HK1166114B - Apparatus, such as a ladder, comprising extendable legs - Google Patents

Description

Device comprising an extendable leg, such as a ladder

The present invention relates to an apparatus including a frame having at least three legs, each of the three legs being independently and selectively extendable to adjust a length of each of the three legs.

Support members, devices and locking members of the above-mentioned kind are known in the prior art. The support member may for example be an extendable leg member for a table or ladder. The extendable leg members may be used to stabilize a ladder or table when placed on an uneven surface. By extending one or more legs of the object, it is possible to carefully place the object in a desired manner. Furthermore, the extendable leg member may be used to place a surface of an object (e.g. a table top or a bucket tray) in a horizontal position.

In one embodiment, the prior art leg comprises two leg members, which are slidably connected to each other. A securing mechanism or locking mechanism may be provided for securing the two leg parts to each other so that the extendable leg member may be secured at a desired length. The fixation may consist of pins or screws which enter holes provided on one or both leg parts.

Furthermore, tables or ladders with one or more extendable legs are also known from the prior art. By adjusting the length of one or more of the legs, the ladder may be positioned in a desired manner.

A disadvantage of the prior art legs is that adjustment of the leg length can be difficult and time consuming.

A disadvantage of the known device with a plurality of extendable legs is that the placement of objects may be difficult. For example, when placing a table or ladder on uneven ground, it may be necessary to adjust multiple legs. This has proven difficult because the user must decide the order of the legs to be adjusted and each leg needs to be adjusted before the object is in the desired state.

It is an object of the present invention to provide a device comprising an adjustable leg in which at least one of the known disadvantages is solved.

In one embodiment, the device includes a frame having at least three legs for positioning the device on a surface. Each of the at least three legs is independently and selectively extendable to adjust the length of each leg. Each leg may include a transmission member and a locking member. The locking member has a locked state for locking the axial extension of the leg and an open state enabling the axial extension of the leg.

In an embodiment, the transmission member connects the locking means in the at least three legs to a central operating mechanism for activating and deactivating each locking member. The central operating mechanism is arranged to activate and deactivate the respective locking members simultaneously. In this way a device such as a ladder, table or tripod is obtained, wherein each locking member of each extendable leg can be unlocked immediately using only a central operating member.

The central operating member allows for one-time operation locking of some legs having a desired length.

Furthermore, each leg may be independently extendable, meaning that the length of each support member may be selected at will by the user. The length of one support member is not dependent on the length of the other support member. This, in combination with the central operating mechanism, enables the user to set the device to a desired state relatively simply and quickly. For example, it may be used to set a table or tripod to a level condition or a ladder to a stable condition on uneven ground.

According to an embodiment, the device comprises at least two legs, the two legs being hinged with respect to each other. Furthermore, each of the at least two legs comprises at least one support member comprising a locking system according to the invention. The support members of the independent hingeable dependable legs are connected to a central operating mechanism which allows simultaneous operation of the locking member of each of the hingeable dependable legs.

It is possible that the operating mechanism comprises an operating handle connected to the lever. The lever is rotatably attached to the frame. The rod may be attached to the frame by a bearing. The lever may comprise at least two push blocks arranged at a distance from each other. Each pusher is arranged to engage with one of the transmission members. The operating mechanism is arranged such that rotation of the lever by rotation of the operating handle results in translation of the transmission member pushed by the push block. The transmission member is arranged such that translation of the transmission member causes a tilting movement of the catch of the locking member. In this way a reliable and safe securing operation and locking of the components is obtained.

The apparatus may include a support platform from which at least three legs extend downwardly. The support platform may be used to position an object on the support platform. Due to the adjustable support members it is relatively simple to set the support platform horizontal.

In one embodiment, the device is a ladder. The ladder may comprise two, three or four support members according to the invention. The ladder may simply be placed on uneven ground. When using a central operating member, the ladder can be positioned relatively quickly and simply.

In one embodiment, the leg includes a support member including a first leg member and a second leg member. The first leg member is axially movable relative to the second leg member to axially extend the support member. The first leg member comprises a housing arranged to slidingly receive the second leg member. The housing includes a locking component having a locked state locking relative axial movement of the first leg member with respect to the second leg member and having an open state enabling relative axial movement of the two members. By providing the locking member in the housing, the locking member is less prone to soiling and remains relatively clean. Therefore, the locking member is less damaged, ensuring safe operation of the locking member.

