WO2010022340A1

WO2010022340A1 - Ladder

Info

Publication number: WO2010022340A1
Application number: PCT/US2009/054630
Authority: WO
Inventors: Rory Frick; Tyler Frick; Zach Frick
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-08-22
Filing date: 2009-08-21
Publication date: 2010-02-25
Anticipated expiration: 2011-02-22

Abstract

A ladder having platform steps, the ladder being convertible between a deployed position for supporting a person or other load, to a storage, scaffold, or ramp position in which the steps lie in a generally planar arrangement. When deployed, the ladder steps remain parallel to each other and form a series of parallelograms with the rails of the ladder. The ladder is also capable of being locked or secured at various angles of deployment.

Description

LADDER

FIELD OF THE INVENTION

[0001] The invention relates to the field of ladders and scaffolding, particularly ladders with platform steps.

RELATED APPLICATIONS

[0002] This application claims priority to US provisional application

61/091,079 filed on August 22, 2008. Thai application is incorporated here by reference.

BACKGROUND OF THE INVENTION

[0003] The ladder of the present invention is a platform step ladder designed to allow the ladder to be positioned at various inclinations, while allowing the platform steps to remain generally parallel to the ground. In another configuration, the platform steps of the ladder can align to form a generally or substantially continuous planar surface to allow the ladder to be used as a platform or as a ramp. In alternate embodiments, the ladder of the present invention can include mechanisms to allow the ladder to be locked or secured at a particular inclination. Additionally, the ladder can include a wheeled base to allow the ladder to be moved from place to place.

SUMMARY OF THE INVENTION

[0004] The ladder base consists of a rectangular frame with four forward attachment brackets and four rear brackets extending upwards from the base. The ladder frame includes a plurality of ladder frame rails and a plurality of steps located between the rails. Pairs of ladder frame rails are connected by support or pivot rods, similar in form to the rungs of a conventional ladder, to form a front frame and a rear frame. In the preferred embodiment, the support rods are welded to the frame rails. In alternate embodiments, the support rods fit through apertures in the rails and are secured to the rails by welds, mechanical fasteners such as threads and nuts, or cotter pins. While the support rods may be free to rotate with respect to the ladder rails, it is not necessary. The platform or steps of each ladder link the front frame and the rear frame. The ladder frame rails attach to the brackets of the base with pivot rods welded to the ladder frame rails, In other embodiments, other means of attachment, such as rivets, nuts and bolts, pins, or other fasteners can be used to pivotably attach the rails to the base.

[0005] The steps or platforms of the ladder are free to rotate about or hinge around the support rods connecting the ladder rails. The pivot arrangement may be improved by means of fitted bushings. The steps are made of a center brace, two end brackets and three support brackets with a tread plate on the top side of the bracket weldment. The steps are secured to the frame with support or pivot rods inserted through the steps and welded to the frame rails. At the ends of the ladder frame are four locking brackets that engage the lock pins to secure the assembly in the ramp or scaffold function.

[0006] When assembled, the ladder is adjustable so that it may be inclined at different angles with respect to the ground while allowing the platform steps to remain generally parallel to the base of the assembly, which is intended to be placed on the ground. As the ladder frame rails rotate with respect to the base, the steps and base act to keep the four rails parallel at any pitch angle. When the ladder is collapsed, the steps line up to form the surface of a scaffold or ramp.

[0007] At or near the top end of the ladder frame, various attachments can be added for certain applications, allowing the ladder to attach to or interface with another object, such as a rail on the side of a farm implement or a receiver mounted on a flatbed trailer. Of course, the ladder can be deployed free-standing against a wall or other structure, or attachments such as hooks, a roller and track configuration or a bracket assembly for securing to a flatbed type semi trailer. Pneumatics or hydraulics could also be implemented to actuate one pair of the rails to quickly flatten the ladder to make a ramp or slide. In other embodiments, supports or jacks between the ladder rails and the ground or other reference surface can be used to secure the ladder at a particular inclination.

[0008] The ladder of the present invention can be described as having three main components:

j ) Ladder frames

2) Ladder base and steps

3) application/attachment assembly 1) Ladder frame:

[0009] Components of ladder frames include a plurality of rails, and a plurality of support rods. In the preferred embodiment, four rails are used. The support rods connect pairs of rails, in a fashion similar to ladder rungs, to form what are akin to two norma] ladders. The spacing of the support rods can vary depending upon the application of the ladder. The spacing of the support rods on each frame will be similar, so that the steps linking the two ladder frames will maintain the same angle with respect to each other. The two ladder frames are linked by the base and steps, the support rods pivotably or hingedly supporting the platform steps. Components of ladder frame can be assembled in a manner that when in an unfolded working position at a 45 degree pitch, ladder will give the appearance of a flight of stairs.

[0010] In addition, when the ladder frame is in a folded position or storage position, it can be used as a ramp or scaffolding, as the steps of the ladder fold to lie in a generally planar arrangement between the rails.

2) Ladder base and steps:

[001 3] The bottom of the ladder frame pivotably attaches to brackets on the ladder base. The base includes brackets that are offset in height. The offset allows one set of frame rails to overlie another set of frame rails, allowing the ladder to fold and form a platform or scaffold surface. Once the frame is attached to base and steps are attached to the support rods, the ladder may be set at different angles, and the steps will remain parallel to the base. While the brackets may be placed at the corners of the base, it is advantageous to have the based extend some distance in front of the front set of brackets. The extension of the base provides leverage to resist the torque that may be generated by loads on the steps of the ladder when the ladder is in use. The base may also include handles on its periphery to allow ease of carrying. The handles can also provide the user a convenient handhold when deploying or stowing the ladder when the ladder is used in a track mounted configuration.

[0012] The ladder base will also provide secure footing for the ladder assembly in addition to having a locking device to be used when ladder is in a folded down position for use as a ramp or for storage. The ladder base is optional, and a ladder consistent with the invention described herein can be constructed without a base. In such an embodiment, the locking mechanism to lock the two ladder frames together is located on the steps, or on the rails.

[0013] In a ladder that does not have a base, the steps link the two ladder frames. In such an embodiment, the ends of the rails may include height adjustment devices to assist in leveling the ladder frames on uneven ground.

[0014] The linkage provided by the base and steps allows the ladder of the present invention to be used at an infinite number of pitches between 0-90 degrees, since the angle formed by the rails with respect to the ground may change, although the platform steps remain parallel to the ground and to each other. When viewed from the side, the frame rails and the steps form a parallelogram.

[0015] The ability to keep the steps parallel is of benefit if the top of the ladder is fixed to a piece of machinery, such as a farm implement or flatbed trailer. The ladder can be deployed to varying levels, such as the ground or a pickup truck bed, while the steps remain parallel to the ground in either instance.

[0016] Additionally, the ladder, when in folded so that the ladder rails lie against one another, or so the base and the rails are parallel, the steps form a generally planar surface, so that the ladder can be uses as a platform or a ramp.

3) Application/attachment assembly:

[0017] ϊn some applications, the top end of ladder simply rests freely against the work area. However, the ladder of the present invention can accommodate optional attachments at the top end of ladder, allowing the ladder to be more securely fixed to an object or work area. Such attachments described herein allow mounting the ladder to all types of machinery, vehicles, and buildings etc. Application/attachment assemblies may consist of one or a combination of the following. 1) Hooks attached to top of ladder may be used to secure ladder to a rod on any given fixed point. 2) Square, rectangular, round tubing or post material or any combination may be pivotably attached to the ladder, allowing the post to be placed in a suitable receiver on the work area. An example of such a receiver would be a vertical hole, receiver, or stake pocket in the frame of a flatbed trailer; 3) Any other form of receiver that will firmly secure ladder to any fixed point. [0018] The above assemblies may also be used on both of ladder ends so as when ladder is in a closed or folded position, it can be used as a form of scaffolding or ramp between two fixed points.

[0019] The ladder assembly may be made of one or more of the following materials; aluminum, steel, fiberglass, wood, composites, or any other material of suitable strength and durability.

