US 3860226 A
A protective shroud for the operating spring of an overhead door assembly comprising an elastomeric tube embracing the spring and sufficiently strong to retain the parts captive upon failure of the spring under load.
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Description (OCR text may contain errors)
United States Patent [191 Hensiek, Jr.
[ 1 PROTECTIVE SHROUD FOR OVERHEAD DOOR TENSION SPRING  Inventor: Fred Hensiek, Jr., 743 N.
Sunnyslope, Pasadena, Calif. 91107 22 Filed: Nov. 23, 1973 21 Appl. No.: 418,468
 US. Cl. 267/69  Int. Cl Fl6f 1/12  Field of Search 267/69, 74, 73
 References Cited UNITED STATES PATENTS 1,598,480 8/1926 Deal 267/74 Jan. 14, 1975 2,129,338 9/1938 Timmons 267/74 3,285,673 11/1966 Dobrikin 3,353,817 11/1967 Bollinger 3,429,072 2/1969 Sammons 267/74 Primary Examiner-James B. Marbert Attorney, Agent, or Firm-Sellers and Brace  ABSTRACT A protective shroud for the operating spring of an overhead door assembly comprising an elastomeric tube embracing the spring and sufficiently strong to retain the parts captive upon failure of the spring under load.
6 Claims, 4 Drawing Figures PROTECTIVE SIIROUD FOR OVERHEAD DOOR TENSION SPRING This invention relates to spring protective devices, and more particularly to a protective shroud adapted for assembly about the operating coil spring of an overhead door assembly.
Overhead door operating assemblies are commonly powered by high energy coil springs normally highly stressed so long as the door is closed, the stored stress being somewhat less than that required to support the door. Accordingly, only slight effort need be applied to the door to raise it to its elevated open position, the major portion of the required energy being that stored in the counterbalanced spring. In consequence, it is not an uncommon experience for such springs to fracture on fail without warning with the result that the high forces thereby released serve to disperse the parts at high velocity and with great force. Both life and property in the vicinity of the door are thereby placed in jeopardy.
Many proposals have been advanced heretofore in an effort to safeguard against these hazards but have not been adopted in any significant extent for various reasons. These proposals complicate the construction of the counterbalance assemblies, increase the cost and maintenance expense thereof and fail to provide adequate protection. Most of these proposals involve auxiliaries adapted to be attached to existing constructions and require alteration of the original construction.
It is therefore a primary purpose of the present invention to avoid the shortcomings and disadvantages of prior protective auxiliaries. To this end the present invention comprises an inexpensive ruggedly constructed elastomeric tube adapted to be assembled over the full length of the counterbalance spring and preferably slightly beyond the ends thereof in order to embrace and conceal the spring itself as well as components holding the spring installed in its operating environment.
Accordingly, upon failure of the spring or of the means connecting it to the operating linkage, all released parts are retained captive and held against escape by the invention elastic shroud. Desirably, the shroud is somewhat shorter than the outstretched spring when the latter is fully extended to the end that the tube will be worked during each operating cycle of the door thereby greatly prolonging its effective life.
Accordingly, it is the primary object of the present invention to provide an improved, rugged, inexpensive, non-metallic protective shroud readily installed about the operating springs of counterbalanced overhead door assemblies.
Another object of the invention is the provision of a non-metallic, elastomeric protective shroud enclosing coil springs and effective to hold the same captive should the spring fail under high stress.
Another object of the invention is the provision of a moisture-tight protective shroud for the coil springs of overhead door assemblies to hold the parts captive and to provide protection against oxidation.
These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.
Referring now to the drawing in which a preferred embodiment of the invention is illustrated:
FIG. 1 is a fragmentary cross-sectional view showing the invention shroud assembled to a typical overhead door operating mechanism with the door shown in closed position;
FIG. 2 is an enlarged view of the counterbalance spring and protective shroud with portions of the shroud broken away to show constructional details;
FIG. 3 is a view similar to FIG. 2 but showing the condition of the shroud when the counterbalance spring is substantially relaxed to support the door in open position; and
FIG. 4 is an enlarged fragmentary view of one end of the protective shroud in open position prior to assembly about the counterbalance spring.
Referring initially more particularly to FIG. 1, there is shown an illustrative overhead door linkage, designated generally 10, assembled to a garage door 11 of a typical garage 12. It will be understood that the operating linkage is duplicated at either end of the door and includes a rigid V-frame 13 having the end of each arm rigidly secured to door 11, as by fasteners 14. The apex of frame 13 includes a bearing 15 journalled on a stub shaft 16 rigidly connected to a mounting bracket 17 suitably and rigidly secured to the garage wall. The counterbalance spring assembly 20 comprises a powerful coil spring, to be described in more detail presently, having its lower end connected to frame 13 by a chain 23 and its upper end connected by a second chain 24 to a fixed beam 25 or other rigid support here shown forming part of the roof structure of building 12.
