Ladder with extendable feet

Abstract

A ladder provided extendable feet, where each extendable foot comprises a tubular box section with an elongated hole, an engaging plate provided with an elongated hole arranged on the inside the box tube section such that the elongated holes align, and a blocking member. The engaging plate has two ribs having ratchet teeth that cooperate with ratchet teeth provided on the blocking member. The blocking member is connected to an actuator mechanism that, when pressed inward, disengages the ratchet teeth of the engaging plate and of the blocking member from each other. When the blocking member is in blocking position the extendable feet can extend but not retract, to retract the extendable feet the actuator mechanism has to be pressed inward by a user.

Description

[0001] LADDER WITH EXTENDABLE FEET

[0002] The present invention relates to a ladder with extendable feet facilitating the use of a ladder on uneven surfaces and allowing to maintain the rungs of the ladder in a substantial horizontal orientation.

[0003] The stability of ladders is a concern, particularly when the ladder is used on uneven surfaces. It is known to use a ladder with extendable feet, wherein the extendable feet allow a user to effectively change the length of each side rail, thereby ensuring that the ladder is stable and the rungs are substantially horizontal when the ladder is placed on an uneven surface.

[0004] For example, US6478113 discloses a ladder with extendable feet which are each telescopically received in the respective side rail of the ladder, such that the extendable feet can extend and retract with respect to the side rails. The side rails and the extendable feet are both provided with cooperating teeth, which can engage each other by using clamping members. These teeth ensure that - when engaged with each other due to tightening of a knob - the extendable feet cannot move relative to the side rail.

[0005] WO9925947discloses a ladder having extendable feet, each being telescopically received in a side rail of a ladder. A ratchet teeth mechanism allows the extendable foot to be extended with respect to the side rail and prevents the extendable foot from retracting. To retract the extendable foot a disengagement means has to be operated by the user, which disengages the cooperating ratchet teeth.

[0006] The present invention aims to provide a ladder provided with individually extendable feet which offers a cost-effective structure, ease of set-up for the user, whilst ensuring enhanced stability during use, e.g. as in load testing of the ladder.

[0007] The present invention provides a ladder according to claim 1.

[0008] The ratchet teeth provided on the two ribs of the engaging plate and on the blocking member allow the extendable foot to extend with respect to the side rail even when the user does not inward press the interface portion. This allows a user to extend the extendable foot just by applying a downward force on the extendable feed (which can also be done by holding the foot pad down and then setting the ladder in its desired position), there is no need of an additional action by the user, leading to a quick set-up of the ladder on an uneven surface.

[0009] When the interface portion is not pressed inward by a user, such that the blocking member is in the blocked position, the ratchet teeth of the blocking member engage multiple ratchet teeth of each of the ribs of the engaging plate. This distributes the forces acting on the blocking member and engaging plate over multiple teeth, preferably all made of steel, which decreases the force acting on each single tooth. Additionally, by fixing the engaging plate to the inside of the tubular box section at the side of the box section that comprises the elongated hole, the stiffness of the hollow tube section is increased.

[0010] The ribs provided with teeth of the engaging plate are arranged directly along the long sides of the elongated hole. So, practically the teeth and ribs are placed close to a longitudinal centre line of the engaging plate, which is advantageous for the absorption of forces, e.g. bending forces, which leads to enhanced stability.

[0011] Due to the placement of the interface portion at the lower portion of the side rail, it is practically impossible for a user standing on the rungs of the ladder to, accidentally, press the interface portion, thereby allowing for retraction of the extendable feet.

[0012] The inventive concept may be applied to many types of ladders. For example, simple rigid ladders, extension ladders, folding ladders, step ladders, platform ladders, and telescoping ladders, etc.

