Patent DE220475C successfully refreshed from Google Patents.
Patent US3920231A successfully refreshed from Google Patents.
US3920231A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rubber springs
Assignee: Dunlop Ltd
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Filing: 1973-04-16
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Granted: 1975-11-18
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Expires: 1993-04-16
Abstract
Abstract A rubber spring comprising an annular rubber member bonded between metal end plates and containing an inelastic fluid which modifies the spring characteristics. The spring may be in the form of several rubber members separated by interleaving plates. The invention also provides a railway suspension using the spring which allows correction of ride height by control of the fluid volume.
Inventors
- 👤 Reginald Harrison
- 👤 Michael John Smedley
- 👤 Bernard Ridge Wing
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:24
CPC Classifications
F; F16; F16F; F16F13/00; F16F13/04; F16F13/06; F16F13/08; B; B60; B60G; B60G2202/00; B60G2202/10; B60G2202/14; B60G2202/143; B60G2204/00; B60G2204/10; B60G2204/12; B60G2204/125; B60G2204/40; B60G2204/45; B60G2204/4504
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
76 words
A spring comprising: means defining a closed chamber, said means comprising a pair of rigid metal end plates, several rubber members bonded between said end plates to form a stack, and annular interleaving plates bonded between adjacent rubber members, damping means within the chamber, and a liquid filling said chamber whereby in displacement of the spring the pressure of the liquid acts on the annular rubber member to modify the resistance to displacement of the spring.
Claim 2
Dependent Claim
76 words
A spring comprising: means defining a closed chamber, said means comprising a pair of rigid metal end plates, several rubber members bonded between said end plates to form a stack, and annular interleaving plates bonded between adjacent rubber members, damping means within the chamber, and a liquid filling said chamber whereby in displacement of the spring the pressure of the liquid acts on the annular rubber member to modify the resistance to displacement of the spring.
Claim 3
Dependent Claim
16 words
A spring according to claim 1 wherein said liquid is a mixture of alcohol and water.
Claim 4
Dependent Claim
40 words
A spring according to claim 1 wherein said means further comprises a liquid inlet in one end plate and a fluid cylinder containing a piston, whereby movement of the piston causes variation in the volume of liquid within the spring.
Claim 5
Dependent Claim
20 words
A spring according to claim 1 wherein the damping means comprises a baffle for restricting liquid movement within the chamber.
Claim 6
Dependent Claim
38 words
A spring according to claim 4 wherein the baffle has provided at least two different area apertures each having a one-way-valve so that liquid may only pass in one direction whereby damping in different directions may be controlled.
Claim 7
Dependent Claim
15 words
A spring according to claim 4 wherein the baffle is attached to an end plate.
Claim 8
Dependent Claim
15 words
A spring according to claim 4 wherein the baffle is attached to an interleaving plate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |