US3719249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power steering system affording emergency steering capability
Assignee: SPX Technologies Inc
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Filing: 1971-03-05
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Granted: 1973-03-06
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Expires: 1991-03-05
Abstract
Abstract The disclosure concerns hydraulically operated power steering systems for vehicles, particularly large articulated vehicles. The system includes a closed center steering valve which normally is supplied with oil from an engine driven pump, and it incorporates an accumulator and a ground drive pump which provide sufficient hydraulic power to permit steering during extended periods of engine-off towing.
Inventors
- 👤 L Becker
- 👤 T Huffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:37
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/17; B; B62; B62D; B62D5/00; B62D5/06; B62D5/30; B62D5/32
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
250 words
A hydraulically operated power steering system for a wheeled vehicle having a propulsion engine comprising a. a closed center steering valve (11) for controlling the flow of fluid to and from steering motor means (12, 13) and having a supply circuit (14) containing an accumulator (15) for storing fluid under pressure; b. a main pumping unit (17 or 54) driven by the engine and connected to deliver fluid to the supply circuit (14) through check valve means (25) which prevents reverse flow from the circuit; c. an auxiliary pumping unit (38 or 59) connected with at least one of the wheels of the vehicle so that it is driven when the vehicle is in motion, this pumping unit also being connected to deliver fluid to the supply circuit (14) through check valve means (25a or 41, 42) which prevents reverse flow from the circuit; d. first control means (19 or 56, 57) responsive to the pressure in the supply circuit (14) and effective when the main pumping unit (17 or 54) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a first level; and e. second control means (19a or 61, 62) responsive to the pressure in the supply circuit (14) and effective when the auxiliary puMping unit (38 or 59) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a second level lower than said first level.
Claim 2
Dependent Claim
250 words
A hydraulically operated power steering system for a wheeled vehicle having a propulsion engine comprising a. a closed center steering valve (11) for controlling the flow of fluid to and from steering motor means (12, 13) and having a supply circuit (14) containing an accumulator (15) for storing fluid under pressure; b. a main pumping unit (17 or 54) driven by the engine and connected to deliver fluid to the supply circuit (14) through check valve means (25) which prevents reverse flow from the circuit; c. an auxiliary pumping unit (38 or 59) connected with at least one of the wheels of the vehicle so that it is driven when the vehicle is in motion, this pumping unit also being connected to deliver fluid to the supply circuit (14) through check valve means (25a or 41, 42) which prevents reverse flow from the circuit; d. first control means (19 or 56, 57) responsive to the pressure in the supply circuit (14) and effective when the main pumping unit (17 or 54) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a first level; and e. second control means (19a or 61, 62) responsive to the pressure in the supply circuit (14) and effective when the auxiliary puMping unit (38 or 59) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a second level lower than said first level.
Claim 3
Dependent Claim
250 words
A hydraulically operated power steering system for a wheeled vehicle having a propulsion engine comprising a. a closed center steering valve (11) for controlling the flow of fluid to and from steering motor means (12, 13) and having a supply circuit (14) containing an accumulator (15) for storing fluid under pressure; b. a main pumping unit (17 or 54) driven by the engine and connected to deliver fluid to the supply circuit (14) through check valve means (25) which prevents reverse flow from the circuit; c. an auxiliary pumping unit (38 or 59) connected with at least one of the wheels of the vehicle so that it is driven when the vehicle is in motion, this pumping unit also being connected to deliver fluid to the supply circuit (14) through check valve means (25a or 41, 42) which prevents reverse flow from the circuit; d. first control means (19 or 56, 57) responsive to the pressure in the supply circuit (14) and effective when the main pumping unit (17 or 54) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a first level; and e. second control means (19a or 61, 62) responsive to the pressure in the supply circuit (14) and effective when the auxiliary puMping unit (38 or 59) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a second level lower than said first level.
Claim 4
Dependent Claim
250 words
A hydraulically operated power steering system for a wheeled vehicle having a propulsion engine comprising a. a closed center steering valve (11) for controlling the flow of fluid to and from steering motor means (12, 13) and having a supply circuit (14) containing an accumulator (15) for storing fluid under pressure; b. a main pumping unit (17 or 54) driven by the engine and connected to deliver fluid to the supply circuit (14) through check valve means (25) which prevents reverse flow from the circuit; c. an auxiliary pumping unit (38 or 59) connected with at least one of the wheels of the vehicle so that it is driven when the vehicle is in motion, this pumping unit also being connected to deliver fluid to the supply circuit (14) through check valve means (25a or 41, 42) which prevents reverse flow from the circuit; d. first control means (19 or 56, 57) responsive to the pressure in the supply circuit (14) and effective when the main pumping unit (17 or 54) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a first level; and e. second control means (19a or 61, 62) responsive to the pressure in the supply circuit (14) and effective when the auxiliary puMping unit (38 or 59) is running for causing that unit to deliver fluid to the supply circuit as needed to maintain said pressure above a second level lower than said first level.
Claim 5
Dependent Claim
58 words
A steering system as defined in claim 1 including an unloading valve (46) which responds to the discharge pressure of the main pumping unit (17 or 54) and opens an exhaust path (47) leading from the auxiliary pumping unit to a reservoir (18) when said pressure rises above a level which is considerably lower than said second level.
Claim 6
Dependent Claim
146 words
A steering system as defined in claim 1 in which a. each pumping unit includes a fixed delivery pump (17 or 39); b. the first control means (19) comprises an unloading valve (23) which controls an exhaust path (24) leading from the main pump (17) to a reservoir (18), the valve serving to close said path when supply circuit pressure decreases to said first level and to open said path when supply circuit pressure rises to a higher third level; and c. the second control means (19a) comprises a second unloading valve (23a) which controls an exhaust path (24a) leading from the auxiliary pump (39) to said reservoir (18), this valve serving to close said exhaust path when supply circuit pressure decreases to said second level and to open said path when supply circuit pressure rises to a fourth level intermediate said first and second levels.
Claim 7
Dependent Claim
90 words
A steering system as defined in claim 1 in which a. the auxiliary pumping unit (38) includes a fixed delivery pump (39); and b. the second control means (19a) comprises an unloading valve (23a) which controls an exhaust path (24a) leading from the auxiliary pump to a reservoir (18), c. the unloading valve serving to close said exhaust path when supply circuit pressure decreases to said second level and to open said exhaust path when the supply circuit pressure rises to a third level intermediate the first and second levels.
Claim 8
Dependent Claim
61 words
A steering system as defined in claim 4 including a second unloading valve (46) which responds to the discharge pressure of the main pumping unit (17 or 54) and opens a second exhaust path (47) leading from said fixed delivery pump to said reservoir (18) when said pressure rises above a fourth level which is considerably lower than said second level.
Claim 9
Dependent Claim
81 words
A steering system as defined in claim 1 in which a. the main pumping unit includes a variable delivery pump (54); and b. the first control means (56, 57) is a delivery control device for the main pump which serves to progressively decrease delivery rate to a minimum as circuit pressure rises from said first level to a maximum level and to progressively increase delivery rate to a maximum as said pressure decreases from said maximum level to said first level.
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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) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |