CA2375792A1 - High capacity linear ball bearing bushing - Google Patents

Abstract

A high capacity linear ball bearing bushing featuring twice the num-ber of rows of the known existing art with only an eleven percent increase in outside diametre, with the additional feature of having separation-proof or much higher separation resistant guidance of the ball rows, depending on choice of either a super heavy duty or heavy duty embodiment of the invention.

Description

~iigh capacity linear Ball Bearing Bushing. Page 2 FIELD OF THE INVENTION.
This invention relates to linear anti-friction bearings, in particu-lar to linear ball bearing bushings.

High Capacity Zinear Ball Bearin.~; Bushing. Page 3.
BACKGROUND OIL THE INYENTIODT.
Both manual and automated production equipment in many or most in-stances use reciprocating motion of critical components; linear an-t~. friction bearings to support and precision guide said components are replacing traditional solid bearings more and more. The lowest cost linear anti-friction bearing often is the linear ball bearing bushing, consisting of an outer sleeve with internal hardened line-ar raceways, for several rows of balls, which are kept on the race-way by linear ~zides, made of either pressed powdered sintered met-al, plastic or stamped steel. These linear ~zidea are in the form of flat horse-track shaped circuits, which at the ends of the rows lift the balls off the linear raceways, gently guide them through a semi-circle into a linear return groove which keeps the balls Suet a lit-tle above the surface of the round reciprocating shaft, to re-enter the active row by way of another semi-circular guide groove. p num-ber of such recirculating ~uideways are integrated into a cylindrical sleeve, which fits over the reciprocating shaft loosely, and is ret-ained inside the hardened outer sleeve by way of a couple of snap-rin~s. The outer sleeve is rosette shaped on the inside diametre to allow clearance for the balls in the return circuit. The maximum number of active rows is usually six, since the horsetrack shaped recirculatin~ circuit requires the space between the active rows.
Under radially applied load directed between two adiacent rows six-ty degrees apart, slight deflection of the outer sleeve can cause a tendency for rows to separate, while under conditions of a~.ehoek load, this separation could cause balls to run off the very narrow linear raceways. furthermore, with only two active rows taking all the load, and with point contact for the balls, the permitted load is very limited.

high Oapacity Linear Ball Bearing Bushing. Page 4.
SUMMARY OF THE INVENTION.
fhe present invention provides a linear ball bearing bushing having twice the number of linear rows of balls, which results in an extra row between the two active rows of the known existing art, thus mak~;.°
king for three active rows, or an increase in radial load capacity of fifty percent, approximately, depending on the stiffness of the mount. To accomodate the recirculatin~ circuits, which are kept the same size as for the known existing art, the return circuit is loca-ted exterior to the hardened interior surface, rather than interior to ft, resulting in an increase in overall outside diametre of ele-ven percent, This disadvantage is however more than outweighed by the fact that for most preferred embodiments of the invention the hardened outer sleeve is a simple cylinder smooth on both inside and outside diametres. fhe super heavy duty veTBiori of the~:invention has the active rows of balls guided by gothic arches on the inside diame-tre of the hardened outer sleeve, makin.~ the active rows eeparation-proof, and providink for much greater capacity and longer life.

