurrence of rotational mass unbalance due to the grease forced out. A retainer (1) of a ball bearing includes a main body (1A) having a circular annular shape, and plural circular pockets (1a) for retaining balls (4) therein that extend through the main body (1A) in a radial direction, wherein intermediate parts between adjacent pockets (1a) in an inner circumferential surface of the main body (1A) define recesses (1b) for holding grease.

Abstract: There is provided an assembling method of a bearing unit which has a bearing having an outer ring and a retainer plate having a retainer hole for holding the outer ring. The assembling method has pressing a plurality of portions in a circumferential direction of a circumferential edge of an inner circumferential portion of the retainer hole of the retainer plate in an axial direction so as to form engagement pawls and moving the engagement pawls of the retainer plate from one axial end of the outer ring to a engagement groove formed on an outer circumferential surface of the outer ring so as to engage the engagement pawls of the retainer plate with the engagement groove of outer ring.

Abstract: In the cage, on opposing edges of an outer circumferential opening of each of some of cage pockets, guiding faces for limiting the inward displacement in the radial direction of each of balls for a pitch circle diameter are provided; and on opposing edges of the inner circumferential opening of each of remaining cage pockets, guiding faces for limiting the outward displacement in the radial direction of each of the balls for the pitch circle diameter are provided, thereby making a ball guide.

Abstract: A retainer portion of a cage of a bearing has a plurality of spokes and web sections extending between an outer ring section and an inner ring section with a plurality of cavities formed on an annular side face of the retainer portion. The cavities communicate with socket portions formed in the retainer portion to provide lubrication to rotational elements of the bearing. A latch and catch mechanism secures like retainer portions together to form a cage of the bearing.

Abstract: An angular contact ball bearing, and a method for lubricating the same, has multiple ball pockets connected to an annulus channel via at least one hole that allows a fluid to flow from the annulus channel to the ball pockets.

Abstract: In a double row rolling bearing for supporting a pinion shaft, an outer ring is fixed to an inner peripheral surface of an annular wall (case) with its axis disposed horizontally, and an inner ring assembly is fitted on a pinion shaft, and is inserted, together with the pinion shaft, horizontally into the outer ring through a larger-diameter opening of the outer ring, and is mounted in the outer ring. A larger-diameter cage has a drop limitation portion for limiting the vertically-downward movement of the larger-diameter case.

Abstract: Double row angular contact ball bearing (10) has split inner rings (18, 24) and two plastic comb snap cages (32, 44). The comb cage has retaining tabs (38, 50) which mate with retaining grooves (22, 28) in the split inner rings. These retaining tabs hold the inner rings into the bearing.

Abstract: A chain for a motion transmission apparatus comprises a plurality of spacers and two links two links at both sides of the respective spacers for connecting spacers together. The spacers are equidistantly spaced from one another by a receiving space which is longitudinally asymmetrical and provided for holding rolling elements.

Abstract: The double row, tandem, angular contact ball bearing assembly uses snap cages for both rows of ball bearings. The use of snap cages reduces straddle between the rows and allows for improvements in spacing and increased load carrying capacity without increased outer dimensions of the bearing.

Abstract: A cage for a ball bearing assembly has a pocket for accommodating one of the balls defined at a plurality of locations in a direction circumferentially thereof and each of the pockets has an inner surface so shaped as to represent a concaved spherical surface. A concaved portion extending from an open edge on the cage inner diametric side towards the cage outer diametric side is provided in an inner surface of each of the pockets. The sectional shape of the inner surface of this concaved portion in a cage circumferential direction is represented by an arcuate shape of a radius of curvature smaller than the radius of curvature of the concaved spherical surface defining the inner surface of the respective pocket. The inner surface of each of the pockets may be formed with a film.

Abstract: A ball bearing cage with an annular rolling element retaining body, which has ball sockets distributed around a circumference of the rolling element retaining body for receiving spherical rolling elements. The ball sockets are distributed around the circumference, such that distances between two adjacent ball sockets increase in a circumferential direction, starting at a smallest distance between two adjacent sockets at least in a circumferential sector.

