US2097242A - Articulated overhead door - Google Patents

Description

Oct. 26, 19 37. D. M. ROBINSON ARTICULATED OVERHEAD DOOR Filed April 30, 1934 3 Sheets-Sheet 2 Qct. 26', 1937. ROBINSON 2,097,242

ARTICULATED OVERHEAD DOOR Filed April 30, 1934 3 Sheets-Sheet 3 Patented st. 26, 937

UNITED STATES ARTICULATED OVERHEAD DOOR David M. Robinson, New Britain, Conn, assignor to The taniey Works, New Britain, Conn, a corporation of Connecticut Application April 30, 1934, Serial No. 723,015"

12 Claims.

This invention relates to improvements in builders hardware, such as is applicable for supporting vertically movable or overhead doors, and has for one of its objects the provision of improved hardware of the character described, that is easy to install and align and does not require special tools or expert workmen.

A further object lies in the provision of such improved hardware that is particularly durable in use and which renders the action of the door unusually smooth and effortless.

A still further object resides in the provision of improved hardware of the character described which renders the counterbalancing of the door particularly easy and accurate and not liable to get out of adjustment in service.

Other objects and advantages will appear as the description proceeds. In the accompanying drawings, in which like reference numerals have been used to indicate similar parts throughout, I have illustrated a suitable mechanical embodiment of the idea of the invention. The drawings, however, are for the purpose of illustration only and are not to be taken as limiting the invention the scope of which is to be measured entirely by the scope of the appended claims.

In the drawings,

Fig. 1 is a vertical sectional view through a garage building showing a section of the door in closed position and the improved hardware in assembled form as applied to the building and door;

Fig. 2 is a plan view of a portion of the door counterbalancing means, the counterbalancing spring being shown in section;

Fig. 2a is a view similar to Fig. 2 showing a continuing portion of the counterbalancing means;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2a;

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2; Fig. 5'is an edge elevational view of a safety stop comprising one element of the improved Referring to the drawings in detail, the numeral l0 generally indicates the structure of a garage building provided with side walls and a front wall and with a door opening l2 in said front wall closed bya door IS. The door l5. as illustrated, is of the type known to the art as an articulated overhead door, and is opened by moving the same from the vertical position illustrated in Fig. 1 to a horizontal overhead position within the garage building. The door is closed by moving it from the horizontal position to the vertical position. In order to support the door and guide the same from one to the other of its two operative positions, I have provided a track, generally indicated at I1, having a vertical portion iii, a. horizontal portion l9, and a partly circular or fillet portion 20 joining the adjacent ends of the vertical and horizontal portions.

It is, of course, understood that similar tracks are positioned at each side of the door opening to engage the opposite edges of the door. However, as these tracks are similar in all respects, except that one may be considered as right-hand and the other as left-hand, it is believed that a description of only one of them is sufiicient for the purpose of this disclosure. This track has a cross section, as particularly illustrated in Fig. 8, substantially channel-shaped except that one leg of the channel is bent inwardly at the extremity thereof to form a roller channel 22. The vertical portions of the track intermediate their ends are secured to the garage building by means of track brackets 23, and the upper end of each vertical portion l8 and the adjoining end of the corresponding curved portion 20 of the track are secured together and secured to the building by a joint plate, particularly illustrated in Figs. 8, 9, and 10.

In order to easily and permanently secure the abutting ends of the vertical and curved portions of the track together in alignment with each other and to the garage atively wide plate edge thereof. This flange is' apertured, as indicated at 26, and screws 21 extend through these apertures into the door jamb tosecure the plate to the building. The upper end of the vertical portion l8 of the track I! is secured to the lower building, I provides. rei- 24 having a flange 25 along one part of one face of this plate 24 by suitable means, such as welding or riveting, and a spacer mem ber 28 is interposed between the adjacent surfaces of the plate and track member to maintain the track member offset from the plate by the thickness of the spacer member. I have also provided a hook plate 29 rigidly secured to the side of the curved portion 20 of the track adjacent to the lower end thereof. This hook plate is of the same thickness as the spacer member 28 and has its end portion, adjacent the outer vertical edge of the plate 24, bent over to form a hook 30 adapted to engage the edge of the plate 24 to bring the abutting ends of the track portions I3 and 20 into exact alignment with each other. The plate 24 and the hook plate 29 are provided with registering apertures 3| and 32 through which a bolt 33 extends to secure the hook plate to the support plate 24 in assembled relation.