High Capacity Zinear Ball Bearing Bushing. Page 5.
BRIEF DESCRIPTION OF THE DRAWINGS.
FIG. 1 is a partial cross section of a typical example of the known existing art.
FIG. 2 is a partial cross section of the super heavy duty embodiment of the invention.
FIG. 3 is a partial cross section of the end caps which reverse the path of the balls.
FIG. 4. is the same for cylindrically shaped end caps , on the plane A-A in Fig.2.
FIG. 5 is a section on the plne B--B in Fig. 2 showing the means of registering the end caps with the outer sleeves. ( To register means to keep in alignment.) FIG. 6 is a partial cross section of two composite construction ver-sions of the invention, using deep drawn outer shell to retain the balls in the return circuit.
FIG. 7 is a partial cross section of two composite construction ver-sions of the invention using aluminum outer shells to provide for e-conomy versions.
FIG. 8 is a cross section on the plane C-C in Fig. 6 showing a cylin-drically shaped end cap.
FIG. 9 is a cross section on the plane D-D in ~'ig. 6 showing the re-tension of the inner ball guide by the ena~ caps.
FIG, 10 is a section on the plane E-~% in Fig. 6 showing the retensi-on of an aluminum outer shell circuit by the end caps which in turn - ire retained by a deep drawn outer shell.
Fig. 11 is a section on the plane F-~' in Fig. 7 showing a drilled passage aluminum outer shell return circuit with end caps retained High Capacity Zinear Ball Bearing Bushing. page 6.
by screws in tapped holes.
FIG, 12 is a section on the plane G-G in Fig. 7 showing an extruded aluminum outer return circuit with the active and return ball rows separated by a plain hardened cylindrical race , and end cap. reten-tion by screws.
FIG. 13 is a section on the plane F-F in Fig. 7 in which the economy composite construction of Fig. 7 is replaced by a smooth bore drilled return passage hardened race, as an alternative to the super heavy duty version of Fig. 2, with end caps retained by screws.

