US2644547A - Elevator overload safety device - Google Patents

Description

July 7, 1953 w. DOOLAN ELEVATOR OVERLOAD SAFETY DEVICE 4 Sheets-Sheet 1 Filed Dec. 29, 1949 INVENTOR. M/y/a/p flap/a ATTORNEY Filed Dec. 29, 1949 w. DOYOLANI ELEVATOR OVERLOAD SAFETY DEVICE 4 Sheets-Sheet 3 Patented July 7, 1953 attest? UNITED STATES PATENT OFFICE ELEVATOR OVERLOAD SAFETY DEVICE William Doolan, Washington, D. C. Application December 29, 1949, Serial N 0. 135,697

12 Claims. 1

This invention appertains to improvements in overload safety devices and load indicators for electrically operated elevators, and more particularly to the type of electrical safety device and load indicator, forming the subject-matter of my co-pending application for Letters Pat ent, filed January 27', 1949.

The principal object of the present invention is to provide a device or system of this character for application to electrically operated elevators to assure against accident due to cage overloading; the load indicator being progressively actuated by the weight of each successive load unit, passenger or freight, added to the cage until the overload point is indicated, when the device or system will function automatically to break the circuit t prevent the starting up of the cage, regardless of whether or not the cage gate, or the switch usually associated therewith, is open or closed.

Another object of the invention is to provide the aforesaid device or system with a means for adjusting its operating moment to accommodate the same for installation on elevators having different indicated maximum load capacities, without in any way affecting the operating efficiency thereof.

Generally, the invention is comprised in a system of electrical circuits and electrical and mechanical instrumentalities, wherein, with the main line and gate actuated switches closed, the cage unoccupied and the cage gate open, both the cage operating and safety control circuits are open. When a load unit, passenger or freight, is added to the cage, its weight causes the closing of a normally open minimum weight switch, which connects the indicator control circuit across the power supply line through a normally closed auxiliary gate actuated switch, and this initially added weight is visually indicated, as is also the weight of successive load units added to the cage. Now, when maximum load within the cage is exceeded, and so indicated, a normally open overload switch is mechanically actuated and closes a circuit on a relay, which operates to open the circuit of the operating motor of the elevator and, at the same time, closes a normally open by-pass switch shunted about the auxiliary cage gate switch. Thus, with the control circuit open on the elevator operating motor, the cage cannot be started up, whether or not the conventional switch or the auxiliary cage gate switch is open or closed, and further cage operation can only be effected by a reduction in the load weight to or below an indicated maxi- I the minimum weight and overload switches; the

point of pivot of the transmission arm being ad- Justable to change the leverage ratio of the arm correspondingly for different indicated maximum cage loads.

with the foregoing and other objects and. advantages of equal importance in view, the invention resides in the certain new and useful combination, construction, and arrangement, of instrumentalities, parts, and circuits, as will be hereinafter more fully described, set forth in the appended claims, and illustrated in the accompanying drawings, wherein:

Figure l is a front elevation of the safety device or system as it appears when installed on the cross-beams on the top of the elevator cage, in accordance with the invention;

Figure 2 is a vertical transverse section taken through the line 2-2 on Figure 1, looking in the direction of the arrows;

Figure 3 is an enlarged horizontal section taken through the line t--3 on Figure 1, looking in the direction of the arrows;

I Figure 4 is an enlarged vertical transverse section taken through line 5-4 on Figure 1, looking in the direction of the arrows;

Figure 5 is a side elevation of the pivot and supporting bracket for the load weight transmission arm; I

Figure 6 is a perspective view of one of the cam or wedge elements for securing the transmission arm in its positions of adjustment on its supporting bracket;

Figure 7 is a sectional view similar to that of Figure 4, but taken through the line 7-7 on Figure 1, looking in the direction of the arrows;

Figure 8 is a diagram of the wiring of the load weight indicator and safety overload control circuits;

Figure 9 is a straight line diagram of the circuit;

Figure 10 is a straight line diagram of the circuit for another embodiment of the invention whereby operation of the elevator will be automatically prevented in the event of the blowing of a fuse or some other failure in the electric system supplying current to the elevator.

