AU2014100476A4 - Castor brace for step ladder - Google Patents

Abstract

Step or platform ladders operable on a supporting surface can be provided a castor arrangement for permitting the ease of movement when the step or ladder is not in use. The step or platform ladder having a pair of rails is arranged to support at least one step on which the user can step to raise themselves and any work tools or working pieces above the supporting surface. The castor arrangement comprises a brace member located between a rail and the step to not only brace the rail with respect to the step but also provide a castor assembly associated with the brace member wherein, in use, the castor assembly raises the respective rail above the supporting surface. 24- 2?1 Figure 1 j

Description

1 CASTOR BRACE FOR STEP LADDER FIELD OF THE INVENTION [0001] The field of the invention is stepladders. BACKGROUND [0002] A stepladder is typically a relatively short folding ladder with steps, which stands by itself without support or being placed against something else. The steps are typically deep and suitable for comfortably standing on the step by a user that when folded out on a supporting surface is used to support the person using the stepladder. Sometimes the stepladder has a platform that makes it even easier to use. [0003] Stepladders are available in a number of configurations. The number of steps/rungs can start at one and can be as many as ten but the maximum number of steps/rungs is merely a matter of constructional stability and safety. A feature that varies between stepladders is whether it is double sided or single sided, meaning whether there are step/rungs on both sides of the ladder or only one side. Some but not many stepladders are provided wheels that allow the whole of the ladder to be more easily moved, where the wheels are of the type that are fixed to a frame located between the rails/stiles of the stepladder. Various arrangements are provided to raise and lower the wheels or for those wheels permanently lowered arranged to halt the rotation of a, or each, wheel by the operation of an appropriate mechanism. Thus the movement of the stepladder is restricted and thus useable to be climbed while in an appropriate location. The same types of configurations can be found in platform ladders. [0004] An alternative configuration of step ladders and platform ladders is provided herein to reduce manufacturing cost while providing additional convenience and operational safety to the user. BRIEF DESCRIPTION OF THE INVENTION [0005] In a broad aspect the invention relates to a castor arrangement for a step or platform ladder operable on a supporting surface. The step or platform ladder has a pair of rails supporting at least one horizontal member and the castor arrangement comprises a brace member located between a rail and the horizontal member to brace the rail with respect to the horizontal member, and a castor assembly associated with the brace member wherein, in use, the castor assembly raises the respective rail above the supporting surface. [0006] In a further aspect of the invention a top surface of the brace member abuts an underside surface of the horizontal member.

2 [0007] In an aspect of the invention the castor assembly has a wheel rotatable on an axle supported by a frame 60 and a spindle connected to a housing frame portion 64 and a biasing element to bias the spindle and associated wheel away from the brace member to raise a respective rail off the supporting surface. [0008] In an aspect the biasing element could include leaf springs or a resilient material associated with the spindle and the housing, or any other arrangement, but preferably the biasing element is an elastomeric element associated with the spindle more preferably a spring surrounding the spindle. The spring is retained at one end by a circlip located in a groove in the outer wall of the spindle and at its other end by the housing of the brace member. The circlip being sized so as to be retained within the housing when the spring is in an expanded state. The expanded state of the spring being in contrast to it being in a compressed state when the ladder is being stepped on by a user. [0009] A step or platform ladder operable on a supporting surface having at least a pair of rails and at least one horizontal member between the pair of rails, the ladder comprises, two brace members bracing the same horizontal member and a respective rail of the pair of rails, each brace member including a castor assembly wherein, in use, the castor assembly raises the respective rail above the supporting surface. [0010] Although the invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing both the process and apparatus of the present invention. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. [0011] Throughout this specification and the claims that follow unless the context requires otherwise, the words 'comprise' and 'include' and variations such as 'comprising' and 'including' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. [0012] The reference to any background or prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such background or prior art forms part of the common general knowledge. [0013] Specific embodiments of the invention will now be described in some further detail with reference to and as illustrated in the accompanying figures. These embodiments are illustrative, and not meant to be restrictive of the scope of the invention. Suggestions and descriptions of other embodiments may be included within the scope of the invention but they may not be illustrated in the accompanying figures or alternatively features of the invention may be shown in the figures but not described in the specification.

