US1749985A - Warehouse door - Google Patents

Description

March 11', 1930. R. s. PEEL'LE 1,749,985

WAREHOUSE noon Filed April 10, 1925 2 Sheets-Sheet. 2

IIIIIIII III II ll! II W5 ATTORNEY,

' tuating mechanism such doors are handled by a grade of labor usually unskilled in the handling of mechanatented Mar. 11, 1939 PATENT OFFICE ROBERT S. PEELLE, OF NEW YORK,'N. Y.,

BROOKLYN, 'NEW YORK, A

ASSIGNOR TO THE PEELLE COMPANY, OF

CORPORATION OF NEW YORK WAREHOUSE DOOR 7 Application filed April 10, 1925. Serial No. 22,189.

My invention relates to warehouse doors,

and more particularly to a one-piece vertically and horizontally sliding door of the so-called trolley type.

Doors of this general construction are extensively used to close openings at loading platforms of buildings, other connections where access is had directly to the floor of a building or other structure, and it is desirable to afford the greatest possible head room at the door opening to facilitate the passage of merchandise or vehicles to the floor of a building. In such doors, the top of the door is guided by overhead tracks imparting a horizontal movement to the upper portion ofthe door while the lower portion-thereof is receiving vertical movement, thus tilting the door from a vertical position to a horizontal position, opening, or vice .versa, during its closing movement.

Doors of this general type heretofore used, have been so constructed that difliculty has been experienced when starting the opening movement of the door, due to the fact that the arrangement of parts has always been such that an upward pull exerted at the lower portion ofthe door will have'no tendency to initiate a horizontal movement of the upper part of the door except by a track arrangement necessitating a loss of considerable space above the door opening, or imparting a normal tendency of the doorto close from its own weight. Furthermore, in such doors, in opening same, no means are provided for controlling the application of power to the door when it has reached its fully open position, thus subjectingthe acto severe stresses since ical devices, strength.

With the above conditions in mind, I have provided a door, the construction of which is such that the load of the door is supported in part from the overhead tracks at all times, in a manner to permit the utilization of the counterbalancing weights for ensuring ease in starting the opening and closing movebut possessing great physical upon piers, and in.

during its tween the load of the door ments of the door. The track construction and the portion of the door co-operating therewith are such that with the application of low power to the actuating means, horia zontal traverse will be imparted to the upper portion of the door substantially simultaneously with vertical movement of the lower portion of the door, this portion of the door having movement only in vertically extending guides at opposite sides of, and within the jambs of, the door. This con struction permits the eiiective application of the load of the counterweight in assisting the opening movement of a door, since the shifting position, during'the early stages of this movement of the upper portion of the door horizontally, results in the development of a progressively increasing ratio beand the loadrof the counterweight, as the door opens. This condition is reversed with the. closing move- -ment of the door, thus assuring ease in the starting of the door when closing same. Expressed in other words, the construction is such that when the door is closed, the efi'ect of the counterbalancing weight is merely that required to overcome the minimum load of the movable door, and this load becomes progressively greater as the upper portion of the door moves away from its vertical position, and the door in its entirety passes to a substantially horizontal position as the door reaches the fully open position, when the load of the door will be substantially equal to, or be slightly less than, that of the counterweights. This requires less exertion during the early stages of the opening movement until moving inertia in the door is developed to an extent to assist in the continued opening movement.

When closing the door, the approximate balanced condition between the door and the counterbalancing weights will ensure ease in the starting of the closing movement, the moving inertia in closing, and the diminished ratio between the load of the door and that of the counterweight, ensuring ease in the closing movement, and the checking of this movementas the door approaches the fully closed position in a manner to relieve the different parts of the door from strains due to a violent impact of the door with the sill. I The door is provided with a guiding mechanism so constructed that the power for opening or closing the door may be applied thereto when the door is either in the open or in the closed position and during its movement from one of these positions to-the other, but whenthe door has reached either the fully open or the fullyclosed-position, the appli! cation of such power will be automatically interrupted notwithstanding a continued actuation of the mechanism through which power is transmitted to the door, thus avoid-.

communicating with said vertical guides and extending inwardly of the building, the portion of said tracks adjacent said vertical guides having a gradual ascent leading from adjacent the lintel of the'door opening to a horizontal portion, each of said tracks comprising parallel rail sections, a door panel adapted to close the door opening, devices adjacent the top of said panel in continuous engaging relation between said rail sections and cb-operating only with said overhead tracks respectively, whereby at all times a support is afforded the upper portion of said panel, devices adjacent the bottom of said panel movable in said vertical guides, sheaves above said guides respectively, a counterweight, flexible connections between said counterweight and the lower portion of said panel and passing over said sheaves, and means operative upon said flexible connections whereby the panel may be opened and closed; and in such other novel features of construction 'and combination of parts as are hereinafter set forth-and described, and more particularly pointed out in the claims hereto appended.