Figure 11 is a diagrammatic illustration of the relay employed in the circuit of Figure 10; and

Figure 12 is a diagrammatic illustration of the dual gate operated switch employed in the second circuit.

Figure 13 is a detail section showing the connection between the movable core and the adjustment spring.

Referring to the drawings, wherein like characters of reference denote corresponding parts throughout the several views, and more particularly to Figures 1 and 2, A designates a pair of parallel cross-beams by which the elevator cage (not shown) is suspended from the usual cables C attached to the bolts B, which depend through apertured plates ID and 12, respectively secured on the top and bottom sides or the crossbearn A, and through a floating plate M; the latter being supported on the lower ends of the bolts between pairs of nuts Hid and lfib screw threaded thereon, which are tightened against the upper and lower sides of the plate, respectively. A compression spring I8 is engaged on each of the bolts B in interposed relation between the upper nut its and the lower side of the plate 12.

By this arrangement, the load weight or the elevator cage is impressed on the compression springs it and through them and the floating plate M on one end of a pivotally supported transmission arm 24, which end is engaged on a bolt 26, that has a rounded head 26 disposed in contact with the exact center of the lower side of the plate i l and a nut 22 on its lower end, beneath the arm. An expansion spring 26 is engaged on the bolt it between the rounded head thereof and the upper side of the arm 2 t.

As best shown in Figures 3 through 6, the piv t mounting for the load weight transmission arm 24 is comprised in a supporting plate 21;? depending from a point of securement, by means of a pair of bolts 32, against the inner side of the rearwardly disposed cross-beams A, and an elongated. horizontal bar 3 2, secured in spaced relation to and along the lower edge por t-ion or the front side of the plate 28 by means of a pair of spaced bolts 36, the latter each carrying a spacer collar 38 interposed between the bar 3 and the opposed side of the plate 2t. Adjustably supported on the horizontal bar is a bracket which has a pair of spaced angled portions or lugs 42 offset rearwardly from its top edge engaged over the top edge of the bar 54 and a horizontally disposed portion i l extending rearwardly from its lower end and underlying the bar. Formed on the top edge of the bracket 40, between the portions or lugs 42, is an enlargement 1B, which is transversely apertured, as at 43, to receive a pivot pin 12 for the oscillatory support of the transmission arm 24. Seated upon the horizontal portion 44 is a clamping element 50, which is abutted against the outer side of the bar 34 and has an offset flange portion 52 underlying the latter, and an inve'ted, substantially V-shaped, recess 54 opening through its lower side for the engagement of the tapered end 58, of a slotted screw 56, with its sloping walls, so that, by tightening up on the screw, the element 50 efiectively clamps the bracket part 4%) to the bar 34, and, contrawise, by loosening up on the screw, the

bracket part may be shifted in desired directions along the bar.

The transmission arm 24 is supported in an identical form of braket part 60 that has forwardly oiiset angled portions or lugs 62 engaged over the top edge of the arm and a horizontal flange portion 84 underlying the lower edge of the same, the latter portion supporting a clamping element '55, identical to the element which is likewise tightened into clamping engagement with the outer side of the arm by a slotted screw 68. The upper edge of the bracket part 6! has a centrally disposed enlargement it, corresponding to the enlargement '46 of the bracket part 4!), from the rear side of which the pivot pin 12 projects and extends through the aperture 48 in the latter; a cotter pin I l being passed through the free end of the pivot pin to retain the same against displacement. Thus, relative adjustments may be readily made between the bracket part 40 and the bracket bar 34, on the one hand, and between the transmission arm 24 and the bracket part ti), on the other hand, to change the leverage ratio of the arm through a wide range to adapt the device or system for effective application to elevators having widely different maximum load capacities.

