intermediate ladder sections, wherein each of the ladder sections comprises two tubular stile members, each having a bottom end and a top end, which tubular stile members are arranged parallel to each other and are interconnected at the top end by a ladder rung to form a U-shaped ladder section, and wherein the tubular stile members of the bottom ladder section are furthermore connected by a bottom ladder rung.

The top ladder section and the one or more intermediate ladder sections are collapsible ladder sections, each having the bottom end of the tubular stile members telescopically inserted into the top end of the tubular stile members of an adjacent ladder section, to allow the collapsible ladder section to be moved relative to the adjacent ladder section between a collapsed position and an extended position.

The ladder assembly further comprises automatic latch mechanisms for locking the telescopically inserted stile members of the collapsible ladder sections relative to the adjacent ladder sections when the collapsible ladder section are in the extended position, the latch mechanisms being associated with actuators for unlocking the stile members in order to allow for collapsing of the ladder assembly. These ladder assemblies have become quite popular as portable ladders, such as a straight telescopic ladder, a stepladder, of another "ladder product" such as a combination ladder, a work platform with ladder like telescopic legs, etc.. The prior art designs have details that are not satisfactory, either with regard to their construction and/or their practical use.

For example, a telescopic ladder assembly may suffer from the problem of an undesirable velocity of the ladder section or sections in motion during collapse as the ladder sections of a straight ladder or stepladder are lowered. It is known in the prior art to provide multiple of the collapsible ladder sections of a telescopic ladder assembly with damper members that provide retardation of gravity induced velocity of the collapsible ladder section. Such ladder assemblies are for example known from US5743355 and EP 2 770 155.

In US5743355 it is proposed to provide air dampers at the bottom end of the tubular stile members, which air dampers provide retardation on the basis that upon collapse of the ladder air has to flow through an orifice in the air damper. This solution has been found to be unpractical. In particular, the damper is active when the ladder is collapsed and when the ladder is extend, while the undesirable velocity of the ladder sections in motion often is only an issue during collapse or extension of the ladder assembly, depending on the type of ladder.

In EP 2 770 155 it is proposed to provide air dampers comprising a sealing ring throttling the flow of air flowing through the annular opening between the telescopically connected tubular stile members of the collapsing ladder sections. These air dampers are active during collapse of the ladder, but enable a less restricted air flow when the ladder is extended. This solution has been found to be unpractical as well. In particular, wear and foreign bodies such as dust particles and small grid may hamper correct functioning of the sealing ring, and thus negatively influence the reliability of the damper. The invention relates to the issue of retardation of gravity-induced velocity of one or more sections of a telescopic ladder assembly, and aims to provide a telescopically extendable and collapsible ladder assembly with improved air dampers.

According to the present invention, this object is achieved by providing a telescopic ladder assembly according to claim 1.

A telescopically extendable and collapsible ladder assembly according to the invention has a bottom ladder section, a top ladder section, and one or more intermediate ladder sections.

Each of the ladder sections comprises two tubular stile members, each having a bottom end and a top end, which tubular stile members are arranged parallel to each other and are interconnected at the top end by a ladder rung to form a U-shaped ladder section. The tubular stile members of the bottom ladder section are furthermore connected by a bottom ladder rung.

The top ladder section and the one or more intermediate ladder sections are collapsible ladder sections, each having the bottom end of the tubular style members telescopically inserted into the top end of the tubular stile members of an adjacent ladder section, to allow the collapsible ladder section to be moved relative to the adjacent ladder section between a collapsed position and an extended position.

The ladder assembly further comprises automatic latch mechanisms for locking the telescopically inserted tubular stile members of the collapsible ladder sections relative to the adjacent ladder sections when the collapsible ladder section are in the extended position, the latch mechanisms being associated with actuators for unlocking the tubular stile members in order to allow for collapsing of the ladder assembly.

It is submitted that automatic latch mechanisms for telescopic ladders are generally known in the state of the art, and will therefore not be explained in great detail herein.

According to the invention, multiple of said collapsible ladder sections are provided with air dampers, being mounted on the bottom end of the tubular stile members of the collapsible ladder sections, which air dampers provide retardation of gravity induced velocity of the collapsible ladder sections upon collapse of the ladder sections on the basis of throttling an airflow flowing from the tubular stile member of the adjacent ladder section into the tubular stile member of the collapsible ladder section during collapse.

According to the invention, each of the air dampers comprises:

a barrier member, which barrier member is mounted on the bottom end of the tubular stile member, which barrier member defines one or more throttle openings that enable air to flow from the tubular stile member of the adjacent ladder section into the tubular stile member of the collapsible ladder section on which the damper member is mounted;

a valve member, which valve member is moveable supported relative to the barrier member, such that the valve member can be moved relative to the barrier member between a non-throttle position, in which air can flow through the one or more throttle openings, and a throttle position, in which the valve member at least partially seals off the one or more throttle openings to throttle air flowing from the tubular stile member of the adjacent ladder section into the tubular stile member of the collapsible ladder section on which the damper member is mounted; and

an actuator member, which actuator member comprises one or more discrete grip pads, which one or more grip pads are each connected to the valve by a connector arm, and which one or more grip pads are each positioned against the inside surface of the tubular stile member of the adjacent ladder section, and a resilient device that pushes the one or more discrete grip pads against the inside surface such that the grip pads make frictional contact with the inside surface. The actuator member pushes the valve member into the throttle position during collapse of the collapsible ladder section, and pushes the valve member into the non-throttle position during extension of the collapsible ladder section.

