Patent US4624583A successfully refreshed from Google Patents.
US4624583A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Foil thrust bearing
Assignee: Garrett Corp
•
Filing: 1984-10-01
•
Granted: 1986-11-25
•
Expires: 2004-10-01
Abstract
Abstract A foil thrust bearing having a thrust disk with integral compliant bearing pads or foils. A number of alternative thrust bearing disks are disclosed, each of which provides a plurality of integral, converging, bearing pads or foils having diverging ramps and/or openings therebetween.
Inventors
- 👤 Marshall P. Saville
- 👤 Alston L. Gu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:28
CPC Classifications
F; F16; F16C; F16C17/00; F16C17/04; F16C17/042
Claims Analysis
Total Claims: 78
Claim 1
Independent Claim
109 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one of said pair of relatively rotatable members, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 2
Dependent Claim
109 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one of said pair of relatively rotatable members, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 3
Dependent Claim
14 words
The fluid thrust bearing of claim 1 wherein said radial slot is generally U-shaped.
Claim 4
Dependent Claim
14 words
The fluid thrust bearing of claim 1 wherein said radial slot is generally L-shaped.
Claim 5
Dependent Claim
119 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one thereof, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound disposed between the thrust disk and the one of said pair of members to which the foil bearing is mounted.
Claim 6
Dependent Claim
119 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one thereof, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound disposed between the thrust disk and the one of said pair of members to which the foil bearing is mounted.
Claim 7
Dependent Claim
140 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one thereof, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound disposed between the thrust disk and the one of said pair of members to which the foil bearing is mounted, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 8
Dependent Claim
140 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one thereof, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound disposed between the thrust disk and the one of said pair of members to which the foil bearing is mounted, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 9
Dependent Claim
14 words
The fluid thrust bearing of claim 5 wherein said radial slot is generally U-shaped.
Claim 10
Dependent Claim
24 words
The fluid thrust bearing of claim 5 wherein said radial slot is generally L-shaped with the base of the L-shape at the outer ramp.
Claim 11
Dependent Claim
21 words
The fluid thrust bearing of claim 4 wherein said diverging surface ramps are at the inner diameter of the thrust disk.
Claim 12
Dependent Claim
21 words
The fluid thrust bearing of claim 4 wherein said diverging surface ramps are at the outer diameter of the thrust disk.
Claim 13
Dependent Claim
151 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one thereof, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound disposed between the thrust disk and the one of said pair of members to which the foil bearing is mounted, said diverging surface ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 14
Dependent Claim
151 words
A fluid thrust bearing comprising: a pair of members arranged for relative rotation with respect to one another, one of said pair of members adapted to rotatably support the other; and a compliant foil bearing operably disposed between said pair of relatively rotatable members and mounted to one thereof, said complaint foil bearing comprising a thrust disk having a plurality of integral, converging surface compliant foils and a plurality of diverging surface ramps disposed generally between the integral, converging surface compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound disposed between the thrust disk and the one of said pair of members to which the foil bearing is mounted, said diverging surface ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 15
Dependent Claim
23 words
The fluid thrust bearing of claim 5 wherein the axial height of the diverging surface ramps is generally between 0.0005 and 0.010 inches.
Claim 16
Dependent Claim
23 words
The fluid thrust bearing of claim 5 wherein the axial height of the diverging surface ramps is generally between 0.001 and 0.002 inches.
Claim 17
Dependent Claim
97 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps facing said thrust runner therebetween, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate.
Claim 18
Dependent Claim
97 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps facing said thrust runner therebetween, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate.
Claim 19
Dependent Claim
114 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps therebetween, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 20
Dependent Claim
114 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps therebetween, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 21
Dependent Claim
14 words
The fluid thrust bearing of claim 14 wherein said radial slot is generally U-shaped.
Claim 22
Dependent Claim
24 words
The fluid thrust bearing of claim 14 wherein said radial slot is generally L-shaped with the base of the L-shape at the outer ramp.
Claim 23
Dependent Claim
21 words
The fluid thrust bearing of claim 13 wherein said diverging surface ramps are at the inner diameter of the thrust disk.
Claim 24
Dependent Claim
21 words
The fluid thrust bearing of claim 13 wherein said diverging surface ramps are at the outer diameter of the thrust disk.