[0020] The length of ladder assembly can be as long as desired, but a!so remaining within an acceptable standard of safety. Lengths will be determined according to application.

[0021] The width of ladder can also vary according to application and desire while remaining within a standard of safety.

[0022] Step construction: standard placement of step assembly within ladder frame shall be 12" center to center as is on conventional ladders from rung to rung. This can also deviate from standard if desired. Step assembly depth or length shall also be as desired. If ladder is to be used as a ramp also, depth/length of step shall be great enough to allow steps to meet end to end while in folded position. Step assembly depth/length can be decreased if desired.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view of the ladder in a deployed configuration.

[0024] Figure 2 is a perspective view of the ladder in a stowed or scaffold configuration.

[0025] Figure 2a is a close-up partial perspective view of a portion of Figure

2.

[0026] Figure 3 is an underside partial perspective view of a representative step assembled on the ladder.

[0027] Figure 4 is a top perspective view of a step. [0028] Figure 5 is a top partial perspective view of the base and bottom step assembled on the ladder, the foot support surface of the step removed.

[0029] Figure 6 is a top perspective view of a base.

[003Oj Figure 7 is a top partial perspective view of the top step assembied on the ladder.

[0031 ] Figure 8 is a top partial perspective view of the top of the ladder with a staker.

[0032J Figure 9 is a top partial perspective view of the top of the ladder attached to rollers and track.

[0033] Figure 10 is a top perspective view of a base having stability extensions and handles.

[0034] Figure 1 1 is a perspective view of a ladder with supports to adjust the inclination of the ladder.

[0035] Figure 12 is a perspective view of a ladder with supports to adjust the inclination of the ladder and a handrail.

[0036] Figure 13 is perspective view of a ladder with supports to adjust the inclination of the ladder, a handrail, and a wheeled base.

[0037] Figure 14 is a partial perspective view of a linkage for adjusting the inclination of the ladder.

[0038] Figure 15 is a top plan view of an infinitely adjustable linkage mounted on the ladder.

[0039] Figure 16 is a side elevational view of an infinitely adjustable linkage mounted on the ladder.

[0040] Figure 17 is a partial perspective view of a ladder fixed to an object and having adjustable actuators to adjust the level of the steps.

[0041] Figure 18 is a side view of a ladder rail having a height adjuster. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0042] The ladder 10 includes four ladder rails 15a-d, each having a top end lόa~d and a bottom end 17a-d. Each rail 15a-d is pivotably connected at their bottom ends 17a-d to a base 18. In the preferred embodiment, the rails 15a-d are square metai tube stock, although other materials, such as solid stock, I beams, angle iron, channel stock, fiberglass, composites, and lumber, could be utilized to form the rails. It is not necessary that the rails be of tube stock. While the rails are square in the preferred embodiment, they may also be of any convenient shape. The length of the rails can vary, although for flatbed trailer applications, it is preferred that the rails be at least 60 in length. It is preferred that at least two of the ladder rails extend 48 inches above the top most step, here step 20a, to provide for a hand grip when a person is on the top most step 20a.

[0043] Each rail 15a-d is pivotaliy attached to a plurality of steps 20a-g positioned at generally equal intervals between the rail top ends 16a-d and the rail bottom ends 17 a-d. The intervals closely match the length of the steps 20, so that the steps form a nearly continuous surface when the ladder 10 is in the folded or ramp configuration shown in Figure 2. In the preferred embodiment, the steps 20 are seven in number and are approximateiy 12 inches square.

[0044] The steps 20a-g are pivotaliy attached to the rails 15a-d by support rods 25a-n that extend between pairs of rails, much like the rungs of a traditional ladder. So constructed, the ladder has a first frame 1 1 and a second frame 12 linked together by the plurality of steps 20a-g. In the embodiments shown in the figures, support rods 25 h-n connect rails 15c and 15d to form the first frame 1 1. The support rods 25a-g connect rails 15a and 15b to form the second frame 12, The support rods 25a-n fit through apertures in the rails 15 a-d and are secured at their terminal ends by welding the support rod ends to the outside surface of the raii. It is also possible to weld the rods at any area in which the rod and the rail contact each other. In other embodiments, the support rods need not go through apertures in the rails, but may be attached to brackets attached to the exterior surface of the rails, or attached to the surface of the rails themselves without the need for brackets. One skilled in the art will recognize that there are may ways to attach the rods to the rails so that the rods will support the steps 20 a-g and allow the steps to move relative to the rails as the angle of the rails with respect to the ground is changed. [0045] In other embodiments, the steps 20a-g are fastened to the rails 15a-d by fasteners, such as nuts and bolts, rivets, pins, or other fasteners known in the industry. In such embodiments, the steps 20a-g in conjunction with the fasteners act to connect the rails to each other.

[0046] The steps 20a-g are shown in detail with reference to a single step in

Figures 3-5. The steps 20 are generally 12 inches square, but one skilled in the art will recognize that the dimension of the steps may be change to suit the application. Each step includes a frame 21 formed by a pair of side members 22a and 22b spaced apart by cross members 23 a-c. The members are preferably joined by welding. A tread plate or other foot support surface 28 overlies the frame 21.

[0047] The side members 22a and 22 b include apertures to accept a support rod 25. The side members 22a and 22 b can be "L" shaped to allow pairs of apertures 26a-b and 27a-b to be offset vertically. The vertical offset is generally the same as the height of a rail, the offset allowing the rails to lie against or in close proximity to one another when the ladder 10 is in the folded, collapsed, storage, or ramp configuration shown in Figure 2. In other embodiments, be side members can be straight, and include downwardly extending brackets to produce the offset. A bushing 121a-d may be placed in the apertures to allow the step 20 to rotate about the rod 25 in an improved fashion. The steps may be spaced apart form the rails by spacers that fit over the rods, the spacers having a diameter larger that the diameter of apertures in the brackets attaching the steps to the rods so as to keep distance between the rails and the steps.

[0048] In alternate embodiments, the brackets are planar metal members with an aperture to accept the rods 25, or other fastener, and thereby allow the step 20 to rotate with respect to the rod 25 or ether fastener. In alternate embodiments, the bracket 30 may be fixed to the fastener, rod 25, or other member, and the fastener allowed to rotate with respect to the rail 15. The apertures in the brackets are offset vertically by a distance equal to the overall height of one rail. The bracket will also allow a surface for welding the support rod in a metal construction.

[0049] The offset of the apertures 27a-b and 27a-b in the side members 22a and 22b is approximately the width of a side rail 15 from front to back. In the preferred embodiment, the offset is approximately 1.25 inches. This offset allows the ladder to form a platform when in the stowed configuration by allowing the rails 15 b and 15 c to lie in close proximity or against each other, as shown in figure 2. Thus, the offset is controlled somewhat by the width of the rails and the placement of the apertures in the rails.

[0050] In other embodiments, a step 20 may be constructed out of a single piece of material. Such material may include metal, wood, plastic, composites, or any other material known to one skilled in the art. For instance, the step 20 may be made as a blow- molded piece of plastic. Such a step may include reinforcing ribs made of plastic or some other materia! such as metal, but may not necessarily need such reinforcement. The single piece step may include a first set of apertures and a second set of apertures vertically off-set from the first set of apertures.

[0051] The base 18 of the preferred embodiment includes a frame composed of four side members 45a-d connected to form a rigid structure. The base 18 is preferably a welded fabrication consisting of two end tubes 45b and 45d and two side tubes 45a and 45c of the same stock size as the rails 15a-d. One skilled in the art will recognize that other sizes and materials may be used to construct the base 18. The end tubes 45b and 45d and the two side tubes 45a and 45 c form a frame that is generally rectangular with dimensions allowing that the rails of the first frame 11 will be separated by at least the overall width of one step assembly, and is the foundation for the hinge brackets.