In one embodiment, the locking member may comprise a catch that moves obliquely within the housing to alternately obtain the locked and open states of the locking member. The trap may be a relatively flat plate. The trap may include a cavity that receives the second leg. The catch includes a stop surface around at least a portion of the periphery of the cavity. The cavity may be a hole in the trap or an open cavity in the trap. A portion of the surface of the trap surrounding the cavity may be a stop surface. The stop surface may be relatively small and may comprise a relatively small portion of the cavity surface, such as the cavity edge. The open cavity may be U-shaped. In the open state of the locking part, the stop surface is not in contact with the second leg member, so that the second leg member can slide freely in the housing. The catch may be arranged such that in the locked state of the locking component the stop surface engages with at least an opposite peripheral portion of the second leg member. The second leg member is secured in the cavity by engaging the opposing peripheral portions. By the inclination of the cavity such that the stop surface engages with the opposite part of the second leg member in the locked state, a moment is exerted on the second leg member. This moment pushes the second leg member obliquely to the stop surfaces (e.g., edges) of the housing and catch. It is possible that the static friction generated between the second leg member and the stop surfaces of the housing and the catch ensures a tight and secure fixation of the second leg member. A further advantage of the invention is that the support element can be infinitely adjusted, i.e. the support element can be fixed in any desired state without the need for a decentralised arrangement of the support elements being required.

In one embodiment, the stop surface is relatively small and the stop surface comprises an edge of the cavity. The edge may be relatively sharp such that in the locked state the edge is pressed into the second leg member. The edge may cut into the second leg member. This ensures that a high locking pressure is obtained, resulting in a good resistance to the relative movement of the two leg parts.

In one embodiment, the longitudinal axis of the cavity extends parallel to the second leg member in the open state. In the open state, the catch may be arranged perpendicular to the second leg member such that the cavity in the catch is parallel to the second leg. In this way, the necessary space is provided for the second leg to move freely. Furthermore, in this way only a small tilting of the catch between the locked and the open state is required. In this way the support member can be designed in a relatively compact manner.

In one embodiment, the locking member, in particular the catch, is biased towards the locked state. By biasing the locking component towards the locked state, a larger force is exerted on the second leg member in the locked state. As a result, the static friction generated will increase, resulting in a tighter fixation of the second leg member. A spring or any other biasing member may also be disposed within the housing. Of course, there may be multiple springs or biasing members. The spring is arranged to urge the catch towards the locked state and to urge a stop surface of the catch securely located on an outer surface of the second leg member to increase the static friction. Thereby, a support member with a rigid locking member providing a secure fit is obtained.

At least a portion of the trap and/or at least a portion of the second leg member is made of hardened steel. Preferably, at least a portion of the catch engaged with the second leg member and a portion of the second leg member engaged by the catch are both made of hardened steel. The coefficient of friction between two surfaces made of hardened steel is relatively high. More specifically, the coefficient of friction of dry static friction is relatively high in this case, resulting in a tight and secure fit.

In one embodiment, the leg member includes a biasing member that biases the support member toward the axially extended condition. The biasing member may urge the legs of the support member toward the axially extended state. This may cause the second leg member to move outwardly when the locking member is at rest (i.e. in an open state). The support member may move toward the maximum extended state due to the force exerted by the biasing member.

Alternatively, the biasing member may be arranged to balance a certain weight that the support member is designed to support. The support member in this manner does not extend nor shorten when the locking member is in the open state. This allows the user to set the support member in a desired state relatively simply. The user may unlock the locking member and then only require a slight force to adjust the length of the support member.

In one embodiment, the biasing force has a force similar to the mass supported by the support member. If the device comprises a plurality of support members or legs, the sum of the biasing forces of the plurality of support members corresponds to the mass of the support. This will allow a "floating feel" of the support member/device when it is placed on a surface, the locking member being in the open condition allowing the legs to be extended or shortened while the mass is supported by the biasing force. The operator can transport the device up or down with no or little resistance felt.

In one embodiment, the locking member comprises an additional catch which is tiltably movable within the housing to alternately obtain the locked state and the unlocked state of the locking member. The additional trap includes a cavity that receives the second leg. The additional catch has a stop surface around the periphery of the cavity compared to the first catch. The stop surface may be arranged to engage with at least an opposite peripheral portion of the second leg member in the locked state of the locking part. The additional catch will result in a balanced tight fixation of the two leg members. Different longitudinal sections of the trap around the second leg member are possible. For example, the second leg member may be fixed at two different axial positions, enabling the leg members to have a rigid and secure fit.

In one embodiment, the catch and the additional catch are arranged to tilt in opposite directions towards the locked state. A relatively compact design in this manner is possible. Further, the catch may engage the second leg member at different angles. In this way, the second leg member is more tightly secured and axial movement of the second leg member is prevented.

In one embodiment, a biasing member, such as a spring, is disposed between the catch and the additional catch. When the biasing member engages both catches, a biasing force is obtained that biases the catches away from each other. Preferably, tilting the catches away from each other corresponds to tilting the catches towards the locked state. Thus, in such an arrangement, the biasing member biases the locking member toward the locked state.