Abstract: A rolling-element bearing in which a rolling element is retained in each of retaining openings formed in a retainer and method for manufacturing the bearing are provided. Each retaining opening is defined by a pair of inner side faces facing each other, and a pair of inner end faces facing each other. In the manufacturing method, with a support die being brought into contact with one of the inner side faces and the inner end faces of one of the retaining openings, the outer and inner circumferential surfaces of the retainer are pressed by an outer punch and an inner punch. Accordingly, on at least one of the inner side faces and the inner end faces, a first retaining piece and a second retaining piece for preventing the rolling element from falling off are formed on the outer circumferential surface and the inner circumferential surface of the retainer, respectively.

Abstract: A ball bearing has an inner ring fitted on a rotational shaft and including an inner ring raceway on an outer circumferential surface thereof, an outer ring including an outer ring raceway on an inner circumferential surface thereof, a plurality of balls rotatably provided between the inner ring raceway and the outer ring raceway and a crown resin cage for retaining the balls at equal intervals in a circumferential direction. A bore diameter of the inner ring is 100 mm or more, and a radial clearance resulting in a state that the inner ring is assembled to the rotational shaft is 20 ?n or more.

Abstract: In certain embodiments, an apparatus includes a cage positioned between an inner race and an outer race. The cage includes a plurality of ball pockets for receiving balls and a grease pocket configured to substantially prevent a solid portion of a semi-solid lubricant from contacting the balls.

Abstract: A bearing unit rotatably supports a shaft of a pressure generating device, such a boost pressure generating device of an internal combustion engine. The bearing unit includes at least a first rolling-element bearing and a second rolling-element bearing, each rolling-element bearing having an inner ring and an outer ring. An annular space is defined between the respective inner and outer rings and rolling elements are disposed in the annular space. At least one volume element is disposed in the annular space and at least partially fills the annular space in an axial area.

Abstract: A multi-row rolling bearing, which has a cage for rows of rolling elements that is detachably connected to a respective adjoining cage. For assembly and safety of assembly, the detachable connection between the cages is at least one predetermined breaking point.

Abstract: A ring-shaped metal rolling bearing cage, which has cage pockets for receiving rolling elements. The cage is formed by a first and a second cage segment. Adjoining ends of the cage segments are connected to one another by suitable connection assemblies. At least one of the assemblies permits a change of the cage diameter when the cage temperature changes. The suitable assembly, on one side, is configured as a joint mechanism and, on another side, as a locking mechanism, and at least one of the assemblies has a lash. A rolling bearing cage configured with the joint mechanism and the locking mechanism can be mounted with low time expenditure in a simple and reliable manner over a shaft, particularly in the case of an idler pinion mourning.

Abstract: A ball roller bearing which has an outer and inner bearing ring and ball rollers arranged between the rings, which roll in two groove-shaped tracks in the rings and are held at a uniform distance to one another by a window cage. The cage has two lateral angle ribs, pocket bridges, which connect the ribs and cage pockets separated by the pocket bridges. The pockets have a cross-shaped hole formed from a contour perpendicular to the circumferential direction and a cross-sectional contour of a ball roller arranged longitudinally to the circumferential direction. The side edges are formed from the pocket bridges, which have radii of arch-shaped guide surfaces corresponding to the running surfaces of two ball rollers. The pocket bridges have additional material profiling between the side edges and on the guide surfaces for axial stiffening of the cage and damping bearing noise.

Abstract: An apparatus for supporting a substrate within a processing chamber is provided. In one aspect, a substrate support member is provided comprising a housing having a bore formed therethrough, a support pin at least partially disposed within the bore, and a plurality of bearing elements disposed about the housing. In one aspect, the bearing elements comprise a roller having a central bore formed therethrough, a contoured outer surface, and a shaft at least partially disposed through the central bore. In another aspect, the bearing elements comprise a ball assembly comprising a larger spherical member and four smaller spherical members arranged about the larger spherical member.