[0052] The hinge brackets 50a-d connect the four rails 15a-d with a minimal amount of free-play, but to allow for free rotation. The hinge brackets holding the first frame 1 1 are preferably spaced apart on the base 18 from the brackets holding the second frame 12 at the same distance that horizontally separates the apertures on the side member 22. The hinge brackets 50 a-d are generally upstanding planar members that include apertures 56 to accept the connecting rods 25. The apertures are vertically offset by approximately the same distance as the apertures 26a and 27a of the steps 20 in order to allow the ladder 10 to fold into a generally flat configuration. In such a folded configuration, the steps 20a-g form a support surface. When in a folded configuration the first frame 1 1 lies over the second frame 12. In the folded configuration, the first frame 1 1 is displaced from the second frame 12 in the horizontal direction by the horizontal distance between the apertures 26 and 27 of the step 20 side member 22. [0053] It is preferred that there is structure to secure the ladder 10 in the folded or platform position shown in Figure 2. In the preferred embodiment, the locking structure secures the first frame 1 1 to the second frame 12. On skilled in the art will recognize that other components can be secured together to maintain the ladder 30 in the platform or folded configuration.

[0054] As shown in figure 2a, the locking structure includes a lock plate 60 with a slot 61 to engage a locking pin 62 and a hole to attach to one end of one support rod 25. Such structure can be placed at or near the ends of the rails on both sides of the ladder 10, as shown in Figures 1 and 2. The lock plate 60 is a generally planar member. The slot 61 is offset from the hole a distance equal to the overall height of one rail 15, and is shaped so that the slot 61 is a small section of a circular arc of a radius that is equal to the overall height of one rail 61. This will allow the lock plate 60 to engage the lock pin 62 smoothly over an angle of approximately 16 degrees. In this arrangement, the support rod 25g is not fastened to the bracket 50a or rail 15, but directly to the lock plate 60 itself allowing for free rotation of the entire length of the support rod 25 g.

[0055] The top end 16a and 16b of the rails 15 a and 15 b may include accessories to allow the ladder 10 to attach or interact with work surfaces or other objects. The top ends 16a and 16b need not be the extreme terminus of the rails 15, but are generally beyond the midpoint of the rails. The top ends 16a and 16b may include hooks 70a and 70b. The hooks 70a and 70b may be formed as an integral part of the rails 15a and 15b, or be separate components attached to the rails by welding, fasteners, or other means or structures known in the art to attach components together.

[0056] The top end may also include brackets 72a and 72b to accept a generally "T" shaped stake or post 75. The post 75 is a structure that allows the ladder to be fixed to another structure such as a flatbed trailer. The post 75 includes a portion that is affixed to the other structure and a second portion that is allowed to rotate with respect to the rails 15 of the ladder 10. In the preferred embodiment the post 75 includes a horizontal portion that is free to rotate in the brackets 72, thus allowing the post 75 to rotate with respect to the rails about an axis that is parallel to the plane of any one of the steps 20a-g. The post 75 has a downwardly extending appendage 76 that can be accepted by a receiver 90, such as a hole in the frame of a flatbed trailer. One skilled in the art will recognize that other receivers can be used to accept the post 75 and that other configurations can be used for the r post such that the post can be fixed to an object and allow the ladder to rotate about the post 75.

[0057] The top ends 16a and 16b may include wheels 80 or other rolling members. The wheels 80 can interact with track 78 mounted to a work surface such as a piece of heavy equipment or flatbed trailer. The track is preferably mounted in a horizontal position, with an end 79 presented or exposed to a user. The track has a length that is preferably equal to the length from the place on the rail that the wheel is mounted to the base of the ladder. This arrangement allows the ladder to be placed in its flat or stowed configuration and then slid along the tracks 78 to be stowed. In such a stowed configuration, the ladder 10 can also be used as a work platform, as the tread plates 28 of the steps 20a;g will form a generally planar surface.

[0058] In an alternate embodiment shown in figure 10, the base 1 18 can include an extension 120 that extends in front of brackets 150c and 150d. Described another way, the brackets are not placed at the corners of the base 18, but are instead displaced from the corners. The extension 120 may include handles 160a and 160b. Handles 160a and 160b may be placed on the sides of the base 1 18. In other respects, the base 1 18 is similar to base 18.

