US1922708A

US1922708A - Electric door operator

Info

Publication number: US1922708A
Application number: US345138A
Authority: US
Inventors: Norton Clifford
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1929-03-07
Filing date: 1929-03-07
Publication date: 1933-08-15
Anticipated expiration: 1950-08-15

Description

Aug. 15, 1933. Q N 1,922,708

YELECTRIC DOQROPERATOR Fild March '7. 1929 7 Sheets-Sheet 2 INVENTOR ATTORNEYS Aug. 15, 1933. c, NORTON ELECTRIC DooR OPERATOR Filed March '7. 1929 7 Sheets-Sheet 5 l N V E N To R UZ/fW'd/Vwfwz W Y LL ATTORNEYS Aug. 15, 1933.- c NORTON ELECTRIC DOOR OPERATOR 7 Sheets-Sheet 4 Filed March '7, 1929 Q 5mm g o w In l W n u \I II llllllllllllllllllllllllllllllllllllll flll i =5 l u u 1., ii Q Q .3 mm

M Z R 0 v mm m 3 m v F W m% A Aug. 15, 1933. c. NQRTQN ELECTRIC DOOR OPERATOR Fil d March 7, 1929 7 Sheets-Sheet 5 i INVENTOR git/ford Mr/on ATTORNEY 5 Aug. 15, 1933. Q NQRTQN ELECTRIC DOOR OPERATOR Filed March '7, 1929 '7 Sheets-Sheet 6 INVENTOR CU/ford Vorfon VZMWQJW ATTORNEYS Aug. 15, 1933. g om- 1,922,708

ELECTRIC DOOR OPERATOR Filed March 7, 1929 7 Sheets$heet 7 INVENTOR h UliF/oraJVor/mz WMML ATTORN E Y$ UNITED "res PATENT ELECTRIC DOOR OPERATOR Clifford Norton, South Orange, N. J assignor, by mesne assignments, to Otis Elevator Company, a Corporation of New Jersey Application March 7, 1929. Serial No. 345,138 17 Claims. (Cl. 187-52) This invention relates to improvements in door same. To this end the door opening mechanism operators and isparticularly designed for use in is shown as actuated by an electric motor operatnigh-speed elevator door operators. ing against the door closing springs so that when It is a primary object of the invention to prothe motor is released the springs close the door.

vide devices mounted mainly on the elevator car Additional spring devices are employed for facili- 60 and having independent operating means for the tating the reversing of the motor, drive shaft and door on the car and the landing door at which the door operating mechanism upon the release of the car stops. motor brake.

It is a further object to assemble the power In the specific embodiment shown herein the devices and door operating mechanism in close elevator car, indicated generally at 12, is pro- 5 relation maintaining contact between all parts vided with any desired type of door or closure 14 of the apparatus, wherever possible, in order on the car. The pow d v Opening the to make more uniform the operation of the doors doors are mounted directly on the super-strucand to avoid all unnecessary noises and harmful ture of the elevator car and include an electric 15 impact between the various door elements. motor 16 provided with a releasable brake mech- To Another object is to employ the dynamic power anism 18 and conected through reduction gear of the door opening motor for slowing down the ing 20 to tl.e slow-speed drive shaft 22 for rotatreverse movement of the parts constituting the ing the latter through the requisite angle of rodoor moving mechanism. tation shown in the present apparatus as substan- 20 These and other objects will appear more fully tially 270. The reduction gearin 0 is of the 75 from the following description when considered Spur gear typ as the apparatus is designed to in connection with the drawings in which: have the motor and shafts reversed by mechanical I Fig. 1 is a front elevational view of an elevator power during th tu n o t e doors t0 Closed car supplied with my invention. tien.

Fig. 2 is a side elevation of the elevator car The car doo 14 is a a g to be moved by an 0 showing the relation thereof to the landing door Operating level 24 Connected to the (1001' as at mechanism. 24' and pivotally supported upon the frame of 3 s a plan View of a portion of the mech the elevator as at 26. This lever is actuated nism mounted on the car. through an angular extension 25 connected by Fig. 4 is an elevational view of the same, parts a s of t fleXible element 29 t0 the Slowbeing broken away. speed shaft 22 and engageable by the eccentric Fig. 5 is a view taken at right angles to Fig. 4. cam 30 p i n f h shaft 22 in a counter- 6 is a ail View of the dynamic switch clockwise direction as viewed in Fig. 1. A spring lever and cams. 31 is interposed in the length of the flexible ele- 35 Fig. 7 is a detail view illustrating the connecment ai 29 to avoid any sudden pp tion of the springs for returning the motor shaft tion of openin power to the lever 25 When the to closed door position. element 29 is engaged by the cam 30.

Fig. 8 is an elevational View looking from with- The p i n clo in m v m n s of the in the shaft at the landing doors and operating (fa (1 gate 14 are preferably Checked as by :0 mechanism for one floor. means of the

liquid dashpots

32 and 34, checking .95

Fig. 9 is a plan View illustrating diagrammatrespectively the opening n l ing movements. ically the relation of door operating mechanism These devices are well known p se and include to the elevator guides. the liquid holding cylinders arranged in upright Fig. 10 illustrates one form of circuit controlposition t prevent l aka f th fluid therein 15 ystem may be employed connection and provided pistons and one Way Valves with the invention. so as to be operative only when the pistons are According to my present invention a relatively entering the cylinders As shown the p stons of strong motor is employed for providing power t the door checks are anchored with respect to the open the car door and the landing door t frame of the elevator by

links

35 and 36. The which the elevator has stopped. h door lower ends of the cylinders are pivotally 0011- ing movement is ordinarily not subject t th nected to rigid projections 3'7 and 38 movable danger of injury to passengers to the same extent with the level 24 during C @1 ovement. as the closing movement so that positive power The level 24 is Constantly urged w d Closed is employed for opening the doors whereas reladoor DOSit O by means f a spring 40 (Fig 5) tively yielding power is employed for closing the tached to the upper end of the lever 24 beyond the pivot thereof. A flexible element 41 connected to the lower end of the spring 40 may be passed around the projection 42 for attachment to the adjustable bolt 43 as shown, bolt 43 being supported upon the rigid framework of the elevator car.

Movement of the hoisting motor is prevented whenever the car door is opened to any substantial extent as by means of the hoisting motor control switch 39 (Fig. 1). This switch includes an insulating plunger 39a connected by lever 23% and link 390 to the car door lever 24 beneath the pivotal point of the latter. The lever 39b is arranged almost in alinement with link 390 so as to afford a sudden motion to the switch plunger when opening the car door, this movement separating the switch contacts on a very slight movement of the car door.

The shaft doors 15, shown as two speed doors, at each of the floors are provided with some form of door operating levers preferably of the toggle lever type as shown at 44 (Fig.8), onelever being connected to each movable door section. The rearward lever 44b is attached to the face plate 50 which affords the base from which the door moving leverage is applied. A suitable handle 44a may be formed on the toggle levers for facilihas been moved slightly from closed position.

tating the manual operation thereof. The toggle lever 44b carries a rigid projection 45 connected by means of links 46 and 47 to the door operating bell crank 48 mounted on the wall of the shaft. The adjacent ends of the links 46 and 47 are supported by the lever 49 pivotally connected to a bracket supported on the face plate 50. Since the levers of the bell crank 48 operate in planes transverse to the plane of movement of the

levers

44 and 49 the ends of the pressure applying rod 47 are formed with universal joints as indicated at 47a and 47b.

Closing movement of the landing door is provided by the spring devices 52 adjustably connected at one end by the flexible element 52a to the bracket 45' formed on the intermediate lever 44 and at the other end to the face plate 50. Lever 44 carries a projecting cam 44c engageable with the flexible element 52a as the doors move toward open position as shown in dotted lines in Fig. 8.

Separate door checks

54 and 55 serve to limit respectively the opening and closing movements of the doors as described above in connection with the car door. These door checks have one way valves causing them to function only when the pistons are entering their respective cylinders. The opening check 54 may, as shown, be attached to the rearward end of lever 49 and the door closing check may be attached to the bracket 45 on lever 44b.

The toggle lever 445 may also actuate the in terlock switch 56 to prevent movement of the elevator car whenever any door or set of doors 15 These switches are of the same type shown at 39 in Fig. 1, the insulating plunger of switch 56 being connected by a link directly to lever 44b.

