US2871009A

US2871009A - Closure operating mechanism and automatic control system therefor

Info

Publication number: US2871009A
Application number: US493161A
Authority: US
Inventors: George G Picatti
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-03-09
Filing date: 1955-03-09
Publication date: 1959-01-27
Anticipated expiration: 1976-01-27

Description

G. PICATTI CLOSURE OPERATING MECHANISM AND AUTOMATIC Jan. 27, 1959 G.

CONTROL. SYSTEM THEREFOR 2 Sheets-Sheet. 1

Filed March 9, 1955 3 2 n 6 2. .4. I1. o r 4 6... 2 I.

mm W m. m v a a e l p i 49 2 Sheets-Sheet 2 G. PICATTI CLOSURE OPERATING MECHANISM AND AUTOMATIC CLOSING RELAY CONTROL SYSTEM THEREFOR mm M O Jan. 27, 1959 Filed March 9, 1955 mmvrpx. George 6.19am; Y

HTTORNEY United States Patent Ofiice v 1 2,871,009 Patented Jan. 27, 1959 CLOSURE OPERATING MECHANISM AND AUTO- MATIC CONTROL SYSTEM THEREFOR George G. Picatti, Yakima, Wash. Application March 9, 1955, Serial No. 493,161

7 Claims. (Cl. 26849) This invention relates to power mechanism for operating one or more movable members, and more particularly relates to mechanism for selectively actuating and automatically operating one or more closure members of the sliding door type.

A primary object of the present invention is to provide for selective remote actuation and automatic operation of a closure member by mechanism which may be safely and readily interrupted in its operation to prevent damage or injury to objects interposed in the closure area.

It is a further object of the present invention to provide closure actuating and operating mechanism exhibiting features of positive and safe operation throughout long periods of use, coupled with simplicity of construction and ease of maintenance not attributable to known conventional automatic closure control systems.

A further object of the present invention is to provide an improved opening and closing mechanism forautomatically operating a sliding door or the like, wherein the operation of such door may be initiated from a remote point to cause an opening and closing cycle, and wherein such cycle of operation may be adjustably and automatically controlled to allow passage of a vehicle or other movable object through the closure area without further attention from an operator.

Yet another object of the present invention is to provide an electrical control circuit for a door operating mechanism whereby the door is automatically returned to or maintained in closed position except when actuated by selective remote control to cause an opening and closing cycle. A further and related object of the invention is 5 to provide an automatic closure operating mechanism particularly adapted to commercial installations where normal activity requires a large number of opening and closing cycles to accommodate passage of commercial vehicles through an accessway, and where the closure 0 member is automatically maintained in a closed position when no access is required, such as in refrigerated or heatedwarehouses, and the like. 1

Yet another and primary object of the present invention is to provide an improved door operating mechanism including a drive unitassembly mounted either on the stationary structure or on the movable closure member, such operating mechanism further including a driven track mounted on the other such structure or member as the case may be, wherein said drive unit assembly is maintained in what may be termed floating engagement with the driven element, as by being pivotally mounted in an unbalanced manner so that at least a portion of the weight of said drive unit assembly provides the sole tractive pressure between the drive element of said drive unit assembly and the driven track element.

Other objects of the invention will be apparent to 1 those skilled in the arts to which my invention relates from the following description taken in connection with the accompanying drawings, wherein like numerals designate like parts, and wherein:

Figure 1 is a side elevational view illustrating a typical single closure member embodying the present invention, with the drive unit mounted on the stationary structure and the associated driven track element mounted on the closure member;

Fig. 2 is a cross-sectional view, taken generally along the line 2-2 of the embodiment of the invention illustrated in Figure 1; s

Fig. 3 is a detail partial section of the embodiment of the invention illustrated in Figure 1, taken generally along the line 3-3 thereof;

Fig. 4 is a fragmentary side view illustrating in enlarged detail the drive unit assembly mounting and a portion of the driven track mounting of the arrangement illustrated in Figure 1; i

Fig, 5 illlustrates in exploded perspective view the fixedly mounted base plate and pivotally mounted hinge plate for the power drive unit, as provided by the form of the invention typified in Figure 1;

Fig. 6 is a floor plan view in diagrammatic form illustrating a typical fluid hose system, operating in conjunction with a fluid actuated switch, to show one manner of selective remote energization for actuation of the opening and closing cycle of operation according to the present invention; p

Fig. 7 illustrates in side elevational view a modified form of the present invention, wherein double closure membersare operated automatically in conjunction with a single accessway;

Fig. 8 is a schematic ladder diagram illustrating a typical electrical control circuit for the novel operating mechanism presented in Figure l; and

Fig. 9 presents in: end elevational cross-section a further modified form of the present invention, generally comparable to theview of Fig. 3, wherein the further modified form of the invention includes the mounting of the power drive unit assembly on the closure member and arrangement of thedriven track on the stationary structure.

In one of its aspects, the present invention contem plates a door operating mechanism, wherein a power drive assembly is mounted in a pivoted, unbalanced manner toplace such drive unit in tractional engagement with a driven track by virtue of the weight of the drive unit. A further aspect of the present invention resides in a remotely actuated electrical system for automatically controlling the operation of such mechanism with maximum safety and simplicity from the point of view of operating personnel and equipment.

More specifically, the door operating mechanism of the present invention contemplates the actuation and 1 operation of a closure member of the sliding door type wherein the operating mechanism comprises a power drive assembly including a rotatable drive element for reciprocating the closure member along a supporting rail, and a driven track, said drive element and driven track being arranged for tractive drive therebetween, With one such tractive element situated on said closure member and the other such tractive element situated on the stationary structure, the power drive unit being pivotally mounted in an .olf-center manner so as to constitute at least a portion of its weight the sole tractive pressure between said drive element and said driven track.

The present invention further contemplates an electrically actuated automatic control system whereby selective remote actuation of such operating mechanism will cause a complete opening andclosing cycle of opera tion without further attention from the operator. As will be understood from the more detailed description hereinafter, the arrangement of the power driven unit on a pivotal or equivalent mounting in a mannerto provide at least a portion of its weight the sole tractive pressure between the drive unit and the driven track produces inherent advantages in terms of safety of operation and simplicity of structure, in that the drive action on the closure member 'may be readily interrupted by slip page of the drive element on the driven track, as by an object interposed in the 'accessway during the closing phase of the cycle of operation or by manually applied force against the drive in 'any emergency situation which may arise, and in that all complicated drive interrupt or release mechanisms are thereby eliminated. The-inherent safety feature afforded by such slippage of the drive 'element is particularly advantageous in protection of small children or in the protection of easily damaged produce from injury by encounter with the closure member.

Turning to a more detailed consideration of one specific embodiment of the presentinven'tion as presented in Figs. 1 through 5, Figure 1 illustrates in side elevational view with certain elements in broken view, a single closure member in partially open position, associated with an accessway 11 arranged in a stationary structure 12, a support rail 13 being mounted on stationary structure 12 to accommodate generally conventional closure member suspension rollers 14 (Fig. 3), and hanger straps 15 alfixed to said closure member 10. Generally conventionally

resilient seals

16 and 17 are provided on the upright edges of closure member 10 for contact with

physical stop members

18 and 19, respectively at the limits of travel of-closure member 10.

In the embodiment of the invention illustrated in Figs. 1 through 5, closure operating mechanism 20 comprises a base plate 21 afliXed to the stationary structure 12 by suitable means such as bolts, one being shown at 22, said base plate 21 in turn mounting a horizontally arranged pivot pin 23 accommodating a power drive assembly comprising a hinge plate 24, an adjustably mounted motor unit 25, such adjustability being provided by suitable means such as bolts, One being 26, and slot means, one being indicated at 27, provided in hinge plate 24, said power drive assembly further comprising drive shaft 28 and a rotatable traction drive element 29. It will be understood that motor unit 25 includes in its housing suitable reduction gearing from the prime mover to drive shaft 28 and rotatable traction element 29, all such elements being designed to be driven by the former at the desired closure member transfer speed. Traction member 29 is advantageously provided with a circumferential covering of resilient material 30, and may simply be a pneumatic rubber tire of the type commonly used on small transfer implement wheels.

In tractive engagement with drive element 29 of the power drive assembly 20 is a driven track member 31 supported by straps, .one such strap being indicated at l 32, in turn attached to closure member 10, as indicated at 33.

From the novel drive unit assembly mounting, including hinge plate 24 supported only adjacent one end thereof, and the tractive engagement of drive element 29 with driven track 31, it will be apparent that the tractive pressure provided for movement of the closure member is contributed solely by the pivotally supported components of the power drive assembly, namely comprising motor unit 25, drive element 29, and hinge plate 24.

