US3749254A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Boom extension lock
Assignee: NORTHWEST ENGINEERING Co A CORP OF
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Filing: 1972-04-28
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Granted: 1973-07-31
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Expires: 1992-04-28
Abstract
Abstract An extensible boom includes main sections and a separately driven extension section which is locked in place by pins on the outer main section. The pins are automatically retracted by means of cam followers actuated by cam tracks on an inner section, and the pins and tracks are near the ends of their sections so that the extension section is operable only when the main sections are substantially retracted. The cam followers operate through override springs to prevent damage, and the pins have enlarged ends which effectively prevent operation of the extension until its drive is actuated.
Inventors
- 👤 L Grider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:59
CPC Classifications
B; B66; B66C; B66C23/00; B66C23/62; B66C23/64; B66C23/70; B66C23/701; B66C23/708; Y; Y10; Y10T; Y10T403/00; Y10T403/32; Y10T403/32254; Y10T403/32467; Y10T403/32516
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
251 words
In an extensible boom including an inner main section and an extensible and retractable outer main section and drive means to extend and retract the outer section with respect to the inner section, the improvement wherein the boom also includes: an extension section that is supported by and extensible and retractable with respect to the outer section and provided with at least one transverse lock aperture; separate drive means to extend and retract the extension section, lock means carried by the outer section, said lock means including a lock pin which faces the extension section and is movable between an extended position in which it is received in the lock aperture to lock the extension section in place and a retracted position in which the extension section is freed, bias means to urge the lock pin toward extended position, and a cam follower outside the outer section which is associated with and operable to move the pin to retracted position; and a cam track connected to the inner section of the boom and positioned to engage and operate the cam follower carried by the outer section when the outer section is near its fully retracted position; wherein the extension section is moved rElative to said outer section with said separate drive means and said extension section is unlocked from said outer section for such movement by the operation of the cam follower when the outer section is moved relative to the inner section to bring said cam track into engagement therewith.
Claim 2
Dependent Claim
251 words
In an extensible boom including an inner main section and an extensible and retractable outer main section and drive means to extend and retract the outer section with respect to the inner section, the improvement wherein the boom also includes: an extension section that is supported by and extensible and retractable with respect to the outer section and provided with at least one transverse lock aperture; separate drive means to extend and retract the extension section, lock means carried by the outer section, said lock means including a lock pin which faces the extension section and is movable between an extended position in which it is received in the lock aperture to lock the extension section in place and a retracted position in which the extension section is freed, bias means to urge the lock pin toward extended position, and a cam follower outside the outer section which is associated with and operable to move the pin to retracted position; and a cam track connected to the inner section of the boom and positioned to engage and operate the cam follower carried by the outer section when the outer section is near its fully retracted position; wherein the extension section is moved rElative to said outer section with said separate drive means and said extension section is unlocked from said outer section for such movement by the operation of the cam follower when the outer section is moved relative to the inner section to bring said cam track into engagement therewith.
Claim 3
Dependent Claim
188 words
A boom according to claim 1 wherein: the lock means includes a sleeve fixed to and extending transversely through the outer section and having an open inner end facing the extension section and an outer end provided with a shoulder; and the lock pin is reciprocally slidable in the sleeve and has a body portion in the sleeve and a reduced stem which projects outwardly through the outer end of the sleeve and is provided with an abutment at its outer end; and the bias means comprises a relatively light compression spring seated between the pin body and the sleeve shoulder; and there is a freely axially movable housing disposed concentrically around the sleeve which has an open outer end disposed around the stem abutment and an inner end provided with an inwardly turned ledge; and there is a relatively heavier override spring disposed within the housing around the sleeve which is seated between the stem abutment and housing ledge; and the cam follower is mounted on the outside of the housing and is operatively engageable by the cam track to be moved away from the outer section.
Claim 4
Dependent Claim
82 words
A boom according to claim 1 wherein the outer and tip sections are capable of relative slippage movement; and lock aperture is in a wall of the extension section; and the pin has an enlarged inner end which passes through the lock aperture with a relatively close fit and is disposed on the inner side of the wall when the pin is extended to define a shoulder which is engageable with the inside of the wall to prevent retraction of the pin.
Claim 5
Dependent Claim
45 words
A boom according to claim 1 wherein the lock means and cam track are disposed near the outer ends, respectively, of the outer and inner sections, the cam track thus being operatively engageable with the cam follower only when the outer section is substantially retracted.
Claim 6
Dependent Claim
125 words
A boom according to claim 4 wherein the extension section is provided with at least two aligned lock apertures located near its inner and outer ends to define, respectively, extended and retracted positions of the extension section; and the cam track is adapted to move between the cam follower and the outer section and has a V-configuration defining an apex facing the follower and which is adapted to move the follower laterally away from the outer section, the track being movable past the follower in either direction, the lock pin being retracted when the follower is approximately at the apex of the track; and the elements are positioned such that the track apex is ahead of the follower when the outer section is fully retracted.
Claim 7
Dependent Claim
188 words
A boom according to claim 5 wherein: the lock means includes a sleeve fixed to and extending transversely through the outer section and having an open inner end facing the extension section and an outer end provided with a shoulder; and the lock pin is reciprocally slidable in the sleeve and has a body portion in the sleeve and a reduced stem which projects outwardly through the outer end of the sleeve and is provided with an abutment at its outer end; and the bias means comprises a relatively light compression spring seated between the pin body and the sleeve shoulder; and there is a freely axially movable housing disposed concentrically around the sleeve which has an open outer end disposed around the stem abutment and an inner end provided with an inwardly turned ledge; and there is a relatively heavier override spring disposed within the housing around the sleeve which is seated between the stem abutment and housing ledge; and the cam follower is mounted on the outside of the housing and is operatively engageable by the cam track to be moved away from the outer section.
Claim 8
Dependent Claim
60 words
A boom according to claim 6 wherein there are two cam followers mounted on opposite sides oF the housing and two aligned cam tracks each engageable with a respective follower; and there is a key and slot connection operatively interposed between the housing and the outer section which allows free axial movement of the housing but prevents rotational movement thereof.
Claim 9
Dependent Claim
82 words
A boom according to claim 7 wherein the outer and tip sections are capable of relative slippage movement; and lock aperture is in a wall of the extension section; and the pin has an enlarged inner end which passes through the lock aperture with a relatively close fit and is on the inner side of the wall when the pin is extended to define a shoulder which is engageable with the inner side of the wall to prevent retraction of the pin.
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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |