WO2006012561A2

WO2006012561A2 - Self attaching ladder dolly and method

Info

Publication number: WO2006012561A2
Application number: PCT/US2005/026167
Authority: WO
Inventors: Kenneth Gayle Sebastian
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-07-22
Filing date: 2005-07-21
Publication date: 2006-02-02
Anticipated expiration: 2007-01-22
Also published as: WO2006012561A3

Abstract

A self attaching ladder dolly is convertible and combinable. The ladder dolly functions as a step or seat in a stationary configuration and as part of a hand truck in a movable configuration. The ladder dolly is convertible from the step or seat to part of the hand truck by placement of any of a variety of ladders within a frame of the ladder dolly and by a clamping action that automatically occurs when a user moves the Madder dolly from the stationary configuration to the movable configuration. The frame is raised as wheels are protracted when a platform is moved into a deployed forwardly extending position of the movable configuration. With the ladder attached, the combination ladder and ladder dolly form a hand truck device for conveniently transporting the ladder and other equipment to and from a work site.

Description

SELF ATTACHING LADDER DOLLY AND METHOD

This application claims priority to U.S. Provisional Patent Application Serial No. 60/590,828, filed July 22, 2004, entitled SELF ATTACHING DOLLY FOR LADDERS, by the same inventor, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention generally relates to an accessory for any type of ladder, and specifically to a device that, with a single motion, can be attached or detached from any type of ladder, and while attached can be utilized in conjunction with the ladder as a hand truck.

2. State of the Art

Service persons, such as electricians, plumbers, and heating and air conditioning mechanics, often work at sites remote from their shops or offices. Typically, tools and materials are transported to the work site using a service truck.

Also, it is common that many jobs require the use of a stepladder. Once the service truck is driven and parked close to the work site, the stepladder, tools, and materials for the specific job must be carried from the service truck to the work site. When working in a location that is remote from the parking area, significant time is spent carrying the stepladder, tools, and materials to and from the work site. For example, one trip between an upper floor of a high rise building and a remote parking location can take more than half an hour. If several trips are required to bring the stepladder, all the necessary tools, and materials to the work site, the total cost of the work is greatly increased. This results in either higher costs to the customer or losses for the service company. One way of carrying a stepladder, tools, and materials between the service truck and the work site is to use a hand truck. A hand truck enables the service person to carry multiple items with less exertion on the part of the service person. On the other hand, use of a hand track requires carrying the hand truck in the service track, which takes up precious space. In fact, it is well known that this space is often completely accounted for in accommodating the necessary ladder(s), tools, and materials.

While it is known to mount wheels on a stepladder for a combination that may function similar to a hand track, doing so has also caused drawbacks.

DISCLOSURE OF THE INVENTION

The present invention relates to an accessory for any type of ladder, and specifically to a device that may be attached to or detached from any ladder by a single motion, and while being attached can be utilized in conjunction with the ladder as a hand truck. In particular, the easy separability of the ladder from the accessory makes the present invention useful for converting between the separated state and the combined state.

The accessory may be a dolly that is clampingly attached to any of a variety of ladders in a movable position for enabling wheeled transport of the dolly and a ladder attached thereto in combination. The accessory or dolly thus has a fixed frame and a moveable frame that may be clamped together on the ladder in the moveable dolly configuration. The fixed frame and the moveable frame are released from the ladder in a stationary configuration in which the accessory is separated from the ladder for placement on a floor or the ground as a step or seat.

In a simple form, the accessory may be a convertible dolly for reliable transport of equipment. The dolly may include a fixed frame and a movable frame movably connected to the fixed frame and movable between a stationary configuration and a movable dolly configuration. The dolly may further include a pair of wheels that are rotatably supported on the movable frame. The dolly may include a deployable platform that is pivotally mounted on the movable frame and is movable between a seat position when the movable frame is in the stationary configuration and a deployed position when the movable frame is in the moveable dolly configuration. The deployable platform may generally overlie and rest on the fixed frame in the seat position and may lie completely outside a perimeter of the fixed frame in the deployed position.

The pair of wheels may be supported in a retracted position generally within a perimeter of the fixed frame when the movable frame is in the stationary configuration. On the other hand, the pair of wheels may be supported in an protracted position extending generally outside the perimeter of the fixed frame when the dolly is in the dolly configuration.

One of the fixed frame and the movable frame may include at least one retaining member. The dolly may further include an adjustable tension member that is adjustably supported on one of the fixed frame and the movable frame for adjustably varying a space between the adjustable tension member and the retaining member. In this regard, the fixed frame may have at least one retaining member for engagement with a first side of a ladder, and the movable frame may have at least one tension member for engagement with a second side of the ladder opposite to the first side. Movement of the movable frame from the stationary configuration to the movable dolly configuration may reduce a space between the retaining member and the tension member for clamping the ladder between the retaining member and the tension member in the dolly configuration.

In another simple form, the invention includes a dolly combinable with a ladder for conversion between a stationary support and a wheelable support. The dolly may include a first portion, a second portion, and an actuation mechanism interconnecting the first portion and the second portion. The actuation mechanism may cause at least one tension member adjustably supported on one of the first and second portions to be moved relative to at least one retaining member of the first portion in order to move the members between an attaching configuration and a release configuration for attaching and releasing the ladder.

The actuation mechanism may include a pivot connection pivotally connecting the first portion to the second portion along a first axis. At least one arm may form part of the second portion. The arm may be connected to and extend from the pivot connection. Movement of the arm may cause movement of the second portion relative to the first portion between the attaching and release configurations. The second portion may include at least one bracket interconnecting the pivot connection and the arm. A wheel may be rotatably supported by the bracket on a second axis offset from the first axis. Movement of the arm may rotate the bracket and move the wheel between a wheelable position extending outside a perimeter of the first portion and a stationary position within the perimeter. Movement of the second portion into the attaching configuration and a corresponding movement of the wheel into a wheelable position is adapted to constructively increase a height of the first portion of the dolly relative to the ground upon which the dolly is to be wheeled. In this regard, the second portion may further include the tension member. The tension member may be rotatably supported on the first portion. The tension member may be engaged directly or indirectly by the bracket and moved thereby between the attaching configuration and the release configuration.

It is to be understood that the pivot connection may be a first of a pair of pivot connections, the arm may be a first of a pair of arms, the bracket may be a first of a pair of brackets, and the wheel may be a first of a pair of wheels. Thus, the pairs of pivots, arms, brackets, and wheels may move generally in unison on opposite sides of the dolly when one or both of the arms is actuated. The dolly may further include a foldable platform interconnecting the pair of arms and rotatably movable between a stowed position superposed on the first portion and a deployed position in which a substantial portion of the platform extends away from the first portion.

The dolly may further include at least one latch pivotally connected to at least one of the arms. The latch may have an engaging portion for lockingly engaging a pin on the second portion. Thus, the latch may engage and lock the second portion in the attaching configuration. The engaging portion may be a first engaging portion, and the pin may be a first pin. The latch may further include a second engaging portion for lockingly engaging a second pin on the second portion. Thus, the latch may engage and lock the second pin on the second portion by the second engaging portion in the release configuration. The latch may further include a main body and a flange extending from the main body. The flange may have a width extending from the main body in a range from approximately one half inch to approximately three inches to facilitate pressing engagement by a user's hand or foot.

In another simple form, the invention includes a method of transporting equipment to or from a work site. The method may include attaching a ladder to a convertible dolly by a single manual motion, using the ladder to control the dolly, and moving the ladder and the dolly together as a unit. In this regard, the method may include converting the dolly from a stationary support configuration to a movable dolly configuration. The step of converting the dolly may include the step of attaching the ladder by moving one portion of the dolly relative to another portion of the dolly to engage the ladder therebetween. The step of converting the dolly may include the step of protracting a pair of wheels from a position generally within a perimeter of the dolly to a position extending out of the perimeter to wheelably engage the ground.

The step of attaching the ladder may include moving one portion of the dolly relative to another portion of the dolly to engage the ladder therebetween. The step of converting the dolly may include actuating an attaching mechanism. Actuating the actuating mechanism may simultaneously: move one portion of the dolly relative to another portion of the dolly to engage the ladder therebetween; protract a pair of wheels; and move a foldable platform from a position superposed on a remainder of the dolly corresponding to the stationary support configuration into a movable dolly configuration extending away from the dolly. The method may further include supporting at least one object on the platform in the movable dolly configuration and moving the ladder, the object, and dolly together as a unit to or from the work site. The advantages of the present invention include the provision of a device that may instantly attach itself during a single manual motion to any of variety of ladders. Likewise, the device advantageously instantly detaches itself from any of the variety of ladders during a single manual motion by a user. The accessory portion of the present invention, once attached to any type of ladder may be utilized for carrying tools, equipment, and/or materials between two locations. When attached to any type of ladder, the accessory will regularly project laterally and provide a wider wheelbase for better balancing of objects being transported by the combination device over any type of terrain. Once detached from any type of ladder, the accessory may be folded into a configuration adapted to form a step or seat. Alternatively or additionally, the accessory may be folded down in size for convenience of moving or storing the accessory. Furthermore, the integrity of any of a variety of ladders is not compromised by attaching or detaching the accessory therefrom.

In addition to the above described advantages, a height and depth of the accessory is automatically adjusted during attachment of a ladder thereto. The automatic adjustment accommodates typical obtrusions common to most stepladders or extension ladders. That is, step ladders typically have top plates and extension ladders typically have feet with a deeper extension that would otherwise obstruct proper clamping of the accessory on the ladders. However, the automatic height adjustment advantageously raises the accessory and avoids interference with these obstructions and enables direct, unobstructed, and flush attachment of the accessory to the vertical members of almost any ladder. Likewise, when the ladder is removed from the accessory, the accessory advantageously automatically readjusts to an open state by following the same path of motion in a reverse direction that once again avoids interference with the typical obstructions of most ladders.

While the accessory may include latches to hold it in a clamped position, the accessory may also advantageously use a weight of an object being transported to create a tension to securely attach the accessory to any of a variety of ladders. Even without the weight of an object being transported, the accessory may be advantageously and securely attached to any of a variety of ladders due to the configuration of the accessory and associated mechanical forces that are automatically exerted by the accessory when it is clamped on a ladder for the sole purpose of moving the ladder itself, for example. Further advantageously, the accessory may be quickly attached and detached from any type of ladder without the use of any tools or hardware.

Rather than mounting or fixing wheels on a ladder in a relatively permanent and protruding position, the accessory of the present invention is removable together with its wheels so that the ladder may be used without the wheels protruding and interfering with the work, mobility, or safety of a service worker. Thus, wheels placed at an upper step that would otherwise encroach on the user's upward movement, are removed before use of the ladder. Thus, encroachment on a user's space by such permanently mounted wheels may have otherwise caused the user to lean away from the stepladder instead of into it. Such encroachment and leaning presents a safety hazard, especially as the user ascends higher on the ladder. Therefore, the present invention advantageously provides easily removable wheels that will not remain and encroach on a user's space.

The capability of removing the accessory and wheels is also important because wheels that are permanently attached near a top plate of a ladder for a hand track configuration will almost surely protrude, push against a user's body, and/or interfere with the user's attempts to reach the sides of the ladder with his or her hands. In this way, permanently mounted wheels may present additional safety issues. Furthermore, such permanently attached wheels would have the disadvantage of protruding above the top of the ladder and would interfere with placement of objects on the top plate of the ladder as is typical when using stepladders. Thus, the easily removable accessory and wheels of the present invention advantageously free up this important space.

The separability of the accessory of the present invention from a ladder further provides the advantage of facilitating storage and transport of both the ladder and the accessory. In particular, the ladder(s) used with the present invention will not have an aggregated size in the separated state. Thus, the ladder(s) may be placed on a standard ladder rail that is typically provided on the top or side of a service truck. Li short, each of the ladder(s) and the accessory of the present invention are more easily stored and transported.

The foregoing and other features and advantages of the present invention will be apparent from the following more detailed description of the particular embodiments of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a device including a combination of an accessory and a ladder according to an embodiment of the present invention;

FIG. 2 is a perspective view of the accessory configured according to an embodiment of the present invention and disposed in a stationary state;

FIG. 3 is a perspective view of the accessory configured according to an embodiment of the present invention and disposed in an intermediate receiving state;

FIG. 4 is a perspective view of the accessory configured according to an embodiment of the present invention and disposed in a movable state;

FIG. 5 is a rear perspective view of the accessory configured according to an embodiment of the present invention and in the stationary state similar to Figure 2, yet having a platform portion removed for clarity;

FIG. 6 is a rear perspective view of the accessory configured according to an embodiment of the present invention and in the movable state similar to Figure 3, yet having the platform portion removed for clarity;

FIG. 7A is a front plan view of the accessory in the stationary state; FIG. 7B is a side plan view of the accessory of Figure 7 A;

FIG. 8 A is a front plan view of the accessory in the intermediate receiving state;

FIG. 8B is a side plan view of the accessory of Figure 8A;

FIG. 9A is a front plan view of the accessory in the movable state;

FIG. 9B is a side plan view of the accessory of Figure 9A;

FIG. 10 is an exploded perspective view of a first portion of the accessory; and

FIG. 11 is an exploded perspective view of the second portion and the platform portion of the accessory.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As discussed above, embodiments of the present invention relate to an accessory for any type of ladder, and specifically to a device that, with a single motion, can be attached or detached from any type of ladder, and while attached can be utilized in conjunction with the ladder as a hand truck.

