US1874903A - Closure operator - Google Patents

Description

1 8 1932- J. T. CONWAY 1,874,903

,CLOSURE OPERATOR Filed Dec. 26, 19%8 3 Sheets-Sheet l AL ATTORNEY a WM W Aug. 30, 1932. J CQNWAY 1,874,903

CLOSURE OPERATOR Filed Dec. as, 1928 3Sheets-Sheef 2 J. T. CONWAY Aug. 30,1932.

CLOSURE OPERATOR Filed Dec. 26, 1928 3 Sheets-Sheet 3 HUM " ATTORNEY Patented Aug. 30, 1932 UNITED Y STATES JOSEPH T. CONWAY, OF QLEVEIQAND, OHIO onos URE OPERATOR Application filed December 26 1928; Serial No. 328,450.

My invention-is an improvement'in closure operating mechanism and relates more particularly to means for opening closures such as engine house and garage doors and then automatically closing the same upon the expiration of a predetermined period of time.

One of the objects of my invention is to open and then automatically close doors or other closures at the expiration of a predetermined period of time. TI

Another object of my invention consists in providing power operated means for opening and closing doors but permitting manual operation thereof withoutinterference from the power operated means.

or premature closing of the doorsas the result of external forcessuch as wind.

Another object of my invention is to give ample warning to passersby that the doors are being opened and that a vehicle is about to leave the building.

Another object is to automatically release trap doors such as are used in fire engine houses communicating one floor of the building with another, almost simultaneously with the energization of the motor circuit.

' Another object of the invention isto simultaneously sound alarms, release traps and open the doors, when the invention is applied to fire engine stations, the said alarms being 'de-energized before the doors are automatically closed.

Further objects and advantages of my infollowing description of an embodiment thereof progresses reference being made to the accompanying drawings inwhich like reference characters are employed to designate like parts throughout the same.

Figure 1 is a diagrammatic view of the electrical circuit employed in connection with my invention showing certain of the parts in dotted and full line positions. r

Figure 2 is a bottom plan view of one embodiment of my invention shown in useas applied to doors swinging about a vertical axis and showingthe extreme positions of some of the parts of the apparatus when the doors are in closed or open position.

A further object is to prevent accidental vention will become more apparent as the Figure 3 is a side elevation of a portion of an apparatus embodied in my invention in which the cover plate of a switchbox ha's'been removed. V I.

Figure 4. is an' enlarged fragmentaryview of a portion of the track showing 'theicarriage in one of its limits of movement along the track. I i I Figure 5 is an enlarged fragmentary view of another fragmentary section vof thetrack representing the forward end of the track'and showing the manner of supporting the means for moving the carriage along the track.

Figure 6 is an enlarged sectional view taken on line 6 6 =of Figure3. c

Figure 7 is a sectional view taken on line 77' of Figure 5. p 3

Figure 8 is an elevational view of the cylinder movable with the carriage showing the by-pass connect-ion forvthe cylinder.

Figure 9 is an enlarged section taken on line 99of Figure 3. a

Figure 10 is an enlarged section taken on line 10'10 of Figure 3. i i -Figure 11 is an enlarged elevation of a part of my invention including means for locking the doors in open positions andv against accidental closure.

Figure 12 is a section taken on line of Figure 11. l

In the accompanying drawings illustrating one embodiment of my invention and referring more particularly to Figures 2 'to' 8 inclusive, 1 represents a frame for doors or other closures 2, which in the present embodi ment'are mounted to move about a vertical axls. I have provided means for moving the doors about their'respective axes, which in the present embodiment I have illustrated as including connecting rods 3 pivotally "connected at one of their ends to the doors, as at 4, and pivotally connected at their other V respective ends 5 to the carriage 6.1 The carriage is movable along a track or other sup- 5 port 7, and in Figure 2 I have illustrated theposition of the carriage and connecting rods in full lines, indicating their position when the doors are closed, while in dotted lines I have illustrated these partsiin their 0 respective positions when the doors are open. Referring more particularly to Figures 4, 5, 6 and 7 it will be seen that the track 0011'- sists of a substantially inverted U-shape housing is provided with a rearwardlyv extending shoulder 13 to which the supporting rod 11 is attached. A depending stop or abutment 14 is'also formed on the housing and is disposed in the path. of movement of the carriage for purposes which will be described more fully hereinafter. The forward end of the casing 9 is supported within a housing or casting 15 which terminatesin a bracket 10, by means of which it is support- ,ed on the door frame 1.

