US1140390A - Extension-trestle. - Google Patents

Description

F. H. MOULTON EXTENSION TRESTLE.

APPLICATION FILED APR. 29, 1913.

1,1 w fi fio Patented May 25, 1915.

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FRED H. IVIOULTON, OF LEXINGTON, MASSACHUSETTS.

EXTENSION-TEESTLE.

, Specification of Letters Patent.

Patented May 25, 1915.

Application filed April 29, 1913. Serial No. 754,319.

To all whom it may concern:

Be it known that I, FRED ILIVTOULTON, a citizen of the United States, residing at Lexington, county of Middlesex, Commonwealth of Massachusetts, have invented certain new and useful Improvements in Extension-Trestles, of which the following is a specification.

This invention relates to extension trestles and is particularly designed for use by painters, masons, paper hangers, and others whose work often lies in high and inaccessible places. Many expedients have been devised to facilitate work of this nature, but in the main they have all been found unsatisfactory in some essential respect. To the end, therefore, of providing a satisfactory extension trestle which will embody the requisite characteristics of safety, compactness and portability, I have devised my present invention, an illustrative embodiment of which is shown in the annexed drawings, it being understood that in use two of these trestles are set up and a plank is laid across the rungs of each at the desired height.

Throughout specification and drawings, like numerals of reference will indicate corresponding parts and in these drawings:

Figure 1. is a perspective view of an extension trestle in accordance with my invention. Fig. 2 is a partial vertical central section thereof. Fig. 3 is a partial end view of the legs folded and the extension lowered. Fig. l is a horizontal section on the line 47-4: of Fig. 2 looking in the direction of the arrows. Fig. 5 is a perspective view of one of the guide and clamping pieces for the extension. Figs. 6 and 7 are detail sections thereof, the hinge being open in Fig. 6 and closed in Fig. 7, and Fig. 8 is a detail section illustrating the action of the extension when being raised to pass the locking latches.

The extension trestle thus illustrated comprises pairs of front and rear supporting legs, 1 and 2, the legs of each pair being joined by cross bars 3 and 4:, respectively. These legs converge and are, as indicated at 5, beveled at their upper ends to frictionally engage the sides of an extension piece 6 vertically slidable relative thereto. The extension member 6 is of substantially the width of the top of the pairs of legs 1 and 2. The opposite legs of each set are hinged near their tops. The leaves 7 of the top hinges are fastened to their respective side pieces of the legs 1 and 2 by suitable fastenings S and are pivoted upon each other intermediate the legs by a pivot stud 9. The leaves therefore have a toggle action when expanded, which action causes the beveled faces of the legs to firmly grip the extension and hold it steady in place when run up, the hinges guiding the extension in its travel.

The pairs of legs 1 and 2 are connected and braced at their sides by hinges of peculiar construction. The leaves 10 of said hinges are fastened to the respective sides of the legs by suitable fastenings 11 and to each other by a pivot stud 12 as in the fastening of the top hinges. Each pivot stud carries a channel iron efiective to guide and steady the extension in its travel. This guide comprises a vertical bearing wall 13, and horizontal side walls 14 terminating at their free ends in inturned flanges 15, an overhanging flange 16 being formed on the vertical bearing wall to limit the upward movement of the leaves.

Referring to Figs. 6 and 7 it will be seen that the vertical bearing wall 13 is of gradually increasing thickness on its outer face from the top to the bottom edge. This presents an inclined surface against which one of the leaves of the side hinges is forced when the supporting legs are expanded. This opens the hinges and causes the lowermost leaf of each pair to wedge against the outer edge of the inclined face, the maximum degree of wedging being reached at the highest point of the incline. In this action, the leaf turning from the upwardly inclined closed position of Fig. 3 wherein the inclination nearly coincides to that of the ladder stiles toward each other, to the transverse expanded position of Fig. 4; produces a wedging or binding action between the nut head and the inclined wall 13 on the leaf, and this action is started from over the inner edge or corner of the stile to which the leaf is attached. This wedging effect serves to hold the leaves in open position and thus prevent the legs from folding up under the weight of a load on the extension. When thelegs are folded, the leaves are first raised upwardly (see Fig. 8) and assume the position shown in Fig. 7. In this position the leaves have a slight play on the pivot stud due to the increased working space afforded by the in clined face of the wall 13. The inner face of the bearing wall 13 is straight to permit the extension to slide freely thereon, the side Walls and end flanges serving with the vertical bearing wall to guide said extension in its travel.