The accompanying drawings have numerals associated with elements of the device of the present invention as follows: 5 overall device, 7 accessory, 10 frame, 12 carriage, 14 vertical supports, 16 retaining bar spacer, 18 top retaining bar, 20 bottom retaining bar, 22 alignment brace, 24 catch pin, 26 carriage retaining pin, 28 multi function bracket, 30 platform arm, 32 wheel, 33 axle lock nut, 34 axle bolt, 35 latch bolt, 36 pivot bolt, 37 latch lock nut, 38 dual latch, 39 single latch, 40 left tension bracket, 42 right tension bracket, 44 follower pin, 46 adjustment pin, 48 adjustable tension bar, 50 hinge housing, 52 hinge pin, 54 folding platform, 55 platform support bar, 58 return tab, 60 spacer, 62 ladder, 64 pivot hole, 66 axle hole, 70 ecentric hole, 72 latch spring, 74 accessory connection point, 76 pivot bolt lock nut.

Figure 1 shows a perspective front view of an embodiment of the invention. An overall device 5 may include an accessory 7 in the form of a self-attaching dolly for ladders. As shown, the accessory has a ladder 62 attached thereto to permit the device 5 to advantageously be used as a hand truck for supporting and carrying equipment on the platform 54 and the ladder 62 in its engaged condition when the device is in its movable state. Alternatively, the accessory can be converted into a stationary state as shown in Figure 2 by releasing the ladder 62 and folding the platform 54 into an overlying position for advantageous use as a step or seat.

The structure that provides these advantageous results includes a frame 10 including at least first and second frame members or portions, a carriage 12 including the foldable platform, and an adjustable tension bar 48. As shown in Figure 4, the first portion or frame member may include a left vertical support 14 and a right vertical support 14, spacer bars 16, top and bottom retaining bars 18, 20, and an alignment brace 22. An end of each of a plurality of retaining bar spacers 16 may be attached to one of a top and a bottom of each vertical support 14 at a rear of the frame 10. To this end, each retaining bar spacer 16 may be welded to the inside faces of the vertical supports. At the opposite front end of retaining bar spacer 16, a top retaining bar 18 and bottom retaining bar 20 may be attached perpendicular to and flush with the end of the retaining bar spacers 16. At an opposite end of the top retaining bar 18 relative to the retaining spacers 16, an alignment brace 22 may be attached to the spacers 16 and/or the vertical support bars 14 at a backside of vertical supports 14. The alignment brace 22 may include or have mounted thereto one or more accessory connection structure or point 74, which may be welded or otherwise fixed to the alignment brace 22 between each vertical support 14 for receipt of a handle or other additional accessory for the device 5. It is to be understood that the accessory connection structure may include a simple sleeve, a threaded connection, or a snap lock connection, for example. The carriage 12 may be composed of or include a second portion or frame member of the frame 10. This second portion of the frame 10 may include the platform arms 30, the multi-purpose brackets 28, the tension brackets 40, 42, the tension bar 48, and the foldable platform 54. A carriage catch pin 24 may be attached to bottom left and/or right retaining bar spacers 16 for retaining the carriage 12 relative to the first portion of the frame 10 in the movable state, as shown. A carriage retaining pin 26 may be attached to one of the vertical supports 14 for retaining the carriage 12 in a stationary or stowed state. On an inside of the vertical supports 14, a left tension bracket 40 and a right tension bracket 42 may attach an adjustable tension bar 48 to the vertical supports 14. The tension bar 48 may be advantageously adjustably supported on the tension brackets 40 and 42 as shown and described with regard to Figure 10 below. The left tension bracket 40 and the right tension bracket 42 could also be spring loaded to provide self adjusting of the tension bar. Further alternatively, the left and right tension brackets 40, 42 could be replaced by springs pivotally mounted on the vertical supports 14 and attached at first ends to respective ends of the tension bar 48. The second ends of the springs may engage in the multipurpose bracket and be pivotally moved similar to the tension brackets shown and described. This configuration would also advantageously provide automatic adjustment of the tension bar 48 relative to a thickness of a ladder engaged thereby.

Figures 2-4 show three different positions or states for the ladder dolly or accessory 7. The first position is the stowed position shown in Figure 2. In this position, the folding platform 54 is folded over the top of the frame 10 and rests on the retaining bar spacers 16 and the top retaining bar 18. The carriage 12 is rotated up with the platform arms 30 extending forwardly and upwardly at approximately forty- five degrees, in which position the dual latch 39 may be held in the locked position by one or more latch springs 72 against the carriage retaining pin(s) 26, (see also the exploded view of Figure 11.) In this stowed position, the accessory 7 may be used as a step stool, a small seat, or a surface on which to support materials or tools by clamping or under the influence of gravity. Figure 3 shows the ladder dolly or accessory 7 in an open or intermediate position with the foldable platform 54 oriented generally vertically. In this position, the accessory 7 is prepared to receive a ladder that may be inserted through a top of the frame 10 and rested on an underlying ground surface. Then the platform 54 and platform arms 30 may be rotated downward in a single movement to engage the accessory on the ladder and place the combination accessory 7 and ladder 62 in a movable condition to operate as a unitary device 5 as shown in Figure 1. Latched locking of the carriage in a position of use in the movable state in this manner will be described in greater detail below.