Typically, the ladder sections of a telescopic ladder assembly, more in particular the tubular stile members of the ladder sections of a telescopic ladder assembly, are

telescopically connected such that they can telescope into and out of each other, and thus enable collapse and extension of the telescopic ladder.

The top ladder section and the one or more intermediate ladder sections are collapsible ladder sections, that is, they are all telescopically connected with an adjacent ladder section, i.e. an intermediate ladder section or the bottom ladder section, such that their tubular stile members can be telescopically inserted into the tubular stile members of the adjacent ladder section to allow the collapsible ladder section to be moved relative to the adjacent ladder section between a collapsed position and an extended position. In other words: a collapsible ladder section is a ladder section that is telescopically received in a receiving ladder sections, i.e. a lower adjacent ladder section.

According to the invention, multiple, preferably all, of the collapsible ladder sections are provided with air dampers, being mounted on the bottom end of the tubular stile members of the collapsible ladder sections.

In an embodiment, only one of the two tubular stile members of a ladder section is provided with an air damper at its lower end. The other tubular stile member may for example be sealed at its lower end, such that air can flow from the adjacent lower ladder section into the ladder section with the single air damper only via the throttle opening of that single air damper.

It is noted that the bottom ladder section does not need to be provided with air dampers. Preferably, the tubular stile members of the bottom ladder section are sealed off at their bottom end, for example are provided with a plug type body that is inserted into the tubular stile member to provide a foot/stand for supporting the ladder on a support surface.

It is noted that the relatively lightweight upper ladder sections only require minimal or possible no damping, and may thus not be provided with dampers. When the upper ladder section is provided with one or two damper members, the tubular stile members are preferably provided with one or more openings that allow air to flow from the outside into the tubular stile member when the ladder section is extended.

The air dampers provided by the invention are one way air dampers. The one way air dampers are active, i.e. throttle the air flow, when the collapsible ladder section onto which the damper has been mounted is moved in a first direction and becomes inactive, i.e does not throttle the air flow, when the collapsible ladder section is moved in the second direction.

The air dampers each comprise a barrier member that defines one or more throttle openings. The one or more throttle openings enable air to flow from the tubular stile member of the adjacent ladder section into the tubular stile member onto which the air damper has been mounted, and vice versa.

The air damper is configured such that the relative movement of the tubular stile members of the telescopically connected ladder sections moves the valve member into or out of the throttle position, depending on the collapsible ladder section collapsing or being extended.

When the collapsible ladder section is extended, the valve members of its air dampers are moved into the non-throttle position, and the one or more throttle openings allow air to flow out of tubular stile member of the ladder section being extend and into the tubular stile member of the adjacent ladder section. This flow of air facilitates extension of the ladder section.

When the collapsible ladder section collapses, the valve members of its air dampers are moved into the throttle position, and at least partially seal off the throttle openings. Thus the airflow flowing through the throttle openings from the adjacent ladder section into the collapsing ladder section is throttled. This reduction of the airflow slows down the movement of the tubular stile members of the collapsing ladder section into the tubular stile member of the adjacent ladder section, and thus provides retardation of gravity induced velocity of the collapsible ladder sections upon collapse of the ladder sections.

In an embodiment according to the invention, the valve member is provided with one or more flow through openings, which flow through openings overlap with the one or more throttle opening defined by the barrier member, when the valve member is in the non- throttle position. When the valve member has been moved into the throttle position, these one or more flow through openings no longer, or only partially, overlap with the throttle opening. Providing the valve member with one flow through openings that line up with the throttle opening when the valve member is in the non-throttle position allows for accurately defining the throttle behaviour of the valve member.

In a preferred embodiment, the one or more throttle openings, and thus if present the optional flow through openings of the valve member, extend in the radial direction, i.e. are configured such that air that flows through them flows in the radial direction, i.e.

perpendicular to a central axis of the tubular stile member onto which the air damper has been mounted. In an alternative embodiment, the valve member has a body that covers the throttle opening when the valve member is in the throttle position, and uncovers the throttle opening when in the non-throttle position. For example, the valve body can be a plug type body that is inserted into and pulled out of the throttle opening to throttle the air flow.

According to the invention, restriction of the outflow of air from the adjacent ladder section is used provide retardation of gravity induced velocity of the collapsible ladder section. By changing the number, size and location of the openings that allow air to escape form the adjacent ladder section, the damping effect of the air damper can be defined.

It is noted that with the valve member in the throttle positions, air can still flow out of the tubular stile member of the adjacent ladder section via the annular opening between the telescopically connected stile members. Optionally, outflow openings may be provided in the adjacent ladder section to further allow air to escape form the adjacent ladder section upon collapse of the collapsible ladder section, and thus reduce the retardation effect of the air dampers. To provide the tubular stiles of the adjacent ladder section with a larger overall outflow, in addition, or as an alternative, to the outflow openings the barrier member can be configured to define pass through openings that are not covered by the valve member and/or the valve member can be designed to only partially cover the throttle openings when the throttle body is in the throttle position.