The bell crank levers and landing doors for each floor are arranged to be moved by a cam 60 carried by a portion of the rigid frame work.

is against the sides of the elevator guides 58 as shown in particular in Fig. 9. The guides cooperate with spring-pressed yokes 59 carried on the opposite sides of the carladjacent the upper and lower portions thereof. These guides e fi e ctively prevent the car from moving forwardly and rearwardly but due to the sliding arrangement of the guides 59 on the car limited movement of the car in a sidewise direction, toward or from the guide rails 58, is permitted. The arrangement disclosed herein, whereby the cam 60 moves toward and away from the sides of guide rails 58 during the application of door opening power, provides a substantial base from which to apply the relatively high door opening pressure required with this type of door mechanism and reduces the necessary clearance between the cam 60 and levers 48 to a minimum.

The cam 60 is connected by means of a flexible element 62 to the slow-speed drive shaft 22. The chain 62 passes over a supporting pulley 64 and is attached as indicated at 65 to the slow-speed shaft 22. This shaft carries a cam 66 similar to cam 30 which engages with the chain to provide relatively rapid door opening movement after the initial movements of the motor and shaft. A relief spring 68 is'preferably interposed between the drive shaft 22 and cam 60 for assisting in avoiding a sudden movement of the cam 60 5 when the chain 62 is engaged by the cam 66.

The shaft 22 and motor 16 arearranged to be rotated reversely to permit the doors to close. This is accomplished by means of the return spring 70 adjustably secured to the overhead frame of the elevator car and connected by means of the flexible element 72 to the pin 74 carried by disk 84 fixedly mounted on the shaft 22. The pin 74 is spaced outwardly from the shaft 22 thus providing additional leverage for returning the 5 shaft to completely closed door position.

In order to facilitate the initial rotation of the motor 16 during door closing movement the devices shown in detail in Figs. 5 and 7 may be employed. These devices include a return spring 78 anchored with respect to the elevator car as indicated at 79 and connected by a link 80 and yoke 81 to the lever 82 pivotally mounted on the shaft 22. Movement of the lever 82 in a clockwise direction is limited by the enlargement of yoke 81, the position shown in Fig. '7 representing the state of rest for the spring 78 and lever 82. The semi-circular disk 84, rotatable with the shaft, is provided with an abutment 85 movable against a corresponding abutment 86 formed on the lever 82 to move the lever 82 and tension the spring 78 during the final movements of the doors in an opening direction. The spring 78 thus serves to slow down the rotation of the shaft in the final stages of the opening movements of the door and also affords a desirable initial force for starting the return of the shaft and motor toward closed door position.

The controlling circuits for the motor 16 are open-circuited when, the shaft 22 reaches door open and door closed positions respectively by means of the devices shown in detail in Fig. 5. The limit switches disclosed are of the type which are normally closed but which may be opened by the upward movement of an insulating plunger between the same. The open limit switch 88 (Fig. 5) includes an operating plunger 89'normally maintained down in inoperative position by means of the spring 90 and movable upwardly by the lever 92 pivotally mounted as at 93 and 1 portion 107a.

attached to the rod 94 which serves to elevate the plunger to open the motor-controlling circuit. The free end 92a of the lever 92 is engageable by a pin 96 when the shaft 22 has rotated to substantially open door position.

The close limit switch 98 is of the same construction as the open limit switch 88 and is arranged to be opened when the pin 96 engages the open limit switch lever 99 for opening the door closing controlling circuit. This condition is illustrated in Figs. 4 and 5.

It is desired to control the reversing movements of the motor 16 and cam 60 by utilizing the dynamic effect of the motor 16. The mechanism employed for opening and closing the circuit of the motor 16 during the reversing of the same under spring power for varying its resistance to rotation is shown in detail in Figs. 5 and 6. This dynamic power is utilized in the present construction during the intermediate portion of the reverse rotation of the shaft 22 during door closing movement.

Cams

100 and 102 are adjustably mounted on a collar 104 carried by the shaft 22. The cam members are adjustable as by means of the set bolts 106. These cams may be similarly constructed and each provided with a cam portion 107 and an enlarged concentric The cam portions 107 are spaced to provide a gap in which the dynamic switch will be closed. The

cams

100 and 102 engage with the anti-friction roller 108 of the lever 109 for elevating the operating rod 110 and plunger 112 for opening the switch 111 when the shaft nears either extreme of its angular movements. This switch 111, herein termed a dynamic switch in that it controls the dynamic effect of the motor during mechanical reversal, is shownin detail in Fig. 4, wherein the contacts 113 are closed as long as the plunger 112 is maintained in its down position but opened when the plunger 112 is elevated through the engagement of the lever 109 with the enlarged portion of either cam.