The opposite end of the transmission arm 24 carries a pivot pin 18, which is engaged with the legs of an inverted U-shaped clip straddled over the top edge of the arm. The top portion oi the clip 80 is engaged on the lower end of a rod :32, of a non-magnetic metal, which extends upwardly through the bottom of wall Elia or" an open frame supported between the cross-beams A and upon a pair of crossbars it? secured to the under sides of the latter; the frame, in addition to the bottom wall its, having a vertical side wall '56 and a top wall The rod 82, below the bottom wall its, carries an adjustable nut 84 and an expansion spring interposed between the nut and the bottom of core 38 and secured to the core. Immediately above the bottom wall 16a, the rod, passes through the open centers of a pair of superimposed solenoidal coils a and set, supported on the bottom wall, and carries a core of a magnetic metal, for cooperation therewith. The extreme upper end of the rod enters the bottom side of a dashpot 92 and connects with the movable element (not shown) thereof; the dashpot being supported on the lower side of the top wall 76b, of the frame Screw threaded on the rod 82, below the dashpot s2, is an adjustable element 24, of disk form, which acts to effect the closing of a minimum weight switch in the initial downward movement of the rod, and of an overload switch 98, in its final downward movement, as will be more fully explained presently. The rnininmm weight switch 96 is .adjustably mounted on a screw threaded rod I60, rising from the upper end or" a resistor I92, which .is supported on the bottom wall 16a, of the frame 76; the upper end of the rod being secured in the top wall 673 of the latter, and the switch is clamped in adjusted position between a pair of nuts Hits. The switch 96 is of micro type and has a movable contact that is normally held on open circuit by an actuating arm 96b, which is pivoted atone of its ends, as at 96c, and has its other end extending into the path of upward movement of the disk 94, on the rod 82, while the-overload switch 98, also of micro type, which is mounted on the inner side of the vertical side wall of the frame 16, has a movable switch ing element 98a disposed in the path of downward movement of the disk 94. The free end of the actuator arm 96b, of the micro-switch 96, is downwardly angled and carries an antifriction roller 555d against which the disk bears, when the rod 82 is disposed in its uppermost position; the disk 94 being adjustably secured on the rod between a pair of nuts 94a. The outer side of the vertical wall of the frame it constitutes a panel for a requisite number of circuit terminals, generally designated at I64 (Figure 1), and has a relay I96 mounted thereon adjacent its lower end.

Referring now to Figure 8, the wiring of the circuits of the several instrumentalities is, as follows: One side of an A. C. power line I08 is connected with one of the panel terminals iMa, IMF), i. e. the terminal I04a, which, in turn, is connected by a conductor Hi) to the movable contact a, of the minimum weight switch 236; the latter having its fixed contact b connected by a conductor II2 to the center tap of the solenoidal coils 90a, 90b, and by a conductor H4 to one terminal of the coil "16a, of the relay hit. The end terminal of the solenoidal coil etc is connected by a conductor M5 to the end terminal of the complemental section mm, of the resistor I02, and the end terminal of the solenoidal coil 96?) by a conductor IId to the end terminal of the complemental resistor section 12b; the two conductors H5 and H3, respectively, leading to and connecting a pair of the panel terminals H340, Mi let, to which the opposite sides of the load weight indicator circuit I20, including an indicating device which may be in the nature of a voltmeter, are also connected. The other terminal of the coil 106a, of the relay IE6, is connected by a conductor I22 to the panel terminal Hide, of a pair of those terminals Iil4e, lc if, which, in turn, is connected by a conductor iii i to the movable contact a, of the overload switch 98; the latter having its fixed contact b connected by a conductor I26 extending between the panel terminal I04 and the panel terminal i64g, of a pair designated I040, I641. These panel terminals 14g, Iil4Z, are also connected by the opposite sides of the circuit I28, to the auxiliary cage gate switch I28a. A conductor iSii leads from the center tap of the resistor I02 and connects with the contact a, of the relay switching contacts I067), while the contact 1) thereof is connected by a conductor I34 to the panel terminal i041), which is connected with the other side of the A. C. power line I68; the conductor I36 being connected by a branch conductor 532 to the panel terminal I44 and the conductor I34 by a branch conductor I36 to the panel terminal I941. The relay I06 has a second pair of switching contacts I060, of which the contact (1 is connected by a conductor I38 to one of the panel terminals I042, and its other contact 0 by a conductor I40 to the panel terminal I642. The elevator cage safety circuit I42 has its opposite sides connected to the panel terminals IBM and I642, and this circuit is shown with the main or conventional cage gate actuated switch. leiia therein which is closed by the closing of the cage gate. With these instrumentalities and circuits so interconnected and arranged, the load weight indicator (not shown) has its movable index normally set at zero by a balancing effect obtaining between the coils 90a, 90b,

and the sections I02a, IIIZb, of the resistor I62; the coils a, 90b, being of equal impedance, and the sections IllZa, I022), of equal ohmic value.

Upon the closing of the overload switch 98 by reason of the overloading of the elevator, the relay coil I650, becomes energized, and functions to close the relay switching contacts I061) (hereinafter called the by-pass switch) to establish a by-pass about the auxiliary elevator cage gate switch I28a, and simultaneously open the relay switching contacts I060 (hereinafter called the operating motor control switch), thereby opening the elevator safety circuit of the operating motor (not shown) of the elevator, in the manner to be presently more fully explained.

In the operation of the device or system, as thus constructed, installed and arranged, its state of readiness is such that the auxiliary cage ate switch I28a, and'the motor control switch Into, of the relay I06, are normally closed, and minimum weight switch 96, the overload switch S3 and the by-pass switch I062), of the relay, are open. Now, upon the cage being occupied by a load unit, passenger or freight, the effect of its weight will move the disk 94 down to close the minimum weight switch 96, and this will be immediately registered on the indicator, by a slight movement of the index thereof off from its zero setting, and thereafter the weight of each added load unit will be likewise registered by progressive movements of the index and, unless an overloading occurs, the cage may be operated in the usual manner. Each unit of weight added to the cage causes a slight compression of the cage suspension springs I8 and movement of the transmission arm 24, by reason of the contact of the bolt head 26' with the plate I4, which allows downward movement of the rod 82 by reason of its own weight. Any jolting, due to load movement within the cage which may cause a vibration of the transmission arm 24 and the rod 82, is absorbed by the spring 26 assisted by the dampening effect of the dashpot 92, to assure of smooth operation of the equipment. As the loading of the cage proceeds, the iron core 88, on the rod 82, will gradually lower, correspondingly with the downward pull on the latter by the pivotal movement imparted to the transmission arm 24, so that the normal balance between the coils sea and 90b and the sections I02a and N223), of the resistor I62, will be altered and such alteration will be progressively shown at the indicator. However, in the event that overloading of the cage occurs, the excessive weight causes pivotal movement of the transmission arm 24 to draw the rod 32 downward so that the disk 94 engages with the movable element 98a, of the overload switch 98, causing it to close. With the closing of the overload switch 98, the coil Ifiiia, of the relay M36, is energized and operates to simultaneously close the by-pass switch I661), shunting it about the auxiliary cage gate switch Him, and open the motor control switch lilEc. Thus, the safety control circuit of the elevator is opened on the motor so that the latter cannot be started up and the closing of the cage gate is of no effect, and further operation of the cage is prevented until after the load weight therein has been reduced to or below its rated load capacity Referring again to Figures 1 and 2, it is to be noted that by providing the plate I4 on the lower ends of the suspension bolts B, beneath the springslt, and having the rounded head 20, of the bolt 2s, disposed in contact with the exact center of the lower side of the plate, a true indication of the load weight within the cage is obtained, regardless of any small irregularities in loading effect on the individual suspension cables.

In the circuit diagram constituting Figure another embodiment of the invention is illustrated whereby in addition to operating to prevent running of the overload safety elevator when overloaded, it functions in the event of failure in the electricsystem for safety device, as for example, the blowing of a fuse or any other interruption of current flow, to open the elevator safety circuit, thus making it impossible to operate the elevator.

In this second embodiment of the invention the regular elevator safety circuit is designated 242 and it has therein the relay operated'switch 2860 which is controlled by the relay coil 206a.

Figure 11 diagrammatically illustrates the relay mechanism which is generally designated 208 and which shows the safety circuit switch contact 2ilc and the overload switch contact 28512.