Facilitating air to flow out of the adjacent ladder section by providing outflow openings and/or pass through openings reduces the retardation effect of the dampers. For example, the lighter and smaller upper ladder sections, which have a smaller gravity induced velocity upon collapse, may thus be provided with air dampers having a reduced retardation effect to not unduly lengthen the collapse of the ladder.

The one or more throttle openings defined by the barrier member determine the maximum air flow into the tubular stile member of the adjacent ladder section, i.e. when the collapsible ladder section is extended and the throttle member has been moved into the non-throttle position air can flow into the adjacent stile member via annular openings between the stile members, via outflow openings in the stile member and/or pass through openings in the barrier member if present, and the throttle opening.

The size of the throttle openings can thus be used to determine the ease with which the collapsible ladder section can be extended.

In an embodiment, the stile members of the adjacent ladder section are provided with one or more outflow openings located at intervals along the length of the stile member, such that the lower end of the collapsing ladder section with the air damper moves along these one or more outflow openings during the collapse of the ladder section. Thus, the ladder assembly is provided with a stepped damping trajectory, the steps of the damping trajectory being separated by the outflow openings.

For example, by providing the tubular stile section with an outflow opening halfway, the trajectory during collapse is divided in a first, fast collapsing trajectory, and a second slow collapsing trajectory. As soon as the collapsible ladder section is collapsed, its tubular stile members are moved relative to the stile members of the adjacent ladder section, which movement causes the valve member to be moved into the throttle position.

However, the air in the adjacent ladder section can still escape the inner space of the tubular stile member of the adjacent ladder section via the outflow opening halfway the tubular stile member, thus, the damping effect of the air damper is limited.

Once the valve member has passed this outflow opening halfway the stile member, the air can no longer escape the inner stile member of the adjacent ladder section via this outflow opening. Thus, the outflow of air is more restricted and the damping of the gravity induced speed is increased.

Thus, the ladder assembly is provided with a stepped damping trajectory, defining a first damping effect upwards from the outflow opening and a second, more increased damping effect below the openings

It is noted that by providing outflow openings at different locations along the tubular stile section, multiple damping stages can be provided.

Thus, the invention provides an air damper of which the design can easily be adapted to make the air damper fit the requirements of a particular collapsible ladder section.

In this context it is noted that the ladder sections of a telescopic ladder differ in weight. Furthermore, when the bottom most intermediate ladder section collapses, it also carriers the weight of the one or more other intermediate ladder sections and the top ladder section. In addition, the size of the annular openings and the friction between the telescopically coupled stile members differs, such that the required retardation of the gravity induced velocity upon collapse of the ladder section may differ for each ladder section.

Therefore, in an embodiment of a telescopic ladder according to the invention, the design of the air damper, i.e. the size of the throttle openings and the extent to which they are covered by the valve member when in the throttle position, may differ with each ladder section, to thus provide each ladder section with the optimal gravity induced velocity when collapsing. Preferably, the time required for a ladder section to move from the extended position into the collapsed position is at least 1 ,5 second for example about 2 seconds per 30 cm collapse, or 1 ,5 seconds per ladder section. In addition, it is noted that, due to the telescopic linkage of the ladder sections, the dimensions, in particular the diameter, of the tubular stile members differ for each ladder section. Thus, the air dampers, which are mounted in the bottom end of the tubular stile members, also differ for each ladder section. Size and shape of barrier member and/or valve member and/or actuator member thus may differ for each ladder section to fit the size of the particular stile member. For example, the length of the connector arms connecting the valve member with the grip pads may differ for each ladder section to compensate for the difference in diameter of the stile members of the respective ladder sections.

Also, an air damper according to the invention comprises a valve member for at least partially sealing of the throttle openings, and an actuator member for moving the valve member between the throttle and the non-throttle position. Thus, the sealing and activating function are not performed by the same component, e.g. a sealing ring.

Even if the valve member and the actuator member are components of a unitary body, for example are each part of a single injection moulded body, the separation of functions still allows for each component to be optimally configured for its specific function.

Thus, an air damper according to the invention is less susceptible to wear and obstruction by foreign particles such as small grid, than known air dampers.

In view of the above it is submitted that the invention provides a telescopically extendable and collapsible ladder assembly with improved air dampers.

In an embodiment a telescopic ladder assembly, e.g. a straight ladder, according to the first aspect of the invention has automatic latch mechanisms (e.g. at each end of a rung) with one or more associated manually operable actuators for unlocking the tubular stile members in order to allow for collapsing of the ladder assembly, wherein these one or more actuators are arranged centrally on a ladder rung (preferably on the front) and are operable simultaneously with a single hand of the user. It has been found that the proposed dampers allow to obtain a very controlled motion of the ladder section upon collapse of the ladder. The user can now operate the one or more actuators simultaneously with one hand and use - at the same time - his other hand to guide the descending ladder section and/or stabilize the ladder during this operation. This allows for safe and gentle handling of the ladder during collapse, and avoids fast motions and undesirable impacts of the descending ladder sections as can be observed in known telescopic ladders.

According to the invention, the grip pads are pushed against the inside surface of the tubular stile member of the adjacent ladder section to provide a frictional contact between the grip pads and the inside surface of the stile member. Thus, the actuator comprise a resilient device that pushes the discrete grip pads against the inside surface such that the grip pads make frictional contact with the inside surface.

The resilient device can be provided in the form of a resilient member, for example a helical spring, mounted on the connector arm to push a grip pad, which in such an embodiment is movably on the connector arm, against the inside surface of the tubular stile member.

In an alternative embodiment, the resilient device is incorporated in the grip pad. In such an embodiment, the grip pad is made out of a resilient material, which is compressed to provide a radially outward directed force that pushes a contact surface of the grip member against the inside surface of the tubular stile member.

In a preferred embodiment, the connector arm is a spring arm, i.e. the resilient device is incorporated in the connecter arm. In such an embodiment, the connector arm is flexible and/or compressible, or is provided with a flexible or compressible section, such that the arm can provide a resilient force that pushes the grip pad in a radially outward direction against the inside surface of the tubular stile member.

In an embodiment, the spring arm, or at least a resilient part of the spring arm, is compressed, providing a biasing force that pushes the grip pad onto the inside surface of the stile member of the adjacent ladder section.

The frictional contact between the actuator member, in particular the one or more discrete grip pads of the actuator member, and the inside surface of the adjacent stile member, causes the actuator member to trail the movement of the stile member onto which the damper has been mounted, when that stile member is moved relative to the adjacent stile member. This trailing movement is used to move the valve member between the throttle and the non-throttle position.

In an embodiment of a ladder assembly according to the invention, the air damper has multiple discrete grip pads and the connector arms are spaced apart from each other, preferably at regular intervals, in the circumferential direction, wherein the connector arms each extend in a radial direction between the valve member which is located on a central axis of the tubular stile member onto which the air damper is mounted, preferably such that a central axis of the valve member coincides with the central axis of the tubular stile member, and the grip pads that are located at the inside surface of the adjacent tubular stile member. Preferably, the connector arms are spring arms and the lines of action of the biasing forces, generated by the two or more spring arms biasing the respective grip pads onto the inside surface of the tubular stile member of the adjacent ladder section, intersect at a point of intersection located at the centre of the stile member onto which the air damper has been mounted.

Providing the spring arms at regular intervals in the circumferential direction, for example four spring arms ant 90 degree intervals, three spring arms at 120 degrees intervals, or two spring arms at 180 degree intervals, provides a balanced support of the actuator member, and thus for a balanced pushing- and pulling of the valve member, preventing tilting forces from being enacted upon the valve member during movement between the throttle and non-throttle position.

In an embodiment, the actuator member comprises two spring arms located diametrically opposite each other, such that the radially directed biasing forces generated the two spring arms have the same line of action. Thus, the spring arms essentially form a single spring arm with the valve body preferably located at the centre thereof.

In an embodiment, the actuator member is a single component, preferably an injection-moulded component, the single component comprising the connector arms and the grip pads, wherein the connector arms preferably are configured as spring arms. In a preferred embodiment, the actuator member is an injection moulded component comprising two or more spring arms, the spring arms being provided with grip pads for engaging the inside surface of a tubular stile member and with resilient sections to enable the arms to bias the grip pads onto the inside surface of the stile member. The spring arms are configured such that, during assembly, they are compressed and or bent when the damper member is inserted into the adjacent ladder section, such that the spring arms are biased when located in the stile member of the adjacent ladder section, thus providing a resilient force for pushing the grip pads against the inside surface of the tubular stile member of the adjacent ladder section.

In an embodiment, the connector arms are provided with a resilient element, for example a plastic or metal spring element or a resilient body such as a rubber body, to provide the spring force for pushing the grip pad against the inside surface of the adjacent tubular stile member. For example, each arm can be provided with a helical spring that is compressed to fit the air damper inside the stile member of the adjacent ladder section, such that the spring arm is biased and the grip pad is pushed against the inside surface of the tubular stile member of the adjacent ladder section.

In an alternative embodiment, the resilient device is incorporated in the grip pad, which grip pad is provided in the form of a resilient body, for example in the form of a rubber body. In this embodiment, the grip pad provides the resilient force for pushing its contact surface against the inside surface of the tubular stile member of the adjacent ladder section. In such an embodiment, the actuator member for example is an injection moulded plastic body with two or more rubber inserts provided along its periphery, which rubber inserts form resilient contact pads having a contact surface engaging the inside surface of the tubular stile member of the adjacent ladder section.

In an embodiment of a ladder assembly according to the invention, the barrier member forms a valve seat, preferably located on a central axis of the tubular stile member onto which the air damper is mounted, preferably such that a central axis of the valve seat coincides with the central axis of the tubular stile member, which valve seat is configured for receiving at least part of the valve member and for guiding said valve member between the throttle position and the non-throttle position, preferably along the central axis of the tubular stile member.

Thus, the barrier member combines the functions of defining the one or more throttle openings and the guiding of the valve member.

In a further embodiment, the barrier member has a lower body portion which is configured to receive at least part of the actuator member, to guide the actuator member when it pushes the valve member into the throttle position or into the non-throttle position. In an embodiment, the barrier member provides guide slots for guiding the actuator member and/or at least part of the connector arms thereof, thus providing a compact air damper with a small number of components. In an embodiment according to the invention, the barrier member of the air damper comprises a central valve seat in the form of a cylindrical shaped recess and the valve body has a cylindrical shape that fits the valve seat, such that the valve seat guides the valve body along a central axis of the tubular stile member onto which the air damper has been mounted.