High Oapacity Zinear Ball Bearing Bushing. Page 7.
DESC~LIfTTpN 'DF THE PREFF~RED EMBODIM~TTS .
Referring first to Fig. 1, there is shown a partial cross section of a typical embodiment of the known existing art. Hardened outer sleeve or "race" 10 has a cylindrical outer surface and concentrically ground narrow linear raceways 11, on which a great number of identi --:
cal hardened steel balls 12 are arranged in linear rows, kept inline and on the raceway by suitably formed groves in linear ball retainer 13. Retainer 13 is moulded plastic or sintered powdered metal, or stamped steel, slotted cylinder, loosely fitted over hardened steel round shaft 14, ~ the reciprocating component which requires radial support and axial guidance,). The less than full length slots are li-nearly in parallel and symmetrically disposed around the retainer 13 and are the bottoms of linear groves which guide balls 12 in continu-ous circuits; the slots allow the balls to protrude slightly to cont act shaft 14 opposite the raceways 11. The row of balls contacting shaft 14 is the "active" row. As balls 12 approach the end of their particular retaining grove, they are intercepted by a semi-circular turn of the retaining grove, to be guided into a return path, which is similar to the slotted retaining grove for the active row, except the grove for the return path is not slooted in the bottom, and the balls travel in a slightly elevated row. As the balls are pushed th through the return grove , they encounter an identical semi-circular turn of the grove, which in turn ~;uic3es the balls back into the acti-ve retaining grove. 'lhe horse-track shaped grove circuit is the "re-circulating circuit'~-and thus consists of an active retaining grove, two semi-circular grove turns, and a return grove. To allow the balls in the return grove to be slightly elevated above the surface of shaft shaft 14, the inside diametre of outer sleeve 1g has to be suitably High Capacity Zinear Ball Bearing Bushing. Page 8.
relieved by way of shallow linearly disposed channels, which thus gi-ve a cross section of sleeve 10 a rosette shape. This rosette shape is exploited to register, meaning to keep permanantly in alignment, the linear ball retainer 13 with outer sleeve 10. Two snaprings at the ends keep retainer 13 in sleeve 10.
Fig. 1 also shows the benefits of spacing the active rows thirty de-grees apart instead of the customary sixty degrees for six active rows. Two small vector diagrams show identical loads "Z" at fifteen and thirty degrees from the centerplane of shaft 14. The reactions "R" and "S" are considerably smaller for the fifteen degrees locati-on. Zhe invention provides for fifteen degree separation between the active row of bails and the centerplane of the shaft, whereas the known existing art has thirty degrees for this, meaning considerably leas unit stress on the balls and shaft and raceways for the embodi-ments of the invention, on the assumption that two rows of balls are symmetrically disposed about said centerplane in both cases, and with all comparisons based on the traditional six active rows of balls for the known existing art, spaced at sixty degrees apart, whereas the in-vention provides for a maximum of twelve active rows spaced at thirty degrees apart. Even with sufficiently stiff mounting for the existing art, the sixty degrees spacing of the active rows does not allow a third row to contribute to the radial load bearing capacity, whereas the thirty degrees spacing of the active rows of balls does provide for the ability of three rows to share the load in the case of the invention, thus providing for a fifty percent increase in radial load bearing capacity.
Turning now to Fig. 2, there is shown a partial cross section of a first preferred embodiment of the invention, the super heavy duty Righ Oapacity Linear Ball Bearing Bushing. gage 9.
version. The advances of the invention over the existing art are firstly the ability to accomodate twelve rows of active balls in-stead of the traditional maximum of six, and secondly, the eliminati-on of the necessary rosette shaped clearance channels on the inside diametre of the outer sleeve or race 10, with additional advances ma-de clear for other figures. In order to accomodate twelve rows, the return passage for the balls in this invention is located exterior to the active interior surface of the outer sleeve or race 10 of fig.
1, with the radius of the semi-circular turns in the ball circuit the see as in the existing art. This novel location of the return passa-ge for the balls of this invention has increased the outside diametre by eleven percent as compared with the existing art, but this disad-vantage is outweighed by the advantage of allowing for thirty degrees active ball row separation in this invention as explained above under the description for fig.l. Gothic arch proved linear outer race 15 is made from high carbon chromium bearing steel traditionally used for these applications, and is provided with precision ground gothic arch linear raceways on the cylindrical inside surface, spaced at thirty degrees apart; numeral 16. Cylindrically shaped inner linear ball re-to mer 17 is made fron moulded plastic or resin, or powdered sintered' pressed metal, or die-cast metal, and is provided with linear ball guiding groves, the same in length as the plain ended length of race 15. Retainer i7 itself is also plain ended, but is longer than race 15 to allow the linear ball guiding groves to radially exit retainer 17 at an outward incline to become the initial part of a semicircu-lar half torus shaped turn, said exit starting at both termini of ra-ce 15. To tie all linear separator bars ~ which between them form the active linear ball guiding groves,) together and thus to form an inte-Pa a 10.
High Capacity Zinear Ball Bearing Bushing. g grated rigid cylinder, retainer 17 extends beyond the extreme ends of the ball guiding groves on both ends; this becomes clear briefly vie-wing Fig. ~. Alternatively, inner linear ball retainer 17 is omitted, with the active linear ball guiding groves machined in the now smal-ler inside diametre of race 15, with the gothic arch raceways part of said guiding groves. ;'he return groves are machined in the outside diametre of race 1.5, the required semi-circular turns are formed in a half torus shaped sintered metal end caps 19 which are kept register-ed with the end faces of race 15 by way of end cap register spigot 20 this is made clear in Fig's 3 and 5. The open ball recireulating cir-_ cuit is closed by a deep drawn steel shell 18, which wraps tightly around end cap 19 on both ends. Balls 12 are installed after grinding the formed ends of shell 18 to conform to the inside diametre of race 15. returning now to the cylindrically shaped end caps of fig. 4 the return groves for the balls are machined in the outside surface of ra-ce l5,to terminate in semi-circular turns moulded in cylindrical end cap 22, a resin or plastic precision moulding, which semi-circular turn smoothly and accurately blends into the exiting groves in retai-ner 17. yhe open return groves machined in the outside diametre of ra-ce 15 are closed by a very tightly fitting deep drawn shell 18, which is swaged or otherwise formed over the ends of end caps 22 to perraa-nantly keep the various parts assembled. Balls 12 may be installed before installation of the second end cap 22 or may be inserted through a suitable hole in shell 18, one hole for each ball circuit.
