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A wheel assembly for a material handling cart includes a wheel hub having first and second openings in first and second hub faces, each concentric with and extending along a central axis of the wheel hub. First and second ball bearings are located in the openings. Inner rings of the bearings are wi

A wheel assembly for a material handling cart includes a wheel hub having first and second openings in first and second hub faces, each concentric with and extending along a central axis of the wheel hub. First and second ball bearings are located in the openings. Inner rings of the bearings are wider than the outer rings, and the inner rings contact one another. The outer rings are separated by, and are in contact with, a hub member. First and second bearing sleeves in the first and second openings contact and retain the bearings, and form first and second journal bearings. The sleeves contact journal surfaces on a portion of each inner ring that extends parallel to the central axis from an outer face of each outer ring away from a medial plane of the wheel assembly.

대표청구항 ▼

What is claimed is: 1. A wheel assembly comprising: a wheel hub having opposing first and second hub faces and a first opening in the first hub face extending from the first hub face along a central axis of the wheel hub; a first ball bearing having a first inner ring and a first outer ring concent

What is claimed is: 1. A wheel assembly comprising: a wheel hub having opposing first and second hub faces and a first opening in the first hub face extending from the first hub face along a central axis of the wheel hub; a first ball bearing having a first inner ring and a first outer ring concentric with the central axis, wherein the first inner ring and the first outer ring are metal, and wherein the first inner ring has a first inner grooved race and the first outer ring has a first outer grooved race, and wherein the width of the first inner ring is greater than the width of the first outer ring, and wherein the first inner ring has an inner ring outside diameter, and wherein the first outer ring is located in the first opening between the first and second hub faces; a first bearing sleeve in the first opening, wherein the first bearing sleeve is separate from the first ball bearing, and surrounds and contacts a journal surface of the first inner ring to form a first journal bearing, wherein the first journal surface is on a portion of the first inner ring that extends parallel to the central axis from a face of the first outer ring toward the first hub face, and wherein the journal surface has a journal surface diameter substantially equal to the inner ring outside diameter; a second opening in the second hub face extending from the second hub face along the central axis of the wheel hub; a second ball bearing having a second inner ring and a second outer ring concentric with the central axis, wherein the second inner ring and the second outer ring are metal, and wherein the second inner ring has a second inner grooved race and the second outer ring has a second outer grooved race, and wherein the width of the second inner ring is greater than the width of the second outer ring, and wherein the second inner ring has the inner ring outside diameter, and wherein the second outer ring is located in the second opening between the first and second hub faces and the second inner ring extends outside the second hub face; and a second bearing sleeve in the second opening, wherein the second bearing sleeve is separate from the second ball bearing, and surrounds and contacts a second journal surface of the second inner ring to form a second journal bearing, wherein the second journal surface is on a portion of the second inner ring that extends parallel to the central axis from a face of the second outer ring toward the second hub face, and wherein the second journal surface has a journal surface diameter substantially equal to the inner ring outside diameter. 2. The wheel assembly according to claim 1, wherein the first ball bearing and the second ball bearing are precision, single row, deep groove ball bearings with integral shafts that are spaced from a medial plane of the wheel, on opposite sides of the medial plane. 3. The wheel assembly according to claim 1, wherein the first inner ring and the second inner ring are in contact and on opposite sides of the medial plane of the wheel. 4. The wheel assembly according to claim 1, further including: a step around the outer surface of the first inner ring at a distal end of the first inner ring that extends past the journal surface; and a thread guard contacting the step on the first inner ring, wherein the thread guard extends radially from the first inner ring and toward a medial plane of the wheel hub inside the plane of the first hub face. 5. The wheel assembly according to claim 1, wherein the first ball bearing is a self-contained, precision ball bearing unit. 6. The wheel assembly according to claim 1, wherein the first bearing sleeve further includes ribs on an outer perimeter surface for holding the sleeve in the first opening. 7. The wheel assembly according to claim 1, wherein the first bearing sleeve further includes a non-cylindrical outer perimeter surface. 