Abstract: An ergonomic method for working in confined work spaces is disclosed. The method, in some cases, includes the steps of: a) providing a support structure that is generally in the configuration of a rectangular prism having six faces, a length, width, and a height in which the length, width, and height differ from one another so that the structure provides three different height positions when the support structure is placed on the floor of the workspace; b) placing the support structure with one of its faces in contact with a contoured floor surface in a confined work space; and c) sitting or standing on the support structure.

Abstract: A processing apparatus includes a chuck table that holds a workpiece, a processing unit that processes the workpiece held by the chuck table, and a panel that surrounds components including the chuck table and the processing unit. Power source sockets are disposed on the panel, and electric apparatuses including an inspection device, a personal computer, a fan, and a cleaner are connected to the power source sockets and are used.

Abstract: A platform system includes a support structure of variable length; a platform mountable on the support structure; and a plurality of platform supports for supporting the platform. At least one of the platform supports is slideably mounted on the support structure such that it is slideable with respect to the support structure. At least one of the platform supports includes a spacing element, which extends between that platform support and an adjacent one of the platform supports and engages the adjacent platform support, such that the maximum spacing between those platform supports is limited by the spacing element.

Abstract: A device supports a platform that is used to lift loads or persons the height of a structure. Together with a platform, the device includes winch-type platform-lifting elements and modular mast-forming elements. Each mast element is attached using the load platform which can be connected to the masts by: (i) the winch-type lifting elements which can be disconnected at will from the masts, and (ii) elements for temporarily blocking the movement of the platform in relation to a modular element of each mast. In this way, when the movement of the platform is blocked, a modular element can be added to, or removed from the top of the masts in accordance with the desired platform lifting height. The platform is positioned between two modular independent masts which form a lifting and guiding path.

Abstract: A mechanic's leaning device includes a base, an upper torso support having an adjustable first height above the base, and a combination step and knee support having an adjustable second height above the base which is less than and adjustable relative to the first height. The mechanic's leaning device can be used by mechanics of all sizes for working on a wide variety of vehicles, ranging from very small to very large.

Abstract: An accommodation ladder includes a body having opposite sides, an upper, and rear and bottom surfaces. The body is formed of a compressible material, such as dense foam material, and the upper surface of the body forms a staircase with a plurality of steps. Spaced stanchions extend upwardly from the staircase and stanchion pipes extend through the body and receive lines therethrough to secure the body to a marine structure. The spaced stanchions are adapted to accommodate a plurality of releasable safety lines therebetween. A method of facilitating access between adjacent first and second marine structures includes arranging the staircase accommodation ladder between the structures, the accommodation ladder being a fender between such structures.

Abstract: An X-ray image processing apparatus includes a calculating unit adapted to calculate the noise amount of a sensor on the basis of a difference value of a plurality of dark images acquired at different timings by the sensor when no X-rays are irradiated, a changing unit adapted to change a predetermined parameter for processing an X-ray image acquired by the sensor when X-rays are irradiated, in order to prevent the noise amount from being superposed on the X-ray image, and an image processing unit adapted to perform image processing on the X-ray image on the basis of the changed parameter.

Abstract: The invention relates to scaffold steps, with two separate side pieces (11) and a plurality of separate step elements (13, 13?, 13?), which can be detachably coupled to each other and to the side pieces.

Abstract: A machine for constructing height adjustable stair steps with tread/riser unit, and riser bracket.

Abstract: Apparatus for use in lining a curved wall comprising staging (5), which staging includes a deck (6) and anchor plates (7, 7a) attached at opposing. ends of the deck (6), wherein the anchor plates (7, 7a) are attached to the deck (6) by respective pivots such that, in use, the anchor plates (7, 7a) engage with the surface of the wall (4) and wherein a line extending between the ends of the anchor plate (7, 7a) forms a chord to the curve of the wall.

Abstract: An apparatus for providing access to vehicles and containers on a pair of railways or thoroughfares. The apparatus is comprised of a raised walkway between the pair of thoroughfares having a tracking platform movable thereon. Pivotally attached to and carried by the tracking platform is a turret. Carried on the turret and hinged thereto is a bridge that is rotatable in a vertical plane. At the end of the bridge is a cage pivotally attached to the bridge so that the cage remains horizontal when the bridge is rotated vertically on the turret. The bridge and cage are dimensioned so that, when the turret is rotated such that the bridge is directed between and parallel to the thoroughfares and the bridge and cage are raised, the apparatus is entirely out of the clearance envelopes of the thoroughfares.

Abstract: There is provided a portable riser having an operator actuated lifting assist assembly operatively coupled to a riser deck. In one aspect, there is a first pivot mechanism coupled to a first support leg and adapted to initiate upward movement of the portable riser from a collapsed position when a downward force is applied to the first support leg, and a second pivot mechanism coupled to a second support leg and adapted to continue the upward movement. The lifting assist assembly provides a lifting force that continues upward movement to an upright position where the portable riser in locked. There is included a riser unlocking means for unlocking the lifting assist assembly. The portable riser remains in the upright position until the riser unlocking means is operated and a collapsing force is applied to the portable riser sufficient to overcome the lifting force and enable collapsed of the portable riser.

Abstract: An embodiment of the present invention relates to a staircase device adapted to fit a bed of a truck, or other similar vehicle. The staircase provides a mechanism for facilitating the loading and unloading of items onto and off a bed of a truck. An embodiment of the present invention is directed to a vehicle staircase device comprising a first lower platform having a first length and a first width, the first lower platform having a hitch connector adapted to connect to a vehicle; a second platform having a second length and a second width, wherein the first lower platform and the second platform are substantially parallel; and a staircase structure connecting the first lower platform and the second platform.

Abstract: A collapsible tree stand includes a generally rigid first locking arm releasably locking a first platform in an extended position in which the first platform extends rearward from and generally transverse to the mounting frame. A second platform is secured to a lower portion of the mounting frame for movement toward and away from the mounting frame. A generally rigid second locking arm releasably locks the second platform in an extended position in which the second platform extends forward from and generally transverse to the mounting frame. The mounting frame, first platform and second platform are relatively moveable to a collapsed position in which the first and second platforms generally overlie one another.

Abstract: There is provided a portable riser having an operator actuated lifting assist assembly operatively coupled to a riser deck. In one aspect, there is a first pivot mechanism coupled to a first support leg and adapted to initiate upward movement of the portable riser from a collapsed position when a downward force is applied to the first support leg, and a second pivot mechanism coupled to a second support leg and adapted to continue the upward movement. The lifting assist assembly provides a lifting force that continues upward movement to an upright position where the portable riser in locked. There is included a riser unlocking means for unlocking the lifting assist assembly. The portable riser remains in the upright position until the riser unlocking means is operated and a collapsing force is applied to the portable riser sufficient to overcome the lifting force and enable collapsed of the portable riser.

Abstract: A device having multiple support members telescopically contained therein, with each member having a set of lights, a set of curtains and various compartments for numerous stage accessories and allows for quick change of the lights and curtains that are used for different sized stage settings.

Abstract: Apparatus for draining fluids from a vehicle has an elevated platform supported on a frame, the platform being pivotable side-to-side and end-to-end, to permit complete draining of fluids from the vehicle through an opening in the platform prior to dismantling the vehicle for scrapping. A unique bracket assembly connects one end of the platform to the frame at first and second perpendicular pivots, to permit pivoting about both a longitudinal and a transverse axis.

Abstract: A maintenance platform (10) comprises a main frame (12) with base frames (12,14) releasably interconnected by split clamps (50) and load transfer couplers (52). Upper extension frames (62,64) are mounted on the base frames (12,14). A balcony (82) and stabilizers (100) are also provided. The platform (10) is of modular construction and can be assembled and disassembled manually without tools for use on either improved or unimproved surfaces.

Abstract: A construction material holding system for supporting a plurality of elongate materials upon a walk board without interfering with the usage of the walk board. The construction material holding system includes a plurality of support units each comprised of a support bracket that is removably attachable to a walk board, a vertical support member extending from the support bracket, a first rack attached to an upper portion of the vertical support member, and a second rack attached to an upper end of the first rack. The second rack is preferably removably attached to the first rack for allowing various configurations thereof.

Abstract: A device having multiple support members telescopically contained therein, with each member having a set of lights, a set of curtains and various compartments for numerous stage accessories and allows for quick change of the lights and curtains that are used for different sized stage settings.

