US3722896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Secondary seal for rotary mechanical seal
Assignee: Crane Packing Co
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Filing: 1971-03-19
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Granted: 1973-03-27
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Expires: 1991-03-19
Abstract
Abstract The invention resides in a secondary seal of polytetrafluoroethylene for a rotary mechanical shaft seal. The novel secondary seal replaces and is interchangeable with a known secondary seal also made of polytetrafluoroethylene which has a wedge shape in radial cross section and which causes fretting over the portion of the shaft contacted by the apex of the wedge. The novel secondary seal is somewhat V-shaped or folded in radial cross section and presents the rounded bottom of the fold to the shaft to produce a rolling action of the secondary seal on the shaft instead of the sliding, fretting-producing wedge action of the wedge-shaped secondary seal.
Inventors
- 👤 H Tankus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:13
CPC Classifications
F; F16; F16J; F16J15/00; F16J15/16; F16J15/34; F16J15/38; Y; Y10; Y10S; Y10S277/00; Y10S277/935; Y10S277/936; Y10S277/937; Y10S277/944; Y10S277/945; Y10S277/946
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
15 words
The combination described in claim 1, said annular flexible sealing element being made of polytetrafluoroethylene.
Claim 2
Dependent Claim
39 words
The combination described in claim 1, said annular flexible sealing element being made of polytetrafluoroethylene and said means urging one of said sealing element walls against the sloping wall of the sealing washer comprising a ring of glass-filled polytetrafluoroethylene.
Claim 3
Dependent Claim
75 words
The combination described in claim 1, said one of said relatively rotatable elements being cylindrical in external contour and said rigid washer surrounding said one of said relatively rotatable elements having a circular opening through which said one of said relatively rotatable elements passes and which forms the aforesaid annular clearance space between the washer and said one of said relatively rotatable elements, no part of said annular flexible sealing element extending into said clearance.
Claim 4
Dependent Claim
116 words
The combination described in claim 1, said annular flexible sealing element being made of polytetrafluoroethylene, and said means urging one of said sealing element walls against the sloping wall of the sealing washer comprising a ring of wedge-shaped radial cross section having a frustrated apex to leave a space between the ring and the rounded apex of the sealing element, said ring having a low coefficient of friction with respect to the walls of the element contacted thereby such that misalignment between the axis of the washer and the axis of the said one of said relatively rotatable elements results in a universal movement of the walls of said sealing element with reference to one another.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |