Abstract: The present invention relates to a facility comprising: a fixed frame fixedly installed on an outer wall of a veranda or a balcony of a high-rise building; a foldable evacuation box which can be unfolded in the form of a rectangular parallelepiped having an open top side and has and evacuation door on a side thereof; a fall prevention and evacuation means which can be structurally changed to an emergency stairway for fire evacuation; an evacuation box locking means which allows the foldable evacuation box to be unfolded in a rectangular parallelepiped form; a locking means which holds and fixes the fall prevention and evacuation means to the fixed frame; and an entry prevention door which prevents an evacuee from entering inside a veranda or a balcony from the foldable evacuation box through the fixed frame.

Abstract: A clutch-brake device having an actuating disc, a braking disc, a shaft sleeve, a friction disc, a main coupling body, an intermediate disc, and a cutting tool seat. The coupling and dis-coupling between the main coupling body and a flange of the shaft sleeve is achieved by a cooperative motion between the intermediate disc and the adjacent main coupling body and the cutting tool seat. The clutch-brake device can be used for coupling of the engine and cutting blades of a lawn mower or other applications, and is reliable, of high load capability, stable and durable.

Abstract: The invention provides a retractable emergency escape system for a high rise building. The emergency escape system is made of a flexible, durable, fireproof, canvas-like material that allows it to retract to the top of the building when not in use. In its deployed configuration, the emergency escape system comprises a series of interconnected support panels connected to one or more vertical ladders or chutes. The diagonal pattern of the support panels provides support to the ladders and chutes, and also provides building occupants with an additional escape route. An occupant stuck in the building could escape the building by way of the diagonal support panels, by way of the vertical ladders or chutes, or by way of a combination of both. Alternatively, the invention can be made with horizontal support panels connecting to the vertical ladders or chutes.

Abstract: A mobile storage tank includes a wall, a platform secured to the wall, and a structure that provides ascending access to the platform. The structure is configured to transition between a retracted position and an extended position.

Abstract: A mobile oilfield storage tank includes a wall and a stair system securely coupled to the wall. The stair system a platform suitable for use as a walkway and a platform extension pivotally engaged with the platform. The platform extension pivots from a folded position to an extended position and creates a continuous walkway between the platform and a platform of an adjacent mobile oilfield storage tank.

Abstract: A mobile oilfield storage tank includes a front wall and a removable stair system coupled thereto. The stair system includes a platform suitable for use as a walkway and a platform extension operably associated therewith. The platform extension creates a continuous walkway between the platform and a platform of an adjacent mobile oilfield storage tank.

Abstract: Article handling machine (1) comprising a frame (2) for receiving article handling elements, a roof (3) covering said frame (2), and, on one lateral side (6) of the machine (1), a catwalk (5) pivotally mounted on the frame (2) between an extended position in which it protrudes in a direction substantially perpendicular to the lateral side (6), with an inner edge facing the machine lateral side (6), and a folded position in which it stretches out in a direction substantially parallel to the lateral side (6).

Abstract: An articulating cage configured to raise and lower with respect to a fixed structure. The articulating cage comprises support structures affixed to the fixed structure and that include one or more springs. The articulating cage includes lifting arms that are pivotally connected to the support structures at one end and to a cage portion at the other end. A load chain connects to the springs at one end and to the lifting arm at the other near to the location where the lifting arm connects to the cage portion.

Abstract: The present invention relates to a work platform assembly (5) for a container (1) with an adjustable work platform (6), which can be adjusted between a horizontal operational position and a rest position. The work platform (5) is configured and positioned such that in its rest position it extends completely within the external contours of the container assembly (1), and in its operational position it forms a horizontal platform. The invention also relates to a container assembly (1) with such a work platform assembly (5).

Abstract: A vehicle having a compactable walkway, including a supporting surface and a plurality of steps, pivotally coupled to the supporting surface, oriented, spaced, and positioned to provide a graduated walkway when in a deployed position and to lie substantially parallel to the supporting surface when in a retracted position. There is also a support member coupled to a distal end of each of the plurality of steps to enforce consistency of position of the plurality of steps between the deployed and retracted positions; a railing coupled to the support member; a motivator coupled to one of the plurality of steps and configured to direct the plurality of steps from the retracted position to the deployed position; a vertical support coupled to the vehicle for bracing; and a shell coupled to the railing for covering when plurality of steps are in the retracted position.

