Lockable ladder hinge

A lockable hinge includes a first and second hinge member, a lock, and an actuator. The lockable hinge is coupled to a pair of ladder-leg sections and is arranged to allow the ladder-leg sections to move among closed-ladder, trestle-ladder, and straight-ladder positions. The lock is used to lock the hinge members to cause the ladder-leg sections to lock in the closed-ladder, trestle-ladder and straight-ladder positions.

Foreign priority is hereby claimed under 35 U.S.C. § 119 to Chinese Patent Application No. 200320107059.8 filed in the People's Republic of China on Nov. 11, 2003, Chinese Patent Application No. 200420038624.4 filed in the People's Republic of China on Feb. 19, 2004, and Chinese Patent Application No. 200430030491.1 filed in the People's Republic of China on Feb. 24, 2004, the disclosures of which are hereby incorporated by reference herein.

BACKGROUND

The present disclosure relates to hinges and particularly to lockable hinges. More particularly, the present disclosure relates to lockable hinges for center-fold or multi-fold ladders.

Hinges are used in a variety of applications. Lockable hinges are often used on ladders to allow one section of the ladder legs to move relative to another section and to lock the ladder-leg sections in predetermined positions.

SUMMARY

According to the present disclosure, a lockable hinge includes a pair of hinge members adapted to be coupled to a pair of ladder-leg sections for movement of the ladder-leg sections among closed-ladder, trestle-ladder, and straight-ladder positions. The lockable hinge is used to lock the hinge members to cause the ladder-leg sections to lock in the closed-ladder, trestle-ladder, and straight-ladder positions.

Illustratively, the lockable hinge includes a lock and an actuator which, along with the hinge members, share a common pivot axis to allow pivotable movement of the ladder-leg sections about the common axis. The lock includes a pair of tabs that are biased to press inwardly toward the common axis against an annular flange portion of the first hinge member. The annular flange portion includes a plurality of tab-receiving spaces associated with the closed-ladder, trestle-ladder, and straight-ladder positions. Upon movement of the tabs into the lock-receiving spaces, the lock blocks pivotable movement of the first and second hinge members about the common axis to lock the ladder-leg sections in a selected position.

The actuator includes a rotary knob coupled to the lock. To unlock the hinge, an input force is applied to the knob to cause the tabs to move away from the common axis and away from the lock-receiving spaces. Upon retraction of the tabs from the lock-receiving spaces, the hinge members and the ladder-leg sections are able to pivot relative to one another to any of the other predetermined ladder positions.

Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived.

DETAILED DESCRIPTION

A ladder11includes a pair of ladder-leg sections76and a pair of lockable ladder hinges10coupled to sections76as shown, for example, inFIGS. 1–3. Hinges10are configured to allow selective movement of sections76between a closed-ladder (e.g., 0°) position shown inFIG. 1, a trestle-ladder (e.g., 40°) position shown inFIG. 2, and a straight-ladder (e.g., 180°) position shown inFIG. 3and to lock sections76in such positions. As suggested in the embodiment ofFIGS. 4–15, a first lockable ladder hinge10, in accordance with a first embodiment of the disclosure, includes a mounting member44for use in coupling an actuator14to a lock12. As suggested in the embodiment ofFIGS. 16–23, a second lockable ladder hinge210, in accordance with a second embodiment of the disclosure, includes a mounting member assembly244for use in coupling actuator214to lock12.

Each hinge10includes a lock12, an actuator14, and first and second hinge members16,18, adapted to be coupled to sections76, as shown, for example inFIGS. 3 and 4. Lock12is used to lock members16,18and sections76in the closed-ladder, trestle-ladder, and straight-ladder positions. A user operates actuator14to unlock lock12to allow selective movement of members16,18and sections76between the ladder positions.

Illustratively, a user is able to lock hinge members16,18to cause ladder-leg sections76to lock. Three locked positions are possible. A closed-ladder position having an included angle of about 0° between ladder-leg sections, a trestle-ladder position having an included angle of about 40° between ladder-leg sections, or a straight-ladder position having an angle of about 180° between ladder-leg sections.

First hinge member16includes an annular flange portion20and an attachment arm portion50, as shown best inFIG. 5. First hinge member16is coupled to second hinge member18for rotation about a common axis28. Annular flange portion20is coupled on a perimeter edge portion22to attachment arm portion50. Annular flange portion20is formed to include a plurality of tab-receiving spaces24and a common axis bore26formed to receive an axis shaft30. Illustratively, first hinge member16is arranged as two segments16A and16B. Each segment16A,16B has the annular flange portion20and attachment arm portion50. Segments16A,16B are configured to be coupled together to form the hinge member16.