Figure 5 shows a rear perspective view of the accessory of Figure 2 without the platform 54 for clarity. Figure 5 provides an view for better understanding the operation of adjustable tension bar 48. In the position shown, the adjustable tension bar 48 is positioned outside the frame 10 and the tension brackets extend at approximately forty-five degrees relative to the frame 10. Multi-function brackets 28 are rotatably supported on the frame 10 and have the platform arms 30 fixed thereto. The multi-function brackets 28 include return tabs 58. Figure 5 also shows follower pins 44 in positions between return tabs 58 and the rest of multi-function brackets 28. The surfaces between the return tabs and the rest of the multi-function brackets form surface cam areas of the multi-function brackets 28. Figure 5 further shows the platform arms 30 extending approximately forty-five degrees upwardly towards the front of frame 10.

The wheels 32 are generally centered relative to a front and back direction of the frame 10. After the ladder has been inserted into the top of frame 10 in its position shown in Figure 3, the user simply pushes down on the tab of the dual latch 38 with his hand or foot to disengage dual latch 38 form carriage retaining pin 26. Once disengaged the user can continue to push down with his hand or foot until at least one of the single latch 39 and the dual latch 38 move into a locked position engaged with at least one of the carriage catch pins 24 to retain the carriage 12 in the position shown in Figure 4. This one simple maneuver performs several different functions. As shown in figure 4, the outer ends of platform arms 30 are flush with the ground and platform 54 is in the movable and/or loading position.

At the same time, as shown in figure 6, the multi-function bracket 28 and platform arms 30 will have rotated approximately ninety degrees relative to the vertical supports 14. This rotation causes the follower pin 44 to ride the cam surface area of the multi-function bracket 28 thereby forcing the left tension bracket 40 and the right tension bracket 42 to pivot forwardly. This in turn causes the adjustable tension bar 48 to push forward inside of frame 10 applying pressure to any vertical members of any ladder that has been placed inside the frame 10. It is to be understood that while the tension brackets 40, 42 and the tension bar 48 have been shown as separate members that are movably mounted relative to the multi-function brackets 28 and the platform arms 30, these members could be formed integrally or as one piece with each other without departing from the scope and spirit of the invention. Furthermore, the adjustable tension bar 48 can be rotated on its eccentric axes to accommodate the different thicknesses in ladders in accordance with the structure to be described with regard to Figure 10 below. This will ensure the proper tension to hold a ladder of a particular thickness in place. Figure 6 illustrates the position of the tension bar in the final position after the ladder has been placed and engaged by the accessory or ladder dolly 7.

In addition to the multi-function bracket 28 having been rotated by ninety degrees, the relative positions of the pivot holes 64, 65 and axle holes 66 have changed. This change moves the axle bolt 34 and wheels 32 from a retracted position within an outline of the frame 10 into a projected position in which the wheels 32 at least partially extend downwardly and to the rear outside the frame 10. This position of the multi-function brackets 28 and the wheels 32 corresponds to the movable state of the ladder dolly or accessory 7. Furthermore, the relative positioning of the pivot holes 64, 65 and the axle holes 66 results in the proper position of the wheels that is consistent with the leverage required for the device 5 to act as a hand truck. A related function and advantage of the multi-function bracket 28 is that when moved to the relative positions of the pivot holes 64, 65 and axle holes 66 shown in Figure 6, the wheels 32 lift the frame 10 to a predetermined height off the ground. Lifting the frame 10 off the ground advantageously accounts for and accommodates obtrusions such as a deeper top plate or feet that are common with most step ladders or extension ladders. The deeper top plates or deeper feet would most likely inhibit the flush attachment of the accessory or dolly 7 to the vertical members of such ladders. On the other hand, as the wheels raise the frame 10 during deployment of the foldable platform into the movable state, the frame moves upwardly above such deeper structures as the top plate or feet and engages on the vertical members of the ladder that present a generally uniform thickness. The alignment brace 22 assists in keeping the frame 10 in the same general vertical orientation and forward as the frame 10 is lifted from the ground by the wheels 32. Specifically, this action by alignment brace 22 may lift the bottom retaining bar 20 out and over any obstacles such as the top plate or feet of an associated ladder.