In a further preferred embodiment, the valve seat is provided with one or more throttle openings, which throttle openings overlap with flow through openings in the valve body when the latter is in the non-throttle position, and which one or more throttle openings are covered by the valve body when the latter is the throttle position.

It is observed that depending on the retardation required in combination with the configuration, i.e. size, shape and location, of the throttle openings, as well as the weight of the ladder section, the valve member can be designed to overlap the throttle openings fully or only partially, when in the throttle position.

When the throttle openings are fully covered by the valve member when in the throttle position, maximum retardation is achieved. Such a configuration can for example be used with the lower collapsible ladder sections, while the damper elements of the higher intermediate ladder sections, which are lighter and support less ladder sections, may require only partial coverage of the throttle openings to provide sufficient retardation.

As an alternative to partially covering the throttle openings, the barrier member may define additional pass through openings which are not covered by the valve member when in the throttle position, and are thus always open, to provide for reduced retardation of the ladder section.

In an embodiment, the barrier member has a substantially disc shaped body having an circumferential outer surface provided with one or more protrusions, preferably a protrusion in the form of a rim extending along the circumference of the outside surface, which one or more protrusions form a guide surface for centring the barrier member in the tubular stile member of the adjacent ladder section, and for guiding the barrier member along a longitudinal axis of the tubular stile member of the adjacent ladder section during collapse and extension of the collapsible ladder section.

The barrier member can thus be used to position and guide the stile member onto which it has been mounted in the stile member into which it has been inserted. In addition, the design of the barrier member can thus be used to define the amount of air that can flow out of the tubular stile member of the adjacent ladder section via the annular opening between the two telescopically connected stile members, when the valve member is in the throttle position. Thus, the design of the barrier member can be used to design the speed at which the ladder section collapses, when the valve member is in the throttle position.

In an embodiment, the barrier member of the air damper has an upper fastening portion which is configured to receive the bottom end of a tubular stile member. For example, the barrier member can be a substantially disc shaped body having an upstanding flange along its periphery, which upstanding flange defines an opening for receiving the bottom end of the stile member.

In a further embodiment, the barrier member is provided with integral elastic fasteners, for example click fingers, that are adapted to snap into associated apertures in the stile member for connecting the barrier member to, and thus mounting the air damper onto, the stile member.

Advantageous embodiments of the telescopic ladder assembly according to the invention are disclosed in the subclaims and in the description, in which the invention is further illustrated and elucidated on the basis of a number of exemplary embodiments, of which some are shown in the schematic drawing.

In the drawings:

Fig. 1 shows in side view a straight telescopic ladder according to the invention in collapsed condition,

Fig. 2 shows the ladder of figure 1 in extended condition,

Fig. 3 shows a perspective view in cross section of an air damper according to the invention in a first position;

Fig. 4 shows a perspective view in cross section of the air damper of Fig. 3 in a second position;

Fig. 5 shows a perspective view of a combined valve member and actuator member of the air damper of Fig. 3;

Fig. 6 shows a perspective top side view of a barrier member of the air damper of

Fig. 3;

Fig. 7 shows a perspective bottom side view of a barrier member of the air damper of Fig. 3;

Fig. 8 shows a top view of a first alternative combination of a valve member and actuator according to the invention;

Fig. 9 shows a top view of a second alternative combination of a valve member and actuator according to the invention;

Fig. 10 shows a top view of a third alternative combination of a valve member and actuator according to the invention; and

Fig. 1 1 schematically shows in cross section a bottom end of a tubular stile member provided with the air damper of fig. 3, which stile member is telescopically inserted in a tubular stile member of an adjacent ladder section. Figures 1 and 2 show an example of a telescopically extendable and collapsible ladder assembly according to the invention, here embodied as a straight telescopic ladder 1. As explained above the ladder assembly may also be part of another "ladder product" such as a stepladder or combination ladder, a work platform with ladder like telescopic legs, etc.

The ladder assembly 1 has a bottom ladder section 2, a top ladder section 3, and multiple intermediate ladder sections 4, in the particular embodiment shown six. Each of the ladder sections 2, 3, 4 comprises two tubular stile members 5, 6, each having a bottom end 5a, 6a and a top end 5b, 6b. The tubular stile members 5, 6 are arranged parallel to each other and are interconnected at the top end by a ladder rung 7 to form a U-shaped ladder section, and in this example the tubular stile members of the bottom ladder section 2 are furthermore connected by a bottom ladder rung 8. The top ladder section 3 and the intermediate ladder sections 4 are collapsible ladder sections. Of each collapsible ladder section the bottom ends 5a, 6a of the tubular style members 5, 6 are telescopically inserted into the top end 5b, 6b of the tubular stile members 5, 6 of an adjacent ladder section to allow the collapsible ladder section to be moved relative to the adjacent ladder section between a collapsed position and an extended position, and thus enable collapse and extension of the telescopic ladder.

According to the invention, the collapsible ladder sections are provided with air dampers 9 (shown in the cross sectional view of Fig. 1 1), which are mounted on the bottom end 5a, 6a of the tubular stile members 5, 6 of the collapsible ladder sections 3, 4. Each damper member is thus located inside the tubular stile member of the adjacent lower ladder section.