[0013] In an embodiment, the tubular box section is provided with two parallel guiding ribs which are arranged on the side opposite to the side comprising the first elongated hole, wherein the guiding ribs are spaced at a distance from each other such that the ribs flank the blocking member. Preferably, the height of the guiding ribs is such that in both the blocked position and un-blocked position the blocking member, at least a part thereof, is flanked by the guiding ribs. The guiding ribs ensure that the ratchet teeth of the blocking member cannot turn with respect to the ratchet teeth of the engaging plate, thereby ensuring proper engagement of the cooperating ratchet teeth. Additionally, the guiding ribs attached to the tubular box section, preferably integrated therein as one aluminium extrusion, act as longitudinal stiffeners which increase the overall longitudinal stiffness of the tubular box section. Preferably, the guiding ribs extend of the majority of the length, e.g. all of the length, of the tubular box section.

[0014] In an embodiment, the blocking member comprises a plate portion and two ribs arranged at the lateral sides of said plate portion, forming a substantially U-shaped cross section, wherein the two ribs are provided with teeth along the length thereof. Preferably, the two ribs of the blocking member are aligned with the ribs of the engaging plate.

[0015] In an alternative embodiment, the blocking member is embodied as a block and each tooth of the blocking member extends over the entire width of the blocking member, e.g. to engage both toothed ribs.

[0016] In an embodiment, the actuator mechanism is provided with a housing which is arranged on the side of the side rails, such that the housing surrounds the hole in the side of the side rail. The interface portion is level or recessed relative to an outer end of the housing, this decreases the chance that a user of another person can accidentally press the interface portion inward, thereby disengaging the teeth and causing an unintentional retraction of the extendable foot.

[0017] In an embodiment, each side rail, at least the lower portion thereof, has a main portion and two lateral portions, as to form a substantial U-shaped cross-section. The tubular box section is telescopically received such that it adjoins the base and the two lateral portions of the side rails.

[0018] In an embodiment, each side rail is provided with brackets which extend between the lateral portions of the side rails to prevent lateral movement of the extendable foot with respect to said side rail.

[0019] In an alternative embodiment, each rail, at least a lower portion thereof, is embodied as a hollow tubular, which - when the tubular box section is telescopically received therein, surrounds the tubular box section.

[0020] In an embodiment, the pitch between each tooth of the engagement plate and the blocking member is between 3 - 9 mm, preferably between 5 - 7 mm, more preferably 6 mm. The relatively small pitch of the ratchet teeth allow the extendable foot to be retracted in small steps, increasing the chance that the optimal, most stable, position is found.

[0021] In an embodiment, when the ratchet teeth of the engagement plate and blocking member are engaged with each other, between 5 and 10 teeth of each of the ribs of the engagement plate and the blocking member engage each other, preferably 7 teeth engage each other.

[0022] Preferably, all teeth of the blocking member are engaged. The large number of teeth engaging each other distributes the force over these teeth, thereby decreasing the force acting on each singular tooth. In an embodiment, the blocking member is provided with a connection nut arranged in the centre of the plate. The connection member is further provided at the lower end thereof with a bolt which is configured to engage the connection nut of the blocking member, thereby connecting the blocking member with the connection member.

[0023] In an embodiment, the engagement plate and the blocking member are made of a metal, e.g. steel, preferably stainless steel. Preferably, the side rails of the ladder are made of aluminium, wherein steel is used for the engagement plate and blocking member to provide extra strength to the ratchet teeth.

[0024] In an embodiment, the tubular box section and the side rails are produced using metal extrusion, preferably wherein the guide ribs are integrally formed with the tubular box section using metal extrusion.

[0025] In an embodiment, the extendable foot is provided with a foot engagement portion, preferably the foot engagement portion is arranged on the side of the hollow box structure. The foot engagement portion is configured to be pressed or held down by, preferably a foot of a user such that the extendable foot can extend relative to the side rail. The foot engagement portion allows for an easier installation of the ladder.

[0026] The invention further relates to a method for stabilising a ladder as described herein, wherein the method comprises extending the extendable foot relative to the side rail as to change the relative length of the side rail, e.g. wherein the foot of a user presses down on the foot engagement portion to extend the extendable feet, or holds down the foot engagement portion and places the ladder vertical.