It is further apparent that an adjustable tractive pressure is available by virtue of suitable means such as bolts 26 cooperating with slots 27 in the hinge plate 24. Practice has demonstrated that the degree of tractive .pressure contributed by such drive assembly is sufficient to drive the closure member 10 with respect to the stationary structure 12 when such transfer is not otherwise impeded, but is not sufficient traction to drive the closure member forcibly against an object interposed by accident or otherwise in accessway 11. The positiveness and ,prac ticality of this manner of operation of the drive mechanism arrangement here presented has been demonstrated throughout wide variations in climate and atmospheric conditions. Stated otherwise, to illustrate the wide flexibility of use of the disclosed drive arrangement, slippage will occur readily between drive element 29 and the driven track 31 when the movement of closure member 10 is impeded by an intervening object, the novel drive mechanism here presented also allowing manual transfer of the closure member against the driving force of drive element 29, or in the absence of a driving force in element 29, in the event an emergency situation should warrant such manipulation.

Practice has further demonstrated that the pivotal or floating mounting arrangement of the motor unit and drive element comprising the drive assembly presents the further feature of inherently and automatically accommodating for any unevenness or difference in level between the supporting rail 13 and drive track element 31, thus rendering precise alignment of these elements in the initial installation or during use unnecessary.

Suitable limit switch actuation and remote energization of the electrical control circuit are also provided by the present invention in order to accomplish automatic operation of an opening and closing cycle of the closure member 10 with respect to accessway 11, to maintain the closure member 10 in a closed position except when ingress or egress is desired, and in order to further provide selective actuation from approach positions with respect to accessway 11. In this connection, certain elements of the control system are illustrated in Figs. 1 through 4, with a typical general arrangement and mode of selective energization of the fluid hoses being shown in Fig. 6. Further details and description of operation of a typical electrical control circuit are presented in Fig. 8.

The control system elements illustrated in Figs. 1 through 4 (from which connector wires have been omitted for the sake of clarity of illustration) are normally closed limit switch 41, maintained with its contacts open when closure member 10 is in closed position by adjustable limit switch camway '42, and normally closed limit switch 43, maintained in open contact condition by adjustable limit switch camway 44 when closurc member 10 is in open position, the position of the leading edges of camways 42 and 44 at the respective closed and open positions of closure member 10 being indicated by dotted line at 45 and 46. Experimentation has demonstrated that there is a lag time between the de-cnergization of the motor unit 25 and the time closure member 10 actually comes to rest from a moving condition, and that the span of travel beyond such point of energization of motor unit 25 is on the order of several inches, this span of travel proving to be about six inches in a typical commercial installation. Accordingly,

limit switches

41 and 43 are positioned with respect to the leading edges of limit switch camways 42 and 44 by pie-selection of the limit switch positions on supporting rail 13 and adjustment of the horizontal position of the camways 42 and 44 to allow for the closure member to come to rest in closed position with the resilient edge 16 adjacent to or contacting physical stop 18 or to come to rest in open position with resilient member 17 adjacent to or contacting physical stop 19, as desired.

Selective remote actuation of the system is advantageously accomplished by means of fluid hose 47, with sections thereof arranged generally as indicated in the floor plan of Fig. 6, the same being connected to a control box 49 incorporating a fluid actuated "switch. (see 62, Fig. 8). The operator desiring passage through accessway 11 can proceed along a course of travel typified at 48 to actuate the hose 47, the entering approach section thereof being indicated by way of example, during approach to acces'sway 11, the operator then proceeding in a manner, as indicated, along course 48 so as not to contact the hose -47 on the path "of departure. From the typical electrical .control system hereinafter rection of drive of driveelement 29. ever, drive motor 25 is subject to separate control from a matic assembly.

discussed in connection with Fig. 8, it will be seenthat an appropriate time delay is provided between the instant of remote actuation and the time of re-closure of closure member so that passage through accessway 11 will not be delayed or otherwise interferred with in normal operation.

