US2781236A - Folding scaffolds - Google Patents

Description

Feb. 12, 1957 P. G. BECKER EI'AL FOLDING SCAFFOLDS 4 Shets-Sheet 1 Filed Oct. 25, 1954 INVENTOR. PAUL G. BECKER CLARK G BECKER 5 mm & M

ATTORNEYS P. G. BECKER EIAL FOLDING SCAFFOLDS Feb. 12, 1957 4 Sheets-Sheet 2 INVEN TOR. PAUL G. BECKER CLARK G. BECKER A TTOR/VEKS P. G. BECKER AL Feb. 12, 1957 FOLDING SCAFF'OLDS 4 Sheets-Sheet 3 Filed 001:. 25, 1954 INVENTOR. PAUL '6. BECKER CLARK G. BECKER BY .M MGQM A7TORNEKS L L L Feb. 12, 1957 P. G. BECKER L FOLDING SCAFF'OLDS Filed Oct. 25, 1954 4 Sheets-Sheet 4 INVENTOR. PAUL G. BECKER CLARA 6. BECKER Mam A TTORNEVS United States Patent FOLDING SCAFFOLDS Paul G. Becker and Clark G. Becker, Los Angeles, Calif. Application October 25, 1954, Serial No. 464,208

2 Claims. (Cl. 304-29) This invention relates to folding scaffolds and more particularly to extensible scaffolds which may be used to hoist men, material and equipment to any desired height within the limits of the physical dimensions of the scaffold.

The scaffold of this invention is adapted to handle many types of materials, equipment and personnel, but its principal application is to the installation of plaster board on ceilings. Conventional plaster boards currently used are approximately 8 feet long and 4 feet wide. Present practice for installing these plaster boards is for two workmen, one with a long 2 x 4 at each end of the plaster board, to balance the plaster board on the upper ends of the 2 x 4s and elevate the board into position on the ceiling. The 2 x 4s are then blocked in position and the workmen secure the board to the ceiling. This procedure requires that the plaster boar-d be elevated to a horizontal position, balanced on the end of the 2 x 4s and then raised by two men against the ceiling in the proper position.

The scaffold of this invention permits one man to rotate a plaster board from an inclined to a horizontal position and then hoist it into final position against the ceilmg. while the man secures the board to the ceiling.

Briefly the invention contemplates a pantograph linkage attached at its lower end to a support member so that the linkage can be pivoted about a substantially horizontal axis. A platform is attached to the upper end of the linkage and means are provided for extending, retracting and pivoting about the support member. This permits the plaster board to be loaded easily on the platform while the platform is in a lowered and inclined position. Operation of the linkage then pivots the platform to a horizontal position and further operation of the linkage elevate the platform to the desired height.

In a preferred form, the pantograph linkage comprises an upper pair of arms pivotally connected to each other at a point between their ends to form an upper pivot, and a lower pair of arms connected to each other at a point between their ends to form a lower pivot. The linkage is pivotally attached to a support member at the lower pivot so as to be pivotable about a substantially horizontal axis. A platform is pivotally connected to the upper end of one of the upper arms andis sli-dably carried by the upper end of the upper arm. A first cable is attached to the lower end of one of the lower arms and a second cable is attached to thelower end of the other arms. The first cable is longer than the second cable and both cables are wound around a winch carried by the support member. The first cable is wound around the winch out of phase with a second cable by an amount substantially equal to the difference in the lengths of the two cables. This permits the twocables not only to actuate the two lower arms to extend and retract the linkage but also to pivot the linkage about the lower pivot when the linkage is in the retracted position.

These and other aspects of the invention will be more clearly understood from the following detailed descrip- The scaffold holds the plaster board in position I 2 tion taken in conjunction with the accompanying drawing in which:

Fig. l is an elevation, partly broken away, of a presently preferred embodiment of the invention showing the linkage retracted and the platform in the inclined or loading position in solid lines, and the linkage and platform in the horizontal position ready for hoisting in phantom lines;

Fig. 2 is an elevation, partly broken away, of the apparatus of Fig. 1 showing the linkage extended so that the platform i in raised position; i

Fig. 3 is a plan view of the apparatus in Fig. 1 showing a plaster board in phantom lines resting on the platform in the horizontal position shown in phantom lines in Fig. 1; and

Fig. 4 is a view taken on line 44 of Fig. 2.