[0027] The invention will now be explained with reference to the drawings. In the drawings:

[0028] - Fig. 1 shows a ladder standing on an uneven ground,

[0029] - Figs. 2a - d show different components of the ladder,

[0030] - Fig. 3a - 3b show the blocking member in the blocking position and the non-blocking position,

[0031] - Fig. 4 show a horizontal cross-sectional view of the extendable foot in the side rail.

[0032] Figure 1 shows a ladder 1 , here by way of example only a folding ladder having two ladder sections hinged to one another at their top end. As discussed, the inventive concept is equally applicable to other types of ladders, e.g. rigid ladders, extensible ladders, telescopic ladders, etc. Here the ladder 1 has two ladder sections, each with a pair of side rails 2a, 2b, wherein a plurality of rungs 3 extend between the pair of side rails 2a, 2b.

[0033] Each side rails is provided with an extendable foot 10.

[0034] The ladder 1 stands on an uneven ground, wherein the extendable foot 10 of the left pair of side rails 2a is substantially extended to ensure that the ladder is stable to operate.

[0035] Each extendable foot 10 comprises a tubular box section 11 , shown in Figure 2a, which is telescopically received in a lower portion of a side rail 2.

[0036] The tubular box section has, in this example and as preferred, a rectangular cross-section peripheral wall having opposed long sides 11a, 11b and opposed short sides.

[0037] The tubular box section 11 is provided on long side 11 a thereof with a first elongated slot 12 extending longitudinally relative to the length of the section 11.

[0038] The lower end of the tubular box section 11 extends beyond the side rail 2 and is provided with a foot pad 13.

[0039] The extendable foot 10 is provided with an engaging plate 20, shown in Figure 2b, which is fixed to the inside of the side 11a of the tubular box section, as is shown in Figure 4.

[0040] The engaging plate 20 has a second elongated slot 21 which is aligned with the first elongated slot 12 of the tubular box section 11.

[0041] The engaging plate 20 has a planar base 20a and two ribs 22 perpendicular to the planar base 20a. Each of the ribs 22 extends along a respective long side of the second elongated slot 21. For example, as preferred, the ribs 22 are formed by bending the ribs 22 out of the plane of the base 20a. For example, the plate 20 is of steel, e.g. about 2 millimeters in thickness.

[0042] The two ribs 22 are each provided with a series of ratchet teeth 23 along the length of the rib 22.

[0043] The ladder further comprises a blocking member 30, shown in Figure 2c, which is provided with ratchet teeth 33. The number of teeth 33 is smaller than the number of teeth 23 on a rib 22. The ratchet teeth 33 of the blocking member 30 are configured to engage multiple ratchet teeth 23 of each rib 22 of the engaging plate 20.

[0044] The ladder is also provided with an actuator mechanism 40 which comprises a connection member 41.

[0045] As shown in Figure 4, the connection member 41 extends through a hole in the side of the side rail 2 and through the first and second elongated slots 12, 21. The connection member

[0046] 41 is at a first end thereof connected to the blocking member 30. The connection member 41 is at a second end thereof provided with an interface portion 42 configured to be pressed inward by a user.

[0047] The actuator mechanism 40 is further provided with a spring 43, shown in Figures 3a-b and Figure 4, wherein the spring 43 is arranged between the interface portion 42 and the side rail 2. The spring 43 urges the blocking member 30 to a blocking position wherein the ratchet teeth 33 of the blocking member 30 engage ratchet teeth 23 of the two ribs of the engaging plate 20.

[0048] Figure 3a shows the blocking member 30 in the blocking position. Here the interface portion

[0049] 42 of the actuator mechanism 40 is not pressed inward, such that the ratchet teeth 33 of the blocking member 30 and ratchet teeth 23 of the engagement plate 20 are engaged with each other. Due to the shape and orientation of the ratchet teeth 23, 33, the retraction of the extendable foot is not possible, i.e. as shown the box section 11 cannot move upward relative to the side rail 2, however, the extension of the extendable foot is possible, i.e. the box section 11 can move downwards relative to the side rail 2.