Each stile member 5, 6 of the bottom ladder section 2 here is provided with a ground engaging foot member (e.g. of rubber or the like). The exemplary ladder assembly 1 shown further comprises automatic latch mechanisms for locking the telescopically inserted tubular stile members of the collapsible ladder sections relative to the adjacent ladder sections when the collapsible ladder section are in the extended position, the latch mechanisms being associated with actuators for unlocking the tubular stile members in order to allow for collapsing of the ladder assembly. These actuators 10 are manually operated actuators, indicated with reference numeral 10 in figure 1. The actuators 10 are slideable actuator and are arranged centrally on the front side of the rung 7 so as to be operable simultaneously with a single hand. The rungs 7 are connected to the associated stile members 5, 6 via connectors.

As explained, an issue related to telescopic ladders such as ladder 1 , is the velocity of the telescopic section when the ladder is collapsed. In order to retard said velocity multiple of the ladder sections are preferably provided with damper members that provide retardation of gravity induced velocity of the ladder section upon collapse or extension of the ladder section. In figure 3 an example is shown of an inventive air damper 10 that provides the desired retardation of gravity induced velocity of the collapsible ladder sections 2, 3 upon collapse of the ladder sections on the basis of throttling an airflow flowing from the tubular stile member of the adjacent ladder section into the tubular stile member of the collapsible ladder section during collapse of the ladder 1. Fig. 1 1 schematically shows the air damper of Fig. 3, mounted on the bottom end of a tubular stile member, which stile member is telescopically inserted in a tubular stile member of an adjacent ladder section.

Each of the air dampers 10 comprises a barrier member 1 1 , a valve member 12 and an actuator member 13.

The barrier member 1 1 is mounted on a bottom end 6a of a tubular stile member, and separates the inner volume of the stile member from the outside of the stile member, in particular the inner volume of an adjacent stile member.

According to the invention, the barrier member defines a throttle opening that enables air to flow from the tubular stile member of the adjacent ladder section into the tubular stile member of the collapsible ladder section on which the damper member is mounted. In the example shown, the barrier member 1 1 is provided with a single throttle opening 14. The valve member 12 is moveable supported relative to the barrier member 1 1 , such that the valve member can be moved relative to the barrier member between a non-throttle position, shown in Fig. 3, and a throttle position, shown in Fig. 4. In the particular embodiment shown, the valve member is supported in a valve seat in the barrier member, and is guided by the barrier member, such that the valve member is moved along a centre line of the tubular stile member. It is noted that the invention allows for other configurations for supporting and guiding the valve member, for example, the valve member and/or the barrier member can be provided with one or more elongate pins, which elongate pins are received in openings in the barrier member and/or the valve member, for guiding the valve member relative to the barrier member between the throttle position and the non-throttle position.

In the embodiment shown, the valve member is provided with a flow through opening 21 , which flow through opening overlaps with the throttle opening when the valve member is in the non-throttle position to allow air to flow through the throttle position. When the valve member is moved out of the non-throttle position, the two openings no longer overlap, and the valve body closes off the throttle opening. It is noted that the invention allows for alternative configurations of the throttle opening and valve body.

In the embodiment shown, the valve member is furthermore provided with an extension at its top end, which extension is received in a guide opening in the barrier member. A plug is inserted in the extension to moveably secure the valve member in the barrier member. This configuration allows for a simple assembly of the air damper.

The actuator member 13 in the exemplary air damper shown comprises two grip pads 15, which grip pads 15 are each positioned adjacent the inside surface of the tubular stile member of the adjacent ladder section 4'.

The actuator member 13 furthermore comprises a connector arm 16 for each grip pad 15, which connector arms connect the corresponding grip pads with the valve member 12. In the particular embodiment shown, the connector arms are provided in the form of spring arms, each spring arm comprising a resilient section 17, and push the grip pads onto the inside surface of the adjacent ladder section. Thus, the spring arms 16 provide a frictional contact between the grip pads 15 and inside surface of the stile member of the adjacent ladder section. Incorporating the resilient device into the connector arm, by providing the connector arm with a resilient section, allows for a simple and compact design of the actuator, in particular of the connector arms of the actuator. In the preferred embodiment shown, the barrier member has a lower body portion 20 which is configured to receive at least part of the actuator member 13, to guide the actuator member when it pushes the valve member 12 into the throttle position or into its non-throttle position.

It is noted that in an air damper according to the invention, the connector arms are located at the bottom side of the barrier member, such that the connector arms and the grip pads are located outside the inside space of the tubular stile member onto which the valve member has been mounted, and inside the inside surface of the tubular stile member of the adjacent ladder section.

In the embodiment shown, the barrier member is provided with a flange section, extending in the downward direction, along its periphery, which flange section defines two guide slots in which the grip pads and/or parts of the connector arms are movably received, such that the guide slots guide the actuator member, or at least the connector arms thereof, when the valve member is moved between its throttle and its non-throttle position.

Alternative configurations, for example using guide ribs or pins provided on the bottom surface of the barrier member that engages the sides of the connector arms or a recess in the bottom surface of the barrier member in which the guide arms are received, are also possible for providing the barrier member with guide means for guiding the actuator or at least a part thereof.