The partly circular portion 20 of each track member is welded or otherwise suitably secured to a substantially triangular flanged plate 35, the flange 36 of which is apertured for the passage therethrouglr of screws 30' for rigidly securing the plate to the garage building. For the pur-- poses of swinging the upper panel of the door away from the door frame upon initial opening movement of the door, and camming the upper panel against the door frame or jamb as the door is brought to final closed position, there are provided, at opposite sides of the door openingand above the curved portions of the tracks, short track or cam members 31. Each short track or cam member 31 is materiallynarrower than the main track member I! and is secured to the plate in such manner that it is tangent to the outside of the curved portion 20 of the main track at substantially the center thereof. Each member 31 is a channel member and, as particularly illustrated in Fig.7, the flanges, at the lower ends thereof, extend beyond the web and are curved and extended downwardly, as indicated at 39 and 39, the downwardly extending portion of the flange 39 having a straight portion 39a inclined toward the door jamb in such a manner as to fcrm a cam cooperating with a stud 40 secured to the upper corner of the door, to urge the top of the door firmly against the jamb when the door is in its lowermost position, and a bent over end portion 39b adapted to rest on the upper sur-' face of the main track portion 20 to provide an abutment to brace the inclined or cam portion 390. The lower end portion of the upper web 39 diverges from the cam portion of the web 39 to constitute a guideway for guiding the stud 40 into the track 31. At the upper end of the member 31, the lower flange is also bent downwardly until it substantially contacts the upper surface of the curved portion 20 of the main track, as indicated at 4|, to guide the stud 40 into the guide track 31 when the door is moved from its .open to its closed position.

In the form of the invention herein illustrated, I have disclosed an articulated door made up of four horizontal sections hinged together along their abutting edges. As indicated in Fig. 1, each of the hinges comprises overlapping members 42 and 43 secured respectively to adjoining sections of the door and hingedly connected together by means of a'pintle 44.- Each of the pintles 44 carries at its outer end an antifriction roller 45 adapted to run in the track I! and to guide and support the door in its movements from one to the other of its two operative positions. In addition to the rollers 45 secured to the hinge pins 44, I have provided at the upper end of the door an additional roller 45' secured to the door by means of an upwardly projecting, hinged radius arm 43, secured to the inner surface of the door adjacent to the edge thereof by means of a suitable hinge connection 49. The hinged radius arms 48 are bent, as indicated at 48a, so that, when the door is in a raised or partly raised position, wherein the rollers 45 are supported on the curved or horizontal portions of the tracks, the upper section of the door will rest upon the arms 48, and the studs 49 will be carried above the curved or horizontal portions of the tracks so that these studs will readily enter the upper ends of the guide tracks 31. As explained above, the construction illustrated comprises a right-hand and left-hand track, and these are illustrated at I1 and I1 in Fig. 2. The track I1 is provided with a curved portion 20' and a plate 35' similar to the plate 35.

Upon the upper portion of the plate 35, I have secured, by suitable means, such as the bolts 5|, an additional plate 53, and upon the plate 35' I have secured a similar additional plate 53'. These plates 53 and 53' are apertured, as indicated at 54 in Fig. 2, and serve as bearing brackets to support roller bearings 55 and 55. A shaft 60, located parallel to the top of the door opening and somewhat above and back of the same, projects through the two roller bearings 55 and 55', and is rotatably supported therein. This shaft 63 is preferably hexagonal in shape and may be formed from a section of cold rolled, hexagonal stock of the proper length and diameter.