Referring to the drawings,

Fig. 1 is a View of a door embodying my invention, from the inside of a building, 2 ad in closed position, portions of the housin for the counterweight structure be ng broken away;

Fig. 2 is a side view of the door structure shown in Fig. 1, with the door in the open position;

Fig. 3 is a plan view of the construction as shown in Fig. 1;

Fig. 4 is a detail view of a portion of the actuating mechanism:

Fig. 5 is a detail view showing the manner of connecting the flexible connections with the floor section, and the position of such pagts when the door is in the open position; an

Fig. 6 is a view similar to Fig. 5 with the door in the closed position.

Like ntunerals refer to like parts throughout the several views.

In the embodiment of the invention shown in the drawings, 10 indicates the wall of a building having therethrough a door opening indicated at 11. Upon opposite sides of this door opening are vertical guides 12 extending from adjacent the floor of a building to adjacent the lintel of the door opening 11. Said guides are preferably mere channels for limiting the movement of'the lower portion of the door, or the portion of the door adjacent the bottom thereof, to a vertical movement only, and preventing any movement of this portion of the door inwardly of the building.

Inwardly of the wall 10 are parallel tracks each consisting of spaced horizontally extending rail sections 13 and 14 adjacent the ceiling and spaced sections 15-16 leading from adjacent the lintel of the opening 11 and the top of the guides 12 and ascending towards said horizontal sections. In the accompanying drawings the sections 15 and 16 are shown as being upwardly inclined, straight sections, but it is apparent that the use of straight rails at this point is not essential. The rail sections 13 and 14, 15 and 16 are respectively supported from the ceiling by brackets 17 at one end thereof, the other end thereof adjacent the vertical guides 12 being supported from brackets 18 upon said guides.

Between the vertical guides 12, is a door panel 19 which may be of any desired construction. In the form of the invention shown, this panel has an angle metal frame 2O closed by a metal sheathed wooden panel, such as are commonly 'used'in elevator doors. The dimensions of this panel are such as to lap the door opening 11 at the lintel and both jainbs thereof. Upon opposite sides of the panel 19, adjacent the top thereof, are devices co-operating with the overhead tracks such as brackets 21 each carrying wheels 22 having a free running fit in the space between the rail sections 13 and let, 15 and 16, flanged wheels preferably being used, so as to ensure ease of movement of the upper portion of the panel along said rails. The brackets 21 project inwardly of the panel so that when the door is in the closed position, the wheels 22 will be offset in relation to the panel 19 so as to be engaged with the ascending portions 15 and 16 of each track structure, thus causing this portion of the tracks to divert the upper portion of the panel inwardly of the wall 10630 I when annpward pull is exerted upon the 1 other desired panel in opening same.

By this construct-ion a portion of the moving load of the panel is supported at all times from the overhead tracks, the proportion of the I load thus supported increasing as the wheels 22 approach the wall 10.

Adjacent the lower portlon of the panel at the opposite edges thereof are pivot fittings 23 extending into the channels of the guides 12, each carrying a roller 24 adapted to track along the guide with which it co-operates. Also mounted upon the pivot 23 is a swivel fitting 25 with which flexible ropes 26 and 27 are connected to the lower part of the pawl. The flexible connection 26 passes about sheaves 28 and 29, an actuating sheave 30, an idler sheave 31 above a counterweight housing 32, and a sheave 33 carried .by't-he counterweight 34, to a fitting 35 to which it is secured. The flexible connection 27 passes about a sheave 36, an

actuating sheave 37, and idler sheaves 38-39,

the latter of which is carried by the counterweight 34, the end of this connection also be ing attached to the fitting 35. The use of a compounding pulley arrangement in relation to the counterweight 34 is merely for the purpose of limiting the quantity of movement required of this counterweight, with a maximum quantity of movementof the panel. The actuating sheaves 30 and 37 are carried by, and rotatable with, a shaft 40 which may be turned in either direction through the sprocker gear 41 and the sprocket actuatin mechanism. With narrow panels, the chain 42 may be a hand ,chain, but with heavier installations this chain may be motor driven.