In the first described embodiment of the invention the relay Hi6 remains unenergized at all times except upon the placing of a load upon the elevator cage in excess of a safe figure. The energization of the relay coil Hlta then causes separation of the contacts 15160 of the safety circult, thereby opening the latter.

In the second embodiment of the invention, as illustrated in the line diagram of Figure 10, the relay 288 is constantly energized and is of such construction as to maintain the safety circuit switch contact 2850, and also the overload switch by-pass contacts 2M1), closed at all times except when an excessive load is placed upon the elevator cage whereupon the overload switch 296, which is in circuit with the relay coil 2955a, will be openedthus interrupting current flow through the coil.

As shown in Figure 16 the overload switch 298, which is normally closed, and the relay coil 288a, are in circuit in the line 288 across the safety device current supply circuit. Bridging the overload switch 298 is the current conductor 234 having the closed'rclay controlled overload switch 2062) and the closed gate switch 22% in circuit therein.

Bridging both the overload switch 298 and the relay coil 288 is the current conductor line 230 in which is connected the balanced bridge circuit 202 which includes the indicating meter M, the minimum weight switch 296 and a second auxiliary gate switch 22 8a.

The auxiliary gate switch 223a and the gate switch 2%?) which bridges or shunts the overload switch 29l3, are separate and distinct from the usual niain elevator cage gate switch as hereinbefore set forth in connection with the auxiliary gate switch 122a.

The auxiliary gate switches 228a and 2281) are alternatively opened and closed by the opening and closing of the elevator cage gate as illus trated in Figure 12. As shown in this figure, the gate, generally designated G, is shown in one position in full lines and in a second position in broken lines. The full line position represents the open position of the gate and when in this position a switch operating lever L will be shifted to effect the closing of the switch 228a. At this time the switch 22% which shunts out the overload switch 298, will be open.

'It will be understood that in this second embodiment the overload switch 298 and the minimum weight switch 298 may be actuated by the same mechanical means as that hereinbeiore described in connection with switches 96 and 98 with the exception that in the second embodiment the overload switch remains closed at all times until the weight imposed upon the elevator cage becomes sufliciently great to shift the rod 82 to the position where it actuates the overload switch 295 whereupon this switch will be opened and the relay coil deenergized. So long as a safe load is maintained upon the elevator cage the minimum weight switch 298 and the overload switch 298 will remain closed and the relay will remain energized. With the elevator cage gate G open the switch 228a will remain closed and the switch 22% will open.

After the cage has been loaded, and if such load is not in excess of the set maximum, when the cage gate is closed the switch 2282) will be closed and the switch 2280. will be opened and the ele vator may be safely operated.

By placing the relay actuated switch 206?) in shunt relation with the overload switch 298, it will be seen that if the switch 298 should be accidently opened while the car is in operation, as might occur upon the jolting of the car if the weight thereon is very close to the maximum, the relay 2% will not be energized and interruption of the running of the elevator will not occur.

When the elevator cage is stationary with the cage gate open, the switch 22% will be open and the switch 1228a will be closed. If the cage is unoccupied the minimum weight switch 298 will be open.

When a weight is placed in the cage as, for example, by a person stepping into the elevator, the lever 24% will be oscillated to impose a downward pull on the rod 82 to cause the minimum weight switch 29:3 to close, as does the switch first described. The shifting of the core 88 within the coils eta and 9% will unbalance the circuit 2% in which the meter M is located, causmovement or deflection of the meter needle.

if the load is continually increased upon the elevator cage until it exceeds the safe operating limit, the core element within the coils of the balanced circuit will be shifted to an extent to unbalance the circuit to a point where the finger will designate an unsafe load and at the same time the element 34 of the rod 82 will function to open the overload switch 298 thus interrupting current flow through the solenoid coil. The armature 258d, Figure 11, will be released by the relay and drawn over by the tensioned spring Nee thus effecting the opening of the switches will) and Etta. The safety circuit will accordingly be opened and even though the gate may then be closed, thereby closing the gate switch 22%, the switch 2960 in the safety circuit will remain opened, as well as the switch 20Gb in the overload switch by pass circuit 234.