Abstract: A light weight bearing cage assembly (100) consisting of a plurality of snap-on bridge elements (104) coupled between first and second cage support rings (102A, 102B) conforming to the surfaces of adjacent rolling elements (10). The snap-on bridge elements maintain rolling element (10) in separation, provide rolling element retention within the bearing assembly, and function as a lubrication reservoir between the rolling elements for grease lubricated bearings. Each snap-on bridge element may be individually removed and replaced by snap-on engagement with the first and second cage support rings. Optional locking clips or rings (300, 302) fitted over each snap fitting end of the bridge elements optionally provides additional security against accidental uncoupling of the bridge elements from the first and second cage rings.

Abstract: A roller bearing comprises an inner ring, an outer ring and an annular cage. The annular cage retains and guides at least one roller body. The annular cage comprises at least one pocket for retaining the roller body and at least one retaining rim disposed on one axial end of the pocket. The retaining rim extends at least in the radial direction relative to a main body of the cage.

Abstract: It is an object of the present invention to provide a resin composition whose flowability is secured when the resin composition is injection-molded into injection-molded articles such as a resin-made crown-shaped cage and a resin-made seal both for a rolling bearing and a resin-made sliding bearing and which is capable of enhancing the mechanical strengths and toughnesses of these injection-molded articles to such an extent that these injection-molded articles can be used as bearing members. The resin composition is formed into a molded article and used as a bearing member. The resin composition is composed of polyamide resin or polyester resin to which polycarbodiimide is added. The polyamide resin is at least one resin selected from among polyamide 66 resin and polyamide 11 resin. The polyester resin is polytrimethylene terephthalate resin. 0.5 to 6 wt % of the polycarbodiimide is contained in an entirety of the resin composition.

Abstract: There is provided a rolling bearing including an inner ring having an inner ring raceway surface, an outer ring having an outer ring raceway surface and a shoulder portion formed on one axial side of the outer ring raceway surface, a plurality of rolling elements which roll between the inner ring raceway surface and the outer ring raceway surface, and a cage adapted to hold the plurality of rolling elements at predetermined intervals in a circumferential direction and having a guided surface which confronts the shoulder portion of the outer ring in such a manner as to be brought into sliding contact therewith. The rotation of the cage is guided through sliding contact of the guided surface of the cage with a guiding surface of the shoulder portion of the outer ring. A guiding space which is a radial space between the guiding surface of the shoulder portion of the outer ring and the guided surface of the cage is made to increase as approaching the rolling elements.

Abstract: A cage for a roller bearing comprises a base body with a plurality of pockets for the reception of the roller elements of the roller bearing. At least a part of the surface of the base body is coated with a layer consisting of or containing fullerene-like carbon nitride (FL-CNx), wherein an inter-layer of chromium (Cr) or aluminum (Al) or molybdenum (Mo) or titanium (Ti) or tungsten (W) or a diamond-like coating (DLC) or a metal-mix diamond-like coating (Me-DLC) is arranged between the surfaces of the base body and the layer consisting of or containing fullerene-like carbon nitride.

Abstract: A vacuum pump includes a high-speed rotor, and an anti-friction bearing for rotatably supporting the rotor and including an inner ring, an outer ring, a rolling body, and a cage for the rolling body both the rolling body and the cage being located in an intermediate space defined by the outer and inner rings, with the cage having a threaded groove in a section of its surface adjacent to the inner ring for insuring a continuous feeding of a lubricant to the bearing.

Abstract: It is a cage that is formed of a resin and that holds balls serving as rolling elements. The cage includes an annular base portion, and a plurality of claw portions that are formed to be arranged at constant intervals on the circumference of the base portion and to protrude therefrom. A pocket for accommodating the ball is formed between each pair of adjacent ones of the claw portions. In the resin cage for a ball bearing, thinning recesses are formed in end parts 11a of the claw portions and a rear surface of the base portion, respectively.

Abstract: A rolling bearing for a turbocharger, which has an outer ring with a first rolling element raceway, an inner ring with a second rolling element raceway, and several rolling elements accommodated in rolling element pockets of a rolling element cage. The rolling element cage has a guide surface, which is guided on an inner surface of the outer ring and arranged on a smaller radius than the radius of the first rolling element raceway. The rolling element cage has an extension, which is arranged over the circumference of the rolling element cage and extended annularly in the radial direction, on the side opposite the guide surface.