The carriage 6 consists preferably of a casting having connecting rod supports 16 on opposite sides thereof, by means of which the ends of the rods may be pivotally connected through the bolts 17. A cylinder 18 is'preferably formed integrally in the carriage body and its longitudinal axis extends substantially parallel to that of thetrack, although the cylinder may be separately formed and conveniently secured in position in'the carriage body if desired. The carriage is suspended from the track by the rollers 19, which are freely rotatable about shafts which extend through the portion 20 of the carriage body. In the particular embodiment illustrated herein, I prefer to employ rollers having rubber tires,in order to minimize noise in operation such as would bemanifcsted where there is metal to metal contact between rollers and the tracks. noted that the rollers travel along the flat portions 21 of the spaced tracks formed in the channel 8.

A piston 22 provided with suitable packing is mounted to reciprocate within the cylinder .18 and is secured by means of a set screw 23 to the rod 24 which is slidable through openings in the ends of the cylinder 18. I have provided bonnets 25 which are detachably screwed upon each end of the cylinder for slidably supporting the rod 24 therein: These bonnets may also be provided with packing means as at 26. Referring more particularly now to Figure 8, it will be seen that I have provided a by-pass consisting of a restricted conduit 27 communicating with the interior of the cylinder 18 adjacent each end thereof. I have pro vided a control valve 28 in the conduit for regulating the flow of oil or other fluid through the conduit from one end of the cylinder to the other, when the piston 22 is shifted from one end of the cylinder to It will be the other. In this manner the carriage may be brought to rest against the desired cushion at either of its extreme positions along the track after the motor has been de-energized by the automatic opening of the respective reversing switches.

I have also provided means for moving the carriage 6 from either one of its extreme positions to the other, which includes a belt or chain 30 having its respective ends secured. to the turn buckles 31 and 32, which are in turn secured to the portion 20 of the carriage. These turn buckles permit the taking up of slack in the belt or chain from time to time. This is clearly shown in Figure 4. The chain passes over idler sprockets 33 and 34, which are rotatably mounted at the forward, and rearward ends respectively of the track 8; the lower portion of the chain extends through the channel 8 while the upper portion of the chain passes over the sprocket 33, the driving sprocket 35 and under the idler sprocket 36 and over the intermediate idler sprocket 37 and about the rear idler sprocket 34. The upper portion of the chain passes through the casing 9. The driving sprocket 35 is keyed to a shaft 38 to which also is keyed a reducing gear 39. The motor M is supported on the casting 15 as shown in Figure I 3, and carries on its shaft 40 a gear 41 which meshes with the reducing gear 39. The shaft 40 of the motor extends into a casing 42 which is formed integral with the casting 15, which houses the gears 39 and 41' and the forward end of the track. A conduit 43 leads from the motor to the interior of the switch box 44, which is formed as a part of the casting 15 and carries therein electrical conductors 108, 110, 112, 113, between the posts of the motor and certain of the elec-' consist of the links 131 and 132 pivotally connected to the respective reversing switches at their outer ends and also pivotally connected to the rod 130. The rod 130 extends substantially parallel along one side of the track and casing 9, and is provided with adjustable lugs or stops 44 and 45 which may be adjusted to the desired positions along the rod 130. The rod 130 is movable axially in suitable bearings to engage oneof the reversing switches with its respective contacts and to disengage the other reversing switch from its respective contacts and rod 46 is supported along the track and extends substantially parallel to the rod 130. The rod 46 carries thereon adjustable depending arms 47 and 48 which are capable of swinging about horizontal axes 49. These arms may be adjusted by means of set screws, to swing from the rod 46 at any desired point thereon, which may be selected bythe operator. In

the position of the parts shown in Figure?) with the carriage to theextreme right; it will be noted thatthe arm 48 is engaged byrthe carriage in its movement to the right and "in turn engages the stop va5 secured to-rod 130.

In this :manner continued movementof the carriage will move, th'erod 130 to itslimit of movement to the right, closingthe reversing switch RS and opening-the reversing switch RS \Vhen the carriage travels towards the left along thetrack it will engage the depending arm 17 which inturn engages the stop irsecuredto the rod 130.