Abstract: A deployable telescopic seating structure employs a backstop arrangement to prevent users and operators from coming into contact with structure that may cause injury, such as interengaging metal elements that limit the extent of deployment The backstop portions are arrangement in the aisle region of the telescopic seating structure and have an overall height that is responsive to the height of one seating level above another, or in another embodiment, to the difference between such height and an intermediate step. The backstop arrangement has an engagement portion with an edge portion that precludes a discontinuity on the walking surface of tile seating structure. Structural integrity and strength of the riser portion is enhanced by forming same as a multi-fascia structure having a reinforcing corrugation therebetween. A curved back portion along the lowermost edge serves as a termination and additionally adds strength to the backstop arrangement.

Abstract: A multi-level vehicle servicing system includes site-erectable units each with four levels, to facilitate vehicle repairs by several technicians at the same time. Each unit includes vertical structural members, horizontal supports, flooring, tool storage, parts storage, panels, stairs, ladders, ramps, lifting mechanisms to raise the vehicle off its wheels, and mechanisms to facilitate removal of heavy repair components to other levels below. Lighting, power, compressed air, fluid delivery and extraction, and fire suppression systems are integrated in the system of components. The system is erected on a conventional building floor and is free-standing, independent of the building structure itself. The modular apparatus is installed without major modifications to an existing building of appropriate size and structural compatibility. Several of the four-level units can be stacked and any number may be combined in any horizontal configuration.

Abstract: A new Extendable Pyramid Ladder System for providing a compact stable ladder system which allows the user to access heightened areas by standing on a broad platform while simultaneously providing maximum stability, and for providing compact storage by folding into a swaged shape. The inventive device includes a vertical series of planar support members aligned parallel to one another, a left scissors bracket pivotally secured to the bottom portion of said planar support members, a right scissors bracket secured to the bottom portion of said planar support member opposite of the left scissors bracket where said scissors brackets allow the series of planar support members to extend vertically upward, a recessed handle on the cornice of the top planar support member, and a securing means to retain a swaged shape for the invention when in the storage position. The series of planar support members fit within each other to form a swaged shape for storage.

Abstract: A workstand for use when servicing heavy tracks or the like, the workstand including opposing curved first and second sides spaced apart from each other and a top support platform extending therebetween. Upper and lower steps extend between the front portions of the curved first and second sides to provide access to the top support platform. The curved first and second sides combine with the top support platform and the steps form a structure having a wheel receiving area therein and having an open backside that provides access to the wheel receiving area. The workstand is constructed to be positioned around a tire of the truck's wheel assembly with the first and second sides immediately adjacent to the frame of the vehicle and the top support platform above the wheel receiving area so as to support a mechanic or the like above the wheel assembly adjacent to the vehicle's engine.

Abstract: This invention relates to a mobile stair system for pets and other small animals, a method of making said mobile stair system, and a method of producing elements of said mobile stair system. Said mobile stair system comprises a number of crossbars, a left side support and a right side support which jointly form a main frame for the mobile stair system. A cord is run through a number of holes in the left side support and in the right side support and through the number of crossbars, forming a number of stairs of the mobile stair system. The method of making the mobile stair system comprises connecting a number of crossbars between a left side support and a right side support to form a main frame, spreading a covering over the number of crossbars of the main frame, and connecting the number of crossbars, the left side support, the right side support and the covering by using a cord such that the covering serves as a number of stairs.

Abstract: The scaffolding includes a tower provided with equally spaced rungs and adapted to be secured to an adjacent building structure, an outer sleeve surrounding the tower and guided therealong and a work platform supported by the outer sleeve. The raising system includes an inner sleeve surrounding and guided on the tower inwardly of the outer sleeve, a pair of latching levers pivoted to the outer sleeve and latching onto the tower, a pair of hydraulic rams pivoted to the outer sleeve and to the inner sleeve and reciprocating the latter for up and down movement relative to the outer sleeve, and a pair of hooks pivoted on the inner sleeve to engage and disengage opposite rungs of the tower. To raise the outer sleeve and work platform, the rams are retracted while the inner sleeve is hooked to the tower. When the ram retracting stroke is completed, the latching levers latch the outer sleeve to the tower and the rams extend to raise the inner sleeve which is then hooked to a higher pair of opposite tower rungs.

Abstract: This relates to a swing scaffold assembly comprising a plurality of frames disposed in alignment with each other in spaced apart generally parallel planes. Each such frame includes a lower cross beam and a secondary frame structure supported on an intermediate section of each said cross beam. Opposing end portions of each cross beam extend outwardly from the intermediate beam section. A pair of uprights are each connected to and extend upwardly from the opposing ends of each cross beam. An upper cross member spans the distance between and is interconnected to the upper ends of each pair of these uprights. The secondary frame structure for each frame is arranged such that when the frames are in their spaced apart parallel positions they serve to provide a plurality of raised centrally located supports upon which longitudinally extending planks or the like may be laid thereby to provide a raised central bench for supporting building materials at a height convenient for masons and the like.