In the event of the opening of the A. C. line which the overload safety circuit is connected, the same action will take place as described in connection with the overloading of the elevator cage. This is particularly important in those places where the safety code for elevator operation forbids the running of an elevator when the lights therein are not functioning.

Having thus fully described preferred embodi ments of my invention, it is to be understood that the words which I have used are words of description rather than of limitation and that changes within the purview of the appended claims may be made, without departing from the true scope 9 and spirit of the invention in its broader aspects.

What I claim is:

1. In an overload safety control system for electrically operated elevators, including a cage, cage suspension means, and the safety circuit thereof; an auxiliary cage gate actuated switch; a minimum wei ht switch in the power circuit of the system and in series with the auxiliary gate actuated switch, a control circuit for said safety circuit, an overload switch in said control circuit, a load indicator mounted within the cage and in circuit with said minimum weight and overload switches, an actuating means common to said minimum weight and overload switches, means interposed between the cage suspension means and said actuating means for progressively transmitting motion from said suspension means to the latter correspondingly for variations in the load within the cage, means cooperative with said actuating means and said indicator to cause the latter to progressively register any increase or decrease in the load, said actu ating means normally holding said minimum weight switch open when the cage is empty and adapted to close the same at a predetermined light load and close said overload switch when an overload is indicated to be within the cage, and a relay adapted for operation upon the closing of said overload switch to open said safety circuit and to simultaneously establish a icy-pass about said gate actuated switch, whereby cage opera=- tion is prevented regardless of the gate being opened or closed.

2. The invention as defined in claim 1, with the said transmitting means comprised in a. pivot mounting for supporting said arm intermediate its ends, and means on said mounting to allow endwise adjustment of said arm relatively thereto, whereb the leverage ratio of the arm may be changed to adapt the system for application to cages having different load capacity ratings.

3. The invention as defined in claim 1, with. the said transmitting means comprised in an elongated arm, a bracket mounted on top of said cage, a member supported on said bracket, a second member supporting said arm, a pivot coupling said second member to the first name-d member, and means carried by said second member to allow endwise adjustment of said arm relatively thereto.

4. The invention as defined in claim 1, with the said transmitting means comprised in an elongated arm, a bracket mounted on to of said cage, a member supported on said bracket, means carried by said member to allow for its lateral adjustment relatively thereto, a second member supporting said arm, a pivot coupling said second member to the first named member, and means carried by said second member to allow endwise adjustment of said arm relatively thereto,

5. The invention as defined in claim 1, with the said cage suspension means including a pair of parallel cross beam-s mounted on top of the cage, plates secured on the upper and lower sides of said cross beams, cable attaching bolts slidably mounted in said plates, a third plate supported on the lower ends of said bolts, compression springs on said bolts and interposed between the lower of the first named plates and said third plate, said transmitting means comprised in an elongated arm, a bracket depending from one of said cross beams, a pivot carried by said bracket and supporting said arm intermediate its ends, one end of said arm being connected with said actuating means, a bolt rising from the opposite end of said arm and having its head bearing against the center of the lower side of said third plate, and an expansion spring carried by said bolt and interposed betweenits head and said arm to maintain the head in contacting relation with said third plate, whereby weight progressively added to said cage acts to correspondingly compress said compression springs and cause an upward movement of said third plate and the underlying end of said arm and the lowering of the opposite end of the latter, whereby to effect the operation of said switch actuating means.

6. The invention as defined in claim 1, with the said minimum weight and overload switches nor mally open, and said actuating means comprised in a vertically disposed rod having its lower end pivotally connected with the said one end of said arm and a member adjustably mounted on the same and normally acting to hold said minimum Weight switch open when the cage is empty and adapted to allow it to close upon the initial downward movement of the rod, due to the entry of a load unit into the cage, and to close said overload switch when the rod approaches the limit of its downward movement caused by an overload within the cage.

7. The invention as defined in claim 1, with the said indicator connected across a balanced circuit and adapted to progressively register the weight of successive load units entering said cage, when the balance of said circuit is gradually changed correpondingly with the entry of successive load units into the cage.