Continued movement of the carriage to the left will cause the rod130to be mo vedto' the left, closing the reversing switch RS and opening the reversing switch RS. v

The intermediate sprocket 37 is rotatably supported at a point substantially midway betweenthe sprockets 33 and 3e and serves to support the chain 30 at this point during its travel between vthe-sprocket 36 and the sprocket 34. The sp'rocket'37 is mounted in a casting50 which is provided with shoulders 51for supporting the ends of the casing section 9. This is shown in detail in Figure .5.

closures, and I have also'illustrated inTthisfigure the electrical "circuits used in connection with this apparatus. I will-now proceed to describe these circuits.- L and L indicate a source of electrical energy and F indicates protecting fuses'in each side of the line. For convenience of description L 'may be designated as the side ofthe line common to all the electrically connected devices; I L is connected through a'conductor L and snap switch A to the manually operated switches B and C. The switches 13 and G are of the normally open or push button type; since it is only necessary to closeone of the switches momentarily to energize one of the respective solenoids S and S depressed, current will flow from L through the normally closed switch A; the switch .13 and conductor through the solenoid S and conductor L part of the currentpassing along the conductor 101, the solenoid S and the conductors 103 and L The solenoid S actuates the plunger P, when energized, to

lift the latch L on the doors2 throughthe lever L and rod R The solenoidsS and S are energized simultaneously.

I of the switch. In this manner a motor When the switchB is noid'Sfl'the conductors 105and L ,-..energizing the solenoid S The plunger P i of the solenoid S ris connected :to actuate a trip or latch L forreleasingthe trap doors T fiand T An audible alarmrA and .a light A are connected across {thelines 104 :and 105. When the doors i2 are closed the reversing switches RS and-RS and the plungerl i and automatic switch blades are in the dotted line positions indicated in Fig.1, before. the'push button switch B isficlosed. "Upon closing the switch B momentarily electric current will energize the solenoid S drawing theplunger P to the right in the figure, engaging the automatic switch blades B B B?"andB with-the respective contacts C 0 51C? and C? and disengaging the blades B B2B? and B? from the respective contacts G C C and G is established as-follows I 1 Part of the current passing through the switch A passes along the wires 1'06 and 107 circuit a tothe blades B and B wwhich are 'now in a contact with the contacts C and C of the" automatic switch": :From the 'contact C -a wire 108 carries the current fromx'L topost M of the motor M, and from the contact (1 a wire 109 also carries the current from L and wire 107 to the blade B of the reversing switch RS. A wire 1:10,1eads from the contact engaged' by B? tof-post M 1 1?- the motor. FL? is therefore connected to. posts M and M? of the motor during thisphase'of theioperation of:the apparatus. 3:

' A wire 111 leads from thecontact blade B which is connected to-IE, toblade B of the reversingswitch RS- A connec= tionis thus made from L ithrough the blade B and a Wire 1152 to post M .of the motor M. Anothericonnection is made froin L through the blade B contact C and wire' 1- 13 to-post It will also'be noted that the siren A and 3.

street-light A will be energized immediately upon the engagement of the blade Br with the contact C which completesithe alarm' circuitand warns passersby'that the doors are passing from L throughtheswitch Af and wire 106 will continue through lthe wire 114 and thenormally closed contacts C and C of the switch I), to the siren A? and'light A being opened.I'Theial'arm circuit just referred to maybe traced as 'follows?Currentthrough the wire1 15. 1 A "wir e'116 connects I through the'contact O and blade B to L completing the'al'arm circuit; The devices A and A? will continue to be energizedfias long a's the'doors 2remainopen and the blade B l engages Ic-ontact Cfiiand as long as the switch arm D lengagesthe contact C Ihave providedmeans for automatically energizing the solenoid S after a predetermined period a of time has elapsed since'the 2. is therefore connected to a energization of the solenoid Sand I have also provided-manually controlled means for energ-iz'ing the solenoids at will, the latter constituting more ofv an auxiliary means to be I through coil R, which is of relatively low resistanceandthence through coil R whichis of relatively high resistance. i