3 BRIEF DESCRIPTION OF THE FIGURES [0014] Figure 1 depicts a perspective view of a stepladder incorporating a castor arrangement according to an embodiment of the invention; [0015] Figure 2 depicts a perspective view of the lower portion of the stepladder depicted in Figure 1; [0016] Figure 3 depicts a perspective view of the embodiment of a castor arrangement depicted in Figures 1 and 2; [0017] Figure 4 depicts a side view of the embodiment of a castor arrangement depicted in Figure 3 plus a cross-sectional view of a horizontal member without the vertical rail so as not to obscure the side view of the castor arrangement; [0018] Figure 5 depicts an inside side view of the embodiment of a castor arrangement; and [0019] Figure 6 depicts an inside side view of the embodiment of a castor arrangement and the condition such that the wheel of the castor has been pushed up towards the base of the brace member thus allowing the foot of an associated rail to be in contact with the supporting surface. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION [0020] As stated previously and now referring to Figure 1 a stepladder 10 is typically a relatively short folding ladder with a step or steps, in this embodiment steps 12 and 14. The steps are typically deep and suitable for the user to comfortably stand on when the ladder is folded out on a supporting surface 16. Sometimes a stepladder will include a platform 18 that is used to support the person using the stepladder in an even more comfortable manner by supporting the whole sole of each foot of the user. [0021] In this specification the term step will be used but is also used to describe a rung and has the more generic term of a horizontal member, being that part of the ladder that the feet of the user of the ladder will step on to raise them above the surface supporting the ladder (the supporting surface 16). [0022] The stepladder depicted in Figure 1 has a pair of rails (collectively referred to as a pair of rails 20 but consisting of rail 20' and rail 20") located on the front of the stepladder 10 (nominally designated the front since that is the location at which the person using the stepladder would step onto the ladder). [0023] The term rail will be used but can also be used to describe a stile or a stringer.