Abstract: A retractable step for use with a boat in water comprising at least one moveable arm pivotally coupled with the boat, a step coupled with the arm such that the step is moveable between a stored position above the water surface and a deployed position below the water surface, and a lock configured to hold the moveable arm in a stationary position when the step is in its deployed position, but is releasable to accommodate movement of the step to its stored position.

Abstract: A hinged docking platform may include a base having a planar surface configured to support a user while suspended adjacent to an elevated unit. The base may be coupled to an elevated unit via a hinge. The hinge may enable a rotational transition of the base between a substantially vertical orientation of the planar surface as a closed position and a substantially horizontal orientation of the planar surface as an open position. The base may also include a guard rail extending around at least a portion of a perimeter of the base where the guard rail protrudes above the base when the base is in the open position. In some aspects, a ladder may be coupled to the base to enable access to the base when the base is oriented in the open position. In further aspects, a biasing component may be coupled between the elevated component and the base to bias the base during the rotational transition between the closed position and the open position.

Abstract: The subject invention features an entrance module for a height adjustable enclosure with a top portion movable with the respect to a bottom portion. The preferred entrance module comprises a hingedly attached platform movable between a stowed folded position and a deployed unfolded position. A locking assembly releasably locks the platform in the folded position independent of the position of the top movable part of the shelter. The preferred locking assembly includes a rail attached to the top movable portion of the shelter, one of a female and a male portion of a lock attached to and slideable along the rail, and the other of the female and the male portion of the lock attached to the platform.

Abstract: A mobile oilfield storage tank includes a front wall and a removable stair system coupled thereto. The stair system includes a platform suitable for use as a walkway and a platform extension operably associated therewith. The platform extension creates a continuous walkway between the platform and a platform of an adjacent mobile oilfield storage tank.

Abstract: A stair system for a mobile storage tank includes a platform subsystem attached to a wall of the mobile storage tank, a staircase subsystem coupled to the platform subsystem, and a rail subsystem attached to the staircase subsystem. The platform subsystem includes a retractable platform extension, and the staircase and rail subsystem are configured to be extended for use and retracted for transit and non-use modes of operation.

Abstract: An access assembly leading to first and second storage tanks of a planting implement is provided. The access assembly includes a central ramp located between and fixed in relation to the first and second storage tanks, and an extended ramp having a forward end opposite a rearward end aligned in a fore-and-aft direction relative to the direction of travel of the implement. The forward end of the ramp is pivotally connected about a first horizontal axis at a rearward end of the central ramp. The access assembly further includes a ladder pivotally independently coupled about a second horizontal axis at the rearward end of the extended ramp. The ladder and the extended ramp pivot together about the first horizontal axis at the forward end of the extended ramp between a lowered, operative position and a raised, inoperative position above the central ramp.

Abstract: The present invention relates to a work platform assembly (5) for a container (1) with an adjustable work platform (6), which can be adjusted between a horizontal operational position and a rest position. The work platform (5) is configured and positioned such that in its rest position it extends completely within the external contours of the container assembly (1), and in its operational position it forms a horizontal platform. The invention also relates to a container assembly (1) with such a work platform assembly (5).

Abstract: The subject invention features an entrance module for a height adjustable enclosure with a top portion movable with the respect to a bottom portion. The preferred entrance module comprises a hingedly attached platform movable between a stowed folded position and a deployed unfolded position. A locking assembly releasably locks the platform in the folded position independent of the position of the top movable part of the shelter. The preferred locking assembly includes a rail attached to the top movable portion of the shelter, one of a female and a male portion of a lock attached to and slideable along the rail, and the other of the female and the male portion of the lock attached to the platform.

Abstract: A movable platform unit (1) for a boat (B), in particular for launching or hauling out a tender or the like, includes a base portion (2) secured to the boat (B) and at least one swing arm (32a, 32b), pivoted at one end onto the base portion (2) and at the other to a load platform (3). The swing arm (32a, 32b) can be rotated by a first drive member (57) secured thereto and rotatable about the axis (x) about which the swing arm (32a, 32b) is pivoted on the base portion (2).