'The sheaves 30 and 37 are so constructed that solong as the flexible connections 26 and 27. are subjected to both theload of thepanel and of the counterweight, the turning of said sheaves will result in movement of said panel and said counterweight in opposite directions, but immediately that the downward movement of either the panel or the counterweight is arrested, said sheaves 30 and 37 will automatically become inoperative with rela-" tion to the said flexible connections to impart movement to the panelor the counterweight in either direction, it being understood that upward movement of the counterweight is essential to permit the closing movement of the panel.

To secure this result, I provide the perime-- ter of each of the sheaves with a V-shaped face, or pinch groove, so that the load of the anel and of the counterweight operative adacent the opposite ends of the flexible connections 26 and 27, will cause an efl'ective binding action of said connections within this groove, but when said connections. are relieved from the load adjacent either end thereof, suflicient slack will be created in said chain 42, or any connections to permit slippage of said sheaves 30 and 37 in relation thereto, and thus instantly and automatically interrupt the ap-' plication of power to the counterweight or to the door panel.

The particular construction of said sheaves 30 and 37 is shown in detail in Fig. 4 of the drawings, the V-shaped faces or pinch grooves being indicated at 43 and 44 respectively. The various sheaves 28-293136 38 and 39 may also have the same construction as the sheaves 30 and 37 if so desired, although this is not essential, the power for raising and lowering the door being applied only through said sheaves 3O and'37.

The actuating sheaves 30' and 37 to secure the desired operative effect, must be positioned between the- sheaves 29 and 36, and 31 The operation of the herein described door is substantially as follows Assuming the door to be in the closed position as shown in Figs. 1 and 3 of the drawings, the panel, 19 will rest upon the sill at the opening 11, the devices or wheels 22 guided by the overhead tracks being oifset inwardly of the building with relation to said panel, will be engaged by the rail sections 1516 of each track, and the devices 1 or wheels 24 will be positioned within the vertical side guides 12, adjacent the sill of the door opening. If, when the parts are in this position, the reach of the chain 42 toward the counterweight 34 has power applied thereto, slippage will occur between the sheaves 30 and 37 and the flexible connections 26 and 27 between the panel 19 and the counterweight 34, since these connections are relieved from the weight of the door and any slight upward movement of the counterweight will merely result in the formation of slack sufiicient to relieve that binding action between said connections and said sheaves due to the V-shaped, or pinch, grooves 4344.' 'If, however, the other reach of said chain has power applied thereto, the

shaft 40, and with it the sheaves 30 and 37 will be turned in a direction to exerta pull upon the connections 26 and 27 between said sheaves and the point with which these connections are attached to the panel 19. This will raise the panel, the slack created as a result of this movement of the panel being immediately taken up by the counterweight 34. This condition continues so long as the connections 26 and 27 are simultaneously.

subjected to the load of the door and the load of the counterweight upon opposite sides of said sheave 3037. Immediately, however, that the downward movement of the counterweight is stopped as by engagement with the bottom of the housing 32, the connections 2G and 27 will be relieved from the load of the counterweight so that the'creation of even the slightest slack by a continued further movement to the door panel.

As a result of this condition, it will be noted that when the door has reached either.

the fully closed or the fully open position, the actuating means including said sheaves 30 and 37 become totally inoperative to impart further movement to the panel and will at the same time relieve all of the mechanisms of the door structure from any breaking stresses, even though the chain 42 be motor driven beyond the point necessary to cause the desired movement of the door.

When starting the opening movement of the door, the major portion of the load of the panel '19 will come upon the overhead track structure, so that so far as the exertion required to move the panel itself is concerned, this is reduced to a minimum. The arrangement of the track sections 15 and 16 and the offset co-operating devices, the rollers22, will result in the development of a horizontal com onent of movement in the upper portion of tie panel substantially simultaneously 7 with the initial vertical movement of the freely in relation to the wheels 24 and the swivel 25 as the panel is passing from the vertical to the substantially horizontal position adjacent the ceiling as is shown in Fig. 2 of the drawings. Aside from this swiveling action at said trunnion fittings, the portion of the panel adjacent the bottom thereof moves vertically upward.