Claim 25
Dependent Claim
125 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps therebetween, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate, said diverging surface ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 26
Dependent Claim
125 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps therebetween, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate, said diverging surface ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 27
Dependent Claim
23 words
The fluid thrust bearing of claim 19 wherein the radial slot is generally L-shaped with the base of the L-shape at the ramp.
Claim 28
Dependent Claim
23 words
The fluid thrust bearing of claim 13 wherein the axial height of the diverging surface ramps is generally between 0.0005 and 0.010 inches.
Claim 29
Dependent Claim
23 words
The fluid thrust bearing of claim 13 wherein the axial height of the diverging surface ramps is generally between 0.001 and 0.002 inches.
Claim 30
Dependent Claim
24 words
The fluid thrust bearing of claim 14 wherein the axial height of the inner ramps differs from the axial height of the outer ramps.
Claim 31
Dependent Claim
25 words
The fluid thrust bearing of claim 23 wherein the axial height of the inner ramps is greater than the axial height of the outer ramps.
Claim 32
Dependent Claim
25 words
The fluid thrust bearing of claim 23 wherein the axial height of the inner ramps is less than the axial height of the outer ramps.
Claim 33
Dependent Claim
27 words
The fluid thrust bearing of claim 14 wherein one side of the radial slots is generally radially aligned with the base of the inner and outer ramps.
Claim 34
Dependent Claim
29 words
The fluid thrust bearing of claim 15 wherein the open side of the U-shaped radial slots is generally radially aligned with the top of the inner and outer ramps.
Claim 35
Dependent Claim
27 words
The fluid thrust bearing of claim 14 wherein the trailing edge of the converging surface compliant foils extends beyond the top of the inner and outer ramps.
Claim 36
Dependent Claim
56 words
The fluid thrust bearing of claim 13 wherein the relationship between the angle formed between the leading edge of the compliant foils and the radial centerline of the underlying upper ridges of the foil stiffener and the angle formed between the leading edge and trailing edge of the compliant foils is between one half to one.
Claim 37
Dependent Claim
54 words
The fluid thrust bearing of claim 13 wherein the relationship between the angle formed between the leading edge of the compliant foils and the radial centerline of the underlying upper ridges of the foil stiffener and the angle formed between the leading edge and trailing edge of the compliant foils is generally two thirds.
Claim 38
Dependent Claim
32 words
The fluid thrust bearing of claim 13 wherein each of said diverging surface ramps comprise a ramp extending from the inner diameter of said disk to the outer diameter of said disk.
Claim 39
Dependent Claim
18 words
The fluid thrust bearing of claim 31 wherein the height of the ramps varies in the radial direction.
Claim 40
Dependent Claim
35 words
The fluid thrust bearing of claim 32 wherein the height of the ramps at the outer diameter of the disk is greater than the height of the ramps at the inner diameter of the disk.
Claim 41
Dependent Claim
35 words
The fluid thrust bearing of claim 31 wherein the height of the ramps at the outer diameter of the disk is less than the height of the ramps at the inner diameter of the disk.
Claim 42
Independent Claim
96 words
A method of rotatively supporting a thrust runner on a thrust plate comprising the steps of: providing a compliant foil bearing between said thrust runner and said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils and plurality of diverging surface ramps therebetween, both said converging surface compliant foils and said diverging surface ramps disposed towards and facing said thrust runner; and providing a stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate.
Claim 43
Independent Claim
96 words
A method of rotatively supporting a thrust runner on a thrust plate comprising the steps of: providing a compliant foil bearing between said thrust runner and said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils and plurality of diverging surface ramps therebetween, both said converging surface compliant foils and said diverging surface ramps disposed towards and facing said thrust runner; and providing a stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate.
Claim 44
Dependent Claim
68 words
A thrust disk for a compliant foil bearing, said thrust disk comprising: a thin compliant ring disk; a plurality of integral, converging surface compliant foils disposed on said disk towards said thrust runner; and a plurality of diverging surface ramps disposed between said converging surface compliant foils, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 45
Dependent Claim
68 words
A thrust disk for a compliant foil bearing, said thrust disk comprising: a thin compliant ring disk; a plurality of integral, converging surface compliant foils disposed on said disk towards said thrust runner; and a plurality of diverging surface ramps disposed between said converging surface compliant foils, said diverging surface ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 46
Dependent Claim
13 words
The thrust disk of claim 36 wherein said radial slot is generally U-shaped.