The two coils are connected in series by the. wire 118, the wire 119leading from the coil R and connecting to vL through the wiresl19 and 111 and blade B? of the auto.- matic switch. The coil R extends axially within a thermally responsive element T. This element consists preferably of a spirally wound metallic strip anchored at its lower end 120 in a suitable supportand carrying an outwardly extending arm 121 at its upper'end. The arm 121 terminates in an insulated head 122 which normally abuts an adjusting screw 123 in the circuit maker and breaker 'D. Thus'it will be seen that as the coil R heats up, the spiral thermostatic element T will respond to the rise in tempera ture by expanding spirally,, whereupon the arm 121 carried-bythe element and abutting the adjusting screw 123 carriedby the switch arm D will move the hinged switch arm toward the observer, (Fig. 1) breakingthe contacts through C 'which' is behind the arm 121 and the switch arm D. As the switch arm continues to movetoward the observer by continued spiral expansion of the thermostat T it will contact with the contact C feeding current from L through the wires 106 and 11 1 and switch arm D and wire 124 to the solenoid S The solenoid S is, con nected to the wire L through the wire 128 to complete the circuit. It will be seen that the movement of the switch arm, which is normally held against the contact 0 b a spring 126 toward the contact C rst breaks the circuit through the siren A and lamp A and then. completes the circuit through the contact C to energize the solenoid S and pull the plunger P to the left in the figure. When the plunger moves to the left the blades B B B and B are disengaged simultaneously from the respective contacts C C C and C of the automatic switch, while the blades B B, B and B are .engaged with the respective contacts C C, C and C As the doors approach the limit of movement representing their open. position, the rod 130 is moved to the left in Figure 1 by means which havebeen described hereinbefore. One end of this rod is connected by links 131 and 132v to the reversing switches RS and RS respectively, and movement of the rod tothe left will engage the blades B and B with the contacts G and C and G V respectively and will disengage. the blades B? and 13 from the .contacts G and C respectively. .I haverepresented these positions of the reversing switches, rod and links by-dottedlines in the figure.

' Itv will be noted that when thesolenoids S is energized vbythe closing ofthe circuit through the switch D and contact C, the blades of the automatic switch are moved to the positions shownv by dotted lines and the heater circuit through wires 119, 111 and contact C is broken. However the return v of'the switch arm D to its normal position to close the contacts D and C is retarded by thecooling'of the coil R and the contraction of the thermostat T. In this manner the automatic-circuit through the solenoid S is of short duration. With the switch blades B B, B and B incontact with the respective contacts G G", C and C and the reversing switches RS and BS in the dotted line position, a motor circuit is established for rotating the motorv armature in a reverse dlrection to that when the doors are being opened. This circuit may be traced as fol lowsCurrent from. L flows through the wire 106, blade B and wire. 108 to post M of the'motor. Current also flows from L andwires 106 and 107 through blade 13",

wires 133 and. 113 to post M of the motor. 7

Post M of the motor is connected to side L doors, while withautomatic'switch in the 1 position shown in full lines, posts M and M are connected to L and posts M and M are connected to L -With the automatic switch in the dotted line position the motor is actuated to close the doors by means which have been described. As the doors'approach theclosed position the rod .130 is shifted. to the rightinFigure 1, whereupon the reversing switches RS and RS will again assume the full lineposition and the motor circuit will be automatically broken. f

When the reversing switches RS and RS are in the dotted line positiona circuit is completed to operate a latch or look L which holds the doors in open position and against accidental or premature closure by wind or other forces. This circuit remains closed only to unlock thelatch whilethe automatic and reversing switches are in the dotted line position and while the motor is operating the contact C The switch RS being in closed A conductor 128 connects the other lead of position, the current passes along the wire 135 and blade B to L A plunger P arranged to operate the latch operates within. the solenoid S when the latter is energized.

I have shown the means for operating the latch L in Figures 11 and 12,-whicl1 includes a bell crank 60 operable by the plunger P to lift the latch L through the connecting link 61. The hooked end of the latch engages one or more stops 62 on one of the connecting rods 3. When the doors are opened the rod 3 moves to the left in Figures 11 and '12, the hookedend of the latch riding up the inclined walls 63 and over the stops 62 providing a positive lock to retain the doors in open position. When the doors are to be closed, however, and the solenoid S is'energized, the latch will be lifted out of the path of movement of the rod 3 to the right.

I have provided a manually controlled electrical circuit for energizing the solenoid '8? when it is desired to close the doors before the thermostat T has had time to move the switch D into contact with the contact C. This circuit includes a push button .switch 0 connected on one side to L and on the other side by means of a wire 138450 the solenoid S the solenoid to L of the line.

The switch Amay be. opened any time to disconnect the power line. Thus the doors may be maintained in either an open or closed position at will. r a i I will now describe the operation of my invention as illustrated in the accompanying drawings.