Abstract: A load support platform for use in conjunction with a vehicle tire wherein a pair of outwardly flared feet 22, 24 interact with the tire such that lateral or downward forces on the platform 6 is resisted by the weight of the vehicle.

Abstract: A hydrant refueler for aircraft is provided with a plurality of decks each at a different fixed height above ground to enable the refueler operator to connect to the fuel tanks of aircraft having wings at different heights above ground. The uppermost deck is provided with foldable side guard railings which when lowered will permit the refueler vehicle to clear the wing of a low wing aircraft and which when raised will provide necessary safety protection to a refueler operator as he services a high wing aircraft. A rigid cross bar guard is provided at at least one end of the foldable side guard railings.

Abstract: A portable scaffold includes a base or chassis mounted on wheels for site-to-site towing or "man-handled" positioning at a job site. Rising rigidly from the chassis are two masts, spaced apart lengthwise of the chassis. A platform is vertically slidably carried by the mast for selective elevation and descent via power devices. Each mast may be increased in height by the addition thereto of a mast extension that functions as a prolongation of the basic mast. One of the power devices is alternately positionable to function as a temporary source of power for moving the scaffold through short distances. Strap elements are provided for temporarily bracing the masts from a structure being worked on by workmen on the platform.

Abstract: A portable foldable sawing machine table and stand assembly which includes structural details and arrangements of parts which provide facilities for usage both on the ground and on scaffolding. The invention incorporates a sawing table with movable saw guide tracks adapted to movably retain a normally hand-held, portable electric motor-driven circular saw for rapid and precise angular cross-cutting of work pieces and in case of scaffold mounting of the table and stand provides for elevation of the table assembly with variations in elevational movement of the scaffold to which it may be releasably yet rigidly attached thereby providing convenience, and added safety for a workman applying structural materials to the vertical faces, for example, of a building structure.

Abstract: A device for helping a handicapped person move up and down a flight of stairs. The device includes a base having a pair of vertically spaced platforms which define intermediate steps between the steps of the stairs. By stepping from a lower step to the platforms and then to the adjacent upper step, a person may climb the stairs while lifting his feet vertically through only relatively short distances. A handle extends upwardly from the base and helps stabilize the person using the device. The handle also is used to move the device from step to step.

Abstract: This scaffolding comprises a base, a pair of spaced posts on said base each formed of modular post sections, releasably secured one on top of the other by fasteners. Each post section is formed of a lattice frame with transversely-extending bars forming anchoring steps, equally spaced along the post. A work platform surrounds the posts and is guided therealong for up-and-down movement. A pair of anchoring hooks are pivoted at theri lower end to the platform and are engageable with the steps of the two posts to suspend the platform. A pair of hydraulic rams are pivoted also to the platform adjacent each post and upwardly-upstanding piston rods are provided with hooks to engage the steps of the post and raise or lower the platform. The hydraulic supply for the rams is mounted on the platform. The hook members are biased towards the posts, so that they automatically engage the steps. A single operator can operate the rams to raise and lower the work platform.

Abstract: A scaffold system has self standing towers and brackets that are guided and supported by the towers. The towers include three legged support bases that are collapsible to make the base convenient to store and transport. The brackets includes safety latches that engage the tower in a fail safe manner to stop a bracket that may fall uncontrollably because of other equipment failure. Some of the safety latches may be rendered inoperable as the bracket is raised and lowered under power, but one safety latch remains operable at all times.

Abstract: A side rail system for interconnecting layered sections of elongated scaffold staging with the sections respectively spanning pairs of opposing upper and lower support arms of pump jacks which respectively ride on spaced apart pump jack poles. The side rail system includes upright posts which are spaced along the staging. A pair of rods are associated with each of the posts. The rods confrontingly project from the respective staging sections. The posts are pivotally coupled to the rods and are secured to the rods by quick adjust pins to prevent separation of the rods and posts. A mid-rail as well as a toe board can be interconnected between the rails. An end rail system can also be included. The scaffolding arrangement can be used exteriorly with a brace onto a wall. It can also be used interiorly between roof and floor with appropriate height adjustment arrangement provided.