[0050] Figure 3b shows the blocking member 30 in the non-blocking position. Here the interface portion 42 of the actuator mechanism 40 is pressed inward, such that the ratchet teeth 33 of the blocking member 30 and the ratchet teeth 23 of the engagement plate 20 are disengaged from each other. In this position, the extendable foot 10 can freely extend and retract.

[0051] As shown in Figure 2a and Figure 4, the tubular box section 11 is further provided with two parallel guiding ribs 14 which are arranged on the long side 11b opposite to the side 11a where the first elongated hole 12 is present. The guiding ribs 14 are spaced at a distance from each other such that the ribs 14 flank the blocking member 30. The height of the guiding ribs 13 is such that in both the blocked and un-blocked position the blocking member 30 is flanked by the guiding ribs. In the shown embodiment, the blocking member 30 comprises a plate 31 and two ribs 32 arranged at the lateral sides of said plate 31 forming a substantially U-shaped cross section. The two ribs 32 are provided with the ratchet teeth 33 along the entire length thereof. The two ribs 32 of the blocking member 30 are aligned with the ribs 22 of the engaging plate 20, as shown in Figure 4.

[0052] The actuator mechanism 40 is provided with a housing 44 which is arranged on the side each of the side rails 2, such that the housing surround the hole in the side of the side rail. As shown in Figure 3a, when the interface portion 42 is not pressed inwards by a user, the interface portion is level with the outer end of the housing 44.

[0053] In the shown embodiment, the side rails 2 each have a main portion and two lateral portions to form a substantial U-shaped cross-section.

[0054] The tubular box section 11 is telescopically received relative to the side rail, here within the space defined by the main portion and the two lateral portions of the side rail.

[0055] In this example, each side rail is further provided with one or more brackets 4 which extend across the lateral portions of the side rail opposite the main portion to form a hollow space in which the section 11 is slidable.

[0056] In an embodiment, the pitch between teeth 23, 33 of the engagement plate and the blocking member is between 3 - 9 mm, preferably between 5 - 7 mm, more preferably 6 mm. This allows for a rather fine adjustment of the extension of the foot 10.

[0057] In the shown embodiment, when the ratchet teeth 23, 33 of the engagement plate 20 and blocking member 30 are engaged with each other, seven teeth of each of the ribs 22 of the engagement plate 20 are simultaneously in engagement with the same number of teeth of the blocking member 30.

[0058] The engagement plate 20 and the blocking member 30 are made of steel.

[0059] The tubular box section 11 is made of aluminium, preferably an aluminium extrusion which includes the guiding ribs 14 to provide enhanced stability of the section 11 and the ribs 14.

[0060] For example, the plate 20 is connected to the section 11 by rivets, e.g. one rivet at the upper end and one rivet at the lower end.

[0061] The plate 20 secured to the inside of long side 11a enhances the strength of the extendable foot 10, e.g. the plate 20 being made of 2 mm thick steel. In the shown embodiment, the extendable foot 10 is provided with a foot engagement portion 15 which is arranged on the side of the hollow box structure 11. The foot engagement portion 15 is configured to be pressed or held down by, preferably a foot of a user such that the extendable foot 10 can extend relative to the side rail 2.

