US2679659A

US2679659A - Sash balance

Info

Publication number: US2679659A
Application number: US231947A
Authority: US
Inventors: Edward L Grupp
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-06-16
Filing date: 1951-06-16
Publication date: 1954-06-01
Anticipated expiration: 1971-06-01

Description

E. L. GRUPP June 1, 1954 SASH BALANCE 3 Sheets-Sheet 1 Filed June 16, 1951 em T 6 A o m M. M 4%. I fi P m WWWW/H a ni w June 1, 1954 Filed June 16, 1951 E. L. GRUPP SASH BALANCE 3 Sheets-Sheet 2 GQUPP,

I N V EN TOR.

Arne/vs E. L. GRUPP SASH BALANCE June 1, 1954 5 Sheets-Sheet 3 Filed June 16, 1951 INVENTOR.

fiDW/IED I. GEL/PR,

ATTORNEY- Patented June 1, 1954 UNITED STATES PATENT OFFICE SASH BALANCE Edward L. Grupp, Glendale, Calif.

Application June 16, 1951, Serial No. 231,947

6 Claims. 1

This invention relates to sash balances and is particularly directed to adjustable dual and single sash balances adapted for use in counterbalancing and facilitating the movement of ordinary window sash as well as other types of vertically movable window screens and the like.

Most prior sash balances have been made from pressed sheet metal parts or elements and inasmuch as windows of different sizes weigh differing amounts, it has been necessary heretofore to make sash balances in difierent styles or weights, each style or weight of sash balance being preset at the factory so as to counterbalance a window weighing a specified number of pounds, the range of utility of a given sash balance being limited to not more than plus or minus two pounds. As a result, six or eight different styles or weights of sash balance had to be manufactured to meet the normal range of variation found in usual building construction.

Furthermore, prior sash balances were relatively bulky and became rapidly worn in usev the forces being applied in such manner that the winding drums would stick, the cable would slip off the winding drum and become wedged, etc. Once a sash balance had been thrown out of kilter, it was practically impossible to repair such sash balance and instead the entire sash balance had to be replaced. The assembly of prior sash balances was not conducive to automatic assembly and labor costs were high. A large number of small parts requiring numerous dies for their formation increased the cost of toois necessary for the production of the balances and made the upkeep of the dies a great burden to the manufacturer.

The present invention is directed to a simplifled and improved sash balance in which a minimum number of parts is employed, such parts presenting relatively smooth outer surfaces in the completed balance thereby eliminating the cuts and hazards resulting from prior constructicns. Furthermore, the sash balance of the present invention may be assembled in a simple and rapid manner by the use of jacks whereby assembly labor is cut down to a minimum. This desirable objective is partly aided by the fact that the sash balance may be assembled in a relaxed condition and tensioned after assembly.

A further advantage of the present invention lies in the fact that the sash balances hereinafter described in detail may be readily adjusted to deliver any desired degree of tension or lift. As a result, a sash balance may be adjusted to lift a six pound, eight-pound, tenound, or even a fourteen-pound window. The sash balance may be installed by the finish carpenter while it is in a relaxed or unwound condition and after it has been properly fitted into the frame and attached to the sash it may be easily tensioned so as to most effectively maintain the window in every position from fully open to fully closed. As a result, installation is facilitated and operation may be maintained at a maximum level of efiiciency.

Furthermore, the adjustable sash balances of the present invention may be readily repaired and in the event the counterbalancing spring is broken (from crystallization or age), the sash. balance may be readily repaired without the necessity of using special tools or equipment.

An object of the present invention therefore is to disclose and provide an adjustable sash balance giving rise to one or all of the advantages above recited.

A further object of the invention is to disclose and provide an adjustable sash balance which may be made either from die cast parts or from drawn or stamped metal parts.

A further object of this invention is to provide a sash balance wherein the various parts of the balance are arranged for facilitating rapid production and assembly of the balance and wherein the several parts of the balance are held and maintained in operative assembly in a novel manner.

Although sash balances embodying the improvements and inventions here contemplated may assume a variety of forms, the invention will be described in detail by reference to the appended drawings in which exemplary or illustrative forms are shown.

In these drawings:

Fig. 1 is a front or face view of a dual adjustable sash balance, portions of the covers being broken away.

Fig. 2 is a rear view of the sash balance shown in Fig. 1, portions of the housings being broken away.