Between the plates 35 and 35', the shaft 69 is surrounded by a coiled spring 10 wound upon the shaft so that the tension thereof counterbalances the weight of the door during the opening and closing movements of the door, and between this spring and the shaft, I have provided a skeleton spring arbor, generally indicated at 12. The spring arbor illustrated comprises three sections, two end sections 12a and 120, and a center section 12b. Each section of the spring arbor comprises, in general, a series of channel-shaped, longitudinally extending members equally spaced about the circumference of the shaft and supported by spaced cup-shaped supporting members, the longitudinally extending members of the several sections being respectively indicated by the characters 13a, 13b, and 130, and the cup members by the characters 14a, 14b, and 140. two cup members 14a to which the rods or members 13a are secured, one of these cup members being at the extreme end of the arbor and the other substantially midway between the ends of the rods 13a. Similarly, the other end section has two cups 140 for supporting the rods 13c, the endmost cup being relatively long, for a purpose hereinafter described. The central section has three cups 14b, one at each end and one centrally located. Each of the cup members is preferably drawn from sheet metal and has a concentric hexagonal aperture (see Fig. 3) adapted to slidably but non-rotatably receive the shaft 60. The longitudinally extending members or rods are preferably welded to the skirts or flanges of the cups. It is, of course, understood that the number of sections of which the spring arbor is comprised will depend upon the length of the spring employed for lifting a particular door. Where three sections are used, as shown in Fig. 2, the parts are assembled so that the free ends of the rods of the end sections overlap the re- The end section 12a has' I spective 'endsof the center section; that is to say, the free or right-hand ends- 'of the rods 19a. are placed in alternating relation to the rods 19b and slide over the left-hand end cup 14b of the center section. In like manner, the rods 13c of the other end section are associated with the opposite end of the center section. With this arrangement, the length of the spring arbor may be readily adjusted by sliding the sections on the shafts so as to more or less overlap the rods of the end sections with respect to the center sections. The right-hand end cup 14c of the section 120 is preferably. secured against movement longitudinally of the shaft 69 by suitable means, such vas the set screw I9.

It will be seen that this spring arbor comprises a relatively light structure supported upon the shaft 69 and substantially filling the interior of the spring I9, the purpose of the arbor being to maintain the spring in cylindrical form as the spring is wound upon the, shaft. The interior diameter of the spring has to be materially larger than the diameter of the shaft in order to provide the proper torsional strength for these two elements and, if no provision were made for maintaining the spring in cylindrical form, the.

pressure of the convolutions of the spring against each other induced by the winding up of the spring would cause the spring to bend or buckle and assume a wavy form, in which condition some of the convolutions would bind upon the shaft 69, thereby causing an uneven distribution of the torsional stresses throughout the length of the spring with the probable consequence that some of the convolutions .would be stressed beyond their modulus of elasticity and thereby assume a permanent set. As the spring is wound and unwound, this condition would eventually result in fatigue of the metal of the" distorted convolutions and lead to ultimate breakage of the spring. This contingency has been circumvented by the application of the spring-arbor described above.-

Surrounding the shaft 69 adjacent to the plate 35, I have provided a fixed anchor member or terminal member, generally indicated at 89, which comprises a tube having a flanged end 8! securely riveted to a ratchet wheel 85. This tube overlaps the long cup member I! of the spring arbor so that the convolution of the spring at the end of the arbor cannot slip down and beconie wedged between the end of thetube and the shaft 69, and is provided with a pair of oppositely disposed, longitudinal slots 86 and 8'! in which are seated a pair of blocks 88, and 89. These blocks are provided with apertures extending in a circumferential direction, as indicated at 99, through which the end of the spring i9 may be threaded, as clearly indicated in Fig. 2. In order to restrain the'spring against movement relative to the spring anchor 89, I have provided in each of the blocks 88 and 89 a plurality of radial apertures, as indicated at 9i, one aperture 9! being aligned with each of the apertures 99. These apertures 9i are screw threaded and accommodate set screws 92 which hear at their inner ends upon the respective convolutions of the spring 19 to firmly wedge the spring in the blocks. As stated above, the anchor member 89 is rigidly secured at its end adjacent to the plate 35 to a ratchet member, generally indicated at 85, which is in the form of an apertured disk surrounding the shaft 69 and freely rotatable relative thereto. The members 89 and are journaled on a bearing collar 99 which surrounds the shaft 69 and is rigidly secured to the plate 53. The ratchet member 85 is polygonal in shape and has alternate sides thereof bent upwardly in the form of triangular extensions 94, the member illustrated being formed by bending up the corners of a square plate. Each'of the extensions 94 is provided with an'aperture 95 which extends through the extension and into the disk portion of the ratchet member 85, and the sides of the ratchet member 85 between the extensions are also provided with indentations 91. A ratchet dog 99 is secured to the plate 53 below the member 95 by means of a bolt I99, and is spring pressed by means of a loop" spring I92 into engagement in the apertures 95 and indentations 91 to secure the ratchet member 85 against rotation in one spring anchor I I9 comprises a pair of plates having their center portions bent so that each fits closely about one-half of the hexagonal shaft 69 to render the member non-rotatable with respect to the shaft. Each plate has radial extensions VH2 apertured, as indicated at H4, so that the end of the coiled spring may be threaded therethrough. The free end of the spring is threaded through the apertures H4 and is secured against movement relative to the terminal member by a pair of apertured blocks H5 and H6, similar in all respects to the blocks 88 and 89, clamped on the spring by set screws so as to bear against the radial extensions of the terminal member H9. From the description so far, it will be observed that the spring i9 may be wound up or adjusted by inserting the end of a bar in the apertures 95 and rotating the ratchet member 85, and that the spring will be maintained in its properly tensioned condition by means of the ratchet dog 99 engaging in the apertures or indentations in the ratchet member 85 and by the terminal I l9 engaging the end of the spring opposite the end engaged by the terminal member 89. When so tensioned, the spring tends to rotate the shaft 69 in a direction to counterbalance the Weight of the door l5.