To look the extension in any position of adjustment I pivot near each end of a rung 17 connecting the sides of the front legs, a latch 18. The free ends 19 of said latches are hooked for locking engagement over a rung 20 similarly connecting the sides of the rear legs. These latches in the normal or unextended position of the extension hang freely from their pivots. In running up the extension the rungs 21 thereof brush past said latches raising them upwardly as shown in Fig. 8. hen the desired height for the extension has beenreached, the nearest rung thereof rests on the latches near each end as shown'in Fig. 2. This insures a firm support for the extension and one which will bear any load up to the breaking point of the rungs 17 and 21.-

In use, two trestles are set .up and a plank rests upon a pair of rungs of the extensions and affords a scaffold. The extensions are run up to the desired height by merely lifting upwardly on them, the latches riding freely over each extension rung until the proper height is reached, whereupon they may be hooked over the rung 20, the extensions being supported on said latches near each end of a rung of their series of rungs 21. g

The expansion of the legs is effective to cause their beveled portions to tightly engage the sides of the extension, and the inclined surfaces of the .guides frictionally hold the side hinges 10 open and wedges them firmly against accidental displacement. In this action the members lO being made of springy material bow out at their outer ends. This forces their inner ends in toward each other and causes the slidable guides to draw in toward each other and out of the line of the stiles to firmly grip the extension.

The folded position of the trestle is indicated in Fig. 3. This position is reached by merely disengaging the hooks and folding the legs inwardly toward each other. This frees the beveled bearing faces 5 of the legs from their engagement with the extension sides and permits the extension to drop under its own weight. The distance between the sets of stiles 11 and 22 gradually increases from top to bottom due to the fact that the stiles are inclined. The angle of inclination of the bearing walls 13 is substantially that of the stiles. The members 10 in their folded position of Fig. 7 are Copies of this patent may be obtained for five cents each, by addressing' the Commissioner of Patents,

loose on their pivots and therefore hang at substantially the angle of inclination of the stiles. The leaves of the side hinges are, in their folded positions, relatively loose ,on their pivot studs and the inclined faces of the verticalbearing walls afi'ord considerably more room for play than would be the case were said bearing walls formed straight I on both sides.

Various modifications in the construction and principle of my invention may obviously be resorted to if found-within the limits of the appended claims.

What I, therefore, claim and desire to se cure by Letters Patent is:

1. An extension trestle comprising two pairs of divergent legs hmged together, an.

pairs of divergent legs hinged together, an-

extension member of substantially the width of the top of the leg pairs, a pair of leaves one pivotally connected at one end to one leg and the other similarly connected to the opposite leg, said leaves having their inner ends overlapped, a pivotal fastening through said overlapped ends, and an extension guide carried by said leaves andslidably receiving the sides of said extension member, and having an inclined surface adapted for frictional binding engagement with a leaf.

3. In trestle construction, two pairs of divergent legs hingedtogether near their tops, an extension member of substantially the width of the top of the leg pairs, hinge leaves for said pairs of legs pivoted to said legs at their outer ends and overlapping and pivoted to each other at their inner ends, and guides carried by said leaves and slidably receiving said extension, and each comprising a bearing wall having an inclined face adapted for binding engagement with one of the hinge leaves, lateral walls terminating in inturned ends for guiding said extension, and a stop effectively disposed to keep the hinge leaves in line.

In testimony whereof I afiix my signature in presence of two witnesses.

VICTORIA LowDEN, MARION C. HOBBS.

Washington, D. C.

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