Fig. 3 is a side elevation, partly in section, along the plane IIIIII in Fig. 1.

Fig. 4 is a transverse section, taken along the plane IV--IV of Fig. 3.

Fig. 5 is a rear view of a cover and hub assembly illustrating means for adjusting the tension.

Fig. 6 is an exploded view of a dual adjustable balance wherein one of the balances is in assembled position. and the other in exploded position.

Fig. '7 is a transverse section through a modified form of construction.

Fig. 8 is a side elevation of a cover and hub assembly used in such modified form of the device.

Fig. 9 is a side view of a cover and hub assembly used in Fig. 7.

Fig. 10 is a perspective view of a glider or sash connector for attaching one end of a cable to a window sash to be raised, the view being taken prior to securing a cable thereto and before bending to final position.

Fig. 11 is a perspective view of the connector after securing the end of the cable thereto and bending the glider to final position.

Fig. 12 is a perspective view of a drum used in the modification shown in Fig. 1 illustrating a method of connecting an end of a cable thereto.

Fig. 13 is a perspective view of a drum employed with the modification shown in Fig. 7 showing the cable attaching means and the means for connecting the spring to the drum.

Fig. 14 is a partially exploded perspective view of a different modification of a dual sash balance contemplated by this invention, one of the balances being in assembled position and the other in exploded position.

Fig. 15 is a fragmentary sectional view of an assembled balance illustrated in Fig. 14, the section being taken in a vertical plane passing through the longitudinal axis of the balance.

The form of device illustrated in Figs. 1-6 may be made from die cast parts and as best shown in Fig. 6 such device may comprise a housing Ill having a bottom I! and upstanding side walls I2 integrally connected to a face plate 18 having extensions such as l9 whereby the face plate may be connected to a window frame. The drawings illustrate a dual sash balance, but single sash balances are also contemplated by the present invention and the description of one sash balance will suflice since duplication of such parts produces a dual sash balance.

Received within the housing In is a hollow drum generally indicated at 20. drum there is positioned a spirally wound fiat spring 30. One end of the spring is connected to the drum and its central end is connected to a hub 45 carried by a cover plate 46. When these elements are properly assembled the outer sura face of the cover plate such as the cover plate 46' is flush with the outer face of the face plate IS.

The bottom of the housing H] is centrally ported as at l3.

H is preferably, recessed around the port It as indicated at [4. The inner surface of the bottom I l is provided with a circular boss l5 surrounding the port I3.

The drum 20 is preferably hollow and includes a web 2| which is axially ported so as to be rotatably journalled upon the boss l5 of the bottom II. The outer cylindrical face of the drum is preferably dished as indicated at 22 which forms edge flanges. The inner face of this drum is preferably provided with a pair of oppositely directed spring-end engaging means. Such means may comprise inwardly

extendin bosses

23 and 24 provided with lateral recesses or slots 25 and 26,

these recesses being arranged to selectively receive an outer bent end 31 of the spring which is carried within the drum.

The cover 46 is provided with an integral hub 40. The hub is longitudinally split as indicated at 4! so as to receive an irmer bent end 3 the Within such The outer face of the bottom -'Z-- spring 3!]. The outer end of the hub 40 extends through the bore or port [3 (see Fig. 3) and is provided with a pair of spaced

lugs

42 and 43 capable of extending into similarly spaced openings in a normally dished washer 44 which, after being placed upon the

upstanding lugs

42 and 43, may be flattened thereby exerting pressure against the inner opposing faces of the

lugs

42 and 43 and locking the hub 40 against axial movement. The washer 44 covers port l3 and is received within the recess I4 formed in the outer surface of the bottom I! thereby presenting a relatively smooth surface, and when the entire housing is within the sash frame frictional rubbing of the washer and hub end against the stationary woodwork of the frame is minimized. It is to be noted that a small outwardly facing recess ll is formed around the openings leading to each of the housings and the edge of the cover 46 is rotatably journalled in such recess or shoulder, thereby preventing lateral movement of the hub and cover in one direction, whereas the washer 44 prevents lateral movement in the opposite direction.

As previously stated, each of the hubs 40 is laterally split as indicated at 4| to furnish an anchor for the inner end of the spiral spring. The outer face of the cover 46 is provided with a centrally transverse recess 41 arranged to receive a tool for turnin the cover and hub so as to tension the device.