8. The invention as defined in claim 1, with the said transmitting means comprised in an elongated arm, a bracket mounted on the top of said cage, a bar supported horizontally on said bracket and spaced therefrom, a member mounted on said bar, a second member supporting said arm and pivotally connected with the first named member, means carried by the first named member to allow its adjustment along said bar, and a like means carried by said second member to allow for lengthwise adjustment of said arm relatively thereto.

9. In an overload safety control system for electrically operated elevators, including a cage, cage suspension means, and the safety circuit thereof; an auxiliary cage gate actuated switch, a minimum weight switch in the power circuit of the system in series with the auxiliary gate actuated switch, a control circuit for said safety circuit, an overload switch in said control circuit, said overload switch having a normally set position for maintaining the control circuit prepared for operation and a second position in which it eifects operation of the control circuit, a load indicator mounted within the cage and in circuit with the minimum weight switch, an actuating means common to said minimum weight and overload switches, means interposed between the cage suspension means and said actuatin means for pro gressively transmitting motion from said suspension means to the actuating means correspondingly for variations in the load on the cage, means cooperative with said actuating means and said indicator to cause the latter to progressively register any increase or decrease in the load, said actuating means being maintained inoperative to close the minimum weight switch when the cage is empty and becoming operative to close the same upon the application of a predetermined light load upon the cage, said actuating means being operatively connected with the overload switch to actuate the same to said second position when an overload is placed upon the cage, and a relay in circuit with said overload switch and functioning upon the actuation of the overload switch to said second position to efiect the opening of said safety circuit whereby cage operation is prevented.

10. In an overload safety control system for electrically operated elevators, including a cage, cage suspension means, and the safety circuit thereof; an auxiliary cage gate actuated switch, a control circuit for said safety circuit, an overload switch in said control circuit, said overload switch having a normall set position for maintaining the control circuit prepared for operation and a second position in which it eiiects operation of the control. circuit, a load indicator mounted within the cage and in circuit with said auxiliary gate switch, an actuating means for said overload switch, means interposed between the cage suspension means and said actuating means for progressively transmitting motion from said suspension means to the actuating means correspondingly for variations in the load on the cage, means cooperative with said actuating means and said indicator to cause the latter to progressively register any increas or decrease in the load, said actuating means becoming operatively connected with the overload switch to actuate the same in said second position when an overload is placed upon the cage, and a relay in circuit with said overload switch and functioning upon the actuation of th overload switch to said second position to effect the opening of said safety circuit whereby cage operation is prevented.

11. In an overload safety control system for electrically operated elevators, including a cage, cage suspension means, and the safety circuit thereof; a power circuit, an auxiliary cage gate actuated switch, a control circuit for said safety circuit, an overload switch in said control circuit,

said overloadswitch being normally closed, a load indicator mounted within the cage and in circuit with the auxiliary gate switch, an actuating means for said overload switch, means interposed between the cage suspension means and said actuating means for progressively transmitting motion from said suspension means to the actuating means correspondingly for variations in the load on the cage, means cooperative with said actuating means and said actuator to cause the actuator to progressively register any increase or decrease in the load, means operatively connecting said actuating means with the overload switch to open the latter when an overload is placed upon the cage, and a constantly energized relay in circuit with the overload switch and functioning upon deenergization through the opening of the overload switch to effect the opening of the safety circuit whereby cage operation is prevented, the said load indicator and the auxiliary gate actuated switch being series connected with the control circuit across said overload switch and relay.

12. In an overload safety control system as set forth in claim 11, a second auxiliary gate actuated switch and a relay controlled switch connected in series with the control circuit across the over load switch, said relay' controlled switch and the safety circuit being maintained closed by the energized relay, the elevator cage gate when open maintaining the first auxiliary gate switch closed and the second auxiliary gate switch open and such auxiliary cage gate upon being closed functioning to open the first auxiliary gate switch and close the second.

WILLIAM DOOLAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,015,874 Cronk June 30, 1912 1,945,502 Jackson 1 Jan. 30, 1934

Images