4 [0024] Also depicted is a pair of rails (collectively referred to as a pair of rails 22 but consisting of rail 22' and rail 22") located on the rear of the stepladder (nominally designated the rear since that is the location not used by the user). [0025] As depicted in Figure 1 the respective pairs of rails 20 and 22 are moveable with respect to each other by way of the provision of a rotating connection 24 that connects the rear pair of rails 22 to the front pair of rails 20 at a location near the top and on the rear facing side of the front pair of rails. Thus it is possible for the rear pair of rails 22 to be folded towards the front pair of rails 20 and thus become substantially parallel to the front rails when the stepladder is not in use. The folded stepladder is thus easier to carry and store in the folded state than in the use state. [0026] It is a preferred feature of the steps of the embodiment depicted in Figures 1, 2 and 4 that the steps have a trapezoidal shape in cross-section with the upper substantially flat horizontal surface (with respect to the supporting surface 16) of the step having a non-slip surface shape or texture. Each step is preferably made of extruded aluminum. Each end of a step is connected to a respective rail and the strength of the step and connection to a respective rail is such as to support a person according to the required standard. The connection in this embodiment is by way of pop-rivets but other types of connections are possible. [0027] Also depicted is a standing platform 18 located at a level above the highest step that extends between the two front rails supporting the steps and two rear rails of the stepladder 10. The standing platform has dimensions of about 600 mm by about 460 mm and is made of polypropylene. The top surface of the platform has a non-slip diamond plate pattern. [0028] The standing platform 18 includes metallic supports to provide sufficient strength, according to the required standard, to support a person standing on the platform plus a load that may accompany the person while they are using the stepladder and in particular the standing platform, noting that in this embodiment the platform also maintains the rails in fixed spaced relationship so as not to spread under the live load. The platform is one way in which that connection between the moveable rails can be made, an alternative being the use of a metallic rod or similar extending from one of the front or rear rails to the other. [0029] The standing platform 18 when in use is horizontal to the supporting surface 16 and connects the pairs of rails (20, 22) at opposite ends of the platform and thus prevents the rails from separating. The platform is arranged to be capable of being detached at one end adjacent either the front pair of rails or the rear pair of rails and rotated to become substantially parallel to the rails when folded. [0030] It is an alternative to having a platform 18 or a rod (not shown) fixable between the front and rear rails (20, 22) to adapt the rotatable connection 24 to lock in a predetermined position. The connection and the 5 locking arrangement needs to be very secure since there are large forces that operate to separate the front and rear rails during use of the stepladder, especially when loaded up with the user and additional loads. [0031] The stepladder 10 depicted in Figure 1 also has a multi-function handrail 26 located above the rotatable connection 24. The handrail is connected between the front pair of rails 20 at their upper ends preferably at their uppermost end. The handrail can be used to store tools and the like during use of the stepladder and also to allow a person to stand on the standing platform 18 and rest against the handrail at about or just below waist level to steady the user and to be grabbed onto by the user as they climb the step ladder. [0032] The structural strength and stability of a ladder needs to conform to standards. The stability is determined by applying various horizontal loads (non-simultaneous to the side, front and rear) to the ladder at the highest point of the handrail. During the application of these forces, the bottom surface of the stiles and back legs shall remain in contact with the level surface. One way to provide the required stability, is to provide braces (not illustrated) across the inner face (inner with respect to the stepladder) of the pairs of rails 20 and 22. Braces would crisscross from an upper portion of a rail 20' to a lower portion of the respective rail 20" and may be fitted to one or both a pairs of rails. Those braces are sometimes inconveniently located and can interfere with the positioning of a user's feet. [0033] Another way in which the required stability can be achieved is to provide a strong member located between a rail and a step. This is a known means for bracing the total structure of a stepladder. Not all steps of a stepladder are braced but typically the lowest step on the front side is braced and sometimes the highest step is braced in this manner. [0034] A lower portion of the stepladder 10 depicted in Figure 1 is depicted in Figure 2. In this depiction step 12 is located between two rails 20' and 20". [0035] In an embodiment of the invention a castor wheel arrangement 28 is provided for a step or platform ladder which combines the functions of a brace and a castor wheel with additional functionality. [0036] The stepladder 10 depicted in Figures 1 and 2 include at the front of the ladder a pair of rails 20' and 20" supporting at least one step/horizontal member 12. The castor arrangement 28 comprises, a brace member 30 which is located between a rail (20' or 20") and the step/horizontal member 12 to brace the rail with respect to the horizontal member and a castor assembly 32 to be described in further detail. In this embodiment the lowest horizontal member on the front pair of rails 20 is the first step of the front of the stepladder.