It will also be observed that the length of the tensible portion of the spring may be adjusted to accommodate the spring to different weights of doors and heights of door openings by loosening the set screws 92 and threading the ends of the spring for a greater or lesser extent through the or jump at either end of its movement may be corrected. As explained above, the spring arbor 12 may be adjusted to follow any change in the length of the spring. The ends of the shaft 69 project beyond the bearings 55 and 55', and have non-rotatablysecured thereon cable pulleys 62 and 62'. Cables 69 and 99 extend from the cables 62 and 62', respectively, to the adjacent bottom corners of the door l5. From an inspection of Fig. 2, it will be observed that these cable pulleys are each provided around the external surface thereof with a spiral groove, as indicated at 66, and that the profile of said external surface of each pulley is a parabolic curve. The purpose of such an arrangement is well understood in the art. It is sufficient to say that by this construction the pulleys are eifective to compensate the decreasing strength of the spring by applying a decreasing radius during the initial.

upward movement of the door in which the weight of the door remains constant; and by applying a. radius changing within narrower limits during the remaining period of the lift, during which the decrease in the weight of the door substantially compensates the decrease in the strength of the spring.

The lower ends of the cables 64 and 64 are secured to the door by means of a construction particularly illustrated in Figs. and 6, which comprises a combined cable attachment and safety stop. In this construction, a bracket member III bent to a generally channel-shaped cross section has one leg thereof secured to the edge of the door, as indicated at I I8, and passes around the associated track member I1. The other leg of this bracket member is offset from the edge of the door and has a catch or dog member, generally indicated at I20, pivotally secured thereto by means of a pivot pin or bolt, generally indicated at I22. The upper end of the dog member I20 is bent over, as indicated at I24, and apertured, as indicated at I25, to receive the anchor means I 21 for the lower end of the cable 64. The lower end of the dog member is directed somewhat inwardly towards the frame of the door opening and terminates in a sharp point I30, as particularly illustrated in Fig. 5.' The pivot bolt I22 is provided with a reduced portion I3I which extends through a suitable aperture provided in the leg of the bracket member and is screw threaded to receive a nut I32. Washers, as indicated at I33, may be disposed between the nut and the adjacent face of the leg of the bracket member. This bolt is also provided with a somewhat enlarged journal portion I34 separated from the reduced portion I3I by a radial shoulder. This journal portion I34 is adapted to be inserted in a suitable aperture provided in the dog member I20 and by means of which the dog member is pivotally secured to the bracket. On the opposite side of the journal portion I34 from the reduced portion I3I, the bolt I22 is provided with a still further enlarged portion I35 separated from the journal portion I 34 by a radial shoulder. This enlarged portion of the bolt is surrounded by a coil spring I36 having its outer end nonrotatably sccured to the bolt, as indicated at I31. The opposite end of the spring is provided with an extension I38 secured to the dog member I20 by suitable means, such as a rivet I39. This spring is covered by a cup-shaped cap member I40 provided with a central aperture through which extends a reduced end portion I M of the bolt I 22. This reduced outer end portion is screw threaded and receives a nut I 42 which securely clamps the cap member I40 against the radial shoulder separating the enlarged portion I35 of the bolt from the reduced portion I4I. From an inspection of Figs. 5 and 6, it will be observed that the action of the spring I36 tends to urge the lower end of the dog member to the left, as viewed in Fig. 5, in which position the sharpened end I30 of the dog member would dig into the jamb of the door opening to prevent the door from being lowered, or from falling. This tendency of the spring is overcome by the tension normally exerted on the cable 64. The operation of these safety catches is such that if the tension on the cables 64 and 64' were released by the failure of any part of the counterbalancing mechanism such, for instance, as the breakage of the spring I0, the springalii would urge the dog members I20 inwardly so that the points I30 thereof would engage in the jambs of the door opening and stop the door in the position at which the failure of the counterbaluncing mechanism occurred and thereby eliminate any danger of injury to the person operating the door.