Abstract: A system for mechanically lowering a load from an elevated position to a lower position in a relatively slow and controlled manner using only gravity and frictional forces. The system includes a vertically aligned glide rod, a glide collar that moves longitudinally over the glide rod, two vertically mounted friction rods mounted on opposite sides of the glide rod, a friction collar that moves longitudinally along each friction rod, and a support platform coupled to each friction collar and to the glide collar. The glide rod includes spiral vane along its entire length upon which the glide collar rides when a load is placed on the support platform, allowing the support platform to descend at a safe speed via gravity.

Abstract: A truck ladder assembly for attachment to the underside of a truck trailer bed having a deployable ladder portion slidable from a folded storage position to an extended operational position in which the ladder portion defines a landing in spaced extended relation from the truck bed with extensible hand rails extending there from. The truck ladder is selectively secured to the underside of the trailer bed allowing for multiple repositioning and deployment of the ladder assembly.

Abstract: A submergible activity platform for attachment to an associated structure on a body of water is disclosed. The activity platform for supporting persons engaged in water activities includes a platform area extending outwardly from and alongside the associated structure. A support structure is carried by the activity platform for mounting the activity platform to the associated structure so that the activity platform is located at a desired depth in the water when mounted to the associated structure. A walkway is included in for providing access between the associated structure and the activity platform when submerged. The activity platform includes a water activity section free of the walkway where water activities may take place. The activity platform also includes a plurality of water flow passages for allowing water to flow through the activity platform when submerged to reduce the force of water currents against the activity platform.

Abstract: A water recreation dock for providing access into and out of the water comprising a main deck platform carried by a dock frame. A stationary platform forms a first part of the main deck platform which is supported above the water on the dock frame. A movable platform forms a second part of the main deck platform which has a raised position and a lowered position. A landing section and a walkway section are included in the movable platform. In the raised position, the landing section and walkway section are located generally in a common horizontal plane with the stationary platform above the water. In the lowered position, the landing section is submerged and the walkway section is partially submerged as extending from the stationary platform to the landing section to provide access into and out of the water.

Abstract: A submergible activity platform for attachment to an associated structure on a body of water is disclosed. The activity platform for supporting persons engaged in water activities includes a platform area extending outwardly from and alongside the associated structure. A support structure is carried by the activity platform for mounting the activity platform to the associated structure so that the activity platform is located at a desired depth in the water when mounted to the associated structure. A walkway is included in for providing access between the associated structure and the activity platform when submerged. The activity platform includes a water activity section free of the walkway where water activities may take place. The activity platform also includes a plurality of water flow passages for allowing water to flow through the activity platform when submerged to reduce the force of water currents against the activity platform.

Abstract: A water recreation dock for providing access into and out of the water comprising a main deck platform carried by a dock frame. A stationary platform forms a first part of the main deck platform which is supported above the water on the dock frame. A movable platform forms a second part of the main deck platform which has a raised position and a lowered position. A landing section and a walkway section are included in the movable platform. In the raised position, the landing section and walkway section are located generally in a common horizontal plane with the stationary platform above the water. In the lowered position, the landing section is submerged and the walkway section is partially submerged as extending from the stationary platform to the landing section to provide access into and out of the water.

Abstract: A submergible activity platform for attachment to an associated structure on a body of water is disclosed. The activity platform for supporting persons engaged in water activities includes a platform area extending outwardly from and alongside the associated structure. A support structure is carried by the activity platform for mounting the activity platform to the associated structure so that the activity platform is located at a desired depth in the water when mounted to the associated structure. A walkway is included in for providing access between the associated structure and the activity platform when submerged. The activity platform includes a water activity section free of the walkway where water activities may take place. The activity platform also includes a plurality of water flow passages for allowing water to flow through the activity platform when submerged to reduce the force of water currents against the activity platform.

Abstract: An access device having a landing and a ladder. The landing is pivotally movable about a first end thereof between a substantially vertically upright stored position and a substantially horizontally outwardly extending access position. The ladder is pivotally connected to a second end of the landing and cooperatively movable with the landing between a substantially vertically downwardly extending stored position and a substantially outwardly inclined access position.

Abstract: A truck catwalk system for allowing an individual to easily access the interior of a truck box. The inventive device includes a pair of support brackets, at least one pivot bracket, a pair of chains attached to the support brackets, a catch mechanism pivotally attached to one of the support brackets, a platform pivotally attached to the support brackets and catchably engaged by the catch mechanism, a handle attached to the platform, and a ladder attached to the platform and the truck box. The platform is comprised of a flat rectangular surface attached to the truck box by pivotal brackets. The support brackets are attached to the truck box to support the weight of the platform. The chains help to support the outer edge of the platform furthest from the box. The handle is utilized to lower and raise the platform. In an alternative embodiment, a pair of gears are attached to the handle and the platform wherein the gears are mechanically engaged with one another.