Assuming" that the doors 2 are'closed and that the various parts ofmy invention are in the full line position of Fig. 2, in order, to open the doors, the operator depresses the push button switch B of Fig. 1 to the full line position, energizing the-solenoids S, S

and S The plunger Bis thus actuated'to release a latch L which normallyretains the doors in closed position. This latch is illustrated inFig..l. v p

The plunger P is likewise actuated upon: the energization of the solenoid S to release a'latchL which has previously been positioned to retain the spring actuated trap visible signals A and A are energized to indicate the doors are open andtoilluminate Their movement may be retarded the area around the trap doors'to prevent accidents. v

When the solenoid S energized, the plunger P is shifted to the rightas shown.

in Figs. 1 and'10, closing the switch blades B B B and B withtheir. respective ,con-

tacts (1 ,020 and G In'this manner the motor M is energized to run in a direction for rotating the reduction gear 39 and vpinion 35(Fig. :5) in aclock-wise' directions-Theupper portion of the chain 30 is thus moved to. the right in Figs. 4 and5, while the lower portion moves toward the left, drawing the;

carriage along the track, and. opening the 3 doors 2; In Fig. 2 I have illustrated the carrlage in dotted lines in its limit of move-' ment to the left to open the doors.

\ Referring now more particularlyto Fig. 3

it will be seen that, as thecarrige approaches" its limit of'movement to the left in opening the doors, a portion16 of the carriage body w1ll engagethe depending arm 47 which is freely movable about its pivot. Continued 'moveme'nt of the carriage to the left will cause this armto engage the stop 44' secured.

to the slide bar or rod 130 and move the stop and rod 'to'the left-a sufficient distance to disengagethe reversing switch RS from'its-contacts C and C and toengage the reversing I switch RS with its contacts G G 5 and C 4 before the carriage comes to rest." Referring to Fig. 1 it will be seen that opening of the swithRSwilldisrupt the motor circuit-and stop the motor, thus stopping the" movement 1 ofthe carriage substantially instantaneously with the'opening of the switch RS. 1

"It ishould also be noted that when the i plunger P is shifted to the right,1an alarm andiy'light circuit is closed through the wires 106 and 114, switch contact" C and D con-.

tact C and. wire 115 to the streetlightAtand the siren A the circuit being completed I l through: the wire 116, contact 0 a switch: blade B and wire L alarm is given during the opening of the doors 2 to warn passersby that the doors are opening or are opened anda vehicle is about.

to pass therebetween.- The audible alarm and. light A? will continueto function as long as the switch arm D remains in contactwith the contact (3 I Q I A circuit isalso .establishedthrough the Thus an audible street regulator and heater COllSR and R when'the plunger P is in the position shown in Fig.1.-

This circuit is traced as follows-from L and switch A, wires 106, 114 and 117 through the coil R of relatively low resistance,'wire 118- and coil R of relatively highresistance, wires 119 and 111, and switch blade .B to L Therefore when the blade B engages its conlylow resistance, wire 118and coil R of rel-' atively high resistance, wires 110 and'lll,

and switch blade Btto L Therefore, when r tact C currentwill pass through thelrelativecuit.

will pass through the relatively low resist ance current regulating coil R. The current that passes through this coil is conducted through the wire to the heater coil R of relatively high resistance. The coil R is 123 may be adjusted toward or away from the disc 122 to determine the time interval between the energization of the coil R and the closing of the contacts D and C and also between the energization of the coil and the breaking of the contact C of the alarm cir- Thus if it is desired that the de-energization of the alarm and the closing of the contacts D and G be retarded, the set screw 123'may be adjusted away from the disc 122 when 'thecoil R is cold, although it is obvious that by adjusting the set screw closer to the disc 122 the elapsed time between the eneigization of the coil R and the beginning of movement of the switch D about its axis will be correspondingly shortened. By this means the energization of the solenoid S and the de-energization of the street alarm A V and light A maybe predetermined over desirable periods such as, for example, from fifteen'seconds to two or three minutes after "ft the coil R is energized. VA compression I spring 126 normally returns the switch arm' Dinto contact withthe alarm contact (1 and breaks the contact C1 as it overcomes the subsiding-e-xpansive forces of thecooling element T when the same is de-energized.