Alternatively, shell 18 may be omitted, with the return passages drilled in the solid body of race 15, as shown in the upper right hand corner of fig. 2. while the linear active raceways for the rows of balls do not have to be gothic arch shaped for reasons of economy, Nigh Oapacity Zinear Eall Bearing Bushing. Fage 11.
to give them the by now traditional gothic arch shape has advan-tages for the logevity or "life'" of the bushing. fhe gothic arch gi-ves two lines of contact for the balls on slightly smaller diametres This means less unit stress per contact point on the balls and slig-htly slower rates of recirculation, both plusses. It also means that the contact line made by the round shaft 14~, on the balls, is not used ed by the linear raceway; this means the balls should last twice as long. Since any line of wear on shaft 18 may be eliminated by simply turning shaft 14 slightly, the use of the gothic arch shape for the active linear raceways means a possible triple life increase expec-tancy for the overall installation, if we also consider the much clo-ser spacing of the rows of balls. For O.E.IZ. applications, where the O.E.TM~ client can control the installation of the bushings, all the advantages cited for the invention so far may be wined even by omit-ting four or six rows of balls, and by clearly marking the bushings for direction of permitted loading. The load would be centered betwe-en two rows of active balls thirty degrees apart, requiring four rows with two rows on each side of the bushing. One additional row would be provided on each side for stability, seventyfive degrees from the nearest rows. Or active rows fortlrfive degrees apart with stability rows at sixtyseven-and-a-half degrees from the nearest active rows.
FIG.'S 3~ 4 and 5 vrere described in the description for Fig. 2.
Turning now to FIG. 6, there is shown a partial cross section of a more economical to manufacture version of the embodiments shown in fig. 2, in the left hand side of the figure, and a yet more econo-~acal version in the right hand side. Smooth bore externally proved outer race 24 is provided with return groves in the outside diametre and plain square ends as before. Full depth linear ball retainer 23 High Capacitor Linear Ball Bearing Bushing. Page 12.
is cylindrically shaped to fit loosely over shaft 14, anal is provid-ed with linearly slotted linear groves to accomor~ate and guide acti-ve rows of balls; said linear groves terminate at the ends of race 24 to exit retainer 23 by waybof outward and inclined radiating part turns. fhe length of retainer 23 extends a short distance beyond said part turns to form bridges of solid material between the groves, ta-king on the appearance of a cylindrical cage with plain square ends.
Beep drawn shell 18 is tightly fitted over race 24to retain the re-circulating rows of balls in the return groves, Turning now to Fig's 8 and 9, cylindrically shaped end cap 27 is provided with part semi-circular ball passages or turns to line up anc~ smoothly blend into the return groves in race 24 and the active ball guide groves in re-tainer 23. Bnd caps 27 are detained by forming shell 18 tightly over the ends as shown. Alternatively, if economy of manufacture proves it more economical to drill return passages, in the solid body of race 24, shell 18 may be omitted, in which case end caps 27 are retained by axially installed screws fitted in tapped holes in race 24. lur-r_ing now to the right hand side of fig. 6, there is shown an economy version of the embodiment of the left hand side. To avoid machined return groves or drilled re+urn passages in race 24, a plain cylin-drical shell is used f or the ball race, thin shell outer race 25.
-n aluminum ball return cage, exterior -roved ball return cage 26, forms the returr_ passage f or the rows of halls, it being a virtual r~irror image of retainer 23. Return cage 26 may he Moulded in high strength reEin as an alternative, veep drawn shell lf~ fits tigrtly over the composite assembly and retains end cap 27 by being snugly formed over the ends, as shown. fig. 10 shows the cy7_indrically shaped end cap 28, provided with in«ard and outward radiating flan high Capacity linear I3a11 bearing ~iushing. Page 13.
ges to retain return cage 26 and retainer 23, said end cap 28 pro-videc~, with part ball turns which ali~-n precisely with the exiting ball guide groves in retainer 23 and return cage 26. Again, end caps 28 are retained by shell 18 tightly formed over the ends.
Turning now to FIG~7, they is shown a partial cross sectior_ of econo-my mersions of the invention, which avoid the need for deep c~.rawn shell 18, and are again of composite cons+,ruction. Deep drawn shell outer race 29 is precision formed and hardened and is based on the well developed and proven deep drawn outer races for needle bearings.
Full ball depth retainer 23 is used as for the embodiments of Fig. 6 Drilled passage linear ball return sleeve 30 is a precision machined aluminum extrusion tightly fitted over race 29 and is the same length as race 29, Turning now to Fig. 11 shows cylindrically shaped end cap 31, provided with an inward radiating flange to retain full depth li-near ball retainer 23, while provided with ball turn passages which line up precisely with the drilled hall return passages in sleeve 30 and the ball exits in retainer 23. ym.d caps 31 are retained by end cap retainer bolts 32 which fit in tapped holes in sleeve 30. the right hand side of I''ig. 7 shows a ball race made of cold drawn seem-less tubing, suitably hardened and honed on the inside diametre. In-terior groved linear ball return sleeve 33 is an alumimun extrusion, tightly fitted over race 25 and precision machined on the outside diametre for concentricity with the inside diametre of race 25, Tur-ping now to Fig. 12 shows end cap 34, virtually identical to end cap 31, Again, end caps 34 are retained by end cap retainer bolts 32.
the description for FIG.'S g~ g~ 10, 11 and 12 are liven in the des-criptions for Fig.~s 6 and ?.