The counterbalance spring assemblies and the protective shroud of this invention will now be described by reference to FIGS. 2-4. Counterbalance spring 25 has its opposite ends connected to chains 23 and 24 by typical S-hook assemblies 26, 27. It will be understood that the invention protective shroud does not require that any part of counterbalance assembly 20 or that any other part of the door operating linkage be modified. Thus, shroud 30 comprises a thick-walled resilient tube of tough rubber, or the like elastomeric material, having a normal relaxed length which is preferably substantially less than the length of spring 25 when door 11 is in its closed position. For reasons which will be explained more fully presently, the opposite ends of shroud 30 are preferably equipped with a plurality of grommeted openings 32 distributed about the periphery of either end through which a strong tie cord 33 is threaded in the manner illustrated in FIG. 4.
The shroud is assembled over spring 25 by temporarily unhooking an end of one of the S-hooks, telescoping the shroud 30 over the free end of the spring, and then reassembling the S-hook to the adjacent one of chains 23 or 24. Cords 33 are then pulled taut about a respective one of the chains and securely tied thereby to hold the shroud ends snugly and securely gathered and assembled to the two chains at points beyond the ends of the S-hook assemblies. It will be understood that the protective shrouds have an internal diameter preferably sufficiently greater than the outer diameter of the relaxed counterbalance spring to permit lengthwise collapsing of the shroud along the length of the spring when door 11 is open. Under these conditions, the shroud 30 will have the general appearance shown in FIG. 3. However, when the door is closed, spring 25 will be very substantially elongated and under high tensile stress and, under these conditions, shroud 30 is also preferably under some tension to provide working" of the elastomeric material so conducive to its long life and maintenance of its full strength for long periods.
Should spring 25 or any part of either S-link assembly 26 or 27 fail or fracture while the counterbalance spring is under stress, it will be understood that the protective shroud will retain any and all parts of the broken assembly securely captive. This safeguards the building or property within the building and particularly safeguards persons in the area upon failure of the spring from risk of damage or injury.
While the particular protective shroud for overhead door tension spring herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.
1. That improvement in an overhead door counterbalance assembly of the type utilizing coil spring means at either end of a door to operate a respective door operating linkage assembly, said improvement comprising a protective tubular elastomeric shroud adapted to embrace the full length of each of said coil spring means and having a relaxed length greater than the length of the associated coil spring means in the position of said linkage means when in the closed door position thereof, said shroud having a wall thickness and strength effective to retain captive the parts of said coil spring means upon failure thereof while under load, and means for closing the ends of said shroud about an adjacent portion of said linkage assembly adjacent to opposite ends of said spring means to prevent the escape of portions of said spring means from said shroud should said spring means fail while under tensile load.
2. That improvement defined in claim 1 characterized in that said means for closing the opposite ends of said shroud includes high strength tie means for securing said shroud ends snugly gathered about a portion of said linkage assemblies closely adjacent the respective ends of said spring means.
3. That improvement defined in claim 1 characterized in that said elastomeric shroud is substantially larger in diameter than said coil means and having a length such that said shroud is placed in tension and stretched as said linkage assembly is operated to the open door position thereof whereby said shroud is tensioned and relaxed during each operating cycle of the door operating linkage assembly.
4. That improvement defined in claim 3 characterized in that the opposite ends of said shroud are equipped with a plurality of grommets spaced about the circumference thereof through which cord means is threaded for use in securing said shroud ends snugly gathered.
5. That method of enshrouding the tension coil spring of an overhead door counterbalance assembly which comprises encasing said coil spring in a high-strength protective elastomeric shroud having a loose fit about the exterior thereof and a length greater than the nor mal relaxed length of said coil spring, and gathering the ends of said shroud together about the respective ends of said coil spring to prevent the escape of said spring or portion thereof upon failure of the spring under load.
6. In combination with an overhead door counterbalance assembly of the type utilizing tension coil spring means to operate said assembly and support a major portion of the door weight, a tubular shroud of high strength elastomeric material embracing the full length of said coil spring means and sufficiently strong to thwart rupture and permit escape of fracture components of said spring means upon failure thereof under load, and means securing said shroud in assembled position about said coil spring means.