As the wheels 22 pass inwardly of the door opening, the load upon the connections 26 and 27 becomes progressively greater as said wheels move inwardly, until when the parts are in the position shown in Fig. 2, this load reaches its maximum. It is at this point that movement of the counterweight 3 1 is stopped as by engagement withthe bottom of the casing 32. I y The. sheave arrangement between the sheaves 31 and 38, and the fitting 35, causes the speed of-movement of the weight34 to be approximately one-half of that of the trunnions of the door panel in both opening and closing'the door, thus avoiding the necessity for providing a well for this counterweight.

The load of the panel 19 upon the conncctions 26 and 27 being at its maximum when the door is open ease in the starting of the closing movement of the door is ensured since the effective action of the counterweight in opposition to the movement of said panel is at its minimum when the parts are so positioned. With the descent of the bottom portion of the panel, and its resulting turning action in its entirety, from the substantially horizontal to the vertical position, the constant change in the position of the panel will result in a gradual reduction in the load upon the connections 26 and 27, thus causing the development of a progressively increasing counterweighing action by the counterweight 3 1 so that as the panel 19 is approaching its vertical position, the counterweight will act as a check to prevent a too rapid final closing movement of the door.

While I have referred herein to the counterweight 34, it will readily be appreciated that there need not be a balanced condition between the panel 19 and its appurtenances, and the weight 34, and that either part may be overbalanced with relation to the other, any differences in the weights. of said parts merely requiring the application of'greater or less power through the chain 42.

During the closing movement of the panel 7 19, the engagement of the rollers 24 with the inner flange of'the channel rails 12, and the swiveling of the panel about the axes of the wheels 22, will result in a movement of the upper portion of the panel toward the door opening 11, first in a substantially horizontal plane until the rail sections 15 and 16 are reached, and then with a downward component of movement, which movement as heretofore stated, will be checked by the increased effective counterweighing action of the counterweight 34, as'a result of the change in position of the panel 19.

In the accompanying drawings, the scale of reproduction is of necessity so small as to preclude the showing of the different mechanisms with their proper relative dimensions. The panel 19 may be only an inch to an inch and one-half in thickness, and with a tenfoot opening the scale of the drawings would be about 1 to 35 which would not permit even a fair showing of relative dimensions. The same is equally true of the overhead track structure. Hence it is apparent that it is not my intention to limit the invention to the proportion or even the fexact arrangement of parts shown in the accompanying drawings,

it being apparent that in full sized structures ryaaeee such may be varied. The parts as shown in the drawings, however, will operate in the manner herein described, as in a full sized structure.

The flexible connections 26 and 27 may either be ropes of hemp or similar material, or of metal, since the friction developed as a result of the pinch grooves in the sheaves 30 lit , 27 resulting from and 37, when said sheaves are operative, re-- sults from binding stresses upon said connections by both said panel and said counterweights, and at opposite diameters of said sheaves which may run into hundreds of pounds.

It, when the panel 19 is in its substantially horizontal position, it should have any tendency to descend of its own accord, such movement is prevented as soon as the counterweight comes to action. The space between the rails 18, 14:, 15 and 16 is slightly greater than the diameter of the wheels 22 intermediate the side flanges thereof, said wheels being flanged wheels as described, so that before engaging the rail section 15 slight vertical upward movement of the panel is necessary. However slight this movement may be, it afi'ords an interval during which the entire load of the panel will be upon the connections 26 and 27, the greater portion of this load, however, being immediately transferred to the rail secti on 16 with the completion of this slight upward movement. I

The rail section 15 is provided to cause the desired initial movement of the panel inwardly of the door opening 11, this section with the section 13 preventing the lifting of the wheels 22 from the lower rail sections 14 and 16v during the upward movement of the door. With the swiveling action of the panel with relation to the wheels 22, notwithstanding the vertical stresses applied to the lower portion of the door, said wheels will track upon the rail sections 14 and 16 during the downward movement of the panel, the variance in the load upon the connections 26 and the transfer of a ortion of this load through said wheels to said rails during this movement. The tilting of the panel will cause the rollers 25 to be thrustby the load of the door, against the flanges of the guides 12 toward the door openin 11,

which will assist in causing the action a ove referred to.