The inner face of the cover 46 is provided with a circular inwardly extending toothed flange 48 provided with a series of interruptions, such as 49, etc. These interruptions are adapted to receive a notched end of a latch or spring-biased pawl 50 pivotally connected to the face plate as at 53 and urged against the toothed flange 48 by means of a spring 52 through an opening 16 formed in the side wall l2 of the housing l0. It will be evident that by turning the cover 46 in the direction of the arrow (Fig. 2) the spiral spring 30 can be tightened or tensioned and the cover and hub assembly is prevented from turning in the opposite direction by reason of the pawl 50 which serves as a tension holding means.

Release means for relaxing spring 30 when repair work is to be done on the balance is provided by a pair of generally arcuate slots 54 provided in face plate [9 above each pawl 50. Each slot 54 receives an upright end 55 of sprin 52, said end 55 passing through a port provided therefor in pawl 58. The release means is conveniently actuated by pressing an end of a slender element or nail in the slot and against the upright end 55 of the spring 52 in order to retract pawl 50 from its engagement with the toothed flange 48.

A cable 68 may be formed of any suitable stranded wire and is connected at one end to the drum as best shown in Fig. 12. The inner end of the cable may be threaded through a port Si in an edge flange of the drum for reception in a groove 62 extending chordwise across a portion of web 2!. A port 63 is provided at the opposite end of the groove 62 for again threading the cable through the flanged edge and the cable end may be secured by bending in the direction of port 6i. Thus the series of virtually right angled bends placed in the cable end serve to securely hold the end of the cable on the drum. The groove 62 provides clearance for the cable run across the web 2| so that interference with rotation of the drum is eliminated.

The cable of the balance being described at the left sides of Figs. 1-3 extends through a bore 04 and a port 85 in the wall of the housing for connection at its other end to a glider or sash connector 60. The cable of the balance at the right sides of Figs. 1-3 extends outwardly through a port til formed in the side walls at the opposite side of the housing. The glider may be bent into right angle shape for snug fitting about a corner of a window sash to be moved.

The glider 55 may be stamped or pressed from a suitable elongated rectangular section of sheet metal. A plurality of spaced openings alon the longitudinal axis of the glider may be formed by punching out centrally split cleats 67. The outer end of cable 60 is secured by laying the cable end across the several openings between the split cleats and then pressing the cleats back into virtually normal position, whereby the cable is firmly held by cooperation of the split cleats and the uncut portions of metal between the openings.

The glider 66 may be preferably formed with inwardly directed parallel upstanding woodengaging ribs 68 along opposite longitudinal edges. A longitudinally extending groove 69 on the outer face of the glider may be formed by parallel raised marginal edges of the glider. The edges I0 may bear against the opposed surface of the window frame member and provide running clearance for cable 60 along the edge of the window sash.

Assembly of the sash balance shown in Figs. 1-6 inclusive is preferably performed by placing the housing I0 on a suitable surface with the faceplate directed upwardly. The drum with the end of the cable attached thereto but not 2 wound thereon may be journably seated in the housing about boss I5. The spirally wound spring may then be inserted within the drum with the outer end in engagement with the drum. The cover 46 including the hub is then placed over the drum with the slotted hub receiving the inner end of the spiral spring. When the cover is in its assembled position with its outer face flush with the outer surface of the face plate, the

lugs

42 and 43 of the hub project slightly beyond the recess in the rear surface of the housing. The washer 44 may be then slipped over the

lugs

42 and 43 and secured by striking the center of the dome-shaped washer to slightly expand the washer. The cover, hub, and washer are thus held and maintained in assembled relation by the frictional contact of the washer with the lugs on the hub, while at the same time permitting rotation of the cover and washer in the recesses surrounding the openings in the housing and face plates, said recesses in effect providing a bearing means. The dome-shaped construction of washer 44 serves to equalize the positioning of the washer within recess I4 when the washer is expanded by striking at the center thereof.

After the sash balance has been assembled the cable may be wound upon the drum by inserting a suitable tool into slot 41 on the cover 46 and turning the cover, hub, and washer while the tension holding means are held in inoperative position so that the spring 30 is not tensioned during winding. After the cable is wound, spring 30 may be slightly tensioned to hold the cable snugly in its wound condition; but sufliciently relaxed to facilitate field installation of the glider on a sash. The balance, after installation, is then tensioned as desired by rotating the cover 40 while the tension holding means 4 are in operative position.