Abstract: A pump jack arrangement for traveling up and down a pole including a frame member upper and lower shackle members supported by the frame member. A pump arm and a support arm are provided for supporting weights. The pump arm is utilized for causing the shackle members to alternately grip the pole. The non-gripping shackle member is stepped upwardly along the pole. The upper and lower shackles include pivotally interconnected yoke members and linkage members which are pivotally connected utilizing the rear gripping rod of the yoke member itself as the pivot. The pump jack is formed of U-shaped channels in order to provide additional supports. The support arms themselves also comprise opposingly interfitted U-shaped channels to provide a slidable support arm. A guard plate is provided over the front gripping rod of the upper shackle.

Abstract: A scaffold assembly for supporting members of a musical choir in a standing arrangement simulating the appearance of a traditional Christmas tree is disclosed. The scaffold assembly is arranged in tiers of horizontal standing boards rising one above and one behind another in stairway fashion from a base tier of standing boards to an uppermost tier of standing boards. The horizontal standing boards of each tier are arranged to form a segmented arc in a plane which is transverse to the vertical axis of the scaffold assembly. The tiers are stabilized by a plurality of horizontal support beams and upright support posts and a central stanchion. A first set of horizontal support beams project radially outwardly from a central plate, which is attached to the central stanchion, to the underside of the standing boards, and are attached to the respective support posts at the perimeter of selected ones of the tier.

Abstract: An automobile mechanic's body support including a T-shaped mobile frame and rectangular tube members supported thereon. The support includes a platform for the mechanic to stand on and also a platform for the mechanic to lie on. Adjustments interconnect the platforms with the remainder of the support for adjusting both platforms for optimum positioning of the mechanic so that his body weight can be distributed between the standing platform and the chest-rest platform. Also, the stem of the T-shape permits the support to be positioned immediately adjacent the automobile front wheel for optimum accessibility to the engine compartment.

Abstract: A pump jack upright pole formed of an elongated metal pole having a rubberized surface formed on only one side of the metal pole. The pump jack securely rides up and down the pole. The rubberized surface is longitudinally offset with respect to the pole so that it extends past one end of the pole while exposing the opposing end of the pole. A splint is arranged to be received within adjacent ends of poles being spliced together with the rubberized surface extending end overlying the exposed pole end of the next adjacent section. The rubberized sections are interfitted to provide a continuity so that the pump jacks can ride up and down the poles without interference.

Abstract: A combined article mover and worker support comprising a plurality of stepped horizontal platforms or steps, at least one of which is supported vertically by vertical frame members, and a handle, supported by one of the steps, which projects vertically above the uppermost step and serves to maintain the balance of a worker standing on the uppermost step. A tool receptacle or support may be placed on the uppermost step providing ready access to tools for the worker and also providing additional means to maintain the balance of a worker standing on the uppermost step.

Abstract: This disclosure describes a multi-purpose adjustable table and bench device having a table top and benches all with adjustable heights so that the device can be used, for example, either as a table with benches attached on either side for sitting, or as a platform. Means are provided to secure two or more table and bench devices together to create larger table and bench arrangements, or stage areas in various configurations.

Abstract: A collapsible frame includes a plurality of legs adapted to engage a floor. The legs are connected by braces to rigidify the legs in an upstanding position. A plurality of arms are connected to the legs to form a plurality of vertically spaced support platforms. Each support platform is formed by a pair of the arms positioned in spaced parallel, horizontal relationship. The pairs of arms are located at selected elevations to provide upper and lower support platforms with at least one intermediate support platform between the upper and lower support platforms. The legs are suitably connected to facilitate assembly and disassembly of the music stand for storage and transportation. The support platforms are adapted to support musical instruments and related accessories, such as percussion instruments, for movement on the music stand to permit the instruments to be placed in selected positions and combinations for playing by the musician.

Abstract: The scaffold unit comprises a pair of towers, each having a pair of rails held together by crossties. Each rail has a gear rack on the front face thereof. The towers are held in fixed lengthwise parallel alignment by cross braces removably attached to the sides of the rails facing each other. A self-elevating, platform-supporting carriage projects outwardly from each tower. The carriage has a frame which supports a pair of upright shoes, each defining a U-shaped channel for slidably receiving a rail therein. The shoes fit over and guide the carriage on the rails when the carriage is in motion. A shaft is rotatably mounted on the frame and carries a pair of gears which mesh with the racks through slots in the shoes. A controllable motor is adapted to rotate the shafts independently of, or in synchronism with, each other.