Pa a 14.
High rapacity Zinear Ball Bearing Bushing.
FIG. 13 shows the end cap construction for a smooth bore Grilled re-turn passage outer race 35. This version of the invention avoids the deep drawn shell 18 of the versions of Fig,.'s 2 and 6, and the compo-site construction of the versions of Fig.'s 6 and ?. Smooth bore out-er race 35 is provided with drilled linear return passages for the balls while the active rows of balls 8re retained by full ball depth retainer ?.3, described for the previous versions of smooth bore embo-diments. The end caps and ball turns are the same as for fig.ll, as is the method of retaining the end caps.
'"Chile the invention has been disclosed. by reference to specific embo-diments, it should be understood that numerous changes coula~ be made within the scope of the inventive concepts disclosed. Accordingly, the invention is not to be limited by the disclosure, but rather to have the full scope permitted by the language of the following claims.

Claims (30)

1. A linear ball bearing bushing comprising in combination an outer race, defining a short cylinder with square ends and pro-vided on the inside surface with a number of axially arranged parallel linear groves og equal depth for ball raceways of the full length of the cylinder, a ball return passage for each of said raceways, each passage ly-ing exterior of the inside confines of said outer race, each pas-sage being linear , continuous and in parallel with each respec-tive raceway and of the full length of said outer race, an end cap for each end of said outer race, each end cap defining a thick ring arranged concentric with said outer race and rigid-ly attached to said race, each end cap having semi-circular ball turn passages arranged radially and oblique, with one of said ball turn passages for each of said raceways, each said ball turn passage communicating at its inward end with the end of one of said raceways and communicating at the outward end with the end of one of said ball return passages to form individual endless circuits for recirculating balls.
balls filling each said endless circuit, means to retain said balls in said endless circuits, whereby a linear ball bearing bushing is provided wherein the return passages of the ball recirculating circuits are located exterior of the interior confines of the outer race.

2. A linear ball bearing bushing as per claim 1 wherein said ball return passages comprise axially drilled holes in the wall of said cylinder.

High Capacity Linear ball bearing bushing. Page 16.

3. A linear ball bearing bushing as per claim 1 wherein said ball return passages comprise a combination of deep axially arranged groves in the outside surface of said cylinder and a deep drawn shell mounted concentrically and tightly around said outer race and around said end caps and thereby closes the open tops of said groves to form the ball return passages of said endless circuits.