Abstract: A marine ladder includes a catch mechanism in which a catch tyne is directly secured to the marine ladder without the need for additional structural members or support. The catch tyne is formed as a substantially L-shaped member that dependingly connects to a transverse bar on the dock-anchored frame of the ladder and defines a channel for receiving a leg of a user-selected one of the un-shaped rungs on an elongated ladder portion. The ladder portion is slidably engageable with and along the anchored frame to thereby selectively adjust the height of the ladder and thereby accommodate ready movement of persons between a dock and a proximate watercraft disposed at relatively different elevations.

Abstract: A free-floating step ladder which can hang on the rim of a trash dumpster has a stepless hook portion for hanging the ladder on the dumpster, a platform to stand on while loading the dumpster, and a stairway from the platform which extends adjustably toward the ground on which the dumpster rests without touching the ground.

Abstract: An easily carried and assembled apparatus for use in moving materials between two elevated locations, such as windows of spaced building, that includes a sending assembly positionable across a window in a first building, and a receiving assembly positioned across the window in the second building. Each assembly included a pair of triangular bracing members with bases that are positioned against the interior of the wall on either side of the opening, and a crossbar that is attached at its ends to the apexes of the bracing members, and extends across the opening. A cable is stretched between the assemblies, and a material support is used to carry materials along the cable between the buildings. The apparatus may be combined with a vertical lifting assembly that is attachable within a wall opening in one of the buildings.

Abstract: A collapsible retriever ladder generally includes a first platform, a second platform, supporting arms and a clamping mechanism. The first platform is pivotally attached to the supporting arms so that the first platform can be closed. The second platform is pivotally attached to the first platform so that the second platform can fold over the first platform so as to be sandwiched between the first platform and the supporting arms when the first platform is closed. The clamping mechanism secures the ladder to the upper edge of a side of a boat and is pivotally attached to the supporting arms so that the supporting arms having the first and second platforms secured thereto can rotate inwardly of the boat for storage and outwardly of the boat for use.

Abstract: An access platform system for an earth-moving machine, such as a grader including a frame, plural ground-engaging drive members, an earth working tool and an operator station, which access platform system includes a first deck structure including deck members adapted to move between an upright storage position and a flat deployed position, stairs for providing access for personnel from ground level to the first deck structure and associated safety barriers. The first deck structure extends, in the deployed position, from the stairs to the operator station and the first deck structure allows, in the storage position, a substantially unobstructed view of at least a front portion of either a ground engaging drive member or the earth working tool from the operator station. The access platform system also includes a second deck structure interposed between the stairs and the first deck structure.

Abstract: An access device for providing access between a substrate surface and the cabin of a vehicle. The device is attached to a rotating actuator extending outwardly from the side of the cabin for moving of the device between the access position (FIG. 1) and the storage position (FIG. 3). The device includes a substantially triangularly shaped platform. A first side of the platform is attached to the rotating actuator. A second side of the platform has the ladder depending therefrom. The third side of the platform is, in the access position (FIG. 1) located proximal to the cabin. The device is rotated by the rotating actuator to the storage position (FIG. 3) wherein the device is substantially upturned relative to the access position (FIG. 1) of the device and wherein a substantial part of the device is positioned above the rotating actuator.

Abstract: An access device (1) for providing access between a lower level and an upper level. The device (1) includes a platform member (2), a ladder member (3) and a rotating actuator (4). The platform (2) and the ladder (3) are movable between an access position (FIG. 1) wherein the ladder (3) is positioned downwardly and the platform (2) is horizontal, and, a storage position (FIG. 3), in which the ladder (3) is positioned upwards and the platform (2) is vertical. In a first step, the actuator (4) rotates the ladder through about a 90.degree. angle to an intermediate position (FIG. 2) at which time the ladder (3) engages with the platform (2). Then, in a second step, the ladder (3) and platform (2) cooperatively rotate between the intermediate position (FIG. 2) and the stored position (FIG. 3).