The modification shown in Figs. '7, 8, 9 and 13 differs from the first modification in that the sash balance is fabricated from pressed or stamped sheet metal parts. It further differs in that the assembly of the completed sash balance is performed in a slightly different manner. In the description of this modification and a third modification, parts of the sash balance corresponding to those already described are designated by the same reference numerals in multiples of one hundred.

In Fig. 7 the sash balance comprises a housing IIO, a drum I20, a, spring I30 and a cover and hub I40. The rear wall III of the hollow housing II 0 is provided with a port II3 defined by an encircling outwardly facing recess H4. .A face plate II8 may be secured to side walls II2 of the housing by means of spaced upstanding lugs II 9a extending through accommodating openings in face plate II8 and secured as by peening. The face plate II8 may be provided with longitudinal extensions H9 for fastening the sash balance to a Window frame member. The face plate H8 is provided with an opening III coaxially aligned with port H3, said opening I I1 being encircled by an outwardly facing recess I I'Ia for reception of the circumferential edge margin of cover I46.

The drum I20 is provided with a web I2I centrally ported to journably receive the hub I40. The outer cylindrical face of the drum I20 may be dished as at I22 for reception of a cable I59 to be wound therearound. The cylindrical face of drum I20 may be provided with inwardly punched and oppositely facing bosses I23 and I24, said bosses forming slots I25 and I20 respectively for selectively receiving an outer end of spring I30. The marginal edge of the cylindrical face of the drum may be provided with a pair of spaced convergingly directed open ended slots I2'I for suitable reception of and securing of the inner end of cable I60, the end of said cable being threaded through a port lying between and slightly below ends of said slots.

The spiral spring I30 may be of the same type as described above and is connected to a hollow tubular hub I40 by reception of the inner end I32 of spring I30 in an axially extending slot MI. The opposite end I3I of the spring I30 is selectively received within one of the slots I25, I26 depending upon the desired direction of rotation of the drum.

The hub I40 is suitably connected to the cover I46 by means of spaced upstanding lugs carried on one end of the hub I40 and secured as by peening within cooperative slots formed in the cover I45. The cover I46 in this modification is provided with an annular downwardly projecting pressed rib I48 spaced inwardly from the circumferential edge and dimensioned so as to be capable of rotation within opening II! as defined by edges of the recess IIIa. The annular rib 48 is provided with a plurality of downwardly extending teeth I49 provided by punching the metal in the bottom of the groove downwardly at spaced intervals. The inner diameter of the annular rib I48 corresponds substantially with the outer diameter of drum I 20 so that the drum may-be suitably journalled for rotation within the housing. The close relation between annular rib I48 and the circumferential edge of the web IEI or the drum virtually eliminates the possibility'of snagging or catching of the cable I60 between the cover I46 and the drum.

Means for releasably holding the spring under 7 tension and for relaxing said tension is provided by a fiat inwardly bent spring I52 secured to face plate II8 as at II and having oppositely directed ends I55 extending toward each hub I40 for cooperative engagement with the teeth I49 as in the manner of the pawl described in the prior modification.

The face plate II8 may be provided with a pair of spaced ports I54 for access to ends I55 by means of a slender pointed nail or other tool whereby depression of ends I55 downwardly and out of engagement with the teeth I49 will release tension in spring I30.

The method of assembly of this modification is somewhat different than that of the first modification. The cover I46 with hub I40 attached thereto may be placed upon a supporting surface with the hub upright. The face plate H8 is positioned by registering the opening In with respect to the ribs I48 on the covers I46. The drum may then be inserted over the hub I40 so that its web I2I is journably mounted on the hub adjacent the cover. The drum may carry a portion of the cable wound therearound when it is inserted over the hub. The spring may then be connected to the hub by inserting the inner end of the spring within slot MI and the other end of the spring may be selectively received within one of the slots formed on the interior surface of the drum. The housing I I0 may then be placed over the drum and the domed washer I44 be connected to the upstanding lugs I42 and I43 formed on hub I45 as in the prior modification by centrally striking the washer. The lugs I I9a of the housing may then be peened for securing walls of the housing to the face plate I46.

The modification shown in Figs. 14 and 15 illustrates a sash balance fabricated from a die cast integral housing and face plate and pressed sheet metal hub, drum, and covering means. The assembly of this modification is also slightly different than the prior modifications. One of the features of this modification is that the face plate is interrupted only by relatively small diameter openings receiving means for permitting adjustment of the tension of the spring means.

