HK1063651B - Collapsible ladder - Google Patents

Description

Foldable ladder

Technical Field

The present invention relates to a collapsible ladder comprising U-shaped ladder sections telescopically inserted into each other.

Background

In order to make the ladder more compact for storage and transport, such ladders with collapsible and expandable ladder sections may be used.

A similar ladder is described in EP-A-0527766. Such ladders comprise ladder bars divided into sections interconnected by ladder bars (ladder pins). The diameter of the ladder bars decreases upwards. This known ladder is characterized in that the retaining mechanism in each rung is designed to automatically release a higher rung when the rung has been lowered towards the next rung located below. This means that with the release of the lowermost ladder section, subsequent ladder sections are automatically released and the ladder collapses. Therefore, accidents may occur, especially injuries caused by squeezing. This known mechanism allows and actually requires a person to manoeuvre it, which may cause said injuries to occur. Moreover, if no manipulation takes place, material wear and tear, undue friction, etc. can also present similar risks and consequences, respectively. Furthermore, it is not possible, at least not without danger, to adjust the length of the ladder somewhere in the middle of the ladder. Furthermore, it is dangerous to deploy the ladder only to a part of the maximum possible length.

DE-73768 relates to a locking device for a hydraulically deployable fire ladder (a) with telescopic rods. At the end of the rung (N) a detent bolt (c) is mounted in the normal position, which bolt can be prestressed by a spring, which can be actuated by a clip (b), said bolt penetrating a hole in the lower part of the bar section in a radial arrangement. There is no constraint for preventing the entire ladder from collapsing in the area where the bolts have been inserted into the matching rung(s), so that the rungs collide with each other, whereby injuries due to crushing or the like may occur.

US-2194856 relates to a ladder with telescopic sections, similar to the pole sections in DE-73768. But the ladder is provided with a spring loaded bolt (10) which automatically acts in the locking direction. This configuration also has the disadvantages described above.

US-4989692 also relates to a ladder with telescopic sections (10), the rungs (13) being provided with buttons (31) designed to release the locking mechanisms at both ends of the respective rung simultaneously with one wire. The locking device may malfunction as soon as the user hits the only button on each rung. The segments involved will then contract and the above mentioned risks will occur.

DE19653003 discloses a foldable ladder with a safety position. However, the ladder does not comprise a manually operable locking pin. Furthermore, once the releasing action is performed, the ladder is in turn folded from the safety position to the transport position, thereby creating a risk of injury.

Since it is not possible to obtain the length of the ladder between two expanding ladder sections, in the known telescopically collapsible ladders the length of the ladder always corresponds to the number of expanding ladder sections.

Disclosure of Invention

The object of the present invention is to overcome and eliminate the above-mentioned drawbacks and risks as much as possible. Moreover, it is another object of the invention to provide a particular safety measure against injuries caused by squeezing in particular, wherein even a released ladder section will not cause the user's hands or feet to be pinched. Moreover, another object is to be able to establish a new ladder section level positioned between adjacent locked ladder sections.

According to the invention, these objects are achieved primarily by a collapsible ladder comprising a number of ladder sections, each ladder section comprising two ladder bars, which are arranged parallel to each other and interconnected at one end by a rung to form a U-shaped ladder section. Each ladder section is telescopically inserted into an underlying ladder section to form a collapsible ladder comprising at least three ladder sections. Each ladder bar includes a retaining mechanism adjacent an upper end of the ladder bar and a locking hole adjacent a lower end of the ladder bar. Each retaining mechanism comprises a locking pin which is resiliently biased towards an extended position to engage a locking hole arranged in a bar of an overlying ladder section, and an actuator for moving the locking pin to a retracted position. According to the invention, the actuators are arranged to be actuated outside the space between the rungs and are designed to be released manually and individually on both sides of the ladder sections. Furthermore, each locking pin has a length sufficient to extend through the locking hole of the ladder section located above and into the hollow space of the ladder bar, and the ladder bar has an extension below the locking hole, so that when an upper ladder section is released and telescopically inserted into an intermediate ladder section, the upper ladder section is prevented from being fully inserted into the intermediate ladder section at a safe distance by engaging the extension of the lower end of the ladder bar of the upper ladder section with the locking pin of the lower ladder section passing through the locking hole into the intermediate space of the ladder bar of the intermediate ladder section, which is locked with respect to the lower ladder section by the locking pin of the lower ladder section engaging with the locking hole of the intermediate ladder section.

In one embodiment of the invention the lowermost ladder section comprises two ladder rungs. The actuator of the retention mechanism may comprise a sliding knob or a rotating knob.

In another embodiment of the invention the holding mechanism comprises a rotation knob protruding from a recess in the front face of the rung and rotatable on an axis parallel to the ladder bar and mounted in the housing. The rotation knob is substantially L-shaped, one leg of which projects obliquely from the recess in the locking position of the retaining mechanism, while the other leg grips the central part of the locking pin between the two flanges of the locking pin. The locking pin is displaceably mounted in the housing and biased by a coil spring surrounding the locking pin and supported at one end thereof by a washer fixed relative to the housing and slidably receiving one end of the locking pin, while the other end of the coil spring abuts against one of the flanges and passes through the locking hole and into the respective ladder bar in the locking position. When the rotation knob is pressed, the spring is compressed and the locking pin leaves the locking hole to release the upper ladder section.

In another embodiment of the invention the retaining mechanism comprises a slide button arranged in a recess in the front face of the rung, movable in the longitudinal direction of the rung and comprising a lever engaging a flange arranged on the locking pin. A coil spring is configured to bias the locking pin towards the locking position, one end of the spring abutting against the flange and the other end thereof abutting against a wall arranged in the rung. When the slide button is pressed, the spring is compressed and the locking pin moves out of the locking hole to release the upper ladder section.

In another embodiment of the invention, the position of the locking pin when it is extracted from the respective ladder bar may be indicated by a zone, preferably red; when the locking pin is in the locking position, the position of the locking pin may be indicated by another area, which is preferably green.

In another embodiment of the invention, the ladder bar is provided with a safety ring at the area of the locking hole, and the safety ring is designed to prevent the ladder section from being pulled out of the ladder section located below it.

Wherein the actuator is arranged to be actuated at the front of the ladder.

Wherein the safe distance is 5-15 cm.

Drawings

Further objects, features and advantages of the present invention will be described hereinafter with reference to the accompanying drawings, in which some preferred, but not limiting, embodiments are shown. The figures show in detail or partly schematically:

FIG. 1 is a front view of a most collapsed ladder according to the present invention;

FIG. 2 is a view from above of the ladder of FIG. 1;

FIG. 3 is a view along the line III-III of FIG. 1, but without the pole segment, wherein the locking pin has an inactive position;

FIG. 4 is a view from above of the segment of FIG. 3, showing the pole segment inserted;

FIG. 5 is a view similar to FIG. 3, showing the locking position of the locking pin for adjacent pole segments;

FIG. 6 is a view similar to FIG. 4 with adjacent pole segments latched;

figures 7-10 are respectively a radial longitudinal section, a schematic view from below, a side view and a cross-sectional view of the alternative retaining mechanism with a sliding button along the line X-X in figure 8;

fig. 11 and 12 are perspective views from below and from above, respectively, of a rung with a slide button substantially according to fig. 7-10;

fig. 13-17 show front views of ladders according to the present invention in successive positions from fully extended to fully retracted positions with a ladder section released to achieve an intermediate or safe position.

Detailed Description

The collapsible ladder 1 according to the invention is shown in its entirety in the attached figures. Fig. 1 shows the ladder bars 2 and 3, respectively, and the ladder bars 4 and 4a-4 i. The rungs are arranged between and connect the ladder bars to each other. The ladder bar is divided into different sections which are mutually telescopic. The right and left side bar sections form a U-shaped ladder section together with the rungs attached to the tops of the bars.

The lowermost ladder section is suitably arranged at the bottom with a fixed rung 4i, the rung 4i being designed for a particular additional foot support and a more stable lowermost ladder section. The ladder sections are suitably made of extruded aluminium profiles 5.

Each rung houses a retaining mechanism 6 at each end thereof, the rung including a housing 7. The housing is inserted into the profile of the rung, for example by press-fitting. The rung of the uppermost ladder section may be free of a retaining mechanism.