From the above description, it will be observed that I have provided a vertically and horizontally movable overhead door which will be especially smooth and positive in action, which may be easily and accurately counterbalanced by properly tensioning the coil spring I0, and which is rendered safe in use against the failure of any of the counterbalancing parts by the novel safety catches described above.

While I have illustrated and described a particular mechanical embodiment of the idea of my invention, it is to be understood that the invention is not limited thereto and that such changes in the size, shape, and arrangement of parts may be resorted to as come within the scope of the appended claims.

Having now described my invention so that others skilled in the art may clearly understand the same, what I desire to secure by Letters Patent is as follows:

I claim as my invention:

1. In an overhead door construction, a pair of tracks each having a vertical section, a horizontal section, and a curved connecting section; an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, an arm pivoted to the rear face of the upper section adjacent each side edge thereof and adapted to support said upper section when the same is in overhead position, rollers carried by the upper free ends of said arms and traveling in the respective tracks, a short channel-shaped track member which is straight throughout the major portion of its length and located above and generally tangential to the curved portion of one of said tracks, tracks at a point between the junctions of said curved portion with the vertical and horizontal track sections, each of said track members having at its lower forward end a cam portion inclined downwardly and forwardly, and a guide member projecting laterally from the side edge of the upper panel adjacent the top edge thereof and adapted to travel in said short track member when the door is raised and lowered, said guide member being adapted to engage said cam portion as the door is brought to final closed position whereby the upper panel is forced towards the door frame.

2. In an overhead door construction, a pair of tracks each having a vertical section, a horizontal section, and a curved connecting section; an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, an arm pivoted to the rear face of the upper section adjacent each side edge thereof and adapted to support said upper section when the same is in overhead position, rollers carried by length of said curved connecting section, each of said track members terminating at its lower end in a forwardly and downwardly inclined cam portion, each short track member having an upper flange and a lower flange, and studs pro- Jecting laterally from the upper door section adjacent the upper edge thereof and adapted to engage in said short track members when the door is raised and lowered, said studs being adapted to engage the upper flanges of said track members upon initial upward movement of the door whereby to swing the upper panel rearwardly, and said studs engaging saidrcam portions while the door is being brought to final closed position whereby said upper panel is cammed towards the door frame.

3. In a track for overhead doors, a pair of track sections of channel-shape, and means for joining abutting ends of said track sections in aligned relation, said means comprising a bracket plate secured to the end of one of said sections and extending therebeyond, and a hook plate secured to the end of the other section adapted to lie against said bracket plate, said hook plate having a hook along one edge embracing the corresponding edge of said bracket plate.

4. In an overhead door construction, a track having a straight section and a curved section,

means for securing the abutting ends of said sections together and to the associated door jamb comprising a plate securing to one of said track sections and extending therebeyond to overlap the other of said track sections, means for securing said plate to said door jamb, a hook plate secured to the other of said track sections and having a bent over edge of hooked shape adapted to receive the corresponding edge of said first plate to align the abutting ends of said track sections with each other, and means for securing said first plate and hook plate together.

5. In an overhead door construction, a vertically movable door, a door jamb, cables for raising and lowering said door and operating means for said cables; a safety catch to restrain said door from falling in the event of failure of said cables or said operating means, said safety catch comprising, a bracket adapted to be secured to the edge of said door adjacent to the bottom thereof, a dog member pivotally secured to said bracket and having a pointed end, a spring acting to urge said pointed end of said dog into engagement with said door jamb, and a connection between said dog member and said cable whereby the tension in said cable overcomes the action of said spring and maintains said dog member clear of said door jamb.

