US2112915A - Lifesaving net - Google Patents

Description

c. c. LENZ April 5, 1938.

LIFESAVING NET Filed-April 25, 1957 I [1 ATTORNW Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE 7 Claims.

The invention relates to life-saving. nets of the kind comprising a net, encircled and yieldingly supported by a rigid frame adapted to :be held by firemen, to receive persons obliged to jumpfrom burning buildings. Such a net is shown and described in my prior Patent No. 2,066,182. The principal object of the present, invention is to minimize the shock experienced by the firemen as the result of the impact of the falling body striking the net, and to provide a net which, in consequence, can safely be held by fewer firemen than are required for nets heretofore used, the men not needed being relieved to perform other important tasks in connection with the fire. The invention consists in a novel organization of energy absorbing connections between the frame and the net and other details, all as described below and illustrated in the accompanying drawing.

Fig. 1 of the drawing is a plan view of a section of net showing the preferred form of the invention applied to it;

Fig. 2 is a section on the line IIII of Fig. 1;

Fig. 3 is a perspective view showing certain of the component parts spaced apart to illustrate the construction; and

Fig. 4 is an illustrated diagram.

As generally constructed, life-saving nets of the kind to which the invention relates consist of a rigid frame in the form of a ring, some nineor ten feet in diameter, made of a heavy gauge of tubular metal stock, encircling a net which is yieldingly secured to it by energy-absorbing connections. A portion of such a frame is indicated by the reference I in Fig. 1 of the drawing. Usually the energy-absorbing connections. include a number of rods 2 spaced around the frame and pivoted to it, as by bending the upper ends of the rods around the frame so that the rods hang vertically, pendulum fashion. Each of the rods forms a spring guide and is encircled by a coil spring 3, the lower end of which bears against a stop 4 and upon the upper end of the spring is seated a collar 5 from the side of which projects a slotted strap lug 6. Straps 1 are passed through these lugs and riveted to the canvas net 8.

In using such a net a number of firemen hold the same, at about shoulder height, the spring rods hanging about as indicated at A in Fig. 4; and, by their weight, serving to distend the net; the latter, which is more or less horizontal, slightly cupped, is indicated at B. After the falling body has landed, the rods and the net occupy positions approximately as indicated at C and D,

respectively, in Fig. 4, the springs on the rods being compressed and energy of the falling body being thereby absorbed.

Notwithstanding the cushioning effect of the springs, the rate of energy dissipation through the frame itself is so great that the firemen sustaining it experience a considerable shock-so much so that, in order to minimize it for each man, as many as twelve firemen are usually employed to hold the net. Even then the shock is appreciable, being felt principally in the wrists and neck. It is believed that this shock or jar is largely due to the inertia of the spring rods.

Some part of the energybf the falling body striking the net is dissipated in the form of work done in moving the rods from their initial position (A) to their final position (C). At the instant of impact the resulting force is applied to the rods in the general direction indicated by the arrow E in Fig. 4 and since its point of ap- 0 plication is close to the frame, about which the rods pivot, and hence is at a substantial me- 1 chanical disadvantage so far as moving the rods is concerned, the force necessary to: overcome the inertia of the rods is considerable. This force, it is believed, giving rise to a brief but severe downward jerk of the frame itself, is responsible for the shock which the firemen experience. As will be apparent, the springs do not become efficient as shock absorbers until the rods have been swung inwardly to a point where the axis of each spring is more nearly in line with the direction of pull of the net.

According to my invention, as applied to a net of this particular type, the parts are so arranged that each of the spring rods initially lies in a substantially horizontal position, as indicated in Fig. 2, or at least so nearly horizontal that the rod, at the point of connection with the net (the location of collar 5 in this instance) is substantially tangential to the net at the instant of impact. As will be understood, the diameter of the net is preferably such that even when the rods are in the position indicated there is no material sagging. The final position of the rods (as indicated in dotted lines in Fig. 4) is of course the same as that already described, but as will be apparent, neither in the initial position nor at any other time during their movement from that to their final position are the rods themselves subjected to any force other than that applied to them through the springs; the latter are so positioned that the pull resulting from the impact of the body striking the net is immediately and directly applied to them, i. e. to the springs, rather than initially to the rods and to the work of moving them. By this means the shock of the impact is much more effectively absorbed and, also, the rods are relieved of the distorting strains to which they would otherwise be subjected.