The scaffold comprises a pantograph linkage 10 having a first lower arm 11 and a second lower arm 12 which are pivotally connected between their ends at a lower pivot 13. A first upper arm 14 and a second upper arm 15 are pivotally connected between their ends at an upper pivot 16. The lower end of the first upper arm i pivotally connected to the upper end of the second lower arm and the lower end of the second upper arm is pivotally connected to the upper end of the first lower arm. The first lower arm consists of two spaced parallel bars 17, 18 disposed on each side of the second upper arm at the upper pivot, the second upper arm being a single bar 22. The forward end of a platform 23 consisting of a pair of elongated spaced platform bar 24, 25 having a plurality of transverse strips 26 welded across the top of the strips is pivotally attached to the upper end of the first upper arm by a pivot pin 27 extending through a separate pillow block 28 attached to the lower edge of each platfcrm bar and extending through the bars of the first upper arm. The first upper arm bars are disposed inside theplatform bars and are held apart by a tubular spacer 34) disposed around the central portion of the pivot pin. A, transverse foot 31 extending above the level of the platform strips is attached to the forward end of the foremost strip which is disposed at the forward, end of the platform bars. The foot serves to support the lower edge of a plaster board hoisted by the scaffold.

A sliding pin 32 is disposed through the upper end of the second upper arm and slidably carries the lower edges of the rear portion of the platform strips. The platform is mounted so that when it is in its lowered and horizontal position (dotted line position shown in Fig. 1) its center is well in front of the vertical connecting the two linkage pivots, and the lower portion of the forward end of the platform bars are beveled at 34. These two latter features allow the platform to be tilted so that the foot rests near the floor when the linkage is retracted and the Ip latftlnm inclines to the position shown in solid lines in The linkage is supported at its lower pivot in the upper end of an upright carriage 36 to pivot about a horizontal axis extending perpendicular to the direction of the platform. The carriage consists of two vertical spaced channel beams 33 placed back to back and having their channels opening outwardly. The flanges of a downwardly opening winch plate, C-shaped in cross section, are rigidly attached to the inner surfaces of the two channel beams in an intermediate portion of the beams. of the two beams are rigidly fastened to base 40. The base comprises a central upwardly opening channel beam 42 and a separate upwardly opening, cross channel beam 43 welded to each end of the central beam. A separate caster 44 is provided under the ends of each cross beam to i of the scafiold assembly.

'A separate brace 45 for each beam of the carriage which is rigidly attached at its lower end to the forward The lower ends'. the center of a.

facilitate the moving and locating" portion of the central beam of the base, extends upwardly and rearwardly and is rigidly attached at its upper end to its respective carriage beam.

A winch assembly 47 is mounted between the two carriage beams, above the winch plate. The winch assembly comprises a .drum 48 having a first pulley 4% and a second pulley 59 mounted to rotate about a horizontal drum shaft 51 disposed between the two channel beams. An internal ring gear 52 attached to one end of the drum is adapted to receive a smaller driving gear powered by a crank 53 through a drive shaft 54 carried by the two channel beams below the drum shaft 51. The winch assembly is provided with a conventional double throw ratchet 56 arranged to engage the teeth of the ring gear at the upper portion of the gear so the winch can be operated in either direction and locked against movement in the opposite direction. g

The traveling end of a first cable 57 is attached to the lower end of the first lower arm. The first cable extends downwardly and inwardly around a rear pulley 58 mounted on the rear end of the central beam of the base, around a first central pulley 59 mounted between the two beams of the carriage, up through a central opening 60 in the winch plate, and then around the first pulley on the drum.

The traveling end of a second cable 62 is attached to the lower end of the second lower arm. The second cable extends rearwardly and downwardly around a forward pulley 63 mounted on the forward end of the central beam of the base, extends rearwardly and around a second central pulley 64 mounted between the two channel beams of the carriage, upwardly through the winch plate opening, and is wound around the second pulley of the winch drum. The first cable is longer than the second cable by an amount approximately equal to the distance from the forward pulley to the lower end of the second lower arm when ,the platform is in a substantially horizontal position. 'This extra length on the first cable is Wound on the drum out of .phase with the second cable on the drum, i. e., when the linkage is in the extended position illustrated in Fig. 2, the first will have more cable wound around it than will the second pulley,

on the drum'by an amount equal to the extra length. This condition is illustrated most clearly in Fig. 4 which shows more cable wound on the first winch pulley than on thesecond.