6. In an overhead door constructionfa vertically movable door, a door jamb, a track for guiding said door, cables for raising and lowering said door, 'and operating means for said cables; and a safety catch to restrain said door from falling in the event of failure of said cables or said operating means, said safety catch comprising, a U-shaped bracket having one leg thereof secured to the edge of said door at the bottom thereof, the intermediate portion of said bracket extending around said track to bring the other leg thereof opposite said door jamb, a dog member pivotally secured on said other leg and having a pointed end, a spring acting to urge said pointed end. of said dog into engagement with said door jamb, and a connection between said dog and said cable whereby the tension in said cable overcomes the action of said spriigg and maintains said dog clear of said door jam 7. In an overhead door construction, a pair of tracks eachhaving a vertical section, a horizontal section, and a curved connecting section; 'an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, and '1 means for counterbalancing said door including a rotatable shaft, a torsion spring about said shaft and fixedly anchored at one end and having its other end secured to said shaft so as to rotate therewith, and a skeleton arbor within said spring and of larger diameter than, surrounding, and fixed to, so as to rotate with', said shaft.

8. In an overhead door construction, a pair of tracks each having a vertical section, a horizontal section, and a curved connecting section; an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, and means for counterbalancing said door including a rotatable shaft polygonal in cross section, a torsion spring of relatively larger diameter than said shaft and surrounding the same, means for fixedly anchoring one end of the spring, means for securing the other end of the spring to said shaft, and an arbor interposed between said spring :and shaft substantially the length of the spring and of smaller diameter than the spring but of relatively larger diameter than the shaft,

said arbor having coaxial apertures adapted to slidably and non-rotatably receive said shaft.

9. In an overhead door construction, a pair of tracks each having a vertical section, a, horizontal section, and a curved connecting section; an articulated door comprising a. plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, and means for counterbalancing said door including a rotatable shaft, a torsion spring about said shaft and fixedly anchored at one end and having its other end secured to said shaft so as to rotate therewith, and a skeleton arbor within said spring and of larger diameter than, surrounding, and fixed to, so as to rotate with, said shaft, said spring arbor comprising a plurality of longitudinally adjustable sections having overlapping ends.

10. In an overhead door construction, a pair of tracks each having a vertical section, a hori zontal section, and a curved connecting section;

an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, and means for counterbalancing said door including a rotatable shaft, a torsion spring about said shaft and fixedly anchored at one end and having its other end secured to said shaft so as to rotate therewith, and a skeleton arbor within said spring and of larger diameter than, surrounding, and fixed to, so as to rotate with, said shaft, said arbor comprising a plurality of longitudinally adjustable sections, each section having a plurality of longitudinally spaced apart supporting members and a plurality of longitudinally extending members equally spaced around and secured to said supporting members, the longitudinally extending members at the end of one of said sections being free whereby such ends may overlap the adjacent end of the next section.

11. In an overhead door construction, a pair of tracks each having a vertical section, a horizontal section, and a curved connecting section; an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, and means for counterbalancing said door including a rotatable shaft, a torsion spring about said shaft and fixedly anchored at one end and having its other end secured to said shaft so as to rotate therewith, anda skeleton arbor within said spring and of larger diameter than, surrounding, and fixed to, so as to rotate with, said shaft, said arbor comprising a plurality of longitudinally adjustable sections, each section comprising a plurality of spaced apart cups surrounding said shaft and slidable but non-rotatable with respect thereto and a plurality of longitudinally extending rod-like members equally spaced around said shaft and connected to said cups, the rod-like members at the end of one section being free so as to overlap a cup at the end of the adjoining section between the rod-like members of said ad- Joining section. I

12. In an overhead door construction, a pair of tracks each having a vertical section, a horizontal section, and a curved connecting section; an articulated door comprising a plurality of hingedly connected sections guided by said tracks and movable from a vertical closed position to an overhead and generally horizontal position, and means for counterbalancing said door including a shaft parallel to the top edge of said door rotatably mounted in fixed abutments, a coil spring surrounding said shaft between said abutments, means for securing one end of said spring against rotation relative to said shaft, means comprising an anchor member and a ratchet member for restraining the other end of said spring against rotation relative to one of said abutments, said ratchet member comprising a polygonal disk having indentations at the sides thereof and having bent up portions on alternate sides to reinforce the same, a ratchet dog pivoted on said abutment for engaging in said indentations to restrain said ratchet against rotation in one direction relative to said abutment, a cable pulley on each end of said shaft, and a cable operatively connecting each of said cable pulleys to said door.

DAVID M. ROBINSON.

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