Furthermore, the biasing member is preferably a spring ring. The biasing means biasing the locking means towards the locked state may be a spring coil arranged around the leg member. This results in a simplification of the construction, a simplification of the assembly of the support part, especially if spring rings are used.

The locking member may comprise a cam disposed in the housing. In one embodiment, the housing includes a cam that engages the catch to operate the catch from the locked state to the open state.

In one embodiment, opposite sides of the cam may engage with two catches. The cam may be arranged to simultaneously tilt the two catches from the locked condition to the open condition. The cam enables both traps to be operated simultaneously. Thereby, a tight fixation of the leg member can be achieved relatively simply.

In one embodiment, the support member comprises a transmission member connected to the locking member and extending towards the outer edge of the leg member. The transmission member may be connected to an operating member provided on the leg member to operate the locking member. In this way, the operation of the locking member can be performed at a distance from the actual position of the locking member. The operating member may be arranged in an ergonomic condition for the user, rather than compromising the compactness of the support member. The ergonomic condition of the operating member ensures that the support member can be adjusted simply and safely.

In a preferred embodiment, the transmission member is connected to the cam. The transmission member may be connected to the cam by a hinge. A transmission member, such as a rod, bar, cable, etc., may be arranged such that operation of the operating member results in a desired movement of the cam and, in addition, a tilting movement of the one or more catches. The transmission member is slidably connected to the housing. The transmission member may be arranged such that it moves parallel to the first leg member to operate the locking member. Axial movement of the transmission member may be translated into tilting movement of the one or more catches by the cam. In this way, a relatively compact support member can be obtained.

Preferably, the transmission member is a rigid member, such as a rod or bar. The rigid part will transfer the movement of the operating mechanism to the locking part very accurately. The forces acting on the rigid part deform the rigid part, as is the case, for example, when using a cable. Repeated tensioning and deformation of the cable can ultimately lead to its failure. This limits the safety of the support member and is undesirable. A rigid transmission member may result in a safer and more accurate support member.

According to an aspect of the invention, there is provided an apparatus comprising a frame having at least two legs. At least one leg may comprise a support member according to the invention. The device may be a ladder or a table. The support member can be simply and safely adjusted, as is apparent from the previous description. In this way, it is relatively simple to set the device in the desired state. In addition, such ladders support a large weight. Such a device with a support member according to the invention can simply support a weight of over 150 kg.

According to another aspect, there is provided an apparatus according to claim 20. The device according to claim 20 may have one of the further features of claims 1-19. This arrangement is advantageous since the locking member in the leg that is pivotable by the hinge operates at a distance.

While the invention has been and will be described with reference to the preferred embodiments, it will be apparent that numerous embodiments and different embodiments are possible within the scope of the invention. The aim of the present application is to protect the described embodiments, the embodiments indicated by the claims, and equivalents thereof. Those skilled in the art, having benefit of the present disclosure, will be able to construct different embodiments. It is the intention of the inventors that those embodiments are also protected by the present application.

In the above description as well as in the following description, aspects of the invention are described and advantages of the solution are described. The inventors intend this application and/or divisional applications to protect all mentioned and non-mentioned advantages of the present invention over the prior art.

The invention will be described with reference to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a ladder;

FIG. 2 is an exploded perspective view of the ladder showing in detail an embodiment of the support member with a locking mechanism and an operating mechanism;

FIG. 3 is a side view of a locking member according to an embodiment of the present invention;

FIG. 4a is a side view of the support member of FIG. 3 in a locked condition;

FIG. 4b shows a detail of the locking mechanism of FIG. 4 a;

FIG. 5a is a side view of the support member of FIG. 3 in a locked condition;

FIG. 5b shows a detail of the locking mechanism of FIG. 5 a;

FIG. 6 shows a perspective view of an operating mechanism for operating the locking member;

FIG. 7 is a side view of the operating mechanism of FIG. 6;

FIG. 8a is a side view of another embodiment of a locking mechanism in a locked state; and

fig. 8b is a side view of the embodiment according to fig. 8a in an unlocked state.

Fig. 1 shows a ladder 1 in a perspective view. The ladder has a frame. The ladder 1 comprises two front legs 5a, 5b and two rear legs 5c, 5 d. The front legs 5a, 5b are horizontally separated from each other by several rungs 6, which rungs 6 may be regularly placed at longitudinal intervals from each other. At the upper ends of the two front legs a bucket tray 9 is provided. The front legs 5a, 5b, the steps 6 and the bucket tray 9 are part of the front frame. The rear legs 5c, 5d are horizontally separated from each other by two connecting rods 13. The rear legs 5c, 5d and the connecting rod 13 are part of the rear frame. The front frame and the rear frame are hinged to each other by a hinge point 8. The top step 7 connects the front frame and the rear frame and ensures a stable and fixed angle state between the front frame and the rear frame. For this purpose, two spacer members 14 are also provided between the front frame and the rear frame. The top rung 7 is rotatably connected to the rear frame in a manner known to the person skilled in the art. The top ladder rung may be detached from the front frame, enabling the rear frame to hinge towards the front frame via the hinge point 8. In this way, the ladder may be in a collapsed position with the rear legs relatively closely spaced and parallel to the front legs.

