Compliantly mountable turbine cartridge assembly for gas-driven dental handpiece

Abstract

A single-unit turbine cartridge assembly for a gas-driven dental handpiece includes a pair of bearing assemblies mounted on a turbine rotor shaft and a ring of resilient material around each bearing assembly. The resilient ring provides radial support for the turbine cartridge assembly within the housing of the handpiece and substantially dampens the transfer of vibration from the cartridge assembly to the handpiece during use of the handpiece. The turbine cartridge assembly may optionally include bearing axial pre-load means in association with one or more of the bearing assemblies. The turbine cartridge assembly also includes means for retaining the resilient radial support means and the bearing axial preload means, when used, in association with the bearing assemblies, so as to permit removal, and reinstallation, of the cartridge assembly as an entire unit from, and to, the housing in the dental handpiece.

What is claimed is: 
     
       1. A dental handpiece comprising a gas-driven motor, said motor including a housing and a turbine cartridge assembly within said housing, said housing defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said side wall, said housing having turbine cartridge assembly support means located on portions of said walls for supporting said turbine cartridge assembly, said turbine cartridge assembly removably positionable as a unitary assembly within said housing, said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft having an axis of rotation substantially coincident with the axis of said substantially cylindrical side wall of said housing;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   radial support means associated with each of said first and second bearing assemblies, said radial support means providing radial support for said turbine cartridge assembly upon said substantially cylindrical side wall of said housing;   rigid axial support means connected to said outer race of said first bearing assembly for axially supporting said first bearing assembly outer race upon said turbine cartridge support means of said housing;   bearing pre-load means comprising flexible axial support means associated with said outer race of said second bearing assembly for yieldingly supporting said outer race upon said turbine cartridge support means of said housing;   first retaining means for retaining said radial support means upon said outer race of said first bearing assembly, said first retaining means preventing movement of said radial support means in an axial direction away from said rotor shaft vanes; and   second retaining means for retaining said radial support means and said flexible axial support means upon said outer race of said second bearing assembly, said second retaining means preventing movement of said radial support means and said flexible support means in an axial direction away from said rotor shaft vanes;   whereby said rigid axial support means and said flexible axial support means coact with turbine cartridge support means of said housing to provide axial pre-loading of said first and second bearing assemblies when said turbine cartridge assembly is operatively positioned within said housing.   
     
     
       2. The dental handpiece of claim 1 wherein said radial support means comprises an outer wall on each of said bearing assembly outer races, said outer wall facing radially outwardly of the axis of said rotor shaft; and   a ring of resilient material frictionally engaged about a circumferential portion of said outer race outer wall of each of said bearing assemblies, said ring having an outer diameter sufficient to provide a compression fit between said outer race outer wall and a portion of said housing side wall when said turbine cartridge assembly is operably positioned within said housing.   
     
     
       3. The dental handpiece of claim 2 wherein said ring of resilient material is an O-ring fabricated of a material selected from the group consisting of neoprene elastomer, fluorocarbon elastomer, ethylene propylene elastomer and butadiene/acrylonitrile elastomer. 
     
     
       4. The dental handpiece of claim 1 wherein said rigid axial support means comprises a flange connected to said outer race of said first bearing assembly, said flange having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon a portion of said housing end wall adjacent said first bearing assembly. 
     
     
       5. The dental handpiece of claim 1 wherein said rigid axial support means comprises: a flange connected to said outer race of said first bearing assembly, said flange extending radially outwardly from said outer race; and   a substantially flat washer interposed between said flange on said first bearing assembly outer race and said turbine cartridge support means of said housing, said flat washer having an inner diameter smaller than the outer diameter of said radially extending flange, and having an outer diameter of sufficient dimension so that said flat washer supports said outer race upon turbine cartridge assembly support means located on an end wall portion of said housing adjacent said first bearing assembly.   
     