Figures 7 A, 8 A, and 9 A are front views and Figures 7B, 8B, and 9B are respective side views that illustrate the placement of the frame 10 and wheel 32 in the open stationary position, the intermediate receiving position, and the closed movable position, respectively. Figures 3, 4, 8B, and 9B also show the position of the dual latch 38 and single latch 39 to lock the carriage 12 in respective stowed stationary and a movable transport positions. In the position or state shown in Figures 1, 6, 9 A, and 9B, the dolly or accessory 7 of the present invention has been converted into the movable state for conversion of an ordinary stepladder 62 or extension ladder into a fully functional hand truck device 5. The conversion is achieved by simply lowering the folding platform 54 into the position of a platform on a conventional hand truck with a ladder inserted in the frame 10. Figures 7A-9B illustrate three positions of the self attaching dolly as have been described, including repositioning of the wheels relative to the frame 10, the raising of the frame, and the activation of the tension bar 48. As shown in Figure 9B, the tension bar 48 is moved forwardly as the platform arms 30 and platform 54 are moved into the deployed movable position. Thus, the tension bar 48 will clamp any ladder inserted into the frame 10 between the tension bar 48 and the retaining bars 18 and 20, as shown in Figure 1.

Once the objects including equipment, tools, and/or materials have been transported from a first location to a second location, the ladder 62 may simply be removed by pushing both single latch 39 and dual latch 38 with a hand or foot and by raising the folding platform 30 back to the open position. Once the right platform arm 30 is returned to its position extending forty-five degree upward and to the front, the dual latch 38 may engage the carriage retaining pin 26 and lock the accessory 7 in its open stationary position again.

It is to be noted that with the pressure of the adjustable tension bar 48 against the ladder in the combined movable state, the rest of the frame structure urges the carriage in a lifting direction so that the latches 38 and 39 exert a force in a direction of coming off the carriage catch pins 24. This tendency provides an unexpected benefit since it allows the user to release the single latch 39 and the dual latch 38 independently of each other. As either latch is released first the carriage 12 will twist slightly. This twisting of the carriage is just enough to keep that latch from reengaging while the other latch is being released. Therefore, there is no need to have to release both latches at the same time, thus making it easier to disengage the carriage 12 from the downwardly deployed position.

Placement of the carriage 12 in the stowed stationary state including lifting the carriage 12 is generally performed by reversing the steps for placing the platform in the downwardly deployed and movable state. Placing the carriage 12 into the stowed stationary state causes the multi-function bracket 28 to rotate approximately ninety degrees in the opposite direction to its original position. This movement repositions the pivot holes 64, 65 and axle hole 66 relative to each other, thereby retracting the wheels 32 and lowering frame 10 back into the stowed position generally within a perimeter of the frame 10. Thus, the frame 10 rests on the ground in an immobile or stationary state. One relative position that may not be reversed exactly is the position of the adjustable tension bar 48. As shown in Figures 5 and 9B, the follower pin 44 is pushed back to its original position by the return tab 58. This in turn rotates the left and right tension brackets 40 and 42 back approximately ninety degrees, thereby retracting the adjustable tension bar 48 and freeing any vertical members of a ladder that would otherwise remain clamped inside of the frame 10. Once the ladder has been removed and the folding platform 54 has been placed in a horizontal position generally overlying frame 10, the ladder dolly or accessory 7 can be used once again as a step stool, seat, and/or a small bench. Alternatively, the accessory 7 may simply be stowed away. Additionally, if the user desires, he may leave the ladder clamped in frame 10 and just lift the folding platform 54 to lie generally adjacent the front of the accessory 7. In this position, the ladder 62 and the accessory 7 may be stored together in an narrow space. For example, the combined device with the platform folded up adjacent to the accessory may be stored in an upright position and placed against any vertical flat surface.

Figure 10 shows an exploded view of the first portion of frame member of the ladder dolly or accessory 7 together with the tension bar 48 and its associated mounting components. The tension bar 48 and its associated mounting components are shown in an exploded view including one end of the tension bar having a threaded mounting hole 70 located eccentrically within the tension bar 48. This structure is utilized for adjustment of the tension bar 48. Each end of the tension bar may have an eccentric hole 70. A left tension bracket 40 and a right tension bracket 42 each have an elongated adjustment pin 46 fixed thereto and extending perpendicularly from an inside face of left and right tension brackets 40 and 42. The adjustment pins 46 may be made from a right hand threaded bar.

Advantageously, each adjustment pin 46 may be screwed all the way into each eccentric hole 70 in both ends of the tension bar 48 until it abuts a maximum depth and comes to a stop therein. Then one adjustment pin 48 may be rotated back out of the eccentric hole 70 approximately one turn or 360 degrees before being mounted. This allows the user to twist the tension bar 48 in either direction in a range between approximately zero and approximately 360 degrees. This twisting of the tension bar 48 causing any one of the four surfaces of the tension bar 48 to selectively face forward and provide four different depths between the tension bar and the retaining bars 18 and 20. This adjustable relationship is enabled by the eccentric hole 70, and provides the advantage of accommodating ladders of different thicknesses.