As shown in fig. 1, each of the legs 5a to 5d includes an extendable leg portion 10a to 10 d. Each system of legs 5 and extendable leg portions 10 forms a support member 2. The leg may be shown as a first leg member and the extendable leg portion may be shown as a second leg member. Both leg members are part of the support part 2. Each of the leg portions 10a to 10d has a foot portion 11a to 11 d. The extendable leg portions 10a to 10d are axially movable relative to the legs 5a to 5 d. An operating handle 3 is provided on one side of the front leg 5 b. As will be discussed below, a locking mechanism 200 is provided for locking the relative axial movement of the extendable leg portions and legs. The locking mechanism includes a locking member. The operating handle 3 is used to lock and unlock the lock mechanism 200. In the locked condition, the extendable leg portion cannot move relative to the leg. In the unlocked or open state, relative movement between the leg and the extendable leg portion is possible. The extendable portion is capable of moving a length relative to the leg. The length of possible movement may be 20cm, for example. Other lengths are also possible.

In another embodiment, a table is provided having one or more legs, and in particular, one or more legs that are pivotable about a hinge that is connected to the table. The central operating mechanism may be coupled to the frame or the table top.

Figure 2 shows an exploded view of the ladder of figure 1. Like parts are indicated by like numerals. In this figure the top rung 7 and the front leg 5b are removed, whereby the operating mechanism 21 and the locking mechanism 200 of the ladder 1 are shown in more detail. Each of the extendable leg portions 10a to 10d includes a slide bar 16, and the slide bar 16 is slidably received in the locking member or locking mechanism 200. The spring 17 is connected between the housing of the lock mechanism 200 and the lower portion of the extendable leg portions 10a to 10 d. The further bar 15 is slidably received in the locking mechanism 200 and extends towards the upper part of the ladder 1. In the upper part of the ladder 1, the rod 15 engages with an operating mechanism 21. The operating mechanism 21 comprises two levers 18. Each rod 18 is pivotally connected between either the front or rear legs. As an example, the link may be attached to the frame by a bearing. The two rods are placed parallel to each other and are connected by a connecting rod 19. The lever 18 has a handle 3 at one end. The handle 3 may be used to lock and unlock the operating mechanism 200, as will be described below.

Fig. 3 shows a side view of an embodiment of a portion of a support member including a locking mechanism 30 having locking members 34, 35. Fig. 4a to 4b and 5a to 5b show further details of the support part 2 of fig. 3. Fig. 4 shows the lock mechanism 30 in a locked state. Fig. 5 shows the locking mechanism 30 in an open state. Like parts are indicated by like numerals. The locking mechanism 30 includes a housing 32. It should be noted that the figures schematically show the locking mechanism and other parts. The figures are not drawn to scale. In the illustrated embodiment, the housing 32 is attached to the first leg member 22 as can be seen in fig. 4 and 5. The first and second leg members 22, 20 are part of the support part 2. At one end of the housing 32, a sliding rod 33 is slidingly received. The slide rod is axially slidable. A stopper is provided at an upper end of the slide bar to limit extension (i.e., downward movement) of the slide bar. The slide lever 33 is connected to the lower leg portion 41. The slide bar 33 and the lower leg portion 41 are part of the second leg member 20. The lower leg portion 41 has a foot 42 for stable placement of a ladder or another object provided with the support part 2 in a situation of use. A spring 44 is provided near the slide lever 33. The spring extends between the outside of the housing 32 and the upper portion of the lower leg portion 41. At the other end of the housing 32 a transmission member 31, such as a transmission rod 31, is slidingly received. A spring 43 is provided in the housing so as to be in contact with one end of the transmission rod 31. Further upwardly, the transfer bar is also slidingly received by the guide block 46. The upper end of the transmission rod 31 engages a push block 50, the push block 50 being connected to the steering rod 48. The push block 50 and the steering rod 48 are rotatable about the steering rod centerline. In the locked state of the locking mechanism 30, it is possible for the corners of the push block to rest on a surface. For example, in the locked state of the locking mechanism 30, the lower right corner of the push block 50 may rest on the guide block 46 and/or the upper right corner rests on the interior of the first leg member 22. Thus, the push block is prevented from rotating in one direction. This ensures that the push block is only rotated a small amount, so that a small rotation of the operating handle 3 is sufficient to release the locking mechanism.