The offsetting of the wheels 22 inwardly of the door opening 11, requires a spacing of the overhead tracks downwardly from the ceiling to permit the tilting or swiveling ac tion of the door panel 19 and the desirability of having these tracks as close to the ceiling as possible results in a condition by which said panel, even when in the fully open pos tion, will be on a slightincline to the horizontal as shown more particularly in Fig. 2

of the drawings, although with doors of full size the angle of inclination will be con-,

siderably less than that shown in the drawvertically extending guides adjacent the wall of abuilding and upon opposite sides of a door opening therein, overhead tracks leading from but not communicating with said vertical guides and extending inwardly of the building, the portion of said tracks adjacent said vertical guides having a gradual ascent leading. from adjacent the lintel of the door opening to a horizontal portion each of said tracks comprising parallel rail sections, a door panel adapted to close the door open;

ing, devices adjacent the top of said panel iii continuous engaging relation between said rail sections and co-operating only with said overhead tracks respectively, whereby at all times a'support is afforded the upper portion of said panel, devices adjacent the bottom of said panel movable in said vertical guides, sheaves above said guides respectively, a counterweight, flexible connections between said counterweight and the lower portion of said panel and passing over said sheaves, and means operative upon said flexible connections whereby the panel may be'opened and closed. I

2. A ware house door embodying therein vertically extending guides adjacent the wall of a building and upon opposite sides of a door opening therein, overhead tracks leading from but not communicating with said vertical guides and extending inwardly of the building, the portion of said tracks adjacent said, vertical guides having a gradual ascent leading from adjacent the lintel of the door opening to a horizontal portion, each of said tracks comprising parallel rail sections, a door panel adapted to close the door opening, fittings upon said panel in olfset relation thereto and projecting toward said overhead tracks, rollers upon said fittings respectively in continuous engaging respectively whereby at all times a support is afforded the upper portion of saidpanel, devices adjacent the bottom of said panel movable in said vertical guides, sheaves abovesaid guides respectively, a counterweight,

'flexiblc connections between said counterweight and the lower portion of said panel H and passing over said sheaves, and means Op erative upon said flexible connections whereby the panel maybe opened and closed.

3. Awarehouse door embodying therein vertically extending channeled guides adjacent the wall of a building and upon op- .posite sides of a door opening therein, overead tracks leading from but not communicating with said vertical guides and extending inwardly of the building, a portion of said tracks adjacent said vertical guides having a gradual ascent leading from adjacent the lintel of the door opening to a horizontal portion, each of said tracks comprising parallel rail sections, a door panel adapted to close the door opening, devices adjacent the top of said panel in continuous engaging relation between said rail sections and co-operating -only with said overhead tr tCkS respectively whereby at all times af upport is afforded the upper portion of said panel, rollers adjacent the bottom of said panel movablein said channeled guides whereby said panel is permitted to have turning movement in relation to said guides, sheaves above said guides respectively, a counterweight, flexible connections between said counterweight and the lower portion of said panel and passing over said sheaves, and means operative upon said flexible connections whereby the panel may be opened and closed. 4..A warehouse door embodying therein verticall extending guides adjacent the wall of a bui ding and upon opposite sides of a door opening therein, overhead tracks leading from said vertical guides and extending inwardly of the building, consisting of spaced horizontally extending rail sections adjacent the ceilin of a building and spaced sections leading therefrom to adjacent the lintel of door opening and ascending toward said horizontal sections, a door panel adapted to close the door opening, fittings upon said panel projecting toward said overhead tracks, rollers upon said fittings respectively positionedbetween the rails of said tracks respectively, devices adjacent the bottom of said panel movable in said vertical guides, sheaves above said guides respectively, a counterweight, flexible connections between said counterweight and the lower ortion of said panel and passing over sai sheaves, and means operative upon said flexible connections whereby. the panel may be opened and closed. 5. A warehouse door embodying therein vertically extending channeled guides adjacent the wall of a building and upon opposite sides of a door opening therein, overhead tracks leading from said vertical guides and extending inwardly of the building, a portion of said tracks adjacent said vertical guides having a gradual ascent leading from adjacent the lintel of the door opening to a horizontal portion, a door panel adapted to the door opening, devices adjacent the tom of said panel movable in said channeled v guides whereby said panel is permitted to have turning movement in relation to said guides, sheaves above said guides respectively, a counterweight, a swiveling fitting adjacent, the bottom of said panel, flexible connections betweengsaid counterweight and said swiveling fitting .and passing over said sheaves, and means operative upon said flexible connections whereby the panel may be opened and closed.