In fig. 1-6, the holding mechanism 6 is shown with a rotary knob 10 serving as an actuator or control member, while the remaining figures show the holding mechanism 6 with a sliding knob 10' serving as a control member.

In the holding mechanism 6 according to fig. 3-6, the rotation knob 10 is rotatably mounted on a shaft 15 in the housing 7. The shaft 15 is parallel to the ladder bars. The rotation knob 10 protrudes from a recess 14 on the surface of the rung 4. The rotation knob 10 is substantially L-shaped. In the locking position, one leg of the knob projects obliquely from the recess, while the other leg, for example with a fork-shaped and rounded end, catches the control part of the locking pin 8 between the two flanges 16. The locking pin 8 is displaceably mounted in the housing and is biased by a coil spring 13. The spring 13 surrounds the locking pin 8 and is supported at one end by means of a supporting ring or washer 17. The washer is constrained by the housing and receives one end of the locking pin, the spring bearing with the other end against the follower flange 16.

The locking pins project radially through the locking holes 11 at the other end into the respective rod section. The coil spring 13 tends to move the locking pin into the hole and hold it in said position. When the knob is pressed into the housing, the spring is compressed, so that the locking pin leaves the locking hole. The corresponding pole segment is then pushed telescopically downwards into the lower pole segment.

The slide button 10' according to fig. 7-10 acts in a similar manner and the retaining mechanism is designed in a substantially similar manner. However, the recess 14' in front of the rung is longer, in which recess the slide button moves. Also in this case, one end of the coil spring 13 ' abuts against the follower flange 16 ', and the other side of the follower flange 16 ' is designed to be actuated by the slide button.

In the position according to fig. 13, the ladder has the greatest length and can be used. A locking pin 8 is inserted into a locking hole of the hollow space 9 of the respective pole segment in order to securely block the respective upper pole segment with respect to the lower pole segment. Safety can be ensured since each locking pin is constantly biased by a spring which tends to push the locking pin out of the rung and into the locking hole of the adjacent upper bar section. The fixing position can be indicated visually by means of an area 18, which area 18 is marked on the rung and has, for example, a red color. This area 18 is visible when the locking pin is withdrawn out of the locking hole. When the locking pin is not engaged, the area 18 is normally covered by the slide button 10'. On the other hand, a green area 19 may be provided on the rung, which area 19 becomes visible when the locking pin performs the locking function.

In the position according to fig. 14, the holding mechanisms on both sides of the next lowest rung have been released by moving the slide buttons towards each other. The locking pin is then retracted from the corresponding hole in the corresponding pole segment. The pole segments slide down past the locking pin ends. Due to the spring loading, the ends of the locking pins remain pressed against the outside of the corresponding pole section. The next lowest bar section is slid downwards until the rung of the third lowest bar section hits said next lowest rung. Since the user must wrap his hands around the outside of the pole segment with his thumbs pressing on the slide buttons, no injury due to squeezing occurs.

In this way the ladder is collapsed according to figures 15 and 16, section by section, until the whole ladder is collapsed.

When the ladder is to be deployed, the user starts from the third rung counted below, i.e. from the second movable rung. The retaining mechanism of the rung does not need to be operated. Once the hole in the upwardly moving pole segment reaches the same height as the locking pin in the lower pole segment, it is inserted into the hole and locks the pole segment. This process continues until the entire ladder or a desired portion of the ladder is deployed.

As shown in the figures, a locking hole 11 for inserting a locking pin is arranged in each pole segment. Furthermore, the pole segment is surrounded in the region for such a locking hole by an outer safety ring 12, which outer safety ring 12 serves to prevent the pole segment from being pulled out of the pole segment located therebelow.

In case of e.g. a malfunction or when a ladder length between two bar section distances is required, the user operates two control units somewhere in the middle of the ladder, the bar section above the retaining mechanism descends due to gravity, but only to the locking pin of the next retaining mechanism. The locking pin of the next retaining means protrudes into said hollow space 9 and restricts downward movement. In this position the two corresponding rungs 4b and 4c of fig. 17 are positioned at a safe distance from each other, e.g. 5-15cm, in order to safely prevent injuries which might occur when the rungs are moved into contact with each other. This position is shown in fig. 17. Otherwise, the ladder may be used in all positions shown. Thus, it is safe to climb or otherwise load the ladder, as each rung is always fixed by itself or by means of the fixed rung below.