The dual sash balance shown in Figs. 14 and 15 comprises a housing, generally indicated at 2H] having a pair of virtually cylindrically formed side walls 2I2. A face plate 2I8 is cast integral with side walls 2I2 and is provided with extensions 2I9 affording fastening means to a window frame member as in the first modification. The rearwardly facing edge of each cylindrical side wall 2 I2 is provided with an annular outwardly facing recess 2I4 formed in the inner surface of said wall.

A relatively small diameter port or opening 2 I l is formed in face plate 2I8 in axial alignment with each cylindrical wall 2 I2 and the rearwardly facing opening 2I3. Encircling opening 2II is an outwardly facing recess 2I'Ia. The recesses 2I4 and 2 Ila provide a bearing means for a cover means 243 received within recess 2I1a and a domed cover means 244 having a flanged edge 244a received within the recess 2I4, said covers 246 and 244 being interconnected by a hollow tubular hub 24!). The cover 246 lies in recess 2I'Ia with its outer surface in flush relationship with the outer face of face plate 2 I8. The cover 244 is connected to hub 24!) by means of spaced

lugs

242 and 243 accommodated within cooperative openings in cover 244. In this modification lugs 242 and 243 are permitted to extend slightly beyond the outer surface of cover 244 so as to space cover 244 from the back wall of a receiving recess in a window frame member and thus avoid contact of the cover 244 with the back wall.

A drum 220 may be substantially identical to that shown in Fig. 13 and comprises a ported Web 22I, a pair of spaced inwardly extending oppositely directed bosses (not shown) forming slots (not shown) for connection to one end of spiral spring means 230, and transversely arranged open ended slots 221 for securing one end of a cable (not shown).

Spring 230 is carried within the drum, the outer end 23I being secured to the drum as in the prior modifications. I'he inner end 232 is received within a longitudinally extending transverse slot 24I formed in hub 240.

The cover means 244 takes the place of the washer 44 shown in the first modification and as above described is provided with a flanged edge 24411 which is journably received in recess 2I4. The flanged edge 244a is provided with a series of spaced interruptions 249 which are adapted to cooperate with an inwardly extending spring end 255 of spring 252, said end 255 projecting through an opening 2l6 in side wall 2 I2. The spring 252 may be generally V-shaped and may be frictionally held within a corresponding V-shaped recess formed between opposed walls 2I2 by a suitable pin disposed at the convergence of said walls. Intermediate portions 256 of the spring lie closely against walls 2 I2.

Tension release means for spring 252 includes ports 254 formed in face plate 2I8 above the intermediate portion 256 of each spring 252. A tool such as a slender nail may be inserted through said port 254 and between portion 256 and wall 2 I 2 for wedging the spring end 255 out of engagement with the cover means 244 for releasing and relaxing tension in the spring means 230. Portion 256 is initially slightly spaced from wall 2I2 by turning cover means 244 so that spring end 256 will be retracted from a notch 249 and will ride on the circumferential edge of the cover means. Thus the cover means and hub assembly are held against incontrollable rotation while the spring is being relaxed.

Assembly of this modification is similar to that of the second modification with the exception that the last assembly step is eliminated; that is, the step of securing housing IIO to the face plate I I8. In this modification, since the face plate 2I8 and the side walls 2I2 are integrally formed, the device is held and maintained in assembled relation by the cover means 244 and 246 secured to hub 24!]. Thus, it will be readily seen that hub 240 interconnecting the covering means 246 and 244, together with the reception of the covering means within their respective recesses holds the sash balance in operative assembled relation.

While three modifications of the sash balance have been illustrated and described, it is understood that other modifications may be made which come within the spirit of this invention. It should be noted that the several parts of the sash balance are so designed that they may be simply constructed and assembled in a convenient fashion, either in a factory, or in the field. It should be noted that the several parts fit together in such a manner that the cable is not permitted to move from the dished portion of the drum so as to become wedged between the drum and adjacent normally stationary parts of the device.

Since the sash balance may be delivered from a factory with only slight tension on the cable, the attachment of the glider or sash connector to a window sash to be balanced is readily made. After such connection and when the balance is properly installed in the window frame, each balance may be conveniently adjusted to a desired spring tension by turning the cover means in the face plate, thereby tensioning the spring means through its connection to the hub. It will be understood of course that the balance may be factory preset if desired. When preset out of the factory, the spiral spring may be held under tension in any suitable manner such as locking the hub against rotation as shown, keying the hub to the cover means, and forming the hub integral with the face plate or housing.