The operation of the scaffold is as follows: Assume that a plaster board (shown in dotted lines in Figs 2 and13) has just been installed on a ceiling and the scatfold is tobe operated from the position shown in Fig. 2 to install another plaster board. The ratchet is set so that the crank can be turned counter-clockwise as viewed in Fig. 2 so that the drum of the winch is revolved in a counter-clockwise direction.

lower arms are elevated to allow the pantograph linkage This allows the first and second cables to be-wound from the condition illustrated in Fig. 4 so that the lower ends of the first and second to retract tothe dotted line position shown in Fig. 1. In 7 this position the second cable is now completely unwound from the second pulley on'the drum and the first cable .is still wound around the drum by an amount equal to the distance from the lower endof thesecond lower arm tothe forward pulley. Continued rotation of the crankhandle in a counter-clockwise direction causes the second: cable to be wound around-the second pulley on the drum in the opposite direction from that shown in Fig. 4. This pulls the pantograph linkage and the platform to the inclined position shown by solid lines'in Fig. l. The lower end (which is now moved to an elevated position) of the first lower arm ispermitted to rise to .the elevated position-shown becauseoftheadditional cable which was initially wound around the first-pulleyof the drum, The plaster board is then easily mounted.ontheplatformby 4 s mply sliding it a ro s he flo an t n it suificienfly to place its lower edge on the platform foot.

The position of the ratchet is then reversed and the crank is turned in a counter-clockwise direction as viewed in Figs. 1 and 2 so that the first cable is wound around the first pulley on the drum in the direction shown in Fig. 4. This pulls the linkage to the horizontal position shown in dotted lines in Fig. l. The second cable is automatically allowed to reel out to the dotted line position because it had previously been wound around the second pulley of the drum in a direction opposite to that shown in Fig, 4. Continued rotation of the crank in the clock-wise direction raises the plaster board to the desired height and the ratchet locks the winch in the proper position. The plaster board is then secured to the ceiling and the scaffold is ready for another operation.

Thus, the scaffold operates quickly and simply to tilt a plaster board from an inclined to a horizontal position and raise it to the desired location on the ceiling. The casters on the base facilitate the proper positioning of the plaster board on the ceiling. All of the parts may be made of lightweight aluminum and either welded or bolted together with simplicity and low cost. One workman operating with the scatfold can easily do work which previously required two men.

We claim:

1. In a folding scafiold, the combination comprising a support member, an extendable and retractable pantograph linkage having an upper pair of arms pivotally connected to each other intermediate their ends at an upper pivot and a lower pair of arms pivotally connected to each other intermediate their ends at a lower pivot, a platform pivotally connected to the upper end of one of the upper arms and slidably carried by the upper end of the other upper arm, the linkage being supported by the support member at the lower pivot of the linkage to be pivotable about a horizontal axis when the linkage is in its retracted position, a winch having a first pulley and a second pulley, a first cable attached to the first pulley and the lower end of one of the lower'arms, and a sec- ,ond cable attached to the second pulley and the lower end of the other lower arm, the cables'being of difierent length and wound'on to their respective pulleys so that when the winch is wound in one direction the linkage is extended, and when wound in the other direction the linkage is collapsed and then pivoted about the lower pivot while the linkage is collapsed.

2. In a folding scaffold, the combination comprising a support member, an extendable and retractable pantograph linkage having an upper pairof arms pivotally connected to each other intermediate their ends at an upper pivotanda lower pair of arms pivotally connected to each other intermediate their ends at a lower pivot, a platform pivotally connected to the upper end of one 'of the upper arms and slidably carried by the upper end of the other upper arm, the linkage being supported by the support member at the lower pivot of the linkage to bepivotable about a horizontal axis when the linkage is in its retracted position, a winch having a first pulley and a second pulley, a first cable attached to the first pulley andthe lower end of one of the lower arms, and a second cable attached to the second pulley and the lower endot'theother lower arm, the first cable being longer than the second cable and wound on the first pulley out. of phase with the second cable by an amount approximately equal to the difference in the lengths of the two cables.

248,345 -Phipard Oct. 18, 1881 1,357,185 Powell :Oct. 26, 1920

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