US5174411A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ladder improvements
Assignee: Abru Aluminium Ltd
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Filing: 1991-09-26
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Granted: 1992-12-29
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Expires: 2011-09-26
Abstract
Abstract A loft ladder which can be pivotally and slidably mounted to loft opening has counterbalancing means including a resiliently biased pivotal arm, connected to the loft ladder by a link member pivotally connected between the pivotal arm and the loft ladder to allow the ladder to turn about is pivotal connection to the loft opening over at least a limited extend. The arm has a two-stage resilient biasing spring offering a greater resilient force over part of the range of movement of the arm. A hand rail of the ladder is supported on a section of the ladder by spacers allowing the hand rail to be carried at a lateral distance from the ladder stile greater than the lateral space occupied by the counterbalance mechanism. A releasable catch for retaining two ladder parts in a selected position comprises two moveable catch members mounted on respective stiles, and interconnected together.
Inventors
- 👤 David P. Oliver
- 👤 David Shrimpton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 21:43
CPC Classifications
E; E06; E06C; E06C9/00; E06C9/06; E06C9/08; E06C9/10
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
70 words
A loft ladder of the type having a slidably pivotal connection to a loft opening and a counterbalance mechanism including a resiliently biased pivoted arm with a two-stage action, wherein said two-stage action is achieved by the provision of a helical coil spring acting in torsion about the axis of the coil and enclosing a resilient sleeve which is gripped when the coil spring is reduced in diameter upon flexing.
Claim 2
Dependent Claim
70 words
A loft ladder of the type having a slidably pivotal connection to a loft opening and a counterbalance mechanism including a resiliently biased pivoted arm with a two-stage action, wherein said two-stage action is achieved by the provision of a helical coil spring acting in torsion about the axis of the coil and enclosing a resilient sleeve which is gripped when the coil spring is reduced in diameter upon flexing.
Claim 3
Dependent Claim
88 words
A loft ladder having pivotal slide coupling means for mounting it to a loft opening and counterbalance mechanism with a resiliently biased pivoted arm, wherein a handrail of said loft ladder is supported on said ladder on a section thereof by spacers allowing said handrail to be carried at a lateral distance from the stile greater then the lateral space occupied by the counterbalance mechanism whereby to allow both the counterbalance mechanism and the handrail to be fitted to the same side of the loft ladder if desired.
Claim 4
Dependent Claim
88 words
A loft ladder having pivotal slide coupling means for mounting it to a loft opening and counterbalance mechanism with a resiliently biased pivoted arm, wherein a handrail of said loft ladder is supported on said ladder on a section thereof by spacers allowing said handrail to be carried at a lateral distance from the stile greater then the lateral space occupied by the counterbalance mechanism whereby to allow both the counterbalance mechanism and the handrail to be fitted to the same side of the loft ladder if desired.
Claim 5
Dependent Claim
117 words
An extended ladder comprising at least two ladder parts constituted by two stiles interconnected by rungs, the parts being relatively movable between a fully extended position and a collapsed position, and at least one releasable catch for retaining said ladder parts in at least one relative position selected from said fully extended position and at least one partly extended position, wherein there are provided two movable catch members mounted on respective stiles of one of said ladder parts, and interconnection means linking said movable catch members such that displacement of one member is transmitted to the other whereby to release the two ladder parts for relative movement or to connect them together in a selected relative position.
Claim 6
Dependent Claim
117 words
An extended ladder comprising at least two ladder parts constituted by two stiles interconnected by rungs, the parts being relatively movable between a fully extended position and a collapsed position, and at least one releasable catch for retaining said ladder parts in at least one relative position selected from said fully extended position and at least one partly extended position, wherein there are provided two movable catch members mounted on respective stiles of one of said ladder parts, and interconnection means linking said movable catch members such that displacement of one member is transmitted to the other whereby to release the two ladder parts for relative movement or to connect them together in a selected relative position.
Claim 7
Dependent Claim
42 words
An extending ladder as claimed in claim 3, wherein said stiles define respective catch openings and each said catch member has a nose portion engageable in at least one cooperating said catch opening in the corresponding stile of the other ladder part.
Claim 8
Dependent Claim
26 words
An extending ladder is claimed in claim 3, wherein each said catch member is rectilinearly displaceable between a first, engagement position and a second, release position.
Claim 9
Dependent Claim
26 words
An extending ladder as claimed in claim 3, wherein each said catch member is angularly displaceable between a first, engagement position and a second, release position.
Claim 10
Dependent Claim
36 words
An extending ladder as claimed in claim 3, wherein said ladder has at least one tubular rung and said interconnection means pass through a said tubular rung of the ladder from one stile to the other.