Under different conditions and with different strength of returning springs and actuating motor the dynamic effect of the motor during the reversal of the door moving parts may be made effective at earlier or later periods. For this reason the

cams

100, 102 are adjustable circumferentially within wide limits so that the gap between the same, representing the closed switch condition, may be made to occupy the major portion of the angular movement of the shaft 22 or only a small proportion of the same,

The door motor 16 is provided with a new type of brake 18 in which the motor shaft 114 carries a brake disk 115 provided with a conical outer surface having a friction material thereon engageable within the inner conical friction surface of the locking disk 116. The disk 116 is slidably mounted upon parallel pins 118 and is movable longitudinally thereof to or from clutching engagement with the motor disk 115. An axial extension or core 120 formed of magnetic material, as soft iron, is carried by the .disk 116 and controls the position of the disk 116 in normal operation. Spring 121 normally presses the disk 116 into clutching engagement with the disk 115, the same being released by means of the brake coil Br (Fig. 10) mounted within the housing 122 and encircling the core 120. The coil Br serves, when energized, to draw the disk 116 outwardly into non-braking position against the tension of the Spring 121.

The clutch may be manually released by operation of the lever 124 retained in inactive position by the spring 125 and engageable with an extension 126 attached to the disk 116. Manual operation of the clutch lever, in the embodiment shown, is afiorded by means of the two

chain sec tions

128 and 129 which pass around suitable guide pulleys, the section 129 being connected to the operating lever 130 (Fig. 1) provided with a foot pedal 132 whereby pressure upon this lever will withdraw the clutch.

The controlling circuits employed herein are illustrated diagrammatically in Fig. 10. The

parts are shown in the positions they' assumewhen the elevator is standingat a landing with the doors open. In this figure certain parts are shown corresponding to the devices described above, for example, the motor 16 and its series field 16a and shunt field 16b, open limit switch 88, close limit switch 98, dynamic switch 111 and brake coil B1. While the control for the motor 16 may be arranged for manual operation, it is preferred that it be automatic so that the movement of the hoisting controller or other mechanism associated with the hoisting device of the elevator will automatically open the doors when the car is stopped and automatically close them on actuation of the elevator controlling devices to start the car.

The function of opening the doors is controlled by a controlling circuit including the coil 0. When the coil 0 is energized the armature thereof is raised to close

contacts

134 and 135. The closing of contacts 134 supplies current to the motor 16 through the following conductors: plus line a, contacts 134, parallel resistances R, conductor b, contacts 136, conductor 0, motor armature 16, series field 16a and low resistance coil 152, and out to the negative side of the line. The circuit through the contacts 135 serves to energize the brake coil Br by way of conductors a and d and resistance R3.

From the above it will be seen that energizing the coil 0 serves to release the brake and to supply electrical energy to the motor 16 for opening the doors.

The main control for the coil 0 is provided in the relay P serving to open the contacts 142 when the coil of relay P is energized and to close contacts 142 when coil P is deenergized. Coil P is shown diagrammatically as controlled from the hoisting controller 144, formed with a cam 145, which opens the switch 146 only when the hoisting controller is in neutral position. When the hoisting controller is moved in either direction away from neutral position the switch 146' is closed thus supplying current to the coil P by way of conductors h and 2. When the coil P is energized the coil 0 is deenergized and vice versa deenergization of coil P closes the circuit through the opening coil 0. It will be understood that other types of control may be used with the apparatus disclosed.

The circuit of coil 0 includes in addition to the contacts 142 the open limit switch 88 (described above) to provide for breaking the circuit to the coil 0 when the doors reach substantially open position. v

In order to prevent injury to the mechanism, and particularly the motor 16, in case of failure of the doors to open upon energization of the door opening motor the motor circuit is arranged to be opened upon a predetermined overload on the motor 16. This is accomplished by continuing the circuit of the opening coil 0 through contacts 143 of the overload unit 148. This unit me cludes a lever 149 carrying one of the contacts 143 and normally tensioned toseparate contacts 143. Lever 149 is latched in closed circuit condition by means of a latch 150 formed as a bi-metallic thermostat and rigidly supported at its base. The thermostatic metal is placed adjacent a low resistance coil 152 which may be placed in the circuit of motor 16. The heat developed in coil 152 is insufficient in normal operation to cause separation of contacts 143 but if for any reason 'the motor 16 is overloaded to a dangerous degree the thermostatic metal is moved to the dottedline position shown (Fig. 10) and the contacts 143 separate thus opening up the door opening circuit and deenergizing motor 16.