Turning to a consideration of a modified form of the present invention, Fig. 7 illustrates in side elevational view with certain elements in broken view, a single accessway 11 having associated therewith. double closure members 10 and 10', shown in open position, the operat ing mechanism utilized for movement of the right-hand closure member 10 being essentially identical with that presented in the single-closure embodiment illustrated in Figs. l through 5. The operating mechanism for the left-hand closure member 10 merely involves a left-hand duplication of the operating mechanism, such left-hand duplicate arrangement and parts being indicated by corresponding primed numerals. Such double-closure member arrangement offers readily apparent advantages for larger accessways. Beyond the duplication of parts indicated, such double-closure arrangement does not unduly complicate the control circuit, since drive motor may be energized from the same control system as drive motor 25, with a reversal of leads to accomplish reversal ofdi- Preferably, howseparate electrical control system including a common lluid switch,

limit switches

41 and 43, and limit switch camways 42 and 43', such system being otherwise a g I duplicate of that presented in Fig. 8. The latter arrange- .ment is considered preferable for the reason that closure member 10 may not under all circumstances be in a positioncomparable to closure member '10 with respect to the center line of accessway 11, and a separate control system for closure member 10 will ensure complete automatic closing of both

closure members

10 and 10 undertall conditions of operation. A more detailed consideration will now be given of a typical electrical control circuit providing selective remote or local actuation and automatic operation of a closure member according to the present invention, with particular reference to the single-closure embodiment thereof illustrated in Figs. 1 through 6. It will be readily apparent that any suitable drive mechanism 25, consistent with the reversible drive feature here presented, can be employed. Thus, drive motor 25 may be of the polyphase type, reversible single-phase, or reversible D.-C., as desired, a three-phase power supply control circuit being illustrated in Fig. 8 for purposes of illustration, the three line system being indicated on the latter diagram at L1, L2, and L3. Selective energization and automatic operation control components are related to two lines of the control system, L1 and L3 being shown by way of example, with the third line, L2, being connected directly to the drive motor 25. A manual line switch 60 for the system is provided in line L1 to deliver power to the control circuitry, in which what may be termed the dominant feature is a time-delay relay 61, preferably of the adjustable pneumatic type which, upon actuation, immediately delivers the contacts thereof to the energized position and releases the contacts to a de-energized position after a predetermined time delay adjustably controlled through a spring-pressed pneu: In the typical system here presented a fluid switch 62, actuated by contact of the operator with fluid hose 47, energizes time-delay relay 61, with optional local energization of the relay being provided by a manual switch .63, asdesired. Normally open contact TDRl of time-delay relay 61 is an interlock contact to deliver power from line L1 across the time-delayrelay 61 after the relatively instantaneous actuation of fluid switch 62 or manual switch 63 in a manner generally conventional with this type of relay. The condition of energized or normal condition and with the closure member in closed position, with normally closed limit switch 41 (labeled LSCLimit Switch, Closed) being held in open position by camway 42 and with limit switch 43 (labeled LSO-Limit Switch, Open) in the normal, closed position. Energization of drive motor 25 after closing of line switch 60 is caused by selective connection of line L1 to the drive motor 25 under control of an opening relay 64 through contact 0R2 thereof, the resultant direction of drive of drive motor 25 being schematically indicated at 65. Transfer of the closure member in a closing direction is accomplished by connection of line L3 to drive motor 25 through contact CR2 of the closing relay 66, the resultant direction of drive being schematically indicated at 67, contact CR1 under control of closing relay 66 being positioned in series with the energization circuit for opening relay 64, and contact 0R1 under control of opening relay 64 being in series with the energization circuit for closing relay 66 to provide for connection of only one of lines L1 and L3 to drive motor 25 at any given instant during the cycle of automatic operation herein provided. Time-delay relay 61, in addition to interlockcontact TDRl, further controls the position of normally closed contact TDRZ in the closing relay 66 energization circuit, and normally open contact TDR3 in the opening relay 64 energization circuit, it being apparent that only the'opening relay 64 circuit is capable of energization when time-delay relay 61 is in energized position, and only the closing relay 66. circuit is capable of being energized when time-delay relay 61 is in deenergized condition. In the energization circuit for closing relay 66 a further normally closed contact 0R1 under control ofopening relay 64 is provided as a further safety feature ensuring that the closure member is opened to the point where limit switch 43 is opened before the closing relay 66 is energized.