First hinge member16further includes a plurality of guide rings58arranged in registered relationship with annular flange portions20. Guide rings58are formed to include an arcuate slide portion62formed on a perimeter of each guide ring and an arcuate mounting notch64formed on the perimeter of each guide ring58and configured to cooperate with a portion of attachment arm portion50to block rotation of guide ring58relative to annular flange portion20. Illustratively, a pair of guide rings58are arranged in registered relationship between segments16A and16B and are concentric to common axis28. Each guide ring58has a larger radius along arcuate slide portion62than annular flange portion20, and is arranged to receive a portion of lock12for slidable movement of lock12along the arcuate slide portion62.

Second hinge member18includes a cylindrical outer housing32, an actuator receiver34, common axis bore26, a slide channel portion36, an attachment arm portion50, and a retention clamp70, as shown, for example, inFIG. 5. Illustratively, actuator receiver34is an arcuately-shaped oblong aperture34arranged to receive a portion of lock12coupled to actuator14. Annular flange portion20is arranged to nest within cylindrical outer housing32such that flange portion20and outer housing32are concentric to common axis28. Illustratively, second hinge member18is arranged as two segments18A and18B. Each segment18A,18B has the cylindrical outer housing portion32and attachment arm portion50. Segments18A,18B are configured to be coupled together to form the hinge member18. Retention clamp70is a U-shaped bracket70and is coupled to an outer portion of segments18A and18B to retain the segments18A and18B as a unitary member.

Second hinge member18is formed to include slide channels36on interior facing portions of attachment arm50, as shown, for example, inFIG. 6. Lock12is arranged to be received by slide channels36for slidable radial movement of lock12relative to common axis28.

Actuator14includes a cylindrical housing portion38, a common axis bore26, an actuator connector receiver40formed on an interior portion of actuator14, a biasing member42, a mounting member44, and a plurality of connecting tabs46projecting radially inwardly from an interior wall of cylindrical housing portion38, as shown, for example, inFIGS. 4 and 5. Illustratively, actuator14is a knob arranged for rotary movement about common axis28. Cylindrical housing portion38is arranged to couple to mounting member44for rotary movement of knob14relative to member44. In the illustrated embodiment, biasing member42is a helical spring and is arranged concentric to common axis28between knob14and mounting member44. Spring42biases knob14away from lock12to block rotary movement of knob14relative to mounting member44. Upon coaxial linear movement of knob14relative to common axis28, knob14is unlocked from mounting member44and is able to be rotated in a first direction15to cause lock12to move radially outwardly away from common axis28and out of tab-receiving spaces24in direction25to unlock hinges16and18and allow rotation of hinge members16,18relative to common axis28.

Lock12is coupled to second hinge member18and includes a cam48, a cam link52, a spring54, and an actuator connector link56, as shown best inFIG. 5. Cam48is formed to include a pair of tabs66formed on a distal end of cam48and a U-shaped aperture68therebetween. Tabs66are arranged to be received by tab-receiving spaces24formed in annular flange portion20upon movement of cam48radially inwardly toward common axis28in direction27. U-shaped aperture68is arranged to be received by arcuate slide portion62formed on guide ring58for slidable movement of cam48along arcuate slide portion62. Cam48is coupled on a proximal end to cam link52.

Cam link52includes two arms72,74and is generally V-shaped, as shown best inFIG. 6. Cam link first arm72is formed to include an oblong aperture78and is configured to receive the proximal end of cam48for radial movement of cam48relative to common axis28. Cam link second arm74is arranged having a generally D-shaped aperture80formed on an end portion of second arm74and is configured to be coupled to actuator connector link56. Cam link52is further configured to have a pivot aperture76arranged to be coupled to (e.g., receive) a pivot post82in an interior portion of attachment arm50for pivotable movement thereabout in response to rotary movement of actuator connector link56in direction17to cause cam48to move relative to common axis28.

Spring54is further arranged to urge cam link52to rotate to cause cam48to extend radially inwardly toward common axis28against annular flange portion38in direction27, as shown, for example, inFIGS. 8 and 9. Upon rotation of first and second hinge members16,18about common axis28, tab-receiving spaces24align with and are able to receive tabs66.

Upon movement of tabs66into tab-receiving space24, movement of first hinge member16and second hinge member18is blocked as shown, for example, inFIG. 6. Each tab-receiving space24is associated with one of the locked positions of hinge10to allow ladder-leg sections76to be arranged in the closed-ladder, trestle-ladder, or straight-ladder positions.