     
       6. The dental handpiece of claim 1 wherein said rigid axial support means comprises an outer wall on said first bearing assembly outer race, said outer wall facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about said outer race outer wall, said groove lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within said groove, said snap ring forming a shoulder extending radially outwardly of said outer race outer wall, said shoulder having an outer diameter in the radial direction sufficient to provide rigid axial support for said turbine cartridge assembly upon one of said end walls of said housing.   
     
     
       7. The dental handpiece of claim 1 wherein said flexible axial support means comprises a flange connected to said outer race of said second bearing assembly, said flange extending radially outwardly from said outer race, and   a resilient spacer member interposed between said flange on said second bearing assembly outer race and a portion of said housing end wall adjacent said second bearing assembly, said spacer member having spring-like resilience adapted to transmit a controlled compression force between said second bearing assembly outer race and said housing end wall.   
     
     
       8. The dental handpiece of claim 7 wherein said resilient spacer member is a ring-like spring washer. 
     
     
       9. The dental handpiece of claim 8 wherein said ring-like spring washer has a spring constant sufficient to provide a pre-load to each of said bearing assemblies in the range of about 0.5 to about 1.5 pounds when said turbine cartridge assembly is operably positioned within said housing. 
     
     
       10. The dental handpiece of claim 1 wherein each of said first and second retaining means comprises: an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said groove by the spring bias of each of said snap rings, each of said snap rings forming an annular-shaped collar extending radially outwardly of each of said outer race outer walls, each of said collars having an outer diameter in the radial direction sufficient to retard movement of said radial support means or said flexible support means, or both, in an axial direction away from said rotor shaft vanes.   
     
     
       11. The dental handpiece of claim 1 further including a bore within said rotor shaft, said bore having an axis substantially coincident with the axis of said rotor shaft, said rotor shaft having a threaded portion along a wall portion of said bore, and a collet having adjustable jaws for gripping a work tool, said collet having a threaded portion on an outer wall portion thereof for threadably engaging said threaded portion of said rotor shaft. 
     
     
       12. A turbine cartridge assembly removably positionable within a housing of a gas-driven motor of a dental handpiece wherein the housing is defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said side wall, and includes turbine cartridge assembly support means located on portions of the end walls of the housing; said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft defining an axis of rotation;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   radial support means associated with each of said first and second bearing assemblies, said radial support means providing radial support for said turbine cartridge assembly when in contact with the substantially cylindrical side wall of the housing, when said turbine cartridge assembly is operatively positioned within the housing of the handpiece;   means for yieldingly coacting with the turbine cartridge assembly support means of the housing of the handpiece for axially pre-loading said first and said second bearing assemblies when said turbine cartridge assembly is operably positioned within the housing, said means for yieldingly coacting with said turbine cartridge support means comprising a ring-like spring washer retained about the outer race of at least one of said first and second bearing assemblies, said spring washer having a spring constant sufficient to provide a static pre-load to said bearing assemblies in the range of about 0.5 to about 1.5 pounds, when said turbine cartridge assembly is operably positioned within a handpiece housing with the spring washer interposed between said bearing assembly outer race and the turbine cartridge support means of the housing, said turbine cartridge assembly being adapted for placement in, and removal from, the housing as a unitary assembly.   
     
     
       13. The turbine cartridge assembly of claim 12 wherein said radial support means comprises an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft; and   a ring of resilient material frictionally engaged about a circumferential portion of each of said outer race outer walls of each of said bearing assemblies, each of said rings having an outer diameter sufficient to provide a compression fit between each of said outer race outer walls and an adjacent portion of a handpiece housing side wall when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       14. The turbine cartridge assembly of claim 13 wherein said ring of resilient material is an O-ring fabricated of a material selected from the group consisting of neoprene elastomer, fluorocarbon elastomer, ethylenepropylene elastomer and butadiene/acrylonitrile elastomer. 
     
     
       15. The turbine cartridge assembly of claim 12 further including rigid axial support means comprising a flange connected to said outer race of said first bearing assembly, said flange having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon a portion of a handpiece housing end wall when said turbine cartridge assembly is removably positioned within a handpiece housing. 
     