In the housing, cam 36 is connected to drive link 31 at hinge point 51. The cam 36 is engageable with both catches 34, 35. One catch 34 is provided at the upper end of the cam and the other catch 35 is provided at the lower end of the cam 36. The upper side 141 of the cam engages the catch 34 and the lower side 142 of the cam 36 engages the catch 35. The cam may be made butterfly, i.e. with two legs extending around the sliding bar 33. Each of the catches 34, 35 has one side disposed in a channel 52, 53 of the housing. The catches 34, 35 can tilt or rotate in the housing about an axis of rotation formed by the longitudinal direction of the grooves 52, 53. It should be noted that in the illustrated embodiment, the catches 34, 35 do not have an axis of rotation fixed within the housing. The trap is not connected to the housing but is free to move within the housing 34 and cavity 52. The outer end of the trap is movable in a horizontal plane. Thereby, less parts are required, and thus the locking mechanism can be simplified without involving a tight and secure locking of the two leg members.

A perspective view of an embodiment of the trap 34 is shown in fig. 3 b. The trap has a cavity 40 formed therein. The sliding bar 33 of the second leg member 41 is slidingly received in the cavity 40 of the catch 34 (see fig. 3 a). The cavity 40 may be cylindrical, although other shapes are possible. The catch has a stop surface 47. The stop surface may comprise the inner shell of the cavity 40. Preferably, the stop surface includes an edge 45 of the cavity 40 having an outer surface 54 of the catch 34. A similar edge is present at the bottom of the trap 34. Furthermore, another cavity 49, which may be a second U-shaped cavity 49, is provided in the trap.

The operation of the locking mechanism 30 will be explained below. In the locked state shown in fig. 4a and 4b, transmission rod 31 is in an upward state, wherein hinge point 51 of cam 36 is also lifted upward. The outer surface of the cam is designed to enable the catches 34, 35 to pivot or tilt towards the centerline of the housing 32. When tilted, different parts of the stop surface 47 of the cavity 40 of the catch 34, 35 will engage with the slide bar 33. More specifically, at least two edges 45 of the cavity 40 will engage with the sliding bar 33. Thereby, portions of both edges 45 on both sides of the cavity 40 will come into contact with the sliding bar 33. The edge may be pressed into the sliding bar. The edges may also cut into the sliding bar 33. This ensures that a high locking pressure is obtained and prevents relative movement of the two leg members. The upper edge 45 and the lower edge are respectively engaged with portions facing each other. Thus, the opposite outer peripheral portion of the second leg member 41, i.e., the slide lever 33, is engaged. This exerts a moment on the slide bar 33. Thus, the slide rod 33 is pressed into the housing 32 and into the stop surface 47. The sliding bar 33 is thus caught by the catch 34 and the housing 32. Each contact point will create static friction that prevents the sliding rod 33 from sliding in the housing 32. Thus, movement of the slide bar and thus extension of the legs is not possible.

It should be noted that it may be sufficient to fix the slide bar 33 only with a single catch 34. An additional catch 35 is provided longitudinally of the first catch. The combination of this additional catch with the first catch 34 ensures a secure fixation. As can be seen from fig. 2, the catches 34, 35 will be inclined in different directions. Thereby, the blocking of the movement in both directions can be ensured. In addition, a secure fixation is also ensured.

The springs 38, 39 disposed against the catches 34, 35 also ensure that the catches 34, 35 rotate or tilt toward the center of the housing 32. The springs 38, 39 ensure that the catches 34, 35 are urged towards the locked condition. The springs 38, 39 also ensure increased engagement of the stop surfaces 47 on the slide bar 33. Thereby, a secure and safe fixation of the sliding rod 33 in the locking mechanism is achieved. In the illustrated embodiment, the spring is positioned parallel to the sliding bar 33 of the second leg member 20 and is positioned around the sliding bar 33. This positioning is compact and convenient and allows for simple assembly of the support member. However other orientations are possible. Other means of biasing the catch towards the locked condition are possible. For example, a spring arranged near the transmission rod 31 and connected to both catches 34, 35 may be used to pull the two catches 34, 35 towards each other, thus biasing the two catches towards the locked state.

Unlocking the locking mechanism 30 may be performed as follows. By rotating the push block 50 about the pivot point 48, the transmission rod 31 is moved downward. The result is that the hinge point 51 of the cam 36 also moves downward. The cam and housing are arranged such that such downward movement causes the cam 36 to rotate about the pivot point 51. The cam 36 is arranged such that movement of the combination simultaneously causes the two catches to tilt from the locked condition to the open condition. Movement of the cam 36 will result in movement of the upper and lower surfaces of the cam 36 which results in tilting movement of the two catches 34, 35 towards the exterior of the housing 32. The stop surface of the cavity is then arranged at a distance from the slide rod 33, enabling the slide rod to move within the housing 32. Thereby, the legs of the ladder may be extended or shortened axially.