6 [0037] A castor assembly 32 is incorporated into the brace member 30. In use, the castor assembly is arranged to raise the respective rail above the supporting surface. The end of each rail is depicted as having fitted thereto a foot structure 34 that in this embodiment is preferably made of rubber so that it provides high frictional resistance to the movement of the foot once located on a supporting surface. However, the castor assembly is arranged to raise the rail associated with the brace member, which happens when the ladder is not being stood upon by the user, so that the wheel/s of the castor/s can be used to easily relocate the step ladder. [0038] The castor assembly 32 has a number of parts, which are depicted more clearly in Figures 3, 5 and 6 that will be described in greater detail later in the specification. [0039] In a preferred embodiment at least two castor arrangements are available, each one associated with a rail of the pair of rails either the front or rear pair of rails, and in this embodiment the castor wheels of the castor arrangement are associated with the front pair of rails. [0040] Figure 3 depicts the top surface 36 of the top of the brace member 30 (top being a reference to when the brace member is in use to provide a brace between a horizontal member and a rail). The top surface of the brace member is shaped and located so that the whole of the top surface abuts a portion of the underside surface 38 of the horizontal member 12, which is depicted in greater detail in Figure 4. The total width of the horizontal member is supported by the top surface of the brace member, while the top surface of the brace member can be smooth or it may have a texture however, in the main, the top surface will substantially conform to the underside surface of the rail to assist the strength of the combination of the brace and rail member union. [0041] Figure 4 depicts a cross-sectional view of the trapezoidal shape of a portion of the underside of the horizontal member 12 located on the top surface of the brace member 30 so as to abut the whole of the top surface of the brace member. Figures 3 and 4 depict a side view of the brace member and in particular show the angle of the top surface 36 with respect to the rail so that forces transferred from the stepping of a user on the horizontal member 12 are partially distributed to the brace member as well as partially transferred to the rail at the connection of the rail to the horizontal member. Also depicted are projections 40 and 42 of the body of the brace member that are located against a portion of a respective side (44, 46) of the horizontal member 12 which in combination cradle the horizontal member. The projections 40 and 42 are fixed to the horizontal member, in one embodiment by pop-rivets 56 and 58. [0042] Figure 5 is a side view of the brace member 30 depicted having a castor assembly 32, which in this embodiment includes the following parts: e a castor wheel 54 (a wheel supported by a frame 60 rotatable about an axis 70); 7 e a spindle 62 which is coaxial with the castor wheel axis 70 and which extends vertically (in use) into a spindle supporting frame portion 64 of the brace member; e an elastomeric element to bias the spindle outward (in use) downward of the brace member, in this embodiment a spring 54; e a retaining element to retain a portion of the elastomeric relative to the spindle, in this embodiment a circlip 50 located along the length of the spindle 62, being a metal ring sprung into a slot or groove in the spindle to maintain one end of the spring in position relative to the spindle and upon which the bias force of the spring acts to bias the castor wheel 54 to which the spindle 62 is connected outward (in use downward) of the brace member. [0043] The spring-load (the bias force) provided by the elastomeric element is sufficient to lift an associated rail off the supporting surface on which the castor wheels are thus located. There are however, many different types of castor arrangements having this functionality each of which could be used in the arrangement described herein. [0044] The spring-loaded castor as depicted in Figure 6 is in the condition such that the wheel of the castor has been pushed up towards the base of the brace member 30, where the spindle of castor arrangement has been also been pushed up into the castor housing. In this condition the foot structure 34 of the rail associated with the castor arrangement is in contact with the supporting surface and thus the stepladder is in use having a person thereon weighing it down against the bias of the castor. [0045] Figure 5 depicts the wheel of the castor biased downward thus raising the associated rail above the supporting surface, and in this condition, if two such castors are in the same state of operation the stepladder is readily moveable using the castor wheels which can both roll and turn to provide maneuverability. The rails not associated with a castor arrangement can thus be lifted and the weight of the stepladder shifted to the castor wheels allowing the stepladder to be readily moved. In the embodiment depicted in Figure 1 both the front and rear pairs of rails (20 and 22) are associated with castor arrangements.

Claims (5)

1. A castor arrangement for a step or platform ladder operable on a supporting surface having a pair of rails supporting at least one horizontal member, the castor arrangement comprising, a brace member located between a rail and the horizontal member to brace the rail with respect to the horizontal member, and a castor assembly associated with the brace member wherein, in use, the castor assembly raises the respective rail above the supporting surface.

2. A castor arrangement according to claim 1 wherein a top surface of the brace member abuts an underside surface of the horizontal member.

3. A castor arrangement according to claim 1 further comprising: a castor assembly has a wheel rotatable on an axle supported by a frame and a spindle connected to the frame, and a biasing element to bias the spindle and associated wheel away from the brace member to raise a respective rail off the supporting surface.

4. A castor arrangement according to claim 1 wherein the biasing element is an elastomeric element.

5. A step or platform ladder operable on a supporting surface having at least a pair of rails and at least one horizontal member between the pair of rails, the ladder comprising: two brace members bracing the same horizontal member and a respective rail of the pair of rails, each brace member including a castor assembly wherein, in use, the castor assembly raises the respective rail above the supporting surface.