     
       16. The turbine cartridge assembly of claim 12 further including rigid axial support means comprising: a flange connected to said outer race of said first bearing assembly, said flange extending radially outwardly from said outer race; and   a substantially flat washer between said flange of said first bearing assembly outer race and said radial support means, said flat washer having an inner diameter smaller that the outer diameter of said radially extending flange, and having an outer diameter of sufficient dimension so that said flat washer supports said outer race upon turbine cartridge assembly support means of a handpiece housing when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       17. The turbine cartridge assembly of claim 12 further including rigid axial support means comprising: an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves, each of said snap rings forming a shoulder extending radially outwardly of each of said outer race outer walls, each of said shoulders having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon an adjacent end wall of a handpiece housing.   
     
     
       18. A turbine cartridge assembly removably positionable within a housing of a gas-driven motor of a dental handpiece wherein the housing is defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said wall, and includes turbine cartridge assembly support means located on portions of said end walls of said housing; said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft defining an axis of rotation;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   radial support means associated with each of said first and second bearing assemblies, said radial support means providing radial support for said turbine cartridge assembly when in contact with the substantially cylindrical side wall of a handpiece housing;   bearing pre-load means associated with at least one of said bearing assembly outer races for yieldingly coacting with the turbine cartridge assembly support means in the housing of the handpiece for axially pre-loading said first and said second bearing assemblies when said turbine cartridge assembly is operably positioned within the housing, said turbine cartridge assembly being adapted for placement in, and removal from, the housing as a unitary assembly;   retaining means mounted on each of said bearing assembly outer races for preventing movement of said radial support means or said means for yieldingly coacting with the housing turbine cartridge assembly support means or both in an axial direction away from said rotor shaft vanes.   
     
     
       19. The turbine cartridge assembly of claim 18 wherein said radial support means comprises an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft; and   a ring of resilient material frictionally engaged about a circumferential portion of each of said outer race walls of each of said first and second bearing assemblies, each of said rings having an outer diameter sufficient to provide a compression fit between each of said outer race outer walls and an adjacent portion of a handpiece housing side wall when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       20. The turbine cartridge assembly of claim 19 wherein said ring of resilient material is an O-ring fabricated of a material selected from the group consisting of neoprene elastomer, fluorocarbon elastomer, ethylenepropylene elastomer and butadiene/acrylonitrile elastomer. 
     
     
       21. The turbine cartridge assembly of claim 18 further including rigid axial support means comprising a flange connected to said outer race of said first bearing assembly, said flange having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon a portion of a handpiece housing end wall when said turbine cartridge assembly is removably positioned within a handpiece housing. 
     
     
       22. The turbine cartridge assembly of claim 18 further including a rigid axial support means comprising: a flange connected to said outer race of said first bearing assembly, said flange extending radially outwardly from said outer race; and   a substantially flat washer between said flange on said first bearing assembly outer race and said radial support means, said flat washer having an inner diameter smaller that the outer diameter of said radially extending flange, and having an outer diameter of sufficient dimension so that said flat washer supports said outer race upon turbine cartridge assembly support means of a handpiece housing when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       23. The turbine cartridge assembly of claim 18 further including rigid axial support means comprising: an outer wall on each of said first and second bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves, each of said snap rings forming a shoulder extending radially outwardly of each of said outer race outer walls, each of shoulders having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon an adjacent end wall of a handpiece housing when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       24. The turbine cartridge assembly of claim 18 wherein said means for yieldingly coacting with turbine cartridge support means of a handpiece housing comprises a resilient spacer member retained about said outer race of at least one of said first and second bearing assemblies, said spacer member adapted to transmit a controlled compression force between said outer race and the turbine cartridge assembly support means of the housing, so as to urge said outer race in a axial direction, toward said rotor vanes. 
     
     
       25. The turbine cartridge assembly of claim 24 wherein said resilient spacer member is a ring-like spring washer. 
     
     
       26. The turbine cartridge assembly of claim 25 wherein said ring-like spring washer has a spring constant sufficient to provide a static pre-load to said bearing assemblies in the range of about 0.5 to about 1.5 pounds, when said turbine cartridge assembly is operably positioned within a handpiece housing with the spring washer interposed between said bearing assembly outer race and turbine cartridge support means of the housing. 
     