From the foregoing it will be seen that when the switch arm D contacts with the contact C a circuit is completed through I the wires L 106, 114 and 12 1 to the solenoid 1 $1, the other side of the solenoid being connected to L through wire 128. In this man ner the plunger 1? is moved tothe left in Fig.1, disengaging the blades B B B andB from their respectivecontacts and i engaging blades 13 ,13 B and B? with the respective contacts C C, C and C". With the control switch blades in this position as shown in Fig. 1 in" dotted lines, a motor circuit is established to rotate the motor armature in a reverse direction to that when the doors 2 were'being opened. This motor circuit may be traced from L wires 106 and 107 toblades B and B From contact C one side of the motor circuit extends through wire 108 to post M ofthe motor M. From contact C 'current is carried by means of conductors 133 and 113 to post M of the motor M. L of the current supply is fed to contacts C and C through the bladesIB and B and the wires 1341:.and 135 to the re versing switch RS it When this switch is closed by the movementof the rod 130 to the left Fig. 1 in opening the doors 2, themotor circuit is completed through wires 111' and 112to posts M and M respectively of the motor. 7 passes through the conductor 137 when the reversing switch BS is closed to engage con tact C energizing the solenoid S which is also connected to L through the wires136 and 106. Energization of the solenoid 8* re.-v tracts the plungerP whic'h in turn releases the latch shown in Figs. 11 and .12. 'This latch, as has been describedabove, normally serves to hold the doors against accidental closing which might result from wind or other external forces. I

.When it. is desired'to energize the sole? 7 noi-d S prematurely, thatis, before thesame is actuated by the automatic means described above, the operator depresses the push button switch C which will close the circuit from L throughwire 138? and the solenoid S to L Thus the doors may be closed at will without waiting for the automatic switch D to function.

t will'be observed that when the doors 2 are closed the contacts C on one of the doors engage the contacts C on the door frame to" close the. circuit throughv the solenoid S hus the circuit, through this solenoid is broken when the doors 2:begin to open. In

Fig. 11 have illustrated these contacts dia-.

grammaticallyin spaced relation-while in energized is also controlled by this set screwr By the use of my invention as applied,

for instance, to. fire en inestationswhere, it is essential that the re apparatus" leave the building as quickly as possible uponthe sounding of a box alarm, the-doors are in the open-position before the fire appa ratus is read to leave since it-isonl neces-T sary for the desk man to depress the switch B as he gets the first round of the alarm.

In: this manner the doors .may' often be opened before the first round is actually completed. My invention provides for automatic closing of the doors after a predeter- I mined lapsed period of time,'which maybe from 15 seconds to 2=or 3 minutes without further attention by the desk man, provided. I

the switch A is left in closed position. If it is, desired'fthat the-doors remain; open until 70 Part of theicurrent from L? the apparatusreturns from its run,the desk man opens the switch A, but upon again closing this switch the doors will be closed promptly.

If desired, a manually operated switch (not shown) may be inserted in the circuit feeding the signal devices A and A, to prevent their energization when the doors are opened for purposes other than-to admit or to discharge the fire apparatus. 7

It will be noted that if the sourceof electrical energy at L and L should fail for any reason while the doors are in open positlon, the doors will not begin to close immediately upon the restoration of the current source, but'the closing will be retarded until the coils R and R heat and the thermostatic element T operates the switch arm D to closethe circuit through the solenoid S. If the current source should fail when the doors are closed and an alarm comes in, the doors may be manually opened without inenergy; a motor reversing switch in said circuitya rodextending along the path of travel of the carriage having one end oper atively 'connected to said reversing switch; stops onsaid last named rod and in the path of movement of the carriage whereby said last named rod may be operated to reverse the switch when the, carriage approaches either of its limits of movement.

In testimony whereof I hereunto afiix my signature this 3rd'day of December, 1928.

JOSEPH TL CONWAY.

terference from the door opening mechanism.

tails of construction and arrangement of parts without departing from the spirit of the invention or the scope of'the'subj oined claims.

Various changes may be made in the de- 7 ice carriage as it is brought tolrest at either of j its extreme limits of movement on the track, and stops arranged in the path of movement of the rod to engage the ends thereof as the carriage approaches either of its limits of movement along the track. 2. In an electrically controlled door operating mechanism; a track;'a carriage capable of travel alongthe track; a cushioning device movable with the carriage and including a cylinder, a piston in the cylinder, a rodslidabl-e in the cylinder and fixed to said piston, the ends of the rod extending beyond the ends of the cylinder; stops supported along the track and extending into the path of movement of the cylinder and rod for engagement by the rod as the carriage approaches either of its extreme limits of travel on the trackyrod's connecting the carriage with a closure for operating the same as the carriage travels along the track; an electric motor, an electrical circuit connecting the motor with a source of electrical

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