8. A wheel assembly comprising: a wheel hub having opposing first and second hub faces and first and second openings in the first and second hub faces, each concentric with and extending along a central axis of the wheel hub; first and second precision ball bearings in the first and second openings, respectively, the ball bearings each having a metal inner ring and an outer ring concentric with the central axis, wherein each metal inner ring has a grooved inner ring race and each outer ring has a grooved outer ring race, and wherein the width of each metal inner ring is greater than the width of each outer ring, and wherein each metal inner ring contacts the other, and wherein each outer ring is spaced apart from the other and located entirely between planes of the first and second hub faces; and first and second bearing sleeves in the first and second openings, respectively, wherein each bearing sleeve has a sleeve opening therethrough forming a journal bearing surface that is independent of either the first or second precision ball bearings, so that each bearing sleeve surrounds and contacts a journal surface of each metal inner ring to form first and second journal bearings, wherein each journal surface is on a portion of each metal inner ring that extends parallel to the central axis from an outer face of each outer ring away from a medial plane of the hub. 9. The wheel assembly according to claim 8, further including: a step around the outer surfaces of each metal inner ring at distal ends of each metal inner ring extending past each journal surface; and first and second thread guards contacting each step on each metal inner ring, wherein each thread guard extends radially from each metal inner ring and toward the medial plane of the wheel hub to points inside the plane of the first hub face. 10. The wheel assembly according to claim 9, wherein the thread guard includes a thread guard inner face and a ridge that are on either side of a groove, wherein the thread guard bends at the groove, allowing the ridge to move toward the medial plane as the thread guard inner face contacts a stop formed by the step of the metal inner ring. 11. The wheel assembly according to claim 8 wherein each outer ring is separated from the other by, and is in contact with, a hub member. 12. The wheel assembly according to claim 8, wherein the first and second ball bearings are precision self-contained, metal, single row, deep groove ball bearing units with integral shafts. 13. The wheel assembly according to claim 8, wherein the first and second bearing sleeves further include ribs on the outer perimeter surfaces of the bearing sleeves for holding the bearing sleeves in the first and second openings. 14. The wheel assembly according to claim 8, wherein the first and second bearing sleeves are secured to the hub for supporting and retaining first and second ball bearings in the hub. 15. A wheel assembly comprising: wheel hub having opposing first and first and second openings in the first and second hub faces, each concentric with and extending along a central axis of the wheel hub; first and second precision ball bearings in the first and second openings, respectively, the ball bearings each having a metal inner ring and an outer ring concentric with the central axis, wherein each metal inner ring has a grooved inner ring race and each outer ring has a grooved outer ring race, and wherein the width of each metal inner ring is greater than the width of each outer ring, and wherein each metal inner ring contacts the other, and wherein each outer ring is spaced apart from the other and located entirely between planes of the first and second hub faces; and first and second bearing sleeves in the first and second openings, respectively, wherein each bearing sleeve has a sleeve opening therethrough forming a journal bearing surface that is independent of either the first or second precision ball bearings, so that each bearing sleeve surrounds and contacts a journal surface of each metal inner ring to form first and second journal bearings, wherein each journal surface is on a portion of each metal inner ring that extends parallel to the central axis from an outer face of each outer ring away from a medial plane of the hub, and wherein the first and second bearing sleeves include a non-cylindrical outer surface and a slot for allowing the first and second bearing sleeves to constrict around each journal surface. 16. A wheel assembly comprising: a wheel hub having opposing first and second hub faces and first and second openings in the first and second hub faces, each concentric with and extending along a central axis of the wheel hub; first and second precision ball bearings in the first and second openings, respectively, the ball bearings each having a metal inner ring and an outer ring concentric with the central axis, wherein each metal inner ring has a grooved inner ring race and each outer ring has a grooved outer ring race, and wherein the width of each metal inner ring is greater than the width of each outer ring, and wherein each metal inner ring contacts the other, and wherein each other ring is spaced apart from the other and located entirely between planes of the first and second hub faces; and first and second bearing sleeves in the first and second