[0059] In alternate embodiments as shown in Figures 1 1 -13, the ladder 210 can be supported by supports 290a and 290b. The supports have one end pivotably attached to the ladder frame rails 215a and 215b, preferably at the rail top ends to improve leverage. However, they may be positioned anywhere along the length of the rails, or may be pivotably attached to any other members of the ladder frame.

[0060] The supports 290a and 290b can be adjusted to vary the inclination of the ladder 210. The supports 290a and 290b can be adjusted by allowing a first support members 291 a and b to slide within the second support members 292a and 292 b. The sliding members may be fixed in place by a pin placed in apertures, locking collars, or other means known to secure sliding members. In other embodiments, the supports may be pneumatically or hydraulically operated.

[0061] The alternate ladder may include a handrail assembly 280 shown in

Figures 12 and 13. The handrail assembly 280 includes a first upright or stanchion 281 fixably mounted to the uppermost step, and a second upright or stanchion 282 fixably mounted to the base 210. The stanchions are pivotably connected to a handrail 285 that extends there between.

[0062] In other embodiments, the ladder, such as the ladder 210, can be mounted on a wheeled frame 300, to allow the ladder to easily be moved from place to place. The wheeled frame 300 includes wheels 310 mounted near the corners. The frame includes brackets 395 to pivotably mount the supports 290a and 290b.

[0063] In any of the ladder embodiments, the ladder may be locked in a particular inclination using a linkage 370 between the ladder side rails such as between 15a and 15d or 15b and 15c. Such linkage links the first frame 11 to the second frame 12. As shown in figure 13, the linkage 370 is pivotably attached to side rail 15c, and extends to side rail 15b, where one of a plurality of slots 375 engages a pin 380 to selectively lock the ladder inclination. One skilled in the art will recognize that other mechanisms or structures can be used to lock or otherwise secure the inclination of the ladder.

[0064] An alternative linkage that allows infinite adjustment is shown in figure 15. The alternate linkage includes a first slotted linking member 471 and a second slotted linking member 472, each liking member having a slot to sunning the length of the linking member. The linking members 471 and 472 are arranged on either side of rails 15a and 15d so that the rails are between the linking members 471 and 472 and the slots of the linking members are aligned with each other. The linking members 471 and 472 are secured to the rails 15a and 15d by fasteners such as nuts 410 and bolts 420. Other fasteners can be used so long as the linking members are allowed to pivot with respect to the rails 15a and ] 5d. In the preferred embodiment, the connection between the linking members 471 and 472 and rail 15a allows pivoting, but does not allow the fastener to move along the slot. Thus the ladder rail 15a is translationally fixed with respect to the linking members 471 and 472. Rail 15d is not translationally fixed with respect to the liking members 471 and 472, and the fastener is allowed to slide in the slots of the linking members 471 and 472. In order to restrain or limit the translational movement, a stop 480 is placed in the slot. The stop 480 can be a nut and bolt. In the preferred embodiment, the stop 480 is a cam action lever clamp that allows the user to selectively secure and unsecure the stop at a position in the slot. The cam action lever clamp includes a stud or post 481 that is inserted in the slot and a cam action lever 482 that attaches to the post 481. A spacer 484 is paced about the post 481 to allow the clamp to grasp the linking member 472 between the lever 482 and the spacer 484, and linking member 471 between the post 481 and the spacer 484. To improve friction, the inside surfaces of the unking members 471 or 472 or the spacer 484 may include surface features such as ridges, grooves 485, or other structures to increase friction.

[0065] In another embodiment, shown in Figure 17, the second frame 12 is fixed or attached to another object so that the first frame is allowed to pivot about the attachment. In the embodiment shown in figure 17, the support rod 25g is fixed in place so that the second frame 12 can pivot with respect to it, but is fixed in other degrees of freedom of movement. The first frame is pivotably connected to adjustable actuators 700a and 700b. The adjustable actuators 700a and 700b are fixed to an object such as the object fixed to the second frame 12, or to yet another object such as the ground. The adjustable actuators are then used to adjust the angle of the steps 10 by moving the first frame 1 1 with respect to the fixed second frame 12.