On an opposite face of the left and right tension brackets 40, 42 relative to the adjustment pins 46, a follower pin 44 may be fixed to extend perpendicularly from the opposite face for engagement and actuation by the multi-function bracket 48 to automatically cause movement of the tension bar 48 when the platform arms 30 are moved. This actuation has been described above with regard to the platform arms 30, multi-function brackets 28, and the return tabs 58. Figure 11 also shows these elements in an exploded perspective view of the carriage 12. In forming the ladder dolly or accessory 7, the pivot holes 65 may be drilled near the cam surface of the multi-function bracket 28 at a position generally centered relative to a width of the platform arms 30. The multi-function bracket 28 may include an L-shaped plate that is generally positioned upside down when the accessory 7 is in the movable position as shown in Figure 11. Axle holes 66 may be placed through the L-shaped plates in a bottom front portion of the upside down L-shaped portion of the multi function bracket 28.

The return tab 58 may be welded or otherwise fixed at a forty-five degree angle on the top of the L-shaped portion of the multi-function bracket 28 above pivot hole 65. The platform arms 30 may be welded or otherwise fixed to a front face of multi function bracket 28 in downwardly and forwardly extending positions that may be parallel to the return tabs 58. It is to be understood that the multi-function brackets 28, which may be considered to include the retaining tabs 58, and the platform arms 30 may be formed integrally or as one piece members that each includes a platform arm 30 and a bracket 28 having a return tab 58. A single latch 39 may be attached to one or both of the platform arms 30. Additionally or alternatively, a dual latch 38 may be attached to the other or both of the platform arms 30. Each latch may be attached with a latch bolt 35 and a latch locknut 37. A latch spring 72 may be located between each latch 38, 39 and a corresponding platform arm 30 to apply a biasing force in a locking direction.

The platform arms pivotally support the platform thereon. At the opposite side-to-side ends of platform, respective ones of the platform arms 30 support a hinge pin 52 that is received in a hinge housing 50 of the foldable platform 54. To this end, the hinge pin 52 may be placed through holes at the end of platform arm 30 and through the hinge housing 50 to form a hinge between the platform arms 30 and the platform 54. The hinge housing 50 may be formed directly in a material of the platform 54, or may be welded or otherwise fixed to the platform. The hinge pin 52 can be fixed to one of the platform 54 and the platform arms 30 such as by spot welding, for example. The hinge pin can thus rotate relative to the other of the platform 54 and the platform arms 30. A platform support bar 55 may be attached to each of the platform arms 30 and extend therebetween behind the hinge housing 50 to limit travel of folding platform 54.

The carriage 12 may be installed on the frame 10 on the outside face of vertical supports 14 by aligning pivot holes 65 on multi function bracket 28 and pivot holes 64 on the vertical supports 14. Spacers 60 may be placed on the inside and outside of the vertical supports 14 before aligning the left tension bracket 40, the right tension bracket 42, and the carriage 12. All of these components may be attached by inserting respective pivot bolts 36 through the tension brackets 40, 42, the multi¬ function bracket 28, the spacers 60, and the vertical supports 14, as shown. The wheels 32 may be mounted in axle hole 66 on multi function bracket 28 by the axle bolts 34. The axle bolts may be welded or otherwise affixed directly to the multi function bracket 28.

The embodiments and examples set forth herein were presented in order to best explain the present invention and its practical application and to thereby enable those of ordinary skill in the art to make and use the invention. However, those of ordinary skill in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the teachings above without departing from the spirit and scope of the forthcoming claims.

Claims

1. A convertible dolly for Tollable transport of equipment, the dolly comprising: a fixed frame; a movable frame movably connected to the fixed frame and movable between a stationary configuration and a movable dolly configuration; a pair of wheels rotatably supported on the movable frame;

2. The convertible dolly of claim 1, further comprising a deployable platform pivotally mounted on the movable frame and movable between a seat position when the movable frame is in the stationary configuration and a deployed position when the movable frame is in the dolly configuration.

3. The convertible dolly of claim 2, wherein the deployable platform generally overlies and rests on the fixed frame in the seat position and lies completely outside a perimeter of the fixed frame in the deployed position.

4. The convertible dolly of claim 1, wherein: the pair of wheels are supported in a retracted position generally within a perimeter of the fixed frame when the movable frame is in the stationary configuration; and the pair of wheels are supported in an protracted position extending generally outside the perimeter of the fixed frame when the dolly is in the dolly configuration.

