US657648A - Knockdown trestle. - Google Patents

Description

Patented Sept. ll, I900. L. W. DAVIDSON.

KNOGKDOWN TRESTLE. (Application filed July 17, 1900.)

(No Model.)

a llllllll lull owzf/amm m;

@X) @a 61mm,

ms Purim on. moYaumu, wasnmamn. o. c.

UNlTED STATES LEWIS 'W. DAVIDSON,

PATENT OFFIcE.

OF NEW YORK, N. Y.

KNOCKDOWN TRESTLE.

SPECIFICATION forming part of Letters Patento. 657,648, dated September 11, 1900.

Application filed J l 17, 1900.

To all whom it may concern:

Be it known that I, LEWIS W. DAVIDSON, a citizen of the United States, residing in New York, in the county of New York and State of New York, have invented a certain new and useful Improvement in Knockdown Trestles, of which the following is a specification.

The object of my invention is the provision of an improved form of trestle for carpenters, plasterers, and the like, which can be folded into small compass for storing and transportation and when needed for use can be quickly erected into a firm and rigid structure.

My invention is illustrated in the accompanying drawings, wherein- Figure 1 is a side View of a pair of supports and an end plank used at one end of a plasterers or painters trestle in a well-known manner; and Fig. 2 is an edge View of such support, showing a portion of the plank in side view.

The trestles now commonly used by painters and plasterers consist of a horse at each end of a platform, each horse consisting in turn of a thick plank upheld at each endby, an A-frame or by two legs spreading like an inverted V. My present improvement lies in the special construction of the legs or frames at the ends of the planks in the horses aforesaid, whereby they may be easily taken apart and put together without impairing the rigidity and strength of the entire trestle.

In the drawings the plank is shown at 1, and the two legs comprising the supporting agents at 2. These logs are arranged to spread in the ordinary manner; but they are joined at their upper ends by special means which permit of their being folded together at will. In the form shown these means consist of two jaws 3, one fixed to the end of each leg 2, said jaws being connected at either side by the jointed links 4 and 5. Two of these links are placed on each side of the pair of jaws, and the upper end of each link ispivoted loosely to the jaw on its own side, as shown at 6. I prefer to give these links the shape substantially as shown in the drawings in Fig. lthat is to say, to provide at the lower end of each link a widely-rounded curve, so that when the plank rests upon the upper Serial No. 23,867. (No model.)

edge of said curve, as shown, its lower corners will not impinge upon the edges of the two links. The links are pivoted together at their meeting ends by a bolt 7, running through both pairs of links, as shown in the drawings. By this disposition of the bolt greater strength is secured as against twisting. Behind each jaw 3 there is pivoted a beak 8, which may be fastened by any convenient pivot, but which I prefer to pivot upon one of the bolts, as 9, which secure the jaws to the ends of the legs. Opposite the point of each beak there is an appropriate opening, as shown in Fig. 2, through which the point of the beak may be made to pass. These points are preferablyturned downward in the manner shown. The lower ends of the legs 2 are joined by a folding brace 10 of any convenient construction.

The mode of use of my device is as follows: The legs having been drawn apart until the brace 10 is extended and secured the jaws are drawn open, and the end of the plank l is inserted between said jaws and pressed firmly downward. The loweredge of the plank resting upon the widened parts of the links 4: and 5 their joint-pivot is pressed downward, and in consequence the jaws 3 are brought together against the sides of the plank, thus clipping the same tightly and tending to hold it in place. It will thus be seen that the greater the weight supported by the plank 1 the tighter will the jaws 3 clip said plank. At the same time the extended ends of the links prevent impingement against the sides of said links of the lower corners of the plank 1. This insures unimpeded action of the full weight of the plank in drawing together the jaws 3, as if such impingement of the corners upon the links were permitted it would exert a material resistance to the narrowing of the angle between the links and the consequent approach of the jaws. The plank having been thus pressed down to its lowest point the beaks 8 are simply driven through the apertures in the jaws into the sides of the plank. This may be done by a few blows of the hammer. The downward turn of these beaks exerts a tightening or wedging action upon the plank, and the beaks secure the legs from movement along the plank or longitudinally, thus providing the utmost rigidity and firmness to the whole structure.

What I claim is- 1. A support for knockdown trestles comprising a pair of spreading legs, links pivoted to said legs and to each other, the joint ends of said links being rounded out in formation of an enlargement, and jaws upon the ends of said legs, substantially as described;-

2. A support for knockdown trestles comprising a pair of spreading legs, jaws at the meeting ends of said legs, aplank adapted to be held by said jaws, links pivoted to said jaws and to each other, the point of junction of said links being beneath said plank and be ing rounded out into an enlargement for taking the weight of the plank.

3. A support for knockdown trestles comprising a pair of spreading legs, jaws on the meeting ends of said legs, pivoted links for joining said'leg's and beaks pivotally supported at the meeting ends of said legs, said beaks being adapted to be driven into any body placed between said jaws for fastening the same.

, V LEWIS W. DAVIDSON. Witnesses:

P. T. TUNISON, H. S. MACKAYE.

Images