Claims

C L A I M S1. A ladder (1) comprising a pair of side rails (2a, 2b) and a plurality of rungs (3) extending between the side rails, wherein each side rail is provided with an extendable foot (10), wherein each extendable foot comprises:- a tubular box section (11) being telescopically received in a lower portion of a side rail (2), wherein the tubular box section is provided on one side thereof with a first elongated slot (12), wherein a lower end of the tubular box section extends beyond the side rail and is provided with a foot pad (13),- an engaging plate (20) which is fixed to the inside of the tubular box section (11), wherein the engaging plate has a second elongated slot (21) which is aligned with the first elongated slot (12) of the tubular box section, wherein the engaging plate has two ribs (22) which each extend along a respective long side of the second elongated slot (21), wherein the two ribs (22) are each provided with ratchet teeth (23) along the length of the rib, wherein the ladder further comprises:- a blocking member (30) which is provided with ratchet teeth (33), wherein the ratchet teeth of the blocking member are configured to engage multiple ratchet teeth (23) of each rib (22) of the engaging plate (20),- an actuator mechanism (40) which comprises a connection member (41) which extends through the side of the side rail (2a, 2b) and through the first and second elongated slots (12, 21), wherein the connection member is at a first end thereof connected to the blocking member (30), and wherein the connection member is at a second end thereof provided with an interface portion (42), e.g. a button, configured to be pressed inward by a user, wherein the actuator mechanism is further provided with a spring (43), wherein the spring urges the blocking member (30) to a blocking position wherein the ratchet teeth of the blocking member (33) engage the ratchet teeth of the two ribs of the engaging plate (23), wherein - when the interface portion of the actuator mechanism (42) is not pressed inward- the ratchet teeth of the blocking member and the engagement plate (23, 33) are engaged with each other as to block the retraction of the extendable foot (10) with respect to the side rail (2) while still allowing the extension of the extendable foot with respect to the side rail, and wherein - when the interface portion of the actuator mechanism is pressed inward - the teeth of the blocking member disengage the engagement teeth of the engaging plate such that the extendable foot can retract and extend with respect to the side rails.

2. Ladder according to claim 1, wherein the tubular box section (11) is provided with two parallel guiding ribs (14) which are arranged on the side opposite to the side comprising the first elongated hole (12), wherein the guiding ribs are spaced at a distance from each other such that the ribs flank the blocking member (30).

3. Ladder according to claim 1 or 2, wherein the blocking member (30) comprises a plate (31) and two ribs (32) arranged at the lateral sides of said plate, wherein the two ribs are each provided with ratchet teeth (33) along the length thereof.

4. Ladder according to any one or more of claims 1 - 3, wherein the actuator mechanism (40) is provided with a housing (44), wherein the interface portion (42) is level or recessed relative to an outer end of the housing.

5. Ladder according to any one or more of claim 1 - 4, wherein each side rail (2a, 2b), at least the lower portion thereof, has a main portion and two lateral portions, as to form a substantial U-shaped cross-section, wherein the tubular box section (11) is telescopically received therein.

6. Ladder according to claim 5, wherein each side rail (2a, 2b) is provided with brackets (4) which extend across the lateral portions of the side rail to confine the extendable foot (10) laterally with respect to said side rail.

7. Ladder according to any one or more of claims 1 - 6, wherein the pitch between adjacent teeth of the engagement plate and of the blocking member (23, 33) is between 3 - 9 mm, preferably between 5 - 7 mm, more preferably 6 mm.

8. Ladder according to any one or more of claims 1 - 7, wherein - when the ratchet teeth of each of the ribs of the engagement plate and blocking member are engaged with each other - between 5 and 10 teeth of each of the ribs of the engagement plate and the blocking member engage each other, preferably 7 teeth engage each other.

9. Ladder according to any one or more of claims 1 - 8, wherein the blocking member (30) is provided with a connection nut arranged in the centre of the plate, and wherein the connection member is provided at the lower end thereof with a bolt which is configured to engage the connection nut of the blocking member.

10. Ladder according to any one or more of claims 1 - 9, wherein the engagement plate (20) and the blocking member (30) are made of a steel and wherein the tubular box section (11) is made of aluminium, e.g. as an extrusion including the guiding ribs of claim 2.

11. Ladder according to any one or more of claims 1 - 10, wherein the tubular box section (11) and the side rails (2a, 2b) are produced using metal extrusion, preferably wherein the guide ribs (14) are integrally formed with the tubular box section using metal extrusion.

12. Ladder according to any one or more of claims 1 - 11, wherein the extendable foot (10) is provided with a foot engagement portion (15), wherein the foot engagement portion is configured to be held or pressed down by, preferably a foot of a user such that the extendable foot can extend relative to the side rail.

13. A method for stabilising a ladder according to any one or more of claims 1 - 12, wherein the method comprises: - extending an extendable foot relative to the side rail, preferably wherein the foot of a user presses down on or holds down a foot engagement portion.

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