Considering the operation of the electrical control circuit in the light of the foregoing elements thereof, with the closure member in closed position, energization of the time-delay relay 61 through fluid switch 62 or manual switch 63 will cause contacts TDRl, TDR2, and TDR3- to be transferred to energized position, closing interlock contact TDRI and closing contact TDR3 in the opening relay circuit, which is completed by contact CR1 of closing relay 66 being in de-energized closed position (limit switch 41 being held in open position), thus energizing opening relay 64 and closing contact 0R2 thereof to connect line L1 to drive motor 25 which is thereupon driven to rotate the prime mover thereof in the direction indicated at 65 to move the closure member in an opening direction with respect to the accessway. The delay period of time delay relay 61 is preset by the adjustable means therein provided, as previously indicated, to provide a delay at least as long as the period of time necessary to transfer the closure member from closed to open position and of sufiicient duration to permit passage through accessway 11 under all normal conditions. As the closure member approaches open position, normally closed limit switch 43 is opened by the associated camway 44 on the closure member and interrupts the circuit energizing opening relay 64, whereupon contact 0R1 is returned to closed position, normally closed limit switch 41 in the meantime having been restored to normally closed position by the opening movement of the closure member. At such time as time delay relay 61 is de-energized, contact TDRZ thereof is returned to closed position, completing the circuit for closing relay 66 which automatically connects line L3 to drive motor 25 through contact CR2, resulting in drive motor 25 being driven in the direction indicated at 67 to accomplish closing of the closure member through the mechanism previously described. The closure operation continues until such time as the closing relay 66 circuit is de-energized by opening of limit switch 41, the circuit thereupon assuming the normal inoperative condition with all of

relays

61, 64, and 66de-energized until nuances -'l' theselective acthation df thenext"cycle "of operation by fluid switch 62m manual-switch 63.

The*automatic'closing feature of the typical'contr'ol circuit presented will be apparent from a reconsideratio'nof theenergization circuit for closing relay 66, wherein cont'a'c'ts 'OR 1 and FDR-2 are in closed position when the associated relays are deenergized, and wherein closing r el'ay -66 circuit is energized whenever limit switch 41 is closed, which-condition is maintained except when the closure "member is in closed position. Thus, should the opening and closing cycle of operation be interrupted as by an object impeding the path of travel in accessway 11 or by manual transfer of closure "member along support rail "13 against the tractive pressure of drive eleinent 29in the event an emergency situation should warrant such manipulation. Thus, the superposed'drive element, by virtue of the floating mounting of the drive unit assembly according to the present invention, can slip with respectto the track, the closing operation never theless continuing after such interruption until such time as the closure member becomes re-established in closed position. I

Fig.9 illustrates in partial side elevational crosssection a modified form of the drive mechanism according to the 'present'invention, wherein the power drive assembly is mounted on the closure member 18 and the driven track is mounted on the stationary structure 12, the 'view of Fig. '9 otherwise corresponding to the view of Fig. 3 in't'he'pr'eviousl'y described embodiment of theinvention, like parts being indicated by likenurnbers. In this embodiment of the'invention, the motor unit 25 ismounted on a hingeplate 24 having provided at the near end thereof a pivotpin 70, inturn supported from closure member 10 by "a mounting bracket 71 adjacent closure member 10 and a 'sec'ond'b'racket member 72, as desired, outwardly from closure member 10, the attachment to closure member 10'being thro-ughsuitable bolt means '73 and 74. The driven track element in the embodiment illustrated in Fig. 9, corresponding to track element 31in Figure l, is driven track '75 affixed to supporting track 13 in a'desired man her, as by welding. Aside from the indicated reversal of mounting of the drive assembly and driven track element, it will be readily apparent that'the operation and tractive advantage of the invention are similarly available from the-modification presented in Fig. 9.

While, as has been indicated, the present invention is considered to have particular utility'in commercial installatio'ns Where the closure member is subject to a relatively large number of opening and closing operations and where the closure member is to be maintained in closed position at all times when access is not required, such as in warehouses involving refrigerated or heated storage of produce or other products, it is to be under stood that the invention has other fields of application and use, garage andelevator doors providing further examples in this regard.