openings, respectively, wherein each bearing sleeve has a sleeve opening therethrough forming a journal bearing surface that is independent of either the first or second precision ball bearings, so that each bearing sleeve surrounds and contacts a journal surface or each metal inner ring to form first and second journal bearings wherein each journal surface is on a portion of each metal inner ring that extends parallel to the central axis from an outer face of each outer ring away from a medial plane of the hub; a step around the outer surfaces of each metal inner ring at distal ends of each metal inner ring extending past each journal surface; and first and second thread guards contacting each step on each metal inner ring, wherein each thread aud extends radially from each metal inner ring and toward the medial plane of the wheel hub to points inside the plane of the first hub face, and wherein the thread guards include a thread guard inner face and a ridge that are on opposite sides of a groove, wherein the ridge includes a slot radially through the ridge, and wherein the thread guard bends at the groove, allowing the ridge to move toward the medial plane as the thread guard inner face contacts a stop formed by the step of the metal inner ringer. 17. A material handling cart comprising; a frame; a material support structure coupled to the frame; a plurality of wheels coupled to the frame, wherein one of the wheels includes: a wheel hub having opposing first and second hub faces and first and second openings in the first and second hub faces, each concentric with and extending along a central axis of the wheel hub; first and second precision ball bearings in the first and second openings, respectively, the ball bearings each having a metal inner ring and an outer ring concentric with the central axis, wherein each metal inner ring has a grooved inner ring race and each outer ring has a grooved outer ring race, and wherein the width of each metal inner ring is greater than the width of each outer ring, and wherein each metal inner ring contacts the other, and wherein the each outer ring is spaced apart from the other and located entirely between planes of the first and second hub faces; and first and second bearing sleeves in the first and second openings, respectively, wherein each bearing sleeve has a sleeve opening therethrough forming a journal bearing surface that is independent of either the first or second precision ball bearings, so that each bearing sleeve surrounds and contacts a journal surface of each metal inner ring to form first and second journal bearings, wherein each journal surface is on a portion of each metal inner ring that extends parallel to the central axis from an outer face of each outer ring away from a medial plane of the hub. 18. The material handling cart according to claim 17, wherein the one of the wheels further includes: a step around the outer surfaces of each metal inner ring at distal ends of each metal inner ring extending past each journal surface; and first and second thread guards contacting each step on each metal inner ring, wherein each thread guard extends radially from each metal inner ring and toward the medial plane of the wheel hub to points inside the plane of the first hub face. 19. The material handling cart according to claim 17, wherein the one of the wheels further includes a hub member separating each outer ring from the other, wherein each outer ring is in contact with the hub member. 20. The material handling cart according to claim 17, wherein the first and second ball bearings in the one of the wheels further includes first and second precision, self-contained, metal, single row, deep groove ball bearing units with integral shafts. 21. A method of making a wheel comprising the steps of: pressing first and second ball bearings into first and second openings in a wheel hub, wherein the first and second openings extend from first and second opposing hub faces along a central axis of the wheel hub, and wherein the first and second ball bearings each have a metal inner ring and an outer ring concentric with the central axis, and wherein a width of each of the metal inner rings is greater than a width of each of the respective outer rings, and wherein the metal inner rings have an inner ring outside diameter, and wherein the metal inner rings contact one another at one end, and are positioned so that the other end is structured and arranged outside the first and second hub faces to contact a yoke that exerts a compressive force along the inner rings, and the outer rings are located entirely between planes of the first and second hub faces and each contacts a stop shoulder that serves to separate the outer rings by a distance to provide lateral stability; and pressing first and second bearing sleeves into the first and second openings, adjacent to the ball bearings, wherein each bearing sleeve has a sleeve opening therethrough with a sleeve opening diameter substantially equal to the inner ring outside diameter, and wherein each bearing sleeve surrounds and contacts a journal surface of each metal inner ring to form journal bearings, wherein the journal surfaces are on portions of the metal inner rings that extend parallel to the central axis from an outer face of each outer ring away from a medial plane of the hub. 22. The method of making a wheel according to claim 21, further including the step of installing a thread guard attached to the first metal inner ring, wherein the thread guard extends radially from the first metal inner ring and toward the medial plane of the wheel hub inside the plane of the first hub face. 23. The method of making a wheel according to claim 22, wherein the step of deforming the thread guard further includes bending the thread guard at a groove to allow a ridge to extend past the stop while contacting a sleeve outer surface. 24. The method of making a wheel according to claim 22, wherein the step of installing a thread guard attached to the first metal inner ring further includes the steps of: sliding the thread guard onto a step to make contact with a stop on a distal end of the first metal inner ring; deforming the thread guard to contact and press the bearing sleeve past the stop along the central axis; and allowing the thread guard to reform, leaving a clearance between the thread guard and the bearing sleeve. 25. The method of making a wheel according to claim 21, wherein the steps of pressing a first ball bearing, pressing a first bearing sleeve, and installing a thread guard are all performed with a single application of force that presses a pre-assembled ball bearing, bearing sleeve and thread guard toward the first opening. 26. A wheel assembly comprising: a wheel hub having opposing first and second hub faces; first and second openings in the first and second hub faces, wherein the first and second openings are concentric with, and extend along, a central axis of the wheel hub, and wherein a diameter of the first and second openings is reduced as the openings extend from the respective first and second hub faces toward a medial plane of the wheel hub, thereby forming a ridge hub member having opposing first and second ridge faces within the first and second openings; and first and second rolling element bearings located in the first and second openings, respectively, wherein each rolling element bearing has a metal inner ring and an outer ring that are concentric with the central axis, wherein each metal inner ring has an inner grooved race and each outer ring is cylindrical and has an outer grooved race, and wherein the width of each metal inner ring is greater than the width of each outer ring, and wherein each metal inner ring contacts the other, and wherein the first and second outer rings are spaced apart from the other, and each outer ring has an outer ring end that directly contacts less than all of a respective one of the first and second ridge faces of the ridge hub member, and each outer ring is located between planes of the first and second hub faces, and has an outer cylindrical surface that contacts an inner surface of the respective one of the first and second openings. 27. The wheel assembly according to claim 26 wherein the first and second rolling element bearings further include first and second precision grooved-race ball bearings. 28. The wheel assembly according to claim 26 wherein the first and second openings have a larger diameter portion that extends inward from each hub face toward the medial plane, and wherein the first and second openings have a smaller diameter portion that extends inward from each larger diameter portion toward the medial plane, and wherein each larger diameter portion is substantially equal to an outer diameter of the first and second outer rings, and wherein each smaller diameter portion is substantially equal to an outer diameter of the first and second metal inner rings. 29. The wheel assembly according to claim 26 wherein the first and second rolling element bearings are press-fit into the first and second openings, wherein the outer ring end of each of the first and second outer rings is seated against a respective one of the first and second ridge faces of the ridge hub member. 30. The wheel assembly according to claim 26 wherein an end of the first metal inner ring is in contact with an end of the second metal inner ring. 31. The wheel assembly according to claim 26 wherein a width of the ridge hub member is greater than or equal to a width of the first and second outer rings. 32. The wheel assembly according to claim 26 wherein outer ring ends of the first and second outer rings are spaced apart about 0. 625 inches. 33. The wheel assembly according to claim 26 wherein a portion of the first and second ridge faces of the ridge hub member is not in contact with the outer ring ends of the first and second outer rings. 34. The wheel assembly according to claim 26 wherein each of the first and second metal inner rings is cylindrical, and each has a first inner ring end in contact with a respective first inner ring end of other metal inner ring, and each has a second inner ring end that extends outward past a plane of the respective first and second hub faces. 35. The wheel assembly according to claim 26 further including a yoke having a pair of yoke legs, an axle, and an axle nut, wherein the axle passes through a hole in one yoke leg, first and second metal inner rings, and a hole in the other yoke leg, and wherein the axle and axle nut compresses the first and second metal inner rings against each other and against a respective yoke leg.