Mounting member44, actuator connector link56, cam link52, and axis shaft30thus cooperate to provide means for coupling knob14to cam48so that, when knob14is moved in a first direction15, cam48moves radially outwardly relative to common axis28to cause tabs66to withdraw from tab-receiving space24to allow pivotable movement of first hinge member16relative to second hinge member18. When knob14is moved in a second direction21, cam48moves radially inwardly relative to common axis28to cause tabs66to move into tab-receiving space24to block pivotable movement of first hinge member16relative to second hinge member18. Referring now toFIG. 5, axis shaft30is arranged to extend from an exterior surface of actuator knob14through a middle portion of spring42through the common axis bore26formed in mounting member44, and first and second hinge members16,18.

Upon pivotable movement of ladder-leg sections76, first hinge member16rotates in direction19to cause cam48to be urged against arcuate slide portion36until tabs66are again able to align with one of tab-receiving spaces24and move radially inwardly toward common axis28to enter tab-receiving spaces24.

To move ladder-leg sections76from the closed-ladder position shown inFIGS. 6 and 7, to the trestle-ladder position, shown inFIGS. 2,9, and10, knob14is rotated from the first position to the second position and hinge member16is moved in direction19, as suggested inFIGS. 7 and 8. Upon rotation of knob14, cam link52rotates in direction29to cause cam48to move radially outwardly away from common axis28wherein tabs66withdraw from tab-receiving spaces24as shown, for example, inFIG. 8. When knob14is rotated to the second position, mounting member44engages and cooperate with knob locking tabs46to retain knob14momentarily in the second position and retain cam48in a retracted position, away from common axis28. When lock12is retained momentarily in the second position, first and second hinge members16and18are free to pivot relative to one another, and thus a user is able to move ladder-leg sections76to the trestle-ladder position, as suggested inFIGS. 8–10.

To move ladder-leg sections76from the trestle-ladder position shown inFIGS. 9 and 10, to the straight-ladder position, shown inFIGS. 3,12, and13, knob14is rotated from the first position to the second position, as suggested inFIG. 9. Upon rotation of knob14, actuator connector link56rotates about common axis28to cause cam link52to pivot to move cam48radially outwardly away from common axis28wherein tabs66withdraw from tab-receiving spaces24as shown, for example, inFIG. 12. When knob14is rotated to the second position, mounting member retainer ridges84engage and cooperate with lock tabs46to retain knob14momentarily in the second position and retain cam48in a retracted position, away from common axis28. When lock12is retained momentarily in the second position, first and second hinge members16and18are free to pivot relative to one another, and thus a user is able to move ladder-leg sections76to the straight-ladder position, as suggested inFIGS. 10–12.

With respect to lockable hinge10, knob14, actuator connector link56, and cam link52cooperate to provide means for coupling knob14to cam48so that, when knob14is moved in a first direction15, cam48moves radially outwardly relative to common axis28to cause tabs66to move away from tab-receiving spaces24to allow pivotable movement of first hinge member16relative to second hinge member18. Lockable hinge10, knob14, actuator connector link56, and cam link52cooperate to provide means for coupling knob14to cam48so that, when knob14is moved in a second direction, cam30moves radially inwardly relative to common axis28to cause tabs66to move toward tab-receiving spaces24to block pivotable movement of first hinge member16relative to second hinge member18.

A guide assembly60shown inFIGS. 13–15is configured to guide movement of cam48. Assembly60includes a first guide86, a second guide92, and a spring98. First guide86and second guide92are arranged in side-by-side relationship between hinge member segment16B and hinge member segment18B and concentric to common axis28for rotary movement about common axis28. First guide86includes a first arm88, a second arm90, and a first arc-shaped slide slot87. Second guide92includes a third arm94, a spring retainer96, and a second arc-shaped slide slot91. Annular flange portion20includes a tab89extending into the first and second arc-shaped slide slots87and91, the first and second arc-shaped slide slots87,91overlap one another such that tab89defines the limits of rotary movement of first guide86and second guide92. In the illustrated embodiment, spring98is a helical spring coupled to a second arm90on a first end and to spring retainer96on a second end.

When ladder-leg sections76are arranged in the straight ladder position, an end portion of first arm88is urged against cam48by spring98as shown, for example, inFIG. 15. When knob14is rotated from the first position to the second position, actuator connector link56rotates about common axis28to cause cam link52to pivot to move cam48radially outwardly away from common axis28wherein tabs66withdraw from tab-receiving spaces24. As tabs66are withdrawn from tab-receiving spaces24, first guide86is able to rotate to cause second arm90to block a tab-receiving space100formed in annular flange portion20and associated with locking hinge members16,18in the straight-ladder position. Second arm90blocks cam48from re-engaging tab-receiving space100so that hinge member16can be rotated in direction23relative to hinge member18about common axis28to either the trestle-ladder or closed-ladder positions. As second arm90moves to block tab-receiving space100, first arm88moves to a tab-receiving space102formed in annular flange portion20and associated with locking hinge members16,18in the trestle-ladder position.