4. A linear ball bearing bushing as per claim 1 wherein said cylin-der is tightly disposed in an equal length concentric soft metal or hard resin sleeve and wherein said ball return passages com-prise a combination of deep axially arranged groves in the out-side surface of said sleeve and a deep drawn shell mounted con-centrically and tightly around said sleeve and around said end-caps and thereby closing the open tops of said groves to form the ball return passages of said endless circuits.

5. A linear ball bearing bushing as per claim 1 wherein said cylin-der is tightly disposed in an equal length concentric soft metal or hard resin sleeve, and wherein said ball return passages com-prise axially drilled holes in the walls of said sleeve.

6. A linear ball bearing bushing as per claim 1 wherein said cylin-der is tightly disposed in an equal length concentric soft metal or hard resin sleeve having axially arranged deep groves on the inside surface the full length of said sleeve, and wherein said groves comprise said ball return passages.

7. A linear ball bearing bushing as per claim 1 wherein said means to retain said balls comprises a ball retaining cage defining a cylinder of somewhat greater length than said outer race and fitting snugly inside said outer race, with the ends protruding High Capacity Linear Ball Bearing Bushing. Page 17.

equally, said cage having a slotted axially arranged grove over each of said raceways for rollably retaining said balls onto said race-ways and allowing the balls to protrude slightly inwardly through the slots to make contact with a round shaft supported by said bus-hing, said groves shaped at the ends of the raceways to cause said balls to exit said cage outwardly during linear travel of said balls, said cage continuing in length a short distance beyond the completed outward exit of the balls and thus beyond the length of said groves in order to form solid bridges acro s the ends of said groves thereby making said cage a one piece rigid cylinder, and whereby said endcaps are each provided with a concentric seat on the inside diametre to accomodate the protruding ends of said ca-ge and to thereby lock it rigidly in place and rotationally, and whereby said passages in the end caps communicate im~rardly with the exits of said groves in the cage to become part of said end-less circuits for recirculating balls.

8. A linear ball bearing bushing as per claim 7, wherein said ball return passages comprise axially drilled holes in the wall of said cylinder.

9. A linear ball bearing bushing as per claim 7, wherein said ball return passages comprise a combination of deep axially arranged groves in the outside surface of said cylinder and a deep drawn shell mounted concentrically and tightly around said outer race and around said end caps and thereby closes the open tops of said groves to form the ball return passages of said endless cir-cuits.

10.A linear ball bearing bushing as per claim 7, wherein said cylin-der is tightly disposed in an equal length concentric soft metal High Capacity linear ball Bearing bushing. Page 18.

or hard resin sleeve and whereby said ball return passages comprise a combination of deep axially arranged groves in the outside sur-face of said sleeve, and a deep drawn shell mounted concentrically and tightly around said sleeve and said end caps and thereby clo-sing the open tops of said groves to form the ball return passa-ges of said endless circuits.

11.A linear ball bearing bushing as per claim 7, wherein said cylin-der is tightly disposed in an equal length concentric soft metal or hard resin sleeve and wherein said ball return passages compri-se axially drilled or arranged holes in the wall of said sleeve.

12.A linear ball bearing bushing as per claim 7, wherein said cylin-der is tightly disposed in an equal length soft petal or hard re-sin sleeve having axially arranged deep groves on the inside sur-face the full length of said sleeve, and wherein said groves com-prise said ball return passages.

13.A linear ball bearing bushing as per claim 1 wherein said linear groves for ball raceways in cross section comprise a gothic arch shape.

14. A linear ball bearing bushing as per claim 2 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

15. A linear ball bearing bushing as per claim 3 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

16. n linear ball bearing bushing as per claim 4 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

17. A linear ball bearing bushing as per claim 5 wherein said linear High Capacity Linear ball Hearing bushing. Pade 19.

groves for ball raceways in cross section have a gothic arch shape.