The closing of the doors and the return of the motor to its initial door closed position is accomplished mechanically by the spring devices described above upon the deenergization of the triotor 16 and the release of the motor brake 18. This operation is controlled by means of coil C, which, when energized, closes

contacts

138 and 139. Contacts 138 close a circuit for actuating the brake coil and contacts 139 prepare a' dynamic circuit that is effective when finally completed by dynamic switch 111 for checking the speed of rotation of the motor 16 during reversal.

The brake releasing circuit is completed by way of conductors a and 7', contacts 138, resistance R3 and brake coil Br. The dynamic braking circuit includes the armature of motor 16, series field 16a, conductor 1, conductor e, dynamic switch 111, contacts 139 and variable resistance R.

The circuit of the door closing coil C includes the close limit switch 98, conductor I0 and the switch 146, shown as automatically controlled from the hoisting control lever. The limit switch 98 opens the circuit of coil C when the shaft22 reaches substantially door closed position, the switch 146 supplying current to coil C on movement of the car controller 144 away from neutral position. I

The effect of the closure of the dynamic switch 111 during door closing movement is to slow down the reversing of motor 16 during a portion of this movement so as to maintain the cam 60 substantially in engagement with the roller on the sill lever 48 adjacent to which the car has stopped. This is of particular importance if the motor 16 should be reversed during door closure to reopen the same. 1

The coil RR and the contacts 136 controlled thereby are particularly useful upon reopening the doors prior to complete closure of thesame. The coil RR is controlled through the same circuit k: which controls the closing coil C. The energization of coil RR with the coil C causes the separation of contacts 136 and opens up the circuit between conductors ,b and c which normally supplies current to the motor 16 for opening the doors. The opening of contacts 136 forces the current for motor 16 to pass through an additional resistanceR2 to reduce the power of the motor until the motor has had time to overcome the inertia of the closing doors. The time during which the resistance R2 is in series with the motor 16 is controlled by means of a dash pot 140 which causes the armature of relay RR to descend slowly on deenergization of] the coil of relay RR. It will thus be seen that on opening the switch 146 while the door is being closed the coils C and RR are deenergized and coil 0 is energized. The armatures of coils O and C drop immediately on deenergization of the coils thus supplying door opening power to the motor 16 by way of resistance R2. After a time interval the armature of coil RR closes contacts 136 and short-circuits resistance R2 thus supplying the full door opening power to motor 16.

The above described mechanism operates as follows: During the travel of the elevator the hoisting controller is maintained out of its neutral position and coil P is energized to break the circuit to the opening coil 0. When the hoisting controller is moved to neutral position the relay P is deenergized. This energizes the coil 0 and actuates the door motor for opening the doors.

The door motor rotates the slow-speed shaft through an angle of substantially 270 and the car door and landing door are opened through the power of the door motor 16. The opening movement of the door tensions the door closing springs 40 and 52 and the spring '10 for returning the shaft and motor to their closed door positions after the doors are released to be closed. The final portion of the opening movement of the doors also tensions the spring 78 for supplying an additional initial power to the shaft 22 for starting the reverse rotation of the motor shaft 22. When the door has reached substantially open position the open limit switch 88 breaks the door opening circuit through. the coil 0 and deenergizes the motor '16 and applies the brake 18. The doors are thus maintained open.

When the hoisting controller is moved slightly to either side of neutral position switch 146 closes, thus supplying current to coil P and opening contacts 142 and opening the circuit through coil 0. The switch 146 also supplies current to coils C and RR. The resulting operation of

contacts

138 and 139 controlled by the coil C releases the brake and partially closes the dynamic circuit f, 111, 139, etc. The spring 52 then moves the landing door or doors toward closed position and the spring 40 closes the car door. The springs 70 and l8.rotate the slowspeed drive shaft and motor 16 mechanically to their initial position. .When the doors have been moved partially toward closed position the dynamic switch 111 is closed through the withdrawal of its plunger, thus completing the dynamic circuit. The motor 16 then serves as a dynamo with a closed circuit including resistance R thus checking the reversing of the motor .16 and cor-- respondingly checking the receding movement of the door operating cam 60. The door checks shown limit the closing movement of the doors, the dynamic switch and resistance R being set to cause the cam 60 to recede at substantially the same rate of speed as the free end of lever 48 adjacent which the car has stopped.