Claim 11
Dependent Claim
25 words
An extending ladder as claimed in claim 7, wherein said interconnection means include a torsion member selected from a torsion bar and a torsion tube.
Claim 12
Dependent Claim
38 words
An extending ladder as claimed in claim 8, wherein a lever arm is provided to operate said torsion member whereby to cause displacement of said catch members between a first, engagement position and a second, release position thereof.
Claim 13
Dependent Claim
21 words
An extending ladder as claimed in claim 9, wherein said lever arms are formed as operating handles for said catch members.
Claim 14
Dependent Claim
25 words
An extending ladder as claimed in claim 3, wherein said catch members comprise resiliently biased sliding bolts engaged by said interconnection means for operation thereon.
Claim 15
Dependent Claim
144 words
A loft ladder of the type having counterbalancing means including a resiliently biased pivotal arm and being adapted to be pivotally and slidably mounted to a loft opening for movement between a stowed position and a lowered position, said pivotal arm having a free end connected to the loft ladder by a link member pivotally connected at one end to said pivotal arm and at the other end to said loft ladder, whereby to allow said loft ladder to turn abut its pivotal connection to said loft opening over at least a limited extent when the loft ladder is in said lowered position, said link member comprising two link elements positioned one on either side of said pivotal arm, said link elements being joined together by pivotal connectors, said pivotal connectors also connecting link elements to said pivotal arm and to said loft ladder.
Claim 16
Dependent Claim
144 words
A loft ladder of the type having counterbalancing means including a resiliently biased pivotal arm and being adapted to be pivotally and slidably mounted to a loft opening for movement between a stowed position and a lowered position, said pivotal arm having a free end connected to the loft ladder by a link member pivotally connected at one end to said pivotal arm and at the other end to said loft ladder, whereby to allow said loft ladder to turn abut its pivotal connection to said loft opening over at least a limited extent when the loft ladder is in said lowered position, said link member comprising two link elements positioned one on either side of said pivotal arm, said link elements being joined together by pivotal connectors, said pivotal connectors also connecting link elements to said pivotal arm and to said loft ladder.
Claim 17
Dependent Claim
115 words
A loft ladder as claimed in claim 12, wherein said resiliently biased pivotal arm is biased by a two-stage spring offering a greater biasing force when said arms is in a position where it largely supports the weight of said loft ladder and a reduced biasing force when said loft ladder is close to said stowed position, wherein said two-stage action is provided by a helical coil spring acting in torsion about the axis of the coil, and wherein said helical coil spring has a central core constituted by a material selected from resilient elastomeric and plastic materials, said core being gripped by said helical coil spring as it is reduced in diameter upon flexing.
Claim 18
Dependent Claim
163 words
A loft ladder of the type having counterbalancing means including a resiliently biased pivotal arm and being adapted to be pivotally and slidably mounted to a loft opening for movement between a stowed position and a lowered position, said pivotal arm having a free end connected to the loft ladder by a link member pivotally connected at one end to said pivotal arm and at the other end to said loft ladder, whereby to allow said loft ladder to turn about its pivotal connection to said loft opening over at least a limited extent when the loft ladder is in said lowered position, said counterbalancing means occupying space laterally of said loft ladder and said loft ladder having a handrail supported thereon at a lateral distance from a stile thereof which is greater than said lateral space occupied by the counterbalancing means whereby to allow both said counterbalancing means and said handrail to be fitted to the same side of said loft ladder.
Claim 19
Dependent Claim
163 words
A loft ladder of the type having counterbalancing means including a resiliently biased pivotal arm and being adapted to be pivotally and slidably mounted to a loft opening for movement between a stowed position and a lowered position, said pivotal arm having a free end connected to the loft ladder by a link member pivotally connected at one end to said pivotal arm and at the other end to said loft ladder, whereby to allow said loft ladder to turn about its pivotal connection to said loft opening over at least a limited extent when the loft ladder is in said lowered position, said counterbalancing means occupying space laterally of said loft ladder and said loft ladder having a handrail supported thereon at a lateral distance from a stile thereof which is greater than said lateral space occupied by the counterbalancing means whereby to allow both said counterbalancing means and said handrail to be fitted to the same side of said loft ladder.
Claim 20
Dependent Claim
24 words
A loft ladder as claimed in claim 12, wherein the resiliently biased pivotal arm is biased by means of a coil spring in torsion.
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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) | 1995-12-29 | 1996-06-29 | 1996-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-29 | 2000-06-29 | 2000-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-29 | 2004-06-29 | 2004-12-29 | $7700.00 | Window Closed / Lapsed |