     
       27. The turbine cartridge assembly of claim 18 wherein said means for yieldingly coacting with turbine cartridge support means of a handpiece housing comprises: a first resilient spacer and member retained about said outer race of said first bearing assembly, said first spacer member adapted to transmit a controlled compression force between said outer race of said first bearing assembly and an adjacent portion of the turbine cartridge assembly support means of the housing;   a second resilient spacer member retained about said outer race of said second bearing assembly said second spacer member adapted to transmit a controlled compression force between said outer race of said second bearing assembly and an adjacent portion of the turbine cartridge assembly support means of the housing;   wherein said first and second spacer members cooperate with the turbine cartridge support means of the housing to provide axial pre-loading of said first and second bearing assemblies.   
     
     
       28. The turbine cartridge assembly of claim 27 wherein each of said resilient spacer member is a ring-like spring washer. 
     
     
       29. The turbine cartridge assembly of claim 28 wherein said ring-like spring washers have spring constants sufficient to provide a static pre-load to said bearing assemblies in the range of about 0.5 to about 1.5 pounds, when said turbine cartridge assembly is operably positioned within a handpiece housing with said spring washer interposed between said bearing assembly outer races and the turbine cartridge support means of the housing. 
     
     
       30. The turbine cartridge assembly of claim 18 wherein said retaining means comprises: an outer wall on each of said first and second bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves by the spring bias of each of said snap rings, each of said snap rings forming an annular-shaped collar extending radially outwardly of each of said outer race outer walls, each of said collars having an outer diameter in the radial direction sufficient to retard movement of said radial support means and said flexible support means in an axial direction away from said rotor shaft vanes.   
     
     
       31. A dental handpiece comprising a gas-driven motor, said motor including a housing and a turbine cartridge assembly within said housing, said housing defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said side wall, said housing having turbine cartridge assembly support means located on portions of said end walls for supporting said turbine cartridge assembly, said turbine cartridge assembly removably positionable as a unitary assembly within said housing, said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft having an axis of rotation substantially coincident with the axis of said substantially cylindrical side wall of said housing;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   radial support means associated with each of said first and second bearing assemblies, said radial support means comprising a resilient member interposed between each of said bearing assemblies and an adjacent portion of said housing side wall for providing radial support for said turbine cartridge assembly when in contact with said substantially cylindrical side wall of said housing;   rigid axial support means connected to each of said outer races of said first and second bearing assemblies for axially supporting said outer races upon said turbine cartridge support means of said housing; and   retaining means associated with each of said bearing assembly outer races for retaining said radial support means upon said turbine cartridge assembly and preventing movement of said radial support means in an axial direction away from said rotor shaft vanes during removal, or insertion, of said turbine cartridge assembly from, or in, said motor housing.   
     
     
       32. The dental handpiece of claim 31 wherein said radial support means comprises an outer wall on each of said first and second bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft; and   each of said resilient members comprise a ring of resilient material frictionally engaged about a circumferential portion of each of said outer race outer walls of each of said first and second bearing assemblies, each of said rings having an outer diameter sufficient to provide a compression fit between each of said outer race outer walls and an adjacent portion of said housing side wall when said turbine cartridge assembly is operably positioned within said housing.   
     
     
       33. The dental handpiece of claim 32 wherein said ring of resilient material is an O-ring fabricated of a material selected from the group consisting of neoprene elastomer, fluorocarbon elastomer, ethylenepropylene elastomer and butadiene/acrylonitrile elastomer. 
     
     
       34. The dental handpiece of claim 31 wherein said rigid axial support means comprises a flange connected to each of said outer races of said first and second bearing assemblies, each of said flanges having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon a portion of said housing end wall. 
     