When the doors near closed position the dynamic switch is opened and on substantially complete closure of the doors the close limit switch 98 is open and the door motor brake becomes effective to maintain the parts in this position.

Having now described my invention, I claim:

1. In combination, an elevator car; a door for permitting access thereto; spring means connected to said door urging said door to closed position; an electric motor having a field and an armature; operative connections from the armature of said motor to said door for effecting the opening of said door by said motor against the action of said spring means when the'armature of said motor is rotated in one direction, and for effecting the rotation of said armature in the.

reverse direction by said spring means when said spring means is effective to close said door; a source of electrical energy; means for energizing the field of said electric motor from said source at least during the opening movement of said door and the latter part of the closing movement of said door; and means, effective during the opening movement of said door, for connecting the armature of said motor to said source so as to cause said motor armature to rotate in the door opening direction and open said door, and eiiective, during closing movement of said door, to disconnect the armature of said motor from said source and to connect together the opposite terminals of said armature, during at least the latter portion of the door closing movement, so as to effect a dynamic brake of said electric motor and assist in retarding the closing movement of said door as said door nears its closed position.

2. In combination with an elevator car and a door for permitting access thereto; spring means connected to said door urging said door to closed position throughout the entire range of positions of said door; an electric motor on the car; means connecting said motor to said door so that operation of said motor in one direction opens said door against the action of said spring means; additional spring means, said additional spring means being connected between a member operable by said motor and a fixed member on the elevator car; and means, effective as said door nears fully open position, for tensioning said additional spring means so as to aid in retarding the opening movement of said door, and effective, as said door starts closed from fully open position, to release the energy stored up in said additional spring means so as .to impart an initial spin to said motor in the door closing direction and thereby relieve said first named spring means from initiating the rotation of said motor in the door closing direction.

3. In combination; an elevator car; a door for permitting access thereto; spring means connected to said door urging said door to closed position; an electric motor; operative connections, including a flexible tension element from said motor to said door for effecting the opening of said door against the action of said spring means by said motor when the armature thereof is rotated in one direction, said spring means normally driving the armature of said motor in the reverse direction through said connections when said spring means is eifective to close said door; and means for imparting an initial spin in such reverse direction to the armature of said motor when said door is started closed from its fully open position so that said spring means is relieved from initiating such reverse rotation of the armature when the door is started closed from its fully open position, and for thereafter retarding such reverse rotation of the armature by causing said motor to operate as a power generator so that said motor then acts to check the closing speed of said door.

4. In combination with an elevator car and a door for permitting access thereto; spring means connected to said door urging said door to closed position; an electric motor; operative connections from said motor to said door for effecting the opening of said door by said motor against the action of said spring means when the armature of said motor is rotated in one direction, and for effecting the rotation of said armature in the reverse direction by said spring means when said spring means is effective to close said door; means for imparting an initial spin in such reverse direction to the armature of said motor when said door is started closed from open position so that said spring means is relieved from initiating such reverse rotation of the armature when the door is started closed from open position; and means, effective after the armature or said motor has been given its initial spin by said last mentioned means, for causing said motor to operate as a dynamic brake and thereby control the closing speed of said door.

5. In combination; an elevator car; a landing door; spring means individual to said landing door for closing the same; an electric motor on the 1 car; connections from said motor to said landing door effective, upon rotation of said motor in one direction, to transmit power from said motor to said landing door so as to open said landing door against the action of said spring means, said connections including a cam upon the car cooperating with a movable element individual to said landing door; additional spring means, mounted on'said car, and eiiective while said landing door is being returned to closed position by said spring means individual to said landing door. to return said motor to its initial, door-closed position; means for imparting an initial spin in the door closing direction to the armature of said motor when said landing door is started closed from open position so as to relieve the pressure between the cam on the car and the movable element individual to said landing door; and means, effective after the initial 'spin of the armature in the door closing direction has been imparted by said last mentioned means, for causing said motor to operate as a dynamic brake to control the speed with which said additional spring means mounted on the car returns the motor to its initial, door-closed position.

6. In combination; an elevator car; a landing door for permitting access to said elevator car; an electric door operating motor mounted on said car; means for energizing said motor and for transmitting power therefrom to said door for opening the same, said means including reduction gearing capable of being operated from the slow speed end thereof to drive said motor; spring means for closing said door and for mechanically returning said motor to its initial door closed position, said means working through said reduction gearing from the slow speed end thereof; a mechanical brake for said motor; means for deenergizing said motor when said door reaches open position and for maintaining it deenergized while said door remains in open position; and means for causing the application of said brake while said door is in open position, thereby holding said door in open position against the action of said spring means.

7. In combination; an elevator car; a landing door for permitting access to said elevator car; an electric door operating motor mounted on said car; means for energizing said motor and for transmitting power therefrom to said door for opening the same, said means including reduction gearing capable of being operated from the slow speed end thereof to drive said motor; spring means for closing said door and for mechanically returning said motor to its initial door closed position, said means working through said reduction gearing from the slow speed end thereof; a spring-applied electromagnetically-released brake for said motor; means for deenergizing said motor when said door reaches open position and for maintaining it deenergized while said door remains in open position; and means effective while said door is being operated, for energizing the releasing magnet of said brake, and eifective when said door attains open position, to deenergize the releasing magnet of said brake and thereby hold said door in open position against the action of said spring means without the consumption of power.

8. In combination with an elevator car, a landing door, an electric motor on the car, means for transmitting power from said motor to said door for opening the same, spring means individual to said landing door for closing said door and additional spring means, mounted on the car, for

" mechanically moving said motor to its initial ing door, an electric motor on the car, means for transmitting power from said motor to said door for opening the same, spring means individual to said landing door for closing said door, additional spring means, mounted on the car, for mechanically moving said motor to its initial door closed position and means for electrically conneting the opposite poles of said motor during a portion of its movement toward itsinitial position.

10. In combination with an elevator car, a landing door, an electric motor on the car, means for transmitting power from said motor to said door for opening the same, spring menas for closing said door, spring means for mechanically moving said motor to its initial door closed position, a brake for said motor, and means for releasing said brake during electrical or spring actuated movement of said motor.

11. In combination with an elevator car, a movable door, a motor for opening said door, a brake for said motor, mechanical devices for closing said door and for reversing said motor to closed door position, a controlling circuit for releasing said brake and operating said motor to open said door and a controlling circuit for releasing said brake during door closing movement.

12. In combination with an elevator car, a movable door, a motor for opening said door, a brake for said motor, mechanical devices for closing said door and for reversing said motor to closed door position, a controlling circuit for releasing said brake and operating said motor to open said door, a controlling circuit for ree leasing said brake during door closingmovement and limit switches for rendering said circuits ineffective when said door approaches open and closed positions respectively.-

13. In combination with an elevator car, a

movable door, a motor for opening said door, a brake for said motor, mechanical devices for closing said door and for reversing said motor to closed door position, a controlling circuit for releasing said brake and operating said motor to open said door, a controlling circuit for releasing said brake during door closing movement and opening and closing relays for controlling said circuits during door opening and door closing movements respectively.

14. In combination with a movable door for permitting access to an elevator, a motor for opening said door, spring means for closing said door, means for supplying electric current to said motor for opening said door from completely closed position, means for supplying a decreased current supply to said motor on the application of door opening power to said motor at an intermediate point on the interruption of door move ment toward closed position.

15. In combination with a movable door for permitting access to an elevator, a motor for opening said door, spring means for closing said door, means for supplying higher voltagelto said motor on door opening movement from completely closed position and lower voltage from intermediate points for opening said door, and

a time relay for limiting the application of said lower voltage to said motor.

16. In combination with an elevator movable vertically in an elevator shaft, fixed guides extending vertically along the side edges of said shaft, a movable landing door positioned adjacent the front edge of said shaft for permitting access thereto, door operating mechanism including a power application element movable toward and from the plane of the front wall of said shaft, means on said elevator for cooperation with said fixed guides for guiding said elevator in its travel, said means being substantially unyielding in a direction toward or from the front of said elevator, a motor on said car, a power transmitting element on said car operated by said motor and having a portion shiftable toward and from the front of said car into engagement with 1 the power application element of said door operating mechanism for opening said door when said elevator is adjacent said landing.

17. In combination with an elevator car, a movable door, an electric motor, a motor brake, 125 means for transmitting power from said motor to said door for opening the same, mechanical means for closing said door and mechanically actuating said motor to its closed door position, means for automatically releasing said motor 13 brake upon supplying electrical energy thereto and manually controlled means for releasing said brake at will.

CLIFFORD NORTON.