18. A linear ball bearing bushing as per claim 6 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

19. A linear ball bearing bushing as per claim 7 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

20. A linear ball bearing bushing as per claim 8 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

21. A linear ball bearing bushing as per claim 9 wherein said linear groves for ball raceways in cross section have a gothic arch shape.

22. A linear ball bearing bushing as per claim 10 wherein said lin-ear groves for ball raceways in cross section have a gothic arch shape.

23. A linear ball bearing bushing as per claim 11 wherein said line-ar groves for ball raceways in cross section have a gothic arch shape.

24. A linear ball bearing bushing as per claim 12 wherein said lin-ear groves for ball raceways in cross section have a gothic arch shape.

25. A linear ball bearing bushing comprising in combination an outer race, defining a short smooth bore cylinder with square ends, a ball detaining cage defining a cylinder of somewhat greater length than said outer race and fitting snugly inside said outer race, with the ends protruding equally, said cage having High Capacity linear Ball Bearing Bushing. Page 20.

a number of axially arranged groves for rollably retaining rows of balls outwardly bearing on the inside surface of said outer race and inwardly bearing on a round shaft supported by said bushing, said groves shaped at the ends of said outer ra ce to cause the balls to exit said cage outwardly during line-ar travel of the balls, said cage continuing in length a short distance beyond the completed outward exit of the balls and thus thus beyond the length of said groves in order to form solid brides across the ends of the groves thereby making the ca-ge a one piece rigid cylinder, a ball return passage for each of said linear groves in said cage, each passage lying exterior of the interior confines of said outer race, each passage being linear, continuous and in parallel with each respective grove in said cage, and of the full length of the outer race, an end cap for each end of said outer race, each end cap defin-ing a thick ring arranged concentric with the outer race and rigidly attached to it, each end cap having a semi-circular ball turn passage for each said grove in said ball retaining cage, arranged radially and oblique to communicate inwardly with the end of one of said groves in said cage and outward-ly with the end of one of said ball retuvn passages to form individual endless circuits for reciroulating balls, each end cap further provided with a concentric seat on the inside diame-tre to accomodate the protruding ends of said ball retaining cage and thereby lock it rigidly in place axially and rotati-onally, balls filling each said endless circuit, High Capacity Linear Ball hearing Bushing. Page 21.

whereby a linear ball bearing bushing is provided with a smooth cylindrical bore outer race to form raceways for the rows of balls ands having ball return passages for the ball reciculating circuits which lie outside the interior confines of the outer race and thereby increase the number of recirculating circuits which can be accomodated as compared with interior confinement of said circuits, while the plain smooth bore of the outer race increases economy of manufacture.

26. A linear ball bearing bushing as per claim 25 wherein said ball return passages comprise axially drilled holes in the wall of said cylinder.

27. A linear ball bearing bushing as per claim 25 wherein said ball return passages comprise a combination of axially arranged gro-ves in the outside surface of said outside race and a deep drawn shell mounted concentrically and tightly around said out-er race and around said end caps and thereby close the open tops of said groves to form the return passages of said endless circuits.

28. A linear ball bearing bushing as per claim 25 wherein said out-er race is tightly disposed in an equal length soft metal or hard resin sleeve and wherein said return passages comprise a combination of deep axially disposed groves in the outside sur-face of said sleeve, and a deep drawn shell mounted concentri-cally and tightly around said sleeve and around said end caps and thereby closing the open tops of said groves to form the ball return passage of said endless circuits.

29. A linear ball bearing bushing as per claim 25 wherein said out-High Capacity Linear Ball bearing Bushing. Page 22.

er race is tightly disposed in an equal length concentric soft metal or hard resin sleeve and wherein said ball return passages compri-se axially drilled or formed holes in the wall of said sleeve.

30. A linear ball bearing bushing as per claim 25 wherein said outer race is tightly disposed in an equal length soft metal or hard resin sleeve having axially arranged deep groves on the inside surface the full length of said sleeve and wherein said groves comprise said ball return passages.