Abstract: There is provided an assembling method of a bearing unit which has a bearing having an outer ring and a retainer plate having a retainer hole for holding the outer ring. The assembling method has pressing a plurality of portions in a circumferential direction of a circumferential edge of an inner circumferential portion of the retainer hole of the retainer plate in an axial direction so as to form engagement pawls and moving the engagement pawls of the retainer plate from one axial end of the outer ring to a engagement groove formed on an outer circumferential surface of the outer ring so as to engage the engagement pawls of the retainer plate with the engagement groove of outer ring.

Abstract: The present invention provides a rolling bearing which is excellent in high-temperatures and high-speed durability and quietness, is capable of effectively preventing hydrogen brittleness-caused peeling from occurring on a rolling surface thereof, and has a low environmental load. A rolling bearing (1) is constructed of an inner ring (2) having a rolling surface on its peripheral surface, an outer ring (3) having a rolling surface on its inner peripheral surface, a plurality of rolling elements (4) disposed between both rolling surfaces, and a cage (5) retaining the rolling elements (4). The inner ring (2), the outer ring (3), the rolling elements (4) or the cage (5) is a metal-made bearing member. Film-coating treatment is conducted on a sliding surface or a rolling surface of at least one of these metal-made bearing members with the plant-derived polyvalent alcohol compounds such as curcumin, quercetin, chlorogenic acid or the like.

Abstract: A disk rotation device is provided, the device including: a bearing assembly including a bearing formed with a rotation shaft hole and a bearing housing that accommodates the bearing; a stator including a core secured at a periphery of the bearing housing and a coil wound on the core; a rotation shaft coupled to the rotation shaft hole; a rotor including a yoke secured at the rotation shaft and a magnet arranged at an inner lateral surface of the yoke facing a distal end of the core; and a turn table including a turn table body coupled to the rotation shaft, balls accommodated inside a circular trench of the turn table body and a cover member that blocks the trench, wherein a curve that line-contacts the balls is formed at an area where an inner lateral surface of the trench and a floor surface connected to the inner lateral surface of the trench meets.

Abstract: A roller bearing cage includes pockets for retaining roller bodies. Radially-extending bulges are disposed on bridges that at least partially define the pockets so as to extend radially inwardly and/or radially outwardly. The radially-extending bulges reduce edge stresses in the cage that develop when the roller bodies contact the cage during operation of the roller bearing.

Abstract: A rolling bearing includes: an inner ring; an outer ring; a plurality of rolling elements; a retainer; and a sealing member. First to third lubricant reservoir portions that store the lubricant are respectively formed on the radially inner side of the retainer, on the inner side of the sealing member, and in an inner peripheral surface of the outer ring at a position near a raceway. An inclined first guide surface that guides the lubricant from the second lubricant reservoir portion toward the raceway is formed in an inner surface of the sealing member. An inclined second guide surface contiguous with the first guide surface and guiding the lubricant toward the raceway is formed in the inner peripheral surface of the outer ring. The first lubricant reservoir portion of the retainer is in communication with pockets of the retainer, which accommodate the rolling elements.

Abstract: An apparatus for supporting a substrate within a processing chamber is provided. In one aspect, a substrate support member is provided comprising a housing having a bore formed therethrough, a support pin at least partially disposed within the bore, and a plurality of bearing elements disposed about the housing. In one aspect, the bearing elements comprise a roller having a central bore formed therethrough, a contoured outer surface, and a shaft at least partially disposed through the central bore. In another aspect, the bearing elements comprise a ball assembly comprising a larger spherical member and four smaller spherical members arranged about the larger spherical member.

Abstract: The present invention resides in a wheel bearing unit (100) having an inner member (105) and an outer member (107) rotationally coupled to each other by at least one row of rolling elements (115), whereby at least one bearing inner ring (110) is mounted on the inner member (105). The inner member (105) comprises a first section (130) and a second section (135) that at least party lies radially inward of the first section (130). According to the invention, the first section (130) is formed from a first material and the second section (135) is formed from a metal material, preferably a lightweight metal such as aluminium.