Other modifications'of the present invention will be apparent to those skilled in the art. Thus, wide variation of electrical control circuits and the particular form of time delay employed readily suggest themselves within the basic modes of operation disclosed. Similarly, various arrangements for the limit switches or other closure position responsive control elements may be employed. Further, it will be apparent that various selective remote controlactuation means can he provided, such as by lightinterrupting devices of the so-called electric eye type or by r'nechanically linked or electrical circuit actuating platforms. Additionally, other means for predetermini'ng and/or adjusting the degree of traction of the drive unit assembly onthe driven track are readily available, other thanby 'slot'means 2.7 and hinge plate 24, such as by a plurality of alternatively employed pivot pin receiving apertures in the motor mounting plate,by counterbalance weight -means extending'from the pivot axis, or by other mechanical "arrangements by means "of which at least 'a portion" of the drive asse'ihbly weight is ut-ilized' for'ttatitive pressure.

l. selective energization sad-operatin "mechanismrsr -a-closure member of 'the'slidirig' doo'r'typefiwherein aid closure member is mounted for reciprocal movement w ith respect to an associated stationary structure in turn provided with an accessway, comprising a'reversible -power drive assembly including a rotatable drive eletnent'in floating, tractiveengagement with a driven track, one-"such tractiveelement being situated on saidblOsitreirimbEr and the other such tra'ct-ive element being s'ituated'onsu'c'h stationary str-ucture, and an-automatic control's'ystemenabling selectiveactuation of such operating me'ch-anism to cause a complete openinga'nd closing cycle of the ope ation without further attention from an operator,fs'id automatic control (system comprising a' -time-del'ay relay, an opening relay, and a closing relay,sw itch'means for selectively energizing said time-delay relay, limit switch means contacted'by associated camways arrang'd in the path of travel of said clos'uremember adjacent-the limits thereof, "a first such limit switch means being established in an open contact condition when said closure member approaches an open positionwith respect to sa'i'd' acces'sway, and a second such limit switch means being established in an open contact condition when said closure member approaches a closed position with respect'to said accessway, the energization circuit for said opening relay comprising a'normally open time-clelayrelay contact, a normallyclosed closing relay contact, and said 'fi'r'st Iii-nit switch means, the energizatio'n circuit for said closing relay comprising a normally closed opening relay contact and said second'limit switch means, "the energizati'oncircuit for said time-delay relay including anormally'op'en interlock contact in parallel with said selectivelyactt'lated switch means, said opening relay further having a normally open contact which, when'closed, energizesthe drive motor of said power drive'assembly to cause rotation thereof in a first or opening direction ope'ni'rigsaid closure member and said closing relay further comprising a normally open contact inanenergization circuit for said drive motor to cause rotation thereof in a direction closing said closure member.

2. Mechanism according to claim 1, wherein said switch means for selectively-energizing "said time delay relay includes a fluid-actuated switch in communication with an actuator therefor arranged in an approach'path of said accessway.

3. Selective energization and automatic operation mechanism for a closure'rnernber of the sliding door type, wherein said closure member is mounted'for horizontal'niovement with respect to an accessway in a'c'o'mmercial warehouse of the refrigerated or heated type, comprising a reversible power drive assembly arranged on a hinge plate pivotally mounted adjacent only one end thereof to place the drive element of said power drive assembly in floatingtractional engagement with a driven track, said power drive assembly being situated on the stationary structure of said warehouse and said driven track. beingsituated on said closure member; and an auto matic control system enabling selective remote actuation of such operating mechanism to cause a complete opening and closing cycle of the operation without further attention from an operator, said automatic'control system comprising a time-delay 'relay, an opening relay, and a closing relay, switch means for selectively energizing said time-delay relay from an approach position with respect to said accessway, limit switch means contacted by associated 'camways arranged in the path of travel of said closure member adjacent the limits thereof, a first such limit switch means being 'establishedi'n an open contact condition when said closure member approaches "an 'open position with respect to said accessway, and a secondsu'ch limit switchmeans being established 'in an o en e fish when "said'closure approaches "a closed position with re spect to said accessway, the energization circuit for said open relay comprising a normally open time-delay relay contact, a normally closed closing relay contact, and said first limit switch means, the energization circuit for said closing relay comprising a normally closed opening relay contact and said second limit switch means, the energization circuit for said time-delay relay including a normally open interlock contact in parallel with said selectively aC- tuated switch means, said opening relay further having a normally open contact which, when closed, energizes the drive motor of said power drive assembly to cause rotation thereof in a direction opening said closure member and said closing relay further comprising a normally open contact in an ener-gization circuit for said drive motor to cause rotation thereof in a direction closing said closure member.