[0066] The ladder 10 may be constructed without the base 18. In such an embodiment, it may be useful to have the bottom ends 17c and 17b of the rails 15c and 15d of the first frame 1 1 be slightly longer than the bottom ends 17a and 17b of the rails 15a and 15b of the second frame. The extra length will depend upon the vertical offset used on the steps 20. The additional length allows for the steps to be level when the ladder 10 with out the base 18 is placed on level ground. The vertical off set is typically the height of one rail 15, as previously discussed.

[0067] The bottom ends 17a-d of the rails 15a-d may also include height adjusters. A representative height adjuster 750 is shown in figure 17. While only one adjuster is shown, it may be applied to any of the rails I5a-d. The adjuster 750 operates by allowing a adjuster support members751 to slide within the rail 15. The support member is sized 751 to fit within the rail 15. The support member 751 and the rail are fixed in place by a pin placed in an aperture 752 in the rail 15, and in one of a plurality of apertures 755, In other embodiments, locking collars, or other means known to secure sliding members may be used. In other embodiments, the supports may be pneumatically or hydraulically operated. When the ladder 10 is used without the base 18, the adjuster support member 751 will contact the ground or other surface. When used with a base 18, the adjuster support member 751 may include an additional aperture 760 for attachment to the base 18 in the place of the bottom ends 17a-d of the rails 15a-d. [0068] The embodiments described herein are merely examples and are not meant to limit the scope of the invention.

Claims

We claim:

1. A ladder, convertible from a ladder configuration to a platform configuration, including:

A first and second ladder frame, each ladder frame including two rails connected by a plurality of support rods,

A plurality of steps, each step connected to a support rod on the first ladder frame and to a support rod on the second ladder frame,

A base pivotably connected to the first ladder frame and to the second ladder frame,

The first and second ladder frames maintaining a parallel relationship as the ladder is converted from a ladder configuration to a platform configuration.

2. The Sadder of claim 1, wherein the first ladder frame and the second ladder frame are linked by a member to lock the ladder at a particular inclination with respect to the base.

3. The ladder of claim 2, wherein the member linking the first and second ladder frames is pivotably attached to at least one of the ladder frames.

4. The ladder frame of claim 3 wherein the member linking the first and second ladder frames includes a slot having a stop, the stop being selectively secured in the slot,

5. The ladder of claim 1, wherein the first ladder frame and the second ladder frame include structures that cooperate to secure the first frame to the second frame when the ladder in the platform configuration,

7. The ladder of claim 1 , where in the ladder includes a staker to secure the ladder to an object.

8. The ladder of claim 1, wherein the second frame includes hooks to secure the ladder to an object.

9. A ladder having a plurality of platform steps, a plurality of rails, and a base, the rails being pivotably attached to the base, the platform steps being pivotably attached to the rails so that at least two platform steps are parallel to each other when the rails are pivoted with respect to the base.

10. The ladder of claim 9, wherein the two platform steps and two side rails describe a parallelogram.

1 1. The ladder of claim 9, wherein all of the platform steps are parallel to each other.

12. The ladder of claim 9, further including a post pivotably attached to the ladder.

33. The ladder of claim 9, where in the ladder may be locked at any inclination between 0 and 90 degrees with respect to the base.

14. A ladder convertible from a ladder having platform steps to a platform wherein the steps align, the ladder including:

a plurality of rails connected to form a first frame and a second frame, and

a plurality of steps pivotably connecting the first frame to the second frame, at least two of the steps remaining parallel to each other as the ladder is converted to a platform.

35. The ladder of claim 14, wherein in the platform configuration, the platform steps align to form a substantially planar surface.

16. The ladder of claim 14, where in the ladder includes a base connecting the first frame and the second frame.

] 8. The ladder of claim 14, wherein the first frame is selectively secured to the second fame so that the frames do not pivot with respect to the steps.

19. The ladder of ciaim 14, wherein the first frame lies over the second frame when the ladder is in the platform configuration.

20. The ladder of claim 14, where in the rails include height adjusters.