# US 4,391,473 A · Linear bearing unit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,473 A - Document ID: US4391473A - Status: Granted - Kind: A - Application number: 06/310,662 - Filed: 1981-10-13 - Granted: 1983-07-05 - Earliest claimed: 1981-10-13 - Inventors: Hiroshi Teramachi - Web page: https://patentgrep.com/patent/US4391473A ## CPC - F16C 29/0647: {with load directions in X-arrangement} - F16C 29/0676: {with a bearing body or carriage almost fully embracing the guide rail or track, e.g. a circular sleeve with a longitudinal slot for the support posts of the rail} - F16C 29/12: Arrangements for adjusting play - F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS ## Abstract An improved linear bearing unit is disclosed which has no reduction in operative performance irrespective of elimination of a conventional retainer. The bearing case of the linear bearing unit contains a plurality of non-loading ball holes and semi-circular deep track grooves whereby an increased contact surface is achieved between the loading balls and track grooves. The upper track grooves involve a right angle therebetween relative to the center of the bearing unit, causing no edge load (referred to as critical load at edge portion) to occur. Further, prestress (or preload) may be applied to loading balls in some of four track grooves. According to another aspect of the invention an outer sleeve is fitted into the bearing case, which contains four track grooves on the inner wall thereof. Side covers (or return plates) firmly secured to both end faces of the bearing case contain annular grooves corresponding to annular projections on both the end faces of the outer sleeve, U-shaped concave portions in alignment with four track grooves thereon which serve for reversing the movement of the loading balls and tongue portions at the innermost end of the side covers. ## Claims ### Claim 1 A linear bearing unit essentially comprising a bearing case having a lower open end and four non-loading ball holes having the substantially same inner diameter as the ball diameter, side covers firmly secured to both end faces of said bearing case, a track table inserted through a cylindrical inner recess of the bearing case and a number of balls arranged in line one after another through four longitudinally extending circular hollow space between semi-circular concave track grooves on the cylindrical inner recess of the bearing case and another corresponding concave track grooves on the track table as well as through the four non-loading ball holes in the bearing case, said longitudinally extending circular hollow spaces being in communication with the non-loading ball holes via U-shaped concave portions formed on both the side covers, wherein the bearing case has annular projections at both the end faces thereof which are located between the non-loading ball holes and the concave track grooves on the cylindrical inner recess and further it has a longitudinally extending deep slit at one side thereof so as to prestress or preload some of the concave track grooves on the cylindrical inner recess, while the side covers contain annular grooves corresponding to said annular projection, U-shaped concave portions and ball guide tongue portions in communication with the longitudinally extending circular hollow space at the innermost end of said U-shaped concave portions. ### Claim 2 (depends on 1) A linear bearing unit as defined in claim 1, wherein said longitudinally extending deep slit is provided midst the outer non-loading ball hole and the inner loading ball track groove. ### Claim 3 (depends on 1) A linear bearing unit as defined in claim 1, wherein a threaded hole extends from the one end of the bearing case and is opened at the longitudinally extending deep slit. ### Claim 4 (depends on 1) A linear bearing unit as defined in claim 1, wherein the upper loading ball track grooves are located at a position where a line extends radially through the center of the bearing case at an inclination angle of 45 degrees relative to the horizontal line passing through said center in symmetrical relation. ### Claim 5 (depends on 1) A linear bearing unit as defined in claim 1, wherein the lower loading ball track grooves are located at a position where a line extends radially through the center of the bearing case at an inclination angle of 15 degrees relative to the horizontal line passing through said center in a symmetrical relation. ### Claim 6 A linear bearing unit essentially comprising a bearing case having a lower open end, four non-loading ball grooves having the substantially same width as the ball diameter and a key groove located at the central part thereof, side covers firmly secured to both end faces of said bearing case, an outer sleeve having four loading ball track grooves on a cylindrical inner recess and a key groove on the outer surface thereof corresponding to said key groove in the bearing case, a track table inserted through the cylindrical inner recess of said outer sleeve, a key received in said key grooves and a number of balls arranged in line one after another through four longitudinally extending hollow spaces between semi-circular concave track grooves on the cylindrical inner recess of the outer sleeve and another semi-circular concave track grooves on the track table and through the four non-loading ball grooves on the inner wall of the bearing case, said longitudinally extending hollow space being in communication with said non-loading ball grooves via U-shaped concave portions formed on both the side covers, wherein the outer sleeve has annular projections at both the end faces thereof which are located midst the non-loading ball grooves and the concave track grooves on the cylindrical inner recess and further the bearing case has a longitudinally extending inclined deep slit at one side thereof so as to prestress or preload some of the concave track grooves on the cylindrical inner recess, while the side covers contain annular grooves corresponding to said annular projection, U-shaped concave portions and ball guide tongue portions in communication with the longitudinally extending hollow space at the innermost end of said U-shaped concave portions. ### Claim 7 (depends on 6) A linear bearing unit as defined in claim 6, wherein said longitudinally extending inclined deep slit is provided outside one of the non-loading ball grooves at a certain inclination. ### Claim 8 (depends on 6) A linear bearing unit as defined in claim 6, wherein a threaded hole extends at a right angle relative to a recessed seat at the one end of the bearing case and is opened at the longitudinally extending inclined deep slit.