First arm88is configured having an oblique arcuate surface at the end portion of arm88. This configuration allows cam48to slide under the end portion of arm88as hinge members16,18are rotated to the trestle ladder position. If the hinge members are then rotated in the opposite direction, the cam48will then engage the end portion of first arm88causing arm88to rotate slightly exposing tab-receiving space102to allow cam48to move radially inwardly toward common axis28and engage tab-receiving space102to block movement of hinge members16,18relative to one another.

To move ladder legs76to the closed-ladder position, knob14is rotated from the first position to the second position. Upon rotation of knob14, cam48moves radially outwardly away from common axis28wherein tabs66withdraw from tab-receiving space102. As hinge members16,18are rotated toward one another, cam48confronts an end portion of guide arm94of second guide92. Rotation of hinge members16,18causes cam48to rotate guide arm94to expose a tab-receiving space104formed in annular flange portion20and associated with the closed-ladder position. When space104is fully exposed, cam48is able to engage space104to block movement of hinge members16,18relative to one another. As guide arm94is rotated to expose space104, spring98urges first guide to rotate relative to common axis28and arm90to block tab-receiving space100and arm88to block tab-receiving space102.

Another lockable ladder hinge210for use with ladder11in place of each hinge10is shown, for example, inFIGS. 16 and 17performs the same function as lockable ladder hinge10. Hinge210has components similar to components of hinge10so that identical reference numbers refer to similar components. Hinge210is different from the hinge10in the way its actuator214is coupled to cam48.

Actuator214includes a cylindrical housing portion238, a common axis bore26, and a plurality of mating posts301as shown best inFIG. 18. Illustratively, actuator214is a rotary knob. Knob214is arranged to couple to mounting member assembly244for rotary movement of knob214relative to hinge members16,18to cause lock12to block or allow movement of hinge members16,18relative to one another in response to a user's input.

Mounting member assembly244includes a cylindrical body246, an annular retainer plate248, a connector sleeve252, a spring42, and a mounting member housing256as shown, for example inFIGS. 18–23Connector sleeve252is formed to include a plurality of mating apertures262and is arranged to receive mating posts301to couple connector sleeve252to an inner surface of knob214in concentric relation to common axis28.

An actuator connector link receiver240is formed on a perimeter surface of connector sleeve252to receive a portion of actuator connector link56. Connector sleeve252is further arranged to receive a first end portion of cylindrical body246and spring42therebetween as shown, for example, inFIG. 21. Connector sleeve252is further formed to include a plurality of hook-shaped radially inwardly facing projections253which align with and couple to a plurality of notches247formed in cylindrical body246.

Cylindrical body246includes a plurality of arcuate projections245arranged to receive arcuate notches250formed on the perimeter of retainer plate248to couple cylindrical body246to annular retainer plate248so that body246is in a fixed position relative to hinge member18as shown, for example, inFIG. 19. Mounting member housing256is formed to include a notch264on a perimeter edge to receive a portion of slide channel36formed in hinge member18to couple mounting member housing256to an outer surface of second hinge member18so that mounting member housing256is in a fixed position relative to hinge member18. Mounting member housing256is further formed to include an oblong arcuate aperture to allow a portion of actuator connector56to pass through mounting member housing256for coupling to actuator receiver240.

Retainer plate248is formed to include a lock notch249which is arranged to project through an aperture262formed in mounting member housing256. Retainer plate248is further arranged to couple to second hinge member18to block rotary movement of annular plate248, and cylindrical body246as shown inFIG. 20.

Spring42is arranged concentrically to common axis28between connector sleeve252and annular retainer plate248. Spring42biases knob214away from lock12to block rotary movement of knob214relative to mounting member assembly244. Upon coaxial linear movement of knob214relative to common axis28, knob214is unlocked from mounting member assembly244and is able to be rotated in a first direction15to cause lock12to move radially outwardly away from common axis28and out of tab-receiving spaces24to unlock hinges16and18and allow rotation of hinge members16,18relative to common axis28.

Cylindrical body246, annular retainer plate248, connector sleeve252, spring42, actuator connector link56, cam link52, and mounting member housing256thus cooperate to provide means for coupling actuator214to cam48so that, when knob14is moved in a first direction15, cam48moves radially outwardly relative to common axis28to cause tabs66to withdraw from tab-receiving space24to allow pivotable movement of first hinge member16relative to second hinge member18. When knob14is moved in a second direction, cam48moves radially inwardly relative to common axis28to cause tabs66to move into tab-receiving space24to block pivotable movement of first hinge member16relative to second hinge member18. Referring now toFIG. 5, axis shaft30is arranged to extend from an exterior surface of actuator knob14through a middle portion of spring42through the common axis bore26formed in mounting member44, and first and second hinge members16,18.