     
       35. The dental handpiece of claim 31 wherein said rigid axial support means comprises: a flange connected to each of said outer races of said first and second bearing assemblies, each of said flanges extending radially outwardly from each of said outer races; and   a substantially flat washer interposed between each of said flanges on each of said bearing assembly outer races and an adjacent portion of said turbine cartridge support means of said housing, each of said flat washers having an inner diameter smaller than the outer diameter of said radially extending flange adjacent to said washer, and having an outer diameter of sufficient dimension so that said flat washers support each of said outer races upon turbine cartridge assembly support means located on wall portions of the housing.   
     
     
       36. The dental handpiece of claim 31 wherein said rigid axial support means comprises an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves, each of said snap rings forming a shoulder extending radially outwardly of each of said outer race outer walls, each of said shoulder having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon one of said end walls of said housing.   
     
     
       37. The dental handpiece of claim 31 wherein each of said retaining means comprises: an outer wall of each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves by the spring bias of each of said snap rings, each of said snap ring forming an annular-shaped collar extending radially outwardly of each of said outer race outer walls, each of said collars having an outer diameter in the radial direction sufficient to retard movement of said radial support means or said flexible support means, or both, in an axial direction away from said rotor shaft vanes.   
     
     
       38. A turbine cartridge assembly removably positionable within a housing of a gas-driven motor of a dental handpiece wherein the housing is defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said wall, and includes turbine cartridge assembly support means located on portions of said end walls of said housing; said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft defining an axis of rotation;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   radial support means associated with each of said first and second bearing assemblies, said radial support means providing radial support for said turbine cartridge assembly when in contact with the substantially cylindrical side wall of a handpiece housing;   retaining means mounted on each of said bearing assembly outer races for preventing movement of said radial support means in an axial direction away from said rotor shaft vanes during removal, or insertion, of said turbine cartridge assembly from, or in, said motor housing.   
     
     
       39. The turbine cartridge assembly of claim 38 wherein said radial support means comprises an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft; and   a ring of resilient material frictionally engaged about a circumferential portion of each of said outer race outer walls of each of said first and second bearing assemblies, each of said rings having an outer diameter sufficient to provide a compression fit between each of said outer race outer walls and an adjacent portion of a handpiece housing side wall when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       40. The turbine cartridge assembly of claim 39 wherein said ring of resilient material is an O-ring fabricated of a material selected from the group consisting of neoprene elastomer, fluorocarbon elastomer, ethylenepropylene elastomer and butadiene/acrylonitrile elastomer. 
     
     
       41. The turbine cartridge assembly of claim 38 further including rigid axial support means comprising a flange connected to each of said outer races of said first and second bearing assemblies, each of said flanges having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon portions of handpiece housing end walls when said turbine cartridge assembly is removably positioned within a handpiece housing. 
     
     
       42. The turbine cartridge assembly of claim 38 further including rigid axial support means comprising: a flange connected to each of said outer race of said first and second bearing assemblies, each of said flanges extending radially outwardly from each of said outer races; and   a substantially flat washer between each of said flanges of said first and second bearing assembly outer races and said associated radial support means, each of said flat washers having an inner diameter smaller that the outer diameter of said radially extending flange, and having an outer diameter of sufficient dimension so that each of said flat washers supports said outer race adjacent said flat washer upon turbine cartridge assembly support means of a handpiece housing when said turbine cartridge assembly is operably positioned within the housing.   
     
     
       43. The turbine cartridge assembly of claim 38 further including rigid axial support means comprising: an outer wall on each of said bearing assembly outer races, each of said outer wall facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said groove by the spring bias of each of said snap rings, each of said snap rings forming a shoulder extending radially outwardly of each of said outer race outer walls, said shoulders having an outer diameter in the radial direction sufficient to provide axial support for said turbine cartridge assembly upon an adjacent end wall of a handpiece housing.   
     
     
       44. The turbine cartridge assembly of claim 38 wherein said retaining means comprises: an outer wall on each of said bearing assembly outer races, each of said outer walls facing radially outwardly of the axis of said rotor shaft;   a groove running circumferentially about each of said outer race outer walls, each of said grooves lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves by the spring bias of each of said snap rings, each of said snap rings forming an annular-shaped collar extending radially outwardly of each of said outer race outer walls, each of said collars having an outer diameter in the radial direction sufficient to retain said radial support means upon said turbine cartridge assembly.   
     