Various auxiliary means may be provided whereby springs 3 may be caused to assume the position specified but in the preferred form illustrated the arrangement contemplates an energyabsorbing, pivotal connection between the rods and the frame in the form of an additional spring. The springs 3 need be under no more initial tension than may be desirable to hold the net against sagging.

In the preferred arrangement means are also provided for spacing and definitely locating the rods on the frame and incidentally protecting the firemens hands from being pinched between the rods and the frame as the former pivot about the latter. Such means may comprise a plurality of pairs of collars 9 located as indicated and locked to the frame by set screws [0. As shown in Fig. 3 the adjacent faces of the collars of each pair are recessed to provide a housing H for springs II, the ends ll of which are anchored by inserting them in holes I3 in the collars. The center turns of each spring are spaced apart to receive the pivot loop of a rod 2 and loop I 4 of each spring passes beneath its rod so that when the collars are secured to the frame in the position indicated, the rods are yieldingly held in the position specified (Fig. 2).

The provision of such means for holding the rods initially in substantially horizontal position results also in the rods being held snugly against the net at all times and thereby facilitates the handling of the net as a whole, in that the firemen are not hampered by the rods swinging loose and in danger of catching in their clothing or against any other nearby objects. It is also of particular advantage to have the rods held snugly against the canvas when, as is now customary, the frame is made in two or four sections to permit the net to be folded and transported more readily. The folding operation is greatly facilitated when there are no free-swinging rods, as will be apparent.

It has been found that in the use of such a net wherein the coil springs 3 are mounted radially and substantially in the plane of the net itself, the vertical shock to which the frame is subjected is minimized to such an extent that, without danger of injury to any of them, far fewer firemen are required to sustain the net than have heretofore been employed.

I claim:

1. A life-saving net comprising in combination with a frame and a net encircled thereby, a plurality of shock-absorbing connections between the frame and the net, each comprising a rod pivoted on the frame, a spring normally holding the rod in a substantially horizontal position, a second spring, encircling the rod and engaging an abutment adjacent the inner end thereof, and a coupling device secured to the net and bearing against the outer end of said second spring.

2. The combination of claim 1, including a plurality of pairs of collars secured to the frame, the collars of each pair being spaced apart to receive and locate one of said rods and being recessed to receive and enclose the first mentioned of said springs.

3. A life-saving net comprising in combination with a frame and a net encircled thereby, a plurality of spaced pairs of collars rigidly secured to the frame, a spring guide rod pivoted on the frame between and located by the collars of each pair, a coupling device mounted on each of the rods and secured to the net and a spring associated with each of the rods and adapted normally to hold the same in a substantially horizontal position.

4. A life-saving net comprising in combination with a frame and a net encircled thereby, a plurality of spaced pairs of collars rigidly secured to the frame, a spring guide rod pivoted on the frame between the collars of each pair, a coupling device mounted on each of the rods and secured to the net and means for holding the rods against the net.

5. A life-saving net comprising in combination with a frame and a net encircled thereby, a plurality of shock-absorbing connections between the frame and the net, each including a rod pivoted on the frame and a spring on the rod, and means for holding said spring and rod against the net.

6. A life-saving net comprising in combination with a frame and a net encircled thereby, a plurality of shock-absorbing connections between the frame and the net, each including a rod pivoted on the frame and a spring on the rod, and energy-absorbing means controlling the pivotal movement of the rod about the frame.

7. A life-saving net comprising in combination a rigid frame, a net within the frame, and a plurality of shock-absorbing connections between the net and the frame each including a guide rod and a spring thereon mounted with its axis radially and substantially in the plane of the net.

CHARLES C. LENZ.

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