It should be noted that in the locked state of the locking mechanism, the cam 36 is free to rotate about the hinge point 51. It is possible that the outer surface of the cam does not come into direct contact with the catches 34, 35. In this case, the movement of the transmission rod 31 may be necessary in order to bring the outer surface of the cam into contact with the catcher so that the catcher can move toward the open state. The locking mechanism can thus be brought into the open state only by the actual movement of the transmission rod. This ensures that the user intentionally opens the locking mechanism, preventing accidental opening of the locking mechanism.

In the unlocked state, the longitudinal axis of the cavity 40 extends parallel to the sliding rod 33. This ensures that the area through which the sliding rod 33 can slide is maximized, i.e. there is a maximum hole for the sliding rod 33. Accidental locking can thereby also be prevented.

In the unlocked state, the spring 44 surrounding the slide lever 33 biases the extendable leg portion 41 toward the extended state. Preferably, the force of the spring is designed to balance the weight force of the object to be supported. In this way, releasing the locking mechanism 30 only results in the extendable leg being extendable without actually sliding within the housing 32. Thus, releasing the locking mechanism does not result in an effective shortening of the extendable leg due to the effect of gravity. When using a plurality of legs, the force of each spring is selected such that the combined force of the springs balances the weighing force of the object to be supported. Each of the plurality of springs may have a different spring force depending on the weight distribution of the object to be supported. According to this embodiment, an object provided with a plurality of support members, such as a ladder, is relatively simply arranged in any desired manner. The force required to change the orientation of the object is relatively small because the object is more or less self-supporting by the biased spring.

When the rotational force on the push block 50 is removed, the action of the springs 38, 39 near the catches 34, 35 and the action of the spring 43 near the drive link 31 will cause the drive link to move upward, thereby locking the locking mechanism 30.

It is desirable that an object having several extendable legs, such as a ladder, can be operated by a central operating mechanism. Fig. 6 and 7 show an embodiment of an operating mechanism 60 suitable for this task. The operating mechanism 60 comprises two steering rods 68 which are arranged at a distance from each other. As shown in fig. 4, the steering levers 68 may be arranged substantially parallel in a plane. The steering rod 68 is connected by the connecting rods 64, 65. The connecting rods 64, 65 are connected to each steering rod 68 by means of a projection 66, 67. A push block 62 is provided at each outer end of the steering rod 68. The push block is rigidly connected to the steering rod 68. A transmission rod 63 is provided at a lower surface of each push block 62. In the illustrated embodiment, the drive link 63 engages a lower surface of the push block 62 and there is no fixed connection between the drive link 63 and the push block 62. The transmission rod 63 may be connected to a locking mechanism, as described above. A handle 61 is provided at one end of the steering rod 68. The handle may be used by a person to operate the locking mechanism for several extendable leg parts simultaneously. It should be noted that the operating mechanism shown in fig. 6 may be used in combination with any support member, regardless of the kind of locking mechanism used in the support member.

By rotating the handle 61 in the direction indicated by the arrow a1, the steering lever is rotated. The rigid connection between the two steering levers, the connection formed by the rigid connecting rods 64, 65, will also move in the direction of arrow a 2. This results in the same rotation of the second lever 68. Thus, both levers 68 will rotate through equal angles. Furthermore, all the push blocks 62 will rotate equally, thereby pushing each transmission rod 63 in a downward direction. As described above, the downward movement of the transmission rod 63 enables the locking mechanism to reach the idle state. Thus, the extendable legs may be positioned in any desired manner.

It may be noted that the extension of the legs is not coupled to the transmission rod 63 in any way. As can be seen from fig. 2, the transmission rod 63 is only used to lock and unlock the locking mechanism of the extendable leg. Thus, it should be noted that all components may extend independently of one another. In other words, the length of each leg member may be arbitrarily selected. The length of one leg does not limit the length of the other leg. Thus, the user may adjust each extendable leg of the object in any desired manner. These degrees of freedom enable the user to position the object at a desired height (within the limits of the extendable legs) and also to position the object at an angle relative to the base on which the object is located. A further advantage is that the locking mechanism of each extendable leg is operable with a central operating mechanism, enabling the user to easily erect his object. The object may be a table or ladder, or any other object that benefits from an extendable leg such as a tripod.