6. A warehouse door embodying therein vertically extending guides adjacent the wall of a building and upon opposite sides of a door opening therein, overhead tracks leading from said vertical guides and extending inwardly of the building, consisting of spaced horizontally extending rail sectionsadjacent the ceiling of a building and spaced sections leading therefrom to adjacent the lintel of the door opening and ascending toward said horizontal sections, a door panel adapted to close the door opening, fittings upon said panel projecting toward said overhead tracks,

" rollers upon said fittings respectively positioned between the rails of said tracks respectively, devices adjacent the bottom of said panel movable in said vertical guides, sheaves above said guides respectively, a counterweight, a swiveling fitting adjacent the bottom of said panel, flexible connections between said counterweight and said swiveling fitting and passing over said sheaves, and means operative upon said flexible connec- .ti1onsdwhereby the panel may be opened and c ose 7. A Warehouse door embodying therein.

inwardly'of the building, the portion of said tracks adjacent said vertical guides having a gradual ascent leading from adjacent the lintel of the door opening to a horizontal portion, a door paneladapted to close the door opening,devices adjacent the top of said panel co-operating with said tracks respectively, devices ad acent the bottom of said panel movable in' said vertical guides, sheaves above said guides respectively, a counterweight, flexible connections between said counterweight and the lower portion of said panel and passing over said sheaves, and an actuating mechanism including therein means frictionally engagingrsaid connections intermediate said sheaves and said counterweight; whereby said actuating means is operative when said connections are subjected to the load of both said counterweight and said panel, and is inoperative when said connections are relieved from the load of said panel or the load of said counterweight.

' 8. A warehouse door embodying therein vertically extending guides adjacent the wall of a building and upon opposite sides of a door opening therein, overhead tracks leading from said vertical guides and extending inwardly of the building, the portion of said tracks adjacent said vertical guides having a gradual ascent leading from adjacent the lintel of the door opening to a horizontal portion, a door panel adapted to close the door opening, devices adjacent the top of said panel co-operating with said tracks respectively, devices adjacent the bottom of said panel movable in said vertical guides, sheaves above said guides respectively, a' counterweight, flexible connections between said counterweight and the lower portion of said panel and passing over said sheaves, and an actuating mechanism including therein sheaves having a pinch groove formed in the surface thereof and operative upon said flexible connections intermediate said first named I sheaves and said counterweight, whereby saidsheaves are operative to impart movement to said panel when said connections are subjected to the load of both said counterweight and said panel, and are inoperative when said' connections are relieved from the load of said panel or the load of said counterweight.

9. A warehouse door embodying therein vertically extending guides adjacent thewall of a building and upon opposite sides of a door opening therein, overhead tracks lead ing from said vertical guides and extending inwardly of the building, the portion of said tracks adjacent said vertical guides having a gradual ascent leading from adjacent the lintel of the door opening to a horizontal-portion, a door panel adapted to close the door opening, devices adjacent the top of said panel co-operating with said tracks respectively, devices adjacent the bottom of said panel movable in said'vertical guides, a coun- I as terweight, flexible connections between said counterweight and opposite edgesadjacent the lower portion of said panel, a sheave above one of said guides, two sheaves above the other of said guides toward said counterweight, the connection at one edge of said panel passing over said first named sheave and one of said second named sheaves, and the other connection passing over the other of said second named sheaves, two actuating sheaves below which said connections pass,

each of said actuating sheaves having a pinch roove in the periphery thereof, two sheaves %eyond and above said actuating sheaves over which said connections respectively pass to said counterweight, whereby said actuat ing sheaves are capable of being made operative when said connections are subjected to the load of both said counterweight and said panel, and are made inoperative when said connections are relieved from the load of said opening, devices adjacent the top of said panel co-operating with said tracks respectively, devices adjacent the bottom of said panel movable in said vertical guides, a counterweight, flexible connections between said counterweight and opposite edges 'adjacent the lower portion of said panel, a sheave above one of said guides, two sheaves above the other of said guides toward said counterweight, the connection at one edge of said panel passing over said first named sheave and one of said second named sheaves, and

the other connection passing over the other of said second named sheaves, two actuating sheaves below which said connections pass, each of said actuatlng sheaves having a pinch 'groove in the periphery thereof, two sheaves beyond and above said actuating sheaves over which said connections respectively pass to said counterweight, whereby said actuating sheaves are capable of being made operative when said connections are subjected to the load of both said counterweight and said panel, and are made inoperative when said connections are relieved from the load of said panel or the load of said counterweights, means above said counterweight to which the ends of said connnections are secured, sheaves upon said counterweight about which said connections pass to said last named means, and means wh ereby power may be applied to said actuatin sheaves.

In witness whereof I have hereunto affixed my signature this 7th day of April, 1925.

ROBERT S. PEELLE.

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