Claim 47
Dependent Claim
23 words
The thrust disk of claim 36 wherein said radial slot is generally L-shaped with the base of the L-shape at the outer ramp.
Claim 48
Dependent Claim
79 words
A thrust disk for a compliant foil bearing, said thrust disk comprising: a thin compliant ring disk; a plurality of integral, converging surface compliant foils disposed on said disk towards said thrust runner; and a plurality of diverging surface ramps disposed between said converging surface compliant foils, said diverging surface ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 49
Dependent Claim
79 words
A thrust disk for a compliant foil bearing, said thrust disk comprising: a thin compliant ring disk; a plurality of integral, converging surface compliant foils disposed on said disk towards said thrust runner; and a plurality of diverging surface ramps disposed between said converging surface compliant foils, said diverging surface ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 50
Dependent Claim
22 words
The thrust disk of claim 39 wherein the radial slot is generally L-shaped with the base of the L-shape at the ramp.
Claim 51
Dependent Claim
22 words
The thrust disk of claim 36 wherein the axial height of the diverging surface ramps is generally between 0.0005 and 0.010 inches.
Claim 52
Dependent Claim
22 words
The thrust disk of claim 36 wherein the axial height of the diverging surface ramps is generally between 0.001 and 0.002 inches.
Claim 53
Dependent Claim
23 words
The thrust disk of claim 36 wherein the axial height of the inner ramps differs from the axial height of the outer ramps.
Claim 54
Dependent Claim
24 words
The thrust disk of claim 36 wherein the axial height of the inner ramps is greater than the axial height of the outer ramps.
Claim 55
Dependent Claim
24 words
The thrust disk of claim 36 wherein the axial height of the inner ramps is less than the axial height of the outer ramps.
Claim 56
Dependent Claim
26 words
The thrust disk of claim 36 wherein one side of the radial slots is generally radially aligned with the base of the inner and outer ramps.
Claim 57
Dependent Claim
28 words
The thrust disk of claim 37 wherein the open side of the U-shaped radial slots is generally radially aligned with the top of the inner and outer ramps.
Claim 58
Dependent Claim
26 words
The thrust disk of claim 36 wherein the trailing edge of the converging surface compliant foils extends beyond the top of the inner and outer ramps.
Claim 59
Dependent Claim
92 words
A thrust disk for a compliant foil bearing, said thrust disk comprising: a thin compliant ring disk; a plurality of integral, converging surface compliant foils disposed on said disk; and a plurality of diverging surface ramps disposed between said converging surface compliant foils, both said converging surface compliant foils and said diverging surface ramps facing in the same direction, said diverging surface ramps comprising a ramp extending from the inner diameter of said disk to the outer diameter of said disk and the height of the ramps varies in the radial direction.
Claim 60
Dependent Claim
92 words
A thrust disk for a compliant foil bearing, said thrust disk comprising: a thin compliant ring disk; a plurality of integral, converging surface compliant foils disposed on said disk; and a plurality of diverging surface ramps disposed between said converging surface compliant foils, both said converging surface compliant foils and said diverging surface ramps facing in the same direction, said diverging surface ramps comprising a ramp extending from the inner diameter of said disk to the outer diameter of said disk and the height of the ramps varies in the radial direction.
Claim 61
Dependent Claim
34 words
The thrust disk of claim 49 wherein the height of the ramps at the outer diameter of the disk is greater than the height of the ramps at the inner diameter of the disk.
Claim 62
Dependent Claim
34 words
The thrust disk of claim 49 wherein the height of the ramps at the outer diameter of the disk is less than the height of the ramps at the inner diameter of the disk.
Claim 63
Dependent Claim
18 words
The fluid thrust bearing of claim 31 wherein the ramps include a plurality of radially spaced openings therein.
Claim 64
Dependent Claim
41 words
The fluid thrust bearing of claim 1 wherein said diverging surface ramps are at the outer diameter of the thrust disk and said disk includes a plurality of radial slots extending from the ramps to the inner diameter of said disk.