     
       45. A dental handpiece comprising a gas-driven motor, said motor including a housing and a turbine cartridge assembly within said housing, said housing defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said side wall, said housing having turbine cartridge assembly support means located on portions of said end walls for supporting said turbine cartridge assembly, said turbine cartridge assembly removably positionable as a unitary assembly within said housing, said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft having an axis of rotation substantially coincident with the axis of said substantially cylindrical side wall of said housing;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race having an outer wall facing radially outwardly of the axis of said rotor shaft, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race having an outer wall facing radially outwardly of the axis of said rotor shaft, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   a flange connected to each of said outer race outer walls, said flange extending radially outwardly from said outer race;   a substantially flat washer interposed between said flange on said first bearing assembly outer race and said turbine cartridge support means of said housing, said flat washer having an inner diameter smaller than the outer diameter of said radially extending flange, and having an outer diameter of sufficient dimension so that said flat washer supports said outer race upon said turbine cartridge assembly support means of said housing;   a ring of resilient material frictionally engaged about a circumferential portion of said outer race outer wall of each of said bearing assemblies to provide radial support for said turbine cartridge assembly upon said motor housing side wall, said ring having an outer diameter sufficient to provide a compression fit between said outer race outer wall and a portion of said housing side wall;   a groove running circumferentially about said outer race outer wall of each of said bearing assemblies, said groove lying in a plane substantially perpendicular to the axis of said rotor shaft;   a spring-like snap ring retained within each of said grooves by the spring bias of said snap ring, said snap ring forming an annular-shaped collar extending radially outwardly of said outer race outer wall, each of said collars having an outer diameter in the radial direction sufficient to retain said flat washer and said ring of resilient material upon each of said turbine cartridge assembly outer race outer walls in cooperation, respectively, with said flange of each of said bearing assembly outer race outer walls; and   a resilient spacer ring interposed between said flange and said flat washer of said second bearing assembly outer race, said spacer ring having a spring-like resilience adapted to transmit a controlled compression force between said outer race and a portion of said housing end wall adjacent said second bearing assembly so as to provide axial pre-loading of said first and second bearing assemblies within said motor housing.   
     
     
       46. The dental handpiece of claim 45 wherein said ring of resilient materials is an O-ring fabricated of a material selected from the group consisting of neoprene elastomer, fluorocarbon elastomer, ethylenepropylene elastomer and butadiene/acrylonitrile elastomer. 
     
     
       47. The dental handpiece of claim 45 wherein said resilient spacer ring is a spring washer. 
     
     
       48. The dental handpiece of claim 47 wherein said spring washer has a spring constant sufficient to provide a static pre-load to said bearing assemblies in the range of about 0.5 to about 1.5 pounds, when said turbine cartridge assembly is operably positioned within said housing. 
     
     
       49. The dental handpiece of claim 45 further comprising a resilient spacer ring interposed between said flange and said flat washer of said first bearing assembly outer race, said spacer ring having a spring-like resilience adapted to transmit a controlled compression force between said first bearing assembly outer race and a portion of said housing end wall adjacent said first bearing assembly so as to provide axial pre-loading of said first and second bearing assemblies within said motor housing in cooperation with said resilient spacer ring of said second bearing assembly. 
     
     
       50. The dental handpiece of claim 49 wherein each of said spacer rings of said first and second bearing assemblies is a spring washer. 
     
     
       51. The dental handpiece of claim 50 wherein said spring washers have spring constants sufficient to provide static pre-loading to said first and second bearing assemblies in the range of about 0.5 to about 1.5 pounds, when said turbine cartridge assembly is operably positioned within said housing. 
     
     
       52. A dental handpiece comprising a gas-driven motor, said motor including a housing and a turbine cartridge assembly within said housing, said housing defined by a substantially cylindrical side wall and by a pair of oppositely disposed end walls transverse to said side wall, said housing having turbine cartridge assembly support means located on portions of said walls for supporting said turbine cartridge assembly, said turbine cartridge assembly removably positionable as a unitary assembly within said housing, said turbine cartridge assembly comprising: a rotor shaft having a plurality of vanes thereon, said rotor shaft having an axis of rotation substantially coincident with the axis of said substantially cylindrical side wall of said housing;   a first bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race;   a second bearing assembly comprising an inner race fixed to said rotor shaft, an outer race, and a plurality of movable bearing elements frictionally engaged with and confined between said inner race and said outer race of said second bearing assembly;   radial support means associated with each of said first and second bearing assemblies, said radial support means providing radial support for said turbine cartridge assembly upon said substantially cylindrical side wall of said housing;   bearing pre-load means comprising flexible axial support means associated with each of said outer races of said first and second bearing assemblies for yieldingly supporting said outer races upon said turbine cartridge support means of said housing;   first retaining means for retaining said radial support means and said flexible axial support means upon said outer race of said first bearing assembly, said first retaining means preventing movement of said radial support means in an axial direction away from said rotor shaft vanes; and   second retaining means for retaining said radial support means and said flexible axial support means upon said outer race of said second bearing assembly, said second retaining means preventing movement of said radial support means and said flexible support means in an axial direction away from said rotor shaft vanes;   whereby said flexible axial support means coact with turbine cartridge support means of said housing to provide axial pre-loading of said first and second bearing assemblies when said turbine cartridge assembly is operatively positioned within said housing. .Iadd.   
     
     
       53.  A self-contained cartridge assembly free of any outer enclosure for insertion and use as a unit in and for removal from a plurality of dental handpieces in which the housing interiors are different in size and in which each housing has a fluid inlet to direct fluid into the housing and an outlet to exhaust fluid from the housing and in which the housing becomes the enclosure for said cartridge assembly when said cartridge assembly is positioned therein, said cartridge assembly comprising sleeve shaped means of substantially the length of the housing and for engagement with a dental tool, a turbine having impeller faces extending into the housing and for impingement thereagainst by fluid directed into the housing through the fluid inlet thereof to rotate said turbine, said impeller being connected with said sleeve for conjoint rotation therewith, rollable bearings fixed on said sleeve on opposite sides of said impeller, and engaging means captured on said rollable bearings extending outward therefrom for fluid tight engagement with the wall of the handpiece housing on opposite ends of said impeller to confine and direct the inlet fluid against said impeller and the faces thereof to contain the fluid from flowing outward from between said cartridge and the engagement of said engaging means with the housing. .Iaddend. .Iadd.54. In a cartridge type turbine assembly as in claim 53, said engaging means being yieldable to cushion the engagement between said cartridge type turbine assembly and the housing to absorb vibrations therebetween. .Iaddend. .Iadd.55. In a cartridge type turbine assembly as in claim 54, said engaging means being of a size and being deformable to engage fluid tightly with housing walls 
     