The invention is not limited to the embodiments described above and shown in the drawings, but additions and modifications can be made thereto at will within the scope of the invention as defined in the appending claims.

Claims (9)

1. A collapsible ladder (1) comprising:

a number of ladder sections, each comprising two ladder bars (2, 3) arranged parallel to each other and interconnected at one end by a rung (4) to form a U-shaped ladder section;

each ladder section is telescopically inserted into an underlying ladder section to form a collapsible ladder comprising at least three ladder sections;

each ladder bar (2, 3) comprises a retaining mechanism (6) adjacent an upper end of the bar and a locking hole (11) adjacent a lower end of the bar;

each holding mechanism includes:

a locking pin (8) resiliently biased towards an extended position to engage with a locking hole (11) arranged in a bar of an upper ladder section; and

an actuator (10) for moving the locking pin to the retracted position;

it is characterized in that

Said actuator is arranged to be actuated outside the space between the rungs and is designed to be released manually and individually on both sides of the ladder sections;

each locking pin (8) has a length which is sufficient to extend through a locking hole (11) of the ladder section located above and into the hollow space in the ladder bar, and the ladder bar has an extension below the locking hole, so that when an upper ladder section (4b) is released and telescopically inserted into an intermediate ladder section (4c), the upper ladder section (4b) is prevented from being fully inserted into the intermediate ladder section by a safety distance by engaging the extension of the lower end of the ladder bar of the upper ladder section (4b) with the locking pin of the lower ladder section (4d) which passes through the locking hole into the intermediate space of the ladder bar of the intermediate ladder section (4c), the intermediate ladder section (4c) being locked relative to the lower ladder section (4d) by the locking pin of the lower ladder section (4d) which engages with the locking hole of the intermediate ladder section (4 c).

2. A foldable ladder according to claim 1, characterized in that the lowermost ladder section comprises two rungs (4i, 4 h). .

3. A foldable ladder according to claim 1 or 2, wherein said actuator of said holding mechanism comprises a rotary knob or a sliding knob.

4. A foldable ladder according to claim 1 or 2, wherein said retaining mechanism comprises:

a rotation knob protruding from a recess in the front of the rung and rotatable on a shaft (15) parallel to the ladder bar and mounted in the housing (7);

said knob being L-shaped, one leg of which projects obliquely from said recess in the locking position of the retaining mechanism, and the other leg of which grips the central part of the locking pin (8) between two flanges (16) of the locking pin,

said locking pin (8) being displaceably mounted in said housing and biased by a coil spring (13) surrounding the locking pin and supported at one end thereof by a washer (17) fixed relative to the housing and slidably receiving one end of the locking pin, while the other end of the coil spring abuts against one of the flanges (16) and passes through said locking hole (11) and into the respective ladder bar in the locking position,

when the rotation knob is pressed, the spring is compressed and the locking pin leaves the locking hole to release the upper ladder section.

5. A foldable ladder according to claim 1 or 2, wherein said retaining mechanism comprises:

a slide button (10 ') arranged in a recess (14 ') in the front of the rung, movable in the longitudinal direction of the rung and comprising a lever engaging a flange (16 ') arranged on the locking pin,

a coil spring (13') configured to bias the locking pin (8) towards a locking position, one end of the spring abutting against the flange (16) and the other end thereof abutting against a wall arranged in the rung;

when the slide button is pressed, the spring is compressed and the locking pin exits the locking hole to release the upper ladder section.

6. A foldable ladder according to claim 5, wherein the position of the locking pin when extracted from each ladder bar is indicated by a zone which is red; when the locking pin is in the locking position, the position of the locking pin may be indicated by another area, which is green.

7. A foldable ladder according to claim 1, characterized in that the ladder bar is provided with a safety ring (12) at the area of the locking hole (11), and that the safety ring (12) is designed to prevent the ladder section from being pulled out of the ladder section located below it.

8. A foldable ladder according to claim 1, wherein said actuator is arranged to be actuated at the front of the ladder.

9. A foldable ladder according to claim 1, wherein said safety distance is 5-15 cm.