The support member can be assembled relatively quickly and in a simple manner. The assembly will be discussed with reference to fig. 4 and 5. First, the second leg member 20 may be prepared. The slide bar 33 is disposed within the housing 32 by sliding its lower end through the top opening of the housing. During this step, two catches 34, 35 and two springs 38, 39 may be installed. The spring 44 may be mounted on the slide bar when the slide bar is in place. Next, the lower portion 41 of the second leg member 20 may be attached. The transmission rod 31 can then be mounted in the housing by sliding the rod 31 into the desired top opening of the housing 32. A spring 43 is also arranged. When the lever 32 and spring 43 are put in place, the cam 36 may be connected and attached to the hinge point 51. Further, the guide block 46 may be installed. It will be apparent to those skilled in the art that the arrangement of the slide bar 33 and the transmission bar 31 is performed in a different order. The locking mechanism 30, the second leg member 20 and the combination of the drive link 31 and the guide block 46 can be slid into the hollow first leg member 22. The hollow first leg member may be an extruded profile. The housing 32 and other parts are aligned using methods known to those skilled in the art and then may be attached to the second leg member using fastening means such as rivets.

Fig. 8a shows another embodiment of a leg or support member 100 with a locking member 101. The housing 102 is mounted in a first leg member 103. The transmission member 104 is formed of a rod. The transmission member may be connected to a central operating mechanism at a distance from the locking mechanism. Since the lever is stiff, movement in the operating mechanism can be transferred to the locking mechanism 101. The transmission member 104 is axially movable in the leg 100 according to arrow 105. The movement may be guided by a housing 102 having a suitable aperture for receiving the transmission member 104.

The biasing member 109 provides a biasing force on the transmission member 104 in the direction of arrow 110.

The transmission member 104 has a first pin 106. Further, a hinge 107 is provided in connection with the cam 108. The cam 108 rests on the housing portion 112.

The transmission member 104 is movable in the direction of arrow 110 from the state shown in fig. 8a to the state shown in fig. 8 b. Fig. 8a shows the locked state of the locking mechanism 101 and fig. 8b shows the unlocked state.

If the transmission member 104 is moved, the cam 108 will rotate according to arrow 113 about the hinge 107. The tip 114 of the cam 108 engages the catch 120. At the same time, the pin 106 will engage the catch 121. The traps 120 and 121 may have an embodiment similar to that of fig. 3 b.

End portions 123, 124 of the catches 120 and 121 are received in cavities of the housing 102 and allow tilting movement of the catches according to arrows 125, 126, respectively.

The catches 120, 121 have cavities that receive the second leg members 130. A biasing member 131, such as a spring, is engaged on the housing 102 and the second leg member 130 providing a biasing force towards extending the leg or support member 100 in an axial direction. The second leg member 130 is telescopically received in the first leg member 103 and is slidable in the axial direction 105.

In the state according to fig. 8a, the cavity in the catch 120, 121 is inclined and the outer periphery of the cavity will engage on the outer surface of the second leg member 130. If sufficiently inclined, the engagement force will lock the second leg member in the locked condition and the leg or support member 100 will have a fixed length.

A further biasing member 140, which in this embodiment is also a spring, in this embodiment surrounds the second leg member 130. The biasing member 140 engages on the catches 120, 121 and provides a force in an axial direction, forcing the catches away from each other.

If moved to the unlocked state according to fig. 8b, the second leg member 130 is free to move relative to the first leg member 103 or the housing 102 and the length of the leg 100 can be adapted axially. The biasing member 131 is biased in the extending direction.

The biasing force in the direction of extension may for example be similar to the mass of the support member 100. In an embodiment, the biasing force is similar to a mass located near the equilibrium state/length of the leg 100. This will provide a "floating feel" if the device to which the leg 100 is attached is positioned on a surface.

The second leg member 130 has a stop 133, the stop 133 being engageable on the housing 101 to limit the length of the axial extension.

The locking mechanism can be brought from the unlocked state according to fig. 8b to the locked state by an axial movement of the transmission member 104 and allows the catcher to be tilted according to the arrows 125, 126 separating from each other by the biasing of the biasing member 140.

As a result of the unlocking, the leg member 130 moves upward a distance indicated by arrow 136. In the sliding arrangement, the portions 135 of the leg members 130 that are directly connected to the leg members are guided the same distance 136 in the frame of the first leg member 103.

By moving upward distance 136, the biasing force from spring coil 131 is overcome resulting in a work load W. This work may be provided by the mass/weight of the ladder/table supported by the support member 100. The weight of the ladder/table is now supported by the support member 100, in particular by the spring 131, resulting in a floating feeling for the operator pushing the first leg member 101.

In an embodiment, an additional pin may be positioned on the drive member on the other side of the trap 121.

In another embodiment, a further biasing member may be arranged around the transmission member 104 between the catch 120 and the catch 121, thereby biasing the catch 120, 121 in the tilted state according to fig. 8 a.