Abstract: A ladder support system, comprising a free-standing frame having an upper and lower horizontal member, and a ladder that is supported on the upper horizontal member and lower horizontal member. The frame further has a pair of ends which each have two legs joined by a top joint which forms an acute angle between the two legs which are both perpendicular to the upper horizontal member, which is also attached to the top joint. The upper horizontal member is parallel to the lower horizontal member. The ladder has wheel assemblies which engage the upper horizontal member and lower horizontal member so that the ladder may move laterally along the frame. A movement mechanism comprises a pair of end pulleys located at the ends, and a rope having a pair of rope extremities. The rope is threaded through the end pulleys with the rope extremities available to a workmen on the ladder, so that the workmen can move the ladder laterally along the frame without climbing down the ladder.

Abstract: An escape apparatus for installation within an upper storey of a building in the proximity of an emergency exit opening, such as a window, comprises a foldable ladder carried by a stage which is mounted on a vertically positioned fixed mounting frame for sliding and pivoting movement together with the folded ladder between a retracted position against the mounting frame to an extended position of use in which the stage projects through the emergency exit opening and in which the ladder may be slid along the stage and unfolded at a leading edge of the stage to form a rigid ladder extending downwardly from the stage outside the building. The escape apparatus may also comprise a child carrier guided by the ladder for controllably lowering a baby or small child down the ladder and an automatically opening folding rescue platform for providing a temporary place of safety for escapes unable to reach the ground while they wait for rescue.

Abstract: A vehicle attachment including an elongated platform pivotally attached along one side of a vehicle for movement between a vertical carrying position adjacent the side of the vehicle and a second horizontal position to enable a user to walk along the side at the rear of the vehicle when launching a boat into a body of water or during recovery of the boat without requiring the user to get into the water.

Abstract: The subject invention relates to a type of escape ladder structural improvement (1), comprising a housing, an inside ladder, an outside ladder, an outside cover and a gear transmission; the hollow interior of the housing comprising an escape channel; the inside ladder, the outside ladder and the outside cover being respectively installed on the rear and front openings of the hollow interior in the housing; said inside ladder can swing backwards to extend itself by way of its own gravitational weight when a handle is pulled, and via the gear transmission mechanism, it in turn drives the outside cover and the outside ladder to swing forwards to extend themselves, so that the escapee will be able to climb the inside ladder, to the hollow interior of the housing, then to the outside ladder, and escape from the scene by means of the escape device on the outside cover; said mechanism will enable easy operation to create a best escape channel without causing bad effects on the appearance of a building.

Abstract: Disclosed is a safety structure provided on an elevator car for the passengers to escape from the elevator car in case of an emergency that causes the elevator car to stop halfway between two floors. Besides, the safety structure can prevent maintenance technicians or objects from falling down through open entrance door to the base ground of the elevator tunnel when the elevator car is lifted halfway between two floors. The safety structure comprises a plurality of sidepieces secured to the bottom of the car and a series of rungs set between the sidepieces. In another embodiment, each of the plurality of sidepieces comprises a first segment and a second segment retractable into the first segment. In still another embodiment, each of the plurality of sidepieces comprises a chain of segments each linked to with a pivot such that the safety structure is collapsible.

Abstract: A modular landing assembly for a commercial trailer, which is transportable with the trailer is disclosed. The landing assembly includes a landing platform pivotally connected to the sidewall of the trailer, a detachable staircase, a detachable safety railing, and a storage frame mounted beneath the undercarriage of the trailer for carrying the staircase and safety railing. The landing platform can be pivoted between a vertical transportation position secured against the trailer side wall and a horizontal operational position extending from the trailer side wall. The landing platform includes a pair of folding legs, which support the landing platform in its operational position and which can be secured against the landing platform during transportation. The platform legs include an extensible foot, which allows the landing platform to be leveled. The staircase is a single unit, which is connected to the landing platform in its operational position by two pins.

Abstract: In the field of materials handling, e.g., in warehouses, there is a need for a low-cost shelving access system which does not require a user thereof to carry objects whilst negotiating, e.g., ladders and steps. The disclosure relates to an apparatus including a framework (11); a generally vertical ladder (12a, 12b) secured to the framework; and a goods hoist (20) secured to the framework in such a way that the platform (22a, 22b) of the goods hoist (20) may be maneuvered to a plurality of locations adjacent the ladder (12a, 12b). The ladder (12a, 12b) is moveable laterally on the framework to enable the platform (22a, 22b) of the goods hoist to access any position within the envelope defined by the framework (11).