In the embodiment shown, the barrier member 1 1 has a substantially disc shaped body having a circumferential outer surface, formed by an upwardly and a downwardly extending flange. This outer surface is provided with a protrusion at the lower end thereof, extending along the circumference of the outside surface. This protrusion forms a guide surface and defines the annular opening between the air damper and the tubular stile member of the adjacent lower ladder section. The design of the barrier member is thus used to define the amount of air that can flow out of the tubular stile member of the adjacent ladder section via the annular opening between the two telescopically connected stile members, when the valve member is in the throttle position. Thus, the design of the barrier member is used to design the speed at which the ladder section collapses, when the valve member is in the throttle position.

In the embodiment shown, the barrier member of the air damper has an upper fastening portion which is configured to receive the bottom end of a tubular stile member. In a further embodiment, the barrier member is provided with integral elastic fasteners, for example click fingers, which are adapted to snap into associated apertures in the stile member for connecting the barrier member to, and thus mounting the air damper onto, the stile member.

As mentioned earlier, the throttle opening 14 defined by the barrier member 1 1 provides a connection between the inner space of the stile member onto which the air damper has been mounted and the inner space of the stile member of the adjacent ladder section, i.e. the inner space of the stile member into which the stile member onto which the air damper has been mounted is telescopically inserted.

When the valve member 12 is in the non-throttle position, shown in Fig. 3, air can flow through the throttle opening 14, and in the particular embodiment shown via the valve opening of the valve, between the inner space of the tubular stile member onto which the air damper has been mounted and the inner space of the stile member of the adjacent ladder section 4'.

This flow of air facilitates the telescopic movement of the tubular stile member relative to the stile member of the adjacent ladder section, into which the stile member has been inserted.

When the valve member 12 is in the throttle position, shown in Fig. 4, the valve member seals off the throttle opening 14 thus throttling the airflow between the inner spaces of the two tubular stile members. This throttling of the flow of air retards the telescopic movement of the tubular stile member relative to the tubular stile member of the adjacent ladder section, into which the stile member has been inserted.

The actuator member 13, via the contact 15 surfaces and the spring arms 16, provides a frictional contact between the valve member 12 and the inside surface of the tubular stile member into which the air damper 9 is inserted. Thus, when the air damper 9 is moved relative to the stile member of the adjacent ladder section, i.e. by telescopic movement of the stile member onto which the air damper 9 has been mounted, the actuator member 13 will cause valve member 12, which valve member is moveable supported, to move relative to the barrier member. During collapse of the collapsible ladder section, the telescopic stile member onto which the air damper is mounted is telescopically inserted into stile member of the adjacent ladder section. This relative movement of stile members causes the actuator member, that frictionally engages the inside surface of the stile member of the lower adjacent ladder section, to push the valve member into the throttle position. Thus, the flow of air from the inner space of the adjacent ladder section into the inner space of the collapsing ladder section is throttled by the air dampers, and the gravity induced velocity of the collapsible ladder section is reduced.

During extension of the collapsible ladder section, the telescopic stile member onto which the air damper is mounted is telescopically extended out of the stile member of the adjacent ladder section. This relative movement of stile members causes the actuator member to push the valve member into the non-throttle position. Thus, air can flow via the throttle opening from the inner space of the adjacent ladder section into the inner space of the extending ladder section, which facilitates extension of the ladder section.

According to the invention the actuator functions as a coupling between the valve member and the adjacent ladder section, such that the movement of the air damper relative to the adjacent ladder section during collapse or extension of the ladder is used for moving the valve damper into and out of its throttle position.

It is noted that with the valve member in the throttle positions, air can still flow out of the tubular stile member of the adjacent ladder section via the annular opening between the telescopically connected stile members. In an alternative embodiment according to the invention further openings may be provided in the adjacent ladder section to further allow air to escape form the adjacent ladder section upon collapse of the collapsible ladder section, and thus reduce the retardation effect of the air damper. It is furthermore noted that, due to the telescopic linkage of the ladder sections, the dimensions, in particular the diameter, of the tubular stile members differ for each ladder section. Thus, the dimensions of the air dampers, which are mounted in the bottom end of the tubular stile members, also differ for each ladder section. Furthermore, the effective weight of the collapsible ladder sections differs from above to below. This because the ladder section decrease in size towards the top ladder section. Furthermore, when the lower most intermediate ladders section collapses, it carries the weight of all the other intermediate ladder sections and the top ladder section.

Thus, the release and subsequent collapse of an intermediate ladder section, for example the lower most intermediate ladder section, causes this intermediate ladder section to move towards the lower ladder section, for example the bottom ladder section, and brings in motion all ladder section above that intermediate ladder section as well.

Therefore it is proposed that the air dampers of the respective ladder sections provide a differing retardation in order to compensate for the total weight of the ladder sections to be retarded. Thus, the damper members are provided with specific damper characteristics for each ladder section. For example, the damper members of the higher ladder sections may be provided with air dampers of which the valve member only partially covers the throttle opening when in the throttle position, to thus reduce the retardation effect of the air dampers. The preferred embodiment shown is a telescopic ladder assembly, e.g. a straight ladder provided with automatic latch mechanisms (e.g. at each end of a rung) with one or more associated manually operable actuators for unlocking the tubular stile members in order to allow for collapsing of the ladder assembly, wherein these one or more actuators are arranged centrally on a ladder rung (preferably on the front) and are operable simultaneously with a single hand of the user. It has been found that the proposed dampers allow obtaining a very controlled motion of the ladder section upon collapse of the ladder. The user can now operate the one or more actuators simultaneously with one hand and use - at the same time - his other hand to guide the descending ladder section and/or stabilize the ladder during this operation. This allows for safe and gentle handling of the ladder during collapse, and avoids fast motions and undesirable impacts of the descending ladder sections as can be observed in known telescopic ladders.