Release of tension in the spring means may be controllably accomplished by inserting a tensioning tool in the slot therefor in the outer cover means while the tension holding means is released by withdrawing the pawl or spring ends from engagement with the cooperative cover means. Thus the spiral spring means is restrained against exploding within the sash balance and thus damage is avoided to the sash balance.

It should further be noted that the outer face of each of the sash balances described above presents a fiat smooth surface which may be installed flush with the face of the window frame member so that interference with movement of the window sash balanced by said device is virtually eliminated.

All modifications or changes coming within the scope of the appended claims are embraced thereby.

I claim:

1. In a sash balance, the combination of: a housing including side walls and provided with a fiat face plate connected to said walls, extensions on said plate projecting beyond said side Walls and adapted for securing said balance to a frame member; means forming front and rear axially aligned openings in said plate and said housing respectively, one of said openings being larger than the other openin each opening being encircled by an outwardly facing annular recess; a hub extending through said openings and journalled in at least one of said openings; a flanged hollow drum adapted to be inserted through the large opening and rotatable about said hub within the housing; a spiral spring contained within said hollow drum; means on the inner surface of said drum to connect one end of the spring thereto; an open ended slot formed in the hub to connect the other end of the spring thereto; a ported means carried by said drum adapted to receive and retain an end of a sash connector cable means for maintaining said balance in assembled relation including covers for said openings rotatably received Within said recesses and connected to ends of the hub; and adjustable means for holding said spring means under selected tension and said hub against rotation, said tensioning means including an aperture in said side wall, a spring-biased element carried by the housing and extending through said aperture, and a toothed inwardly directed flange carried by one of said covers movable past said aperture for releasable engagement with said element.

2. In a sash balance, th combination of: a housing including side walls and provided with a flat face plate connected to said walls; means forming front and rear axially aligned openings in said plate and said housing respectively, each opening being encircled by an outwardly facing annular recess: a hub extending through said openings and journalled in at least one of said openings; a. flanged hollow drum adapted to be inserted, through the other of said openings and rotatable about. said hub within the housing; a spiral spring contained within. said hollow drum and having one and connected to. saidv drum and the other end connected to said hub; means for maintaining said balance in assembled relation including covers for said openings rotatably re-' ceived within said recesses and fixedly connected to ends of the hub; and means carried by the housing and cooperable with means on at least one of said covers for holding said spring means under tension and said hub against rotation.

3. In a sash balance adapted to be installed in a window frame member with th exposed portion of the balance presenting a smooth flat face flush with said member and adapted to be adjustably tensioned from said exposed face, the combination of: a face plate having an opening therein and having inwardly extending side walls connected thereto defining a chamber; an annular recess encircling said opening; a cover for said opening journably received within said recess, the outer face of said cover lying in the plane of the outer face of said plate; an inwardly extending hub connected to said cover, extending through said opening into said chamber, and normally restrained against rotation; a hollow drum within the chamber normally rotatable about said hub; a spring within the drum connected to said drum and to said hub; means journably supported by said inwardly extending side walls and connected to the inner end of said hub for holding said balance in assembled relationship and for closing said chamber; and means carried by said balance, releasable from the face plate, and cooperable with said holding means for restraining said hub against rotation.

4. A balance as defined in claim 3, wherein means are provided on the cover for turning said cover and connected hub, and wherein means are provided in the face plate for releasing the rotation restraining means for the hub.

5. In a sash balance, including a cable, the combination of: a hollow housing provided with a face plate; means forming front and. back auxiliary aligned openings in said housing and in said face plate; bearing means surrounding each opening; a hollow rotatable drum within the housing for holding a cable; a spiral spring means contained within the drum, one end of said spring means being connected to said drum; means covering said openings journably mounted in said bearing means, the outer faces of said covering means lying in virtually the same planes as defined by adjacent outermost portions of the housing and face plate; a hub means connecting said covering means and connected to the other end of said spring; and means for maintaining said spring means under tension, including resilient means carried by the housing in coopera- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Kimball July 19, 1892 Erb Mar, 10, 1908 Mantz Feb. 21, 1933 Kersting Apr. 25, 1933 Jessup Dec. 8, 1942 Jessup Dec. 8, 1942