Claim 65
Dependent Claim
23 words
The fluid thrust bearing of claim 53 wherein the radial slot is generally L-shaped with the base of the L-shape at the ramp.
Claim 66
Dependent Claim
24 words
The fluid thrust bearing of claim 1 wherein the axial height of the inner ramps differs from the axial height of the outer ramps.
Claim 67
Dependent Claim
27 words
The fluid thrust bearing of claim 1 wherein one side of the radial slots is generally radially aligned with the base of the inner and outer ramps.
Claim 68
Dependent Claim
29 words
The fluid thrust bearing of claim 1 wherein the open side of the U-shaped radial slots is generally radially aligned with the top of the inner and outer ramps.
Claim 69
Dependent Claim
27 words
The fluid thrust bearing of claim 1 wherein the trailing edge of the converging surface compliant foils extends beyond the top of the inner and outer ramps.
Claim 70
Dependent Claim
41 words
The fluid thrust bearing of claim 4 wherein said diverging surface ramps are at the inner diameter of the thrust disk and said disk includes a plurality of radial slots extending from the ramps to the outer diameter of said disk.
Claim 71
Dependent Claim
118 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps therebetween with the surface of the ramps inclined in a direction which slopes oppositely to the direction of inclination of the surface of the compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate.
Claim 72
Dependent Claim
118 words
A fluid thrust bearing comprising: a thrust runner; a thrust plate to rotatably support the thrust runner; and a compliant foil bearing operably disposed between said thrust runner and said thrust plate and mounted on said thrust plate, said compliant foil bearing including a thrust disk having a plurality of integral, converging surface compliant foils disposed towards said thrust runner and a plurality of diverging surface ramps therebetween with the surface of the ramps inclined in a direction which slopes oppositely to the direction of inclination of the surface of the compliant foils, and a foil stiffener disk having a plurality of upper and lower ridges alternately transversely disposed therearound between the thrust disk and the thrust plate.
Claim 73
Independent Claim
89 words
A method of fabricating a thrust disk for a compliant foil bearing comprising the steps of: forming a thin compliant ring disk; and forming a plurality of radially extending ramps around the disk whereby a converging surface compliant foil is formed between adjacent ramps, said radially extending ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk, the surface of the ramps inclined in a direction which slopes oppositely to the direction of inclination of the surface of the compliant foils.
Claim 74
Independent Claim
89 words
A method of fabricating a thrust disk for a compliant foil bearing comprising the steps of: forming a thin compliant ring disk; and forming a plurality of radially extending ramps around the disk whereby a converging surface compliant foil is formed between adjacent ramps, said radially extending ramps comprising an inner ramp and an outer ramp separated by a radial slot in the thrust disk, the surface of the ramps inclined in a direction which slopes oppositely to the direction of inclination of the surface of the compliant foils.
Claim 75
Dependent Claim
27 words
The method of claim 35 wherein said diverging surface ramps comprise an inner ramp and an outer ramp separated by a radial slot in the thrust disk.
Claim 76
Independent Claim
100 words
A method of fabricating a thrust disk for a compliant foil bearing comprising the steps of; forming a thin compliant ring disk; and forming a plurality of radially extending ramps around the disk whereby a converging surface compliant foil is formed between adjacent ramps, said radially extending ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk, the surface of the ramps inclined in a direction which slopes oppositely to the direction of inclination of the surface of the compliant foils.
Claim 77
Independent Claim
100 words
A method of fabricating a thrust disk for a compliant foil bearing comprising the steps of; forming a thin compliant ring disk; and forming a plurality of radially extending ramps around the disk whereby a converging surface compliant foil is formed between adjacent ramps, said radially extending ramps at the outer diameter of the thrust disk and said disk including a plurality of radial slots extending from the ramps to the inner diameter of said disk, the surface of the ramps inclined in a direction which slopes oppositely to the direction of inclination of the surface of the compliant foils.
Claim 78
Dependent Claim
39 words
The method of claim 35 wherein said diverging surface ramps are at the outer diameter of the thrust disk and said disk includes a plurality of radial slots extending from the ramps to the inner diameter of said disk.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-11-24 | 1990-05-26 | 1990-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-24 | 1994-05-26 | 1994-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-24 | 1998-05-26 | 1998-11-25 | $7700.00 | Window Closed / Lapsed |