4. Mechanism according to claim 3, wherein said switch means for selectively energizing said time-delay relay from an approach position with respect to said accessway includes a fluid-actuated switch in communication with a fluid-containing hose arranged in the path of the operator passing through said approach position.

5. Selective energization and automatic operation mechanism for closure members of the sliding door type, wherein said closure members are mounted for reciprocal movement with respect to an associated stationary structure in turn provided with an accessway common to said closure members, comprising each such closure member having associated therewith a power drive assembly and a driven track, each of said power drive assemblies including a rotatable drive element in tractive engagement with the associated driven track, one such tractive element being situated on said closure member in each instance, and the other such tractive element being situated on said stationary structure in each instance, each such rotatable drive element mounting enabling floating engagement thereof with the associated driven track to provide tractive pressure between said rotatable drive element and said driven track from at least a portion of the weight of the power drive assembly, each said mechanism further comprising an automatic control system enabling selective remote actuation of the associated closure operating mechanism to cause a complete opening and closing cycle thereof without further attention from an operator, said automatic control system including a time-delay relay, an opening relay, and a closing relay, switch means for selectively energizing said time-delay relay, limit switch means contacted by associated camways arranged in the path of travel of the associated closure member adjacent the limits of travel thereof, a first such limit switch means being established in an open contact condition when said associated closure member approaches an open position with respect to said accessway, and a second such limit switch means being established in an open condition when said associated closure member approaches a closed position with respect to said accessway, the energization circuit for said open relay comprising a normally open timedelay relay contact, a normally closed closing relay contact, and said first limit switch means, the energization circuit for said closing relay comprising a normally closed opening relay contact and said second limit switch means, the energization circuit for said time-delay relay including a normally open interlock contact in parallel with said selectively actuated switch means, said opening relay further having a normally open contact which, when closed, energizes the drive motor of said power drive assembly to cause rotation thereof in a direction opening said associated closure member and said closing relay further comprising a normally open contact in an energization circuit for said drive motor to cause rotation thereof in a direction closing said associated closure member.

6. Mechanism according to claim 5, wherein said switch means for selectively energizing said time-delay relay further comprises a fluid-actuated switch in communication with a fluid-containing hose arranged in the path of an operator approaching said accessway.

7. Selective energization and operating mechanism for a closure member mounted for reciprocal movement with respect to an associated stationary structure in turn provided with an accessway, such mechanism comprising a reversible power drive assembly including a rotatable drive element in tractive engagement with a driven track, one such tractive element being situated on said closure mem' her and the other such tractive element being situated on said stationary structure, and an automatic control system enabling selective actuation of such operating mechanism to cause a complete opening and closing cycle of the operation without further attention from an operator, said automatic control system comprising a time-delay relay, an opening relay, and a closing relay, switch means for selectively energizing said time-delay relay, limit switch means contacted by associated camways arranged in the path of travel of said closure member adjacent the limits thereof, a first such limit switch means being established in an open contact condition when said closure member approaches an open position with respect to said accessway, and a second such limit switch means being established in an open contact condition when said closure member approaches a closed position with respect to said accessway, the energization circuit for said opening relay comprising a normally open time-delay relay contact, a normally closed closing relay contact, and said first limit switch means, the energization circuit for said closing relay comprising a normally closed opening relay contact and said second limit switch means, the energization circuit for said time-delay relay including a normally open interlock contact in parallel with said selectively actuated switch means, said opening relay further having a normally open contact which, when closed, energizes the drive motor of said power drive assembly to cause rotation thereof in a first or opening direction opening said closure member and said closing relay further comprising a normally open contact in an energization circuit for said drive motor to cause rotation thereof in a direction closing said closure member.

References Cited in the tile of this patent UNITED STATES PATENTS 566,839 Burdett et al. Sept. 1, 1896 1,694,431 Russell et al Dec. 11, 1928 1,874,903 Conway Aug. 30, 1932 1,928,698 Morris Oct. 3, 1933 1,952,681 Peelle Mar. 27, 1934 2,166,527 Johnson July 18, 1939 2,294,041 Mims Aug. 25, 1942 2,346,388 Peebles Apr. 11, 1944 2,526,503 Raque Oct. 17, 1950 2,572,196 Raque Oct. 23, 1951 FOREIGN PATENTS 1,095,247 France Dec. 15, 1954