5. The convertible dolly of claim 1, wherein one of the fixed frame and the movable frame comprises at least one retaining member, the dolly further comprising an adjustable tension member adjustably supported on one of the fixed frame and the movable frame for adjustably varying a space between the adjustable tension member and the retaining member.

6. The convertiBϊe dolly of claim 1, wherein: the fixed frame has at least one retaining member for engagement with a first side of a ladder; the movable frame has at least one tension member for engagement with a second side of the ladder opposite to the first side; and movement of the movable frame from the stationary configuration to the movable dolly configuration reduces a space between the retaining member and the tension member for clamping the ladder between the retaining member and the tension member in the dolly configuration.

7. A dolly combinable with a ladder for conversion between a stationary support and a wheelable support, the dolly comprising: a first portion; a second portion; an actuation mechanism interconnecting the first portion and the second portion; wherein the actuation mechanism causes at least one tension member adjustably supported on one of the first and second portions to be moved relative to at least one retaining member of the first portion in order to move the members between an attaching configuration and a release configuration for attaching and releasing the ladder.

8. The dolly of claim 7, wherein the actuation mechanism comprises: a pivot connection pivotally connecting the first portion to the second portion along a first axis; at least one arm that also forms part of the second portion, the arm connected to and extending from the pivot connection; wherein movement of the arm causes movement of the second portion relative to the first portion between the attaching and release configurations.

9. The dolly of claim 8, wherein the second portion comprises: at least one bracket interconnecting the pivot connection and the arm; a wheel rotatably supported by the bracket on a second axis offset from the first axis; wherein movement of the arm rotates the bracket and moves the wheel between a wheelable position extending outside a perimeter of the first portion and a stationary position within the perimeter.

10. The dolly of claim 9, wherein movement of the second portion into the attaching configuration and a corresponding movement of the wheel into a wheelable position is adapted to constructively increase a height of the first portion of the dolly relative to the ground upon which the dolly is to be wheeled.

11. The dolly of claim 9, wherein the second portion further comprises: the tension member; the tension member rotatably supported on the first portion; and the tension member is engaged directly or indirectly by the bracket and moved between the attaching configuration and the release configuration.

12. The dolly of claim 9, wherein: the pivot connection is a first of a pair of pivot connections; the arm is a first of a pair of arms; the bracket is a first of a pair of brackets; and the wheel is a first of a pair of wheels; wherein the pairs of pivots, arms, brackets, and wheels move generally in unison on opposite sides of the dolly when one or both of the arms is actuated.

13. The dolly of claim 12, further comprising a foldable platform interconnecting the pair of arms and rotatably movable between a stowed position superposed on the first portion and a deployed position in which a substantial portion of the platform extends away from the first portion.

14. The dolly of claim 12, further comprising:

connected to at least one of the arms; the latch having an engaging portion for lockingly engaging a pin on the second portion; wherein the latch engages and locks the second portion in the attaching configuration.

15. The dolly of claim 14, wherein the engaging portion is a first engaging portion, and the pin is a first pin, the latch further comprising: a second engaging portion for lockingly engaging a second pin on the second portion; wherein the latch engages and locks the second pin on the second portion by the second engaging portion in the release configuration.

16. The dolly of claim 14, wherein the latch further comprises a main body and a flange extending from the main body, the flange having a width extending from the main body in a range from approximately one half inch to approximately three inches to facilitate pressing engagement by a user's hand or foot.

17. A method of transporting tools to or from a work site, the method comprising: attaching a ladder to a convertible dolly by a single manual motion; using the ladder to control the dolly; and moving the ladder and the dolly together as a unit.

18. The method of claim 17, further comprising converting the dolly from a stationary support configuration to a movable dolly configuration.

19. The method of claim 18, wherein the step of converting the dolly comprises the step of attaching the ladder and includes moving one portion of the dolly relative to another portion of the dolly to engage the ladder therebetween.

20. The method of claim 18, wherein the step of converting the dolly comprises the step of protracting a pair of wheels from a position generally within a jprørøtø: of ftf :^©lLy;tea position extending out of the perimeter to wheelably engage the ground.

21. The method of claim 17, wherein the step of attaching the ladder comprises moving one portion of the dolly relative to another portion of the dolly to engage the ladder therebetween.

22. The method of claim 18, wherein the step of converting the dolly comprises actuating an attaching mechanism, thereby simultaneously: moving one portion of the dolly relative to another portion of the dolly to engage the ladder therebetween; protracting a pair of wheels; and moving a foldable platform from a position superposed on a remainder of the dolly corresponding to the stationary support configuration into a movable dolly configuration extending away from the dolly.

23. The method of claim 22, further comprising supporting at least one object on the platform in the movable dolly configuration and moving the ladder, the object, and dolly together as a unit to or from the work site.

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