In the embodiment shown, all of the collapsible ladder sections, i.e. all the intermediate ladder sections and the top ladder section, are at the bottom ends of their tubular stile members provided with air dampers.

The tubular stile members of the bottom ladder section are at their bottom end provided with a plug type body that is inserted into the tubular stile member to provide a foot/stand for supporting the ladder on a support surface.

The air dampers provided by the invention are one way air dampers. In the exemplary type of ladder shown, the one way air dampers are active, i.e. throttle the air flow, when the collapsible ladder section onto which the dampers have been mounted is moved in a first direction, i.e. towards the bottom ladder section. The air dampers become inactive, i.e. do not throttle the air flow, when the collapsible ladder section is moved in the opposite direction. Thus the ladder can be quickly and easily extended.

Figs. 4 and 5 show the barrier member 1 1 in isolation. It is noted that in the particular embodiment shown, the barrier member forms a valve seat 19 located at the centre of the tubular stile member. The valve seat 19 is configured for receiving the valve member 12 and for guiding the valve member 12 between the throttle position and the non-throttle position, along a central axis of the tubular stile member. Thus, the barrier member combines the functions of defining the one or more throttle openings and the guiding of the valve member.

In a further preferred embodiment, the valve seat is provided with multiple throttle openings, which throttle openings overlap with flow through openings in the valve body when the latter is in the non-throttle position, and which on or more throttle openings are overlapped by the valve body when the latter is the throttle position. Fig. 3 shows the valve member and actuator member. It is noted that in the particular embodiment shown, the valve member is combined with the actuator member in a unitary component. In an alternative embodiment, the actuator member is a separate component, which during assembly of the air damper is connected to the valve member.

In the exemplary embodiment shown, the actuator member 13 comprises two spring arms 16 located diametrically opposite each other, such that the biasing forces generated the two spring arms have the same line of action. Thus, the spring arms 16 essentially form a single spring arm with the valve body preferably located at the centre thereof.

Furthermore, in the embodiment shown, the actuator member 13 is a single component, manufactured by injection-moulding. The single component comprising the spring arms 16 and the grip pads 15, which are integral parts of the spring arms.

The connector arms 16 are each provided with resilient sections 17 to enable the connector arms to bias the grip pads 15 onto the inside surface 18 of the stile member.

Figures 8-10, show schematic top views of alternative embodiments of injection moulded combined valve member and actuator member. The valve member is substantially the same as the valve member shown in Figs. 3 and 4. The configuration of the spring arms differs.

The embodiments shown in fig. 8 and 9 are provided with alternatively shaped spring arms, which spring arms are provided with integral grip pads. The spring arms are configured such that they are compressed or bent when the damper member is inserted into the adjacent ladder section, such that the spring arms are biased when located in the stile member of the adjacent ladder section, thus providing a resilient force for pushing the grip pads against the inside surface of the tubular stile member of the adjacent ladder section.

Fig. 10 shows an embodiment of a combined valve member and actuator member in which a disc shaped body is provided with resilient rubber inserts that form the grip pads and are, when the air damper is inserted inside a tubular stile member, compressed to provide the bias that presses the contact surface of the contact pads against the inside surface of the stile members.

In an alternative embodiment, the connector arms comprise a separate resilient element, for example a plastic or metal spring element to provide the spring force for pushing the grip pad against the inside surface of the tubular stile member. It is observed that depending on required retardation in combination with the configuration, i.e. size, shape and location, of the throttle openings, as well as the weight of the ladder section, the valve member can be designed to overlap the throttle openings fully or only partially, when in the throttle position.

When the throttle openings are fully covered by the valve member, when in the throttle position, maximum retardation can be achieved. Such a configuration can for example be used with the lower collapsible ladder sections, while the damper elements of the higher intermediate ladder sections, which are lighter and support less ladder sections, may require only partial coverage of the throttle openings to provide sufficient retardation.

As an alternative to partially covering the throttle openings, the barrier member may define additional pass through openings which are not covered by the valve member when in its throttle position, and are thus always open, to provide for reduced retardation of the ladder section. Fig. 1 1 schematically shows a bottom end of a tubular stile member provided with an air damper and telescopically inserted in a tubular stile member of an adjacent ladder section in cross section. The spring arms each push a grip pad against the inside surface of the tubular stile member of the adjacent ladder section. The spring arm, or at least a resilient part of the spring arm, is compressed, providing a biasing force that pushes the grip pad onto the inside surface of the stile member of the adjacent ladder section. The frictional contact between the actuator member, in particular the multiple grip pads of the actuator member, and the inside surface of the adjacent stile member, causes the actuator member to trail the movement of the stile member, when that stile member is moved relative to the adjacent stile member. This trailing movement is used to move the valve member between the throttle and the non-throttle position.