Variations of the embodiments shown are conceivable without departing from the main idea of the invention. It is apparent that the invention has been described using preferred embodiments. The present invention is not limited to these embodiments.

Claims (17)

1. Device comprising a frame with at least three legs (2, 5a-5d) for placing the device on a surface, wherein each of the at least three legs (2, 5a-5d) is independently and selectively axially extendable for adjusting the length of each of the at least three legs (2, 5a-5d), wherein each of the at least three legs (2, 5a-5d) comprises a transmission member (31) and a locking member (30), the locking member (30) having a locking state locking the axial extension of the leg and having an open state enabling the axial extension of the leg, wherein the at least three locking members are connected to a central operating mechanism (21) via the transmission member, the central operating mechanism (21) is arranged to activate and deactivate the at least three locking members (30) simultaneously, wherein at least two legs (2, 5a-5d) are articulated with respect to each other.

2. Device according to claim 1, wherein the central operating mechanism (21) comprises an operating handle (3, 61) connected to a lever rotationally attached to the frame, the lever comprising at least two push blocks (62) arranged at a distance from each other, wherein each push block (62) is arranged to engage with one of the transmission members (63), wherein the operating mechanism (21, 60) is arranged such that rotation of the lever by rotation of the operating handle (3, 61) causes translation of the transmission member by pushing of the push block (62), wherein the transmission member (63) is arranged such that translation of the transmission member (63) causes tilting movement of the first catch (34) of the locking member (30).

3. The device according to claim 1 or 2, wherein the device (1) comprises a support platform (7) from which the at least three legs extend downwards.

4. The device according to claim 1, wherein the device is a ladder (1).

5. The device according to claim 1, wherein the leg (2, 5a-5d) comprises a first leg member (22) and a second leg member (20), wherein the first leg member (22) is axially movable relative to the second leg member (20) for axially extending the leg (2, 5a-5d), wherein the first leg member (22) comprises a housing (32) arranged to slidingly receive the second leg member (20), wherein the locking part (30) is received in the housing (32), the locking part (30) comprises a first catch (34), the first catch (34) being angularly movable within the housing (32) for alternately obtaining a locked state and an open state of the locking part (30), wherein the first catch (34) comprises a cavity (40) receiving the second leg (20), the first catch (34) comprises a stop face (47) around the periphery of the cavity (40), the stop face (47) being arranged to engage at least two opposing peripheral portions of the second leg member (20) in the locked state of the locking part (30).

6. The device according to claim 5, wherein a longitudinal axis of the cavity (40) extends parallel to the second leg member (20) in the open state.

7. The device according to claim 5 or 6, further comprising a further biasing member (38, 39), the further biasing member (38, 39) biasing the first catch (34) towards the locked state.

8. The device according to claim 5, wherein the locking member (30) comprises a second catch (35), the second catch (35) being tiltably movable within the housing (32) to alternately obtain a locked state and an unlocked state of the locking member (30), wherein the second catch (35) comprises a cavity (40) receiving the second leg member (20), wherein the second catch (35) comprises a stop surface (47) around the periphery of the cavity (40), wherein the stop surface (47) is arranged to engage at least two opposing peripheral portions of the second leg member (20) in a locked state of the locking part (30), wherein the stop surfaces (47) of the first and second catches (34, 35) surround different longitudinal portions of the second leg member (20).

9. The device according to claim 8, wherein the first catch (34) and the second catch (35) are arranged to be tilted in opposite directions towards the locked state.

10. The device according to claim 9, wherein a biasing member is provided between the first catch (34) and the second catch (35), biasing the first catch (34) and the second catch (35) away from each other.

11. The device of claim 10, wherein the biasing member is disposed about the leg member (20, 22).

12. Device according to claim 8 or 9, wherein the locking means (30) comprises a cam (36) provided in the housing (32), wherein opposite sides (141, 142) of the cam (36) engage with the first catch (34) and the second catch (35), wherein the cam (36) is arranged to simultaneously tilt the first catch (34) and the second catch (35) from a locked state to an open state.

13. The device of claim 5, wherein the housing further comprises a cam (36), the cam (36) engaging the first catch (34) to operate the first catch (34) from a locked condition to an open condition.

14. The device according to claim 13, wherein the transmission member (31) is connected to the cam (36).

15. The device according to claim 1, wherein the leg (2, 5a-5d) comprises a first leg member (22) and a telescopic second leg member (20).

16. The device according to claim 1, wherein the leg (2, 5a-5d) further comprises a biasing member (44) for biasing the leg (2, 5a-5d) towards an axially extended state.

17. The device according to claim 7, wherein the biasing member (38, 39) biases the locking member (30) towards the locked state.