Abstract: A cage used in a ball bearing assembly is rendered to be of a ring shape having a plurality of pockets defined therein to hold a corresponding number of balls in a circumferential row. The radius of a bore of a circumferentially extending body of the cage as measured from the geometric center of the bore to an inner peripheral surface area of the circumferentially extending body aligned with each of the pockets is chosen to be greater than the radius as measured from the geometric center of the bore to a different inner peripheral surface area of the circumferentially extending body intermediate between the neighboring pockets.

Abstract: Various embodiments of the present invention relate to bearing assemblies configured to accommodate non-uniform loading and misalignment with an adjacent bearing assembly. In one embodiment of the present invention, a bearing assembly for use in a subterranean drilling system is disclosed. The bearing assembly includes a support ring and a retention ring attached to the support ring, with the retention ring including a plurality of through holes. The bearing assembly includes a plurality of bearing elements each of which includes a superhard bearing surface. Each of the bearing elements is positioned in and extends from a corresponding through hole of the plurality of through holes. At least a number of the bearing elements are configured to restrict displacement through the corresponding through hole and away from the support ring.

Abstract: A ball bearing includes an inner ring having a raceway surface, an outer ring having a raceway surface, a plurality of rolling elements rollably disposed between the raceway surface of the inner ring and the raceway surfaces of the outer ring, and a resin cage configured to retain the plurality of rolling elements between the inner ring and the outer ring. The cage is a crown type cage having an annular base portion and a plurality of pockets formed in an axial end face of the annular base portion, in which the pockets retain the rolling elements. An axial distance between an axial position of a center of gravity of the cage and a curvature center of a spherical or cylindrical inner surface of each of the pockets is 0.6 or more times a radius of curvature of the inner surface. A hybrid vehicle transmission has this ball bearing.

Abstract: A ball bearing arrangement for a turbocharger. This ball bearing arrangement has a turbocharger shaft, which is to be mounted, and a housing part of the turbocharger. An inner raceway of the ball bearing arrangement is formed on an outer surface of the turbocharger shaft, an outer raceway of the ball bearing arrangement is formed on an inner surface of the housing part, and balls are inserted between the outer raceway and the inner raceway. The inner raceway and/or the outer raceway are/is fabricated from an M62 steel.

Abstract: A retainer portion of a cage of a bearing has a plurality of spokes and web sections extending between an outer ring section and an inner ring section with a plurality of cavities formed on an annular side face of the retainer portion. The cavities communicate with socket portions formed in the retainer portion to provide lubrication to rotational elements of the bearing. A latch and catch mechanism secures like retainer portions together to form a cage of the bearing.

Abstract: A radial antifriction bearing which has an outer bearing ring, an inner bearing ring and a multitude of rollers, arranged between the bearing rings and held by a bearing cage. The rollers are configured as spherical disks that each have two parallel lateral surfaces which are symmetrically flattened from a basic spherical shape. The bearing cage has cage pockets in which the rollers are axially guided between the bearing rings via two low-friction point contacts between the center areas of their lateral surfaces and the longitudinal webs of the cage pockets. The rollers have a defined degree of freedom for tilt movements exerted at an angle to the running direction and a defined degree of freedom for self-adjustment to the pressure angle of the radial antifriction bearing.

Abstract: A cage for inclined ball bearings with adjacent ball pockets separated from each other by webs. Elastically-deformable retainer lugs extend from the webs with flanks facing opposing directions and facing each other.

Abstract: Retaining cage for balls of a rolling bearing, comprising an annular shoulder (16) extended axially by projecting portions (18) defining between them sockets (15) for the balls, emerging radially on either side of the cage. The cage was made from a metal and the surface of each socket (15) is designed to cooperate with one of the balls and is defined by an imaginary cylinder with an axis oriented radially and cut by the plane axially delimiting the cage on the side opposite the shoulder (16) so as to form an axial opening of the socket, the width of this opening being smaller than the diameter of the said imaginary cylinder.