Abstract: A self-contained scaffold and lift unit includes first and second pairs of parallel, spaced apart vertical rails joined together by horizontal braces. A movable lifting carriage unit is disposed between the pairs of vertical rails and includes pairs of rollers engaging and captured between the pairs of vertical rails to provide smooth vertical motion with respect to the rails. A primary load-bearing platform is removably attached to a lower portion of the carriage unit and an auxiliary load-bearing platform is removably attached to an upper portion of the carriage unit. A manually driven hoist is attached to the carriage to allow controlled movement. The carriage unit is positioned with respect to the rails by the hoist. An auxiliary base assembly is removably mounted to the scaffold unit to secure the scaffold unit in an erect and freestanding manner. The rigid scaffold units are assembled in modular interfitting sections to allow a scaffold of any desired height to be formed.

Abstract: A sawhorse having a crossbar and support legs at each end of the crossbar is provided with a workpiece support member supported on the sawhorse at a position laterally offset from the crossbar and at least as high as the crossbar. A second workpiece support member may be arranged on the opposite side of the crossbar and third and fourth workpiece support members may be provided in longitudinally spaced relation from the first and second workpiece support members respectively. The workpiece support members may have flat top surfaces disposed in a common plane situated higher than the crossbar so that a workpiece supported thereon may be cut along a line directed between the workpiece support members and either parallel to or perpendicular to the sawhorse crossbar with both cut portions of the workpiece supported on the workpiece support members.

Abstract: An assembly is shown, which provides a framework that fits in an excavation such as a grave, including two side frames that exert considerable horizontal pressure against two end frames by means of eight horizontal adjustable screws and integral bearing means to produce a rigid frame adapted for carrying heavy surface loads for example, machinery for lowering a casket into the grave and providing a support for a platform for mourners adjacent to the grave for those wishing to approach closely to the graveside. The load on the rigid frame and including any load from the platform supported on the frame is transmitted to bearing pads supported on the floor of the excavation to eliminate, insofar as possible, injury, and/or embarrassment caused by the caving in of the walls of the excavation while at the same time making it possible to provide a much neater appearing gravesite than would be attainable without the framework.

Abstract: The present invention provides a combination scaffold and utility platform that is adapted to be used with two, at least, spaced apart support members. There is provided a first platform that is positioned on the support members in a spanning relationship therewith. The first platform includes therein a plurality of transverse openings that are spaced apart along the length dimension thereof and in a common plane. A second elongated platform is positioned in a plane above and alongside the first platform. The two platforms are coupled to each other by means of rods, each of which has a first portion that is adapted to be removably inserted in one of the openings in the first platform and a second portion that is spaced above and alongside the openings in the first platform in order to support the second platform. The rods that support the second platform with respect to the first platform are also provided with means for preventing the tilting of the second platform with respect to the first platform.

Abstract: A portable riser having a plurality of steps which have a travel position in superimposed relation with structure for rolling the riser along the floor, hinge means interconnecting the steps whereby they may be folded out of superimposed relation, a pair of sliders pivotally associated with each step and which are hinged to sliders of an adjacent step by said hinge means whereby lifting of one step causes erection of the riser to an erected position, and latch means automatically operable to prevent movement of the steps beyond erected position and to lock the riser in erected position for use.

Abstract: A portable riser having a plurality of steps which have a travel position in superimposed relation with structure for rolling the riser along the floor, hinge means interconnecting the steps whereby they may be folded out of superimposed relation, a pair of sliders pivotally associated with each step and which are hinged to sliders of an adjacent step by said hinge means whereby lifting of one step causes erection of the riser to an erected position, and latch means automatically operable to prevent movement of the steps beyond erected position and to lock the riser in erected position for use.

Abstract: A portable scaffold includes a base or chassis mounted on wheels for site-to-site towing or "man-handled" positioning at a job site. Rising rigidly from the chassis are two masts, spaced apart lengthwise of the chassis. A platform is vertically slidably carried by the mast for selective elevation and descent via power devices. Each mast may be increased in height by the addition thereto of a mast extension that functions as a prolongation of the basic mast. One of the power devices is alternately positionable to function as a temporary source of power for moving the scaffold through short distances. Strap elements are provided for temporarily bracing the masts from a structure being worked on by workmen on the platform.