Abstract: Emergency stairs are designed to be mounted externally on buildings and are provided with platforms at each floor as well as ladders/staircases between the platforms. Platforms are hinged to the house wall and are at their extreme edges connected by the air of mutually articulated connecting means. The ladders/staircases are suspended from the underside of the platforms in articulated members under openings in the platforms and with the rungs of the ladder arranged in parallel with the house wall. The ladders are at their lower ends slidably supported by the next lower platform. In a position of non-use platforms and ladders are retracted into contact with the house wall and may be actuated by an actuating mechanism which may be operated from each floor.

Abstract: An emergency escape system for multistory buildings in which stair units are stored in recesses in the floor of each above grade level of the building. The stair units are released for gravity depolyment to the next below balcony in an emergency, and a cover panel is opened to enable egress by building occupants through the recess, down the deployed stairs to the next balcony and so on until ground level is reached.

Abstract: A normally retracted escape ladder assembly that includes a framework mountable on a building wall, a plurality of ladder sections movably interconnected and having at least one such section attached to the framework, a platform, and a latch maintaining the ladder sections in a collapsed condition and actuated to release the ladder sections upon application of weight to the platform. The framework includes a wall abutment section and a ladder support section projecting therefrom. The platform is carried by the framework and is pivotally attached to either the wall abutment section or the ladder support section of the framework. Connected to the platform and carried by the framework is a latch which engages at least one of the ladder sections to maintain the ladder sections in a collapsed condition. The application of weight to the platform allows the ladder sections to assume an extended condition.

Abstract: The side ladder has upper and lower footpaces (1, 3) connected with side elements (5) on which a flight of steps (7) is hinged. A first actuator (11) is provided for withdrawing the ladder from a housing (15) on the boat and a second actuator (13) is provided for rotating the ladder about a horizontal axis. A leverage (21, 23, 27, 29) keeps the steps (7) and the lower footpace (3) in their horizontal position during rotation of the ladder. A piston and cylinder system (53) is provided for operating a handrail (41) and a further rotation of the ladder about a vertical axis can be carried out by a hydraulic motor (31).

Abstract: A foldable ladder for use with a swim platform of a boat is disclosed. A hinged panel adapted to fit in an opening in the swim platform pivots between a closed position and an open position. An upper ladder portion, which includes handrails, is fixed to the underside of the panel and pivots with the panel. A lower ladder portion, which includes a rung, is pivotally connected to the upper ladder portion. A control link is pivotally connected at one end to the boat and at the other end to the lower ladder portion. Raising the panel automatically deploys the ladder and closing the panel automatically stows the ladder beneath the panel.

Abstract: A boat platform ladder attaches at one end to the stern of a vessel and can be raised and lowered between stored and in use positions. A ladder is rotatably mounted to the opposite end of the platform. When the platform is lowered, locking mechanism fix the ladder in a perpendicular orientation relative to the platform. When the platform is raised, the ladder is unlocked so as to rotate into a parallel orientation relative to the platform.

Abstract: Platform and ladder combinations for the transom of a boat have a platform unit and a step unit that may be moved between a use position with a step thereof immersed in the water in which the boat floats and a storage position where the step is located above the platform out of the water, which step in the use position extends aft of the platform unit and permits a person to climb out of the water and onto the platform without the step making any appreciable movement during such climb. The platform unit has a pair of tubular members with an inboard portion, a U-shaped outboard portion, a central portion and planking attached to the central portion of each the tubular members holding them spaced apart. The step unit is a tubular member defined by a middle section, two parallel, spaced apart end sections and planking fixed to short legs of the end sections forming a step.

Abstract: A ladder device for the transom of a boat has a platform unit and a step unit that may be moved between a use position with a step thereof immersed in the water in which the boat floats and a storage position where the step is located out of the water. The step in the use position extends aft of the platform unit and permits a person to climb out of the water and onto the platform unit without the step making any appreciable movement relative to the platform unit during such climb. The platform unit includes a pair of ring members that each depends from a respective longitudinal section of the unit. The step unit includes a U-shaped tubular member defined by two parallel side sections joined integrally to a transverse section. The side sections each have a long leg and a short leg with one end thereof unattached and a stop member is carried on such unattached end.