     
        of different sizes. .Iaddend. .Iadd.56.  In a cartridge type turbine assembly as in claim 55, seat means on said rollable bearings mounting said engaging means to support the same in fixed position thereon and to prevent removal of said engaging means from their respective bearing. .Iaddend. .Iadd.57. In a cartridge type turbine assembly as in claim 55, said rollable bearings being spaced from and on opposite sides of said impeller faces from between 0.030 inches to 0.060 inches, and said impeller faces being spaced from the wall of the housing from between 0.010 inches and 0.030 inches. .Iaddend. .Iadd.58. In a cartridge type turbine assembly as in claim 53, said rollable bearings being spaced from and on opposite sides of said impeller faces from between 0.030 inches to 0.060 inches. .Iaddend. .Iadd.59. In a cartridge type turbine assembly as in claim 53, said impeller faces being spaced from the wall of the housing from between 0.010 inches and 0.030 inches. .Iaddend. .Iadd.60. In combination with a turbine operated dental handpiece having a housing with an interior wall to accommodate a turbine and fluid inlet and outlet means for the supply and exhaust respectively of fluid from the housing, a unitary turbine assembly free of any enclosure comprising rollable bearings relatively spaced from each other and each said bearing having inner and outer races, a rotatable turbine in said space between said bearings and having a plurality of impeller faces to receive the impingement of fluid thereagainst in the housing, seal means captured on the outer races of said bearings in fluid tight direct engagement with the interior wall of the housing to enclose said turbine between said spaced bearings and the interior wall such that fluid entering the housing is caused to impinge upon the impeller faces and to exhaust outward from the housing through the fluid outlet means, and an elongated dental tool holder mounting said bearings in their spaced relationship and with said turbine therebetween, said tool holder including a sleeve connected with said inner races of said bearings and with said turbine to rotate conjointly therewith, and said seal means being releasably engageable with the interior wall of the housing to enable said unitary turbine assembly to be inserted into and removed from engagement as a unit with the housing wall so that the housing becomes the enclosure for the unitary turbine assembly. .Iaddend. .Iadd.61. A unitary turbine assembly as in claim 60, said seal means being of a yieldable material and engaging with the interior walls of different sizes of housings fluid tightly to cause the outer race of its respective bearing to be non-rotatable relative to such engaged wall. .Iaddend. .Iadd.62. A unitary turbine assembly as in claim 60, said bearings being spaced from and on opposite sides of said rotatable turbine from between 0.030 inches to 0.060 inches. .Iaddend. .Iadd.63. A unitary turbine assembly as in claim 60, said impeller faces being spaced from the wall of the housing of the dental handpiece from between 0.010 inches to 0.030 inches. .Iaddend. .Iadd.64. A unitary turbine assembly as in claim 60, a recessed seat defined in the periphery of each of the outer races of said bearings, and said seal means on each of the outer races of said bearings being mounted within a respective one of said peripheral seats to retain the seal means fixed with respect to its respective bearing until forcefully removed therefrom for replacement. .Iaddend. .Iadd.65. A wall-less unitary cartridge type turbine assembly free of an outer enclosure for use in a circular housing of a dental handpiece in which the interior circular wall of the housing is utilized as the wall of the turbine assembly, said assembly comprising a rotatable axially elongated chuck having operable means for releasable engagement with a dental tool, a sleeve connected with said chuck for rotation therewith and rotation relative thereto to actuate with said operable means to releasably engage a dental tool, a turbine on said sleeve intermediate the ends thereof for rotation therewith, said turbine having a plurality of circumferentially spaced impeller faces against which fluid may impinge to rotate said turbine, rollable bearings spaced axially along said sleeve and on opposite sides of said impeller and axially from said impeller faces, each of said rollable bearings having inner and outer races with said inner race connected with said sleeve for rotation therewith and said outer race being rotatable with respect thereto, and seal means of yieldable deformable material mounted on said outer race of each of said bearings and from displacement therefrom so that said chuck, sleeve, turbine, rollable bearings and seal means are connected together as a unit free of an enclosing wall and for use as a cartridge type insert into and for removal from the housings of different dental handpieces with said seal means yielding to fit into the interior wall of the housing and deforming into fluid-tight engagement therewith such that the housing wall becomes the temporary enclosing wall of said turbine assembly while the same is therein and until said turbine assembly is removed from said housing by disengagement of said seal means therefrom. .Iaddend. .Iadd.66. A wall-less unitary cartridge type turbine assembly as in claim 65, said outer races of each of said rollable bearings having a circumferential seat defined in the outer periphery thereof in which said seal means is mounted and prevented from displacement. .Iaddend. .Iadd.67. A wall-less unitary cartridge type turbine assembly as in claim 65, said rollable bearings being spaced on opposite axial sides of said impeller faces from between 0.030 inches and 0.060 inches and said impeller faces being arranged on said unitary cartridge type turbine assembly such that when the same is within the housing said impeller faces are spaced from the interior wall thereof from between 0.010 inches and 0.030 inches. .Iaddend.