US1561251A - Control system - Google Patents

Description

Nov. 10, 1925.

E. S. LAMMERS, JR

CONTROL SYSTEM Filed May 12, 1919 INVENTOR Edwm S. Lammerqu'r:

b I /%AM/ ATTORNEY WIIIIIIIIfiVJI MIIIJ f;

S E S S E N H W Patented Nov. 10, 1925 UNITED STATES PATENT OFFICE.

EDWIN S. LAMMERS, (TIL, OF ELYRIA, OHIO, ASSIGNOB TO \VESTIIIGHOTJ'SE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

con'rnor. SYSTEM.

Application filed May 12, 1919.

To all whom it may concern:

Be it known that I, EDWIN S. LAMMERS, Jr., a citizen of the United States, and a resident of Elyria, in the county of Lorain and State of Ohio, have invented a new and useful Improvement in Control Systems, of whichthe following is a specification.

My invention relates to control systems and'mechanisms for machinery and particularly to systems and mechanisms for controlling dynamo-electric machinery.

An objectof my invention is to provide an an upper chamber controlled by the small bell, and the latter of which is opened, after a predetermined' number of openings of the small bell, to discharge the contents of the charging chamber into the blast furnace. The bells are operated by individual motors.

During normal operation, it isessential that.

the motors shall be operated in strict conformity toa preselected sequence, so that a given number of skiploads of coke, limestone, scrap-iron, etc. shall be depositedin th'e'charging chamber before the accumu' latedloads are'togethe'r dumped into'th'e blast furnace. It is essential that one bell shall be closed while the other is open; that is, that only one motor shall operate at any one time, for the opening of both bells would result'in th e escape ofheat and gases to the outside air. Occasionally, however,itis de si-rable to efl'ectan' extra operation of one of thebells and, at times, a's-when the blast furnace is started, itisadvantageous to operate both bells together.

A further obje'cflof my invention, therefore; is to provide a control system for a with which it is associated.

Serial No. 296,392.

pair of motors which cannot normally operate together and which are operable according to a predetermined sequence,as determined by a rotatable sequence device, whereby the independent operation of either motor or the simultaneous operation of both motors may be effected by an authorized person and whereby such operation shall not disrupt the said sequence.

Another object of my invention is to provide-an improved switching mechanism for such a system.

Other objects will appear hereinafter.

According to the present invention, a pair of interlocking drums is provided for each motor, one of the drums having operative positions in one of which it effects automatic control of the operation of the motor This drum may be actuated, as described hereinafter, to a second position to effect manual control of the motor and to a third position to effect an extra operation of the motor, but such actuation to the secondposition is normally prevented by a locking mechanism which may be unlocked by a foreman or other anthorized person. Before this drum may be actuated to the said other positions, the other drum,.which is interlocked with the first drum, as noted above, must be moved to render the previously mentioned sequence device inoperative to control the motors and also to render the'operation of each motor independent of the other motor. The motors may thus be operated independently, individually or simultaneously, without disturbing the sequence of their normal opera tion.

In the accompanying drawings, Figure 1 is a diagrammatic view of circuits and apparatus embodying my invention; the circuits for one of the motors being for the mostpart omitted; Fig. 2 is a view of an improved controller which is of special application in connection with the system illustrated in Fig. 1(the cover being removed), and Figs. 3 and't are views of a'detail.

Line conductorsd and 2, whiclrmay be connected to any suitable source of direct] current, supply energy to electric motors 3 and i. The'motor 3 is provided withan armature winding 5, a series-field-magnet winding 6, and a shunt-field-magnet winding 7. The motors 3 and 4 may be employed, respectively, to control the small bell and the large bell of a blast furnace. Each motor is provided with a starting resistor 9 which is controlled by a series of electromagnetically operable switches 10, 11 and 12. The circuit of each of the motors is controlled by electromagnetically operable line switches 13, 14 and 15. The switches 13 are provided with mechanically connected switches 113 and 114, the former of which controls a dynamic-braking circuit for the motor through a resistor 51. A dynamicbraking circuit may also be established through the same resistor by an electromagnetically operable switch 112.

A plurality of limit switches 16, 17, 117, 18, 19 and 20 for each of the motors are controlled by cam mechanisms that are operated by shafts 21 and 21a which are respectively rotatable by the motors 3 and 4. In the drawing, although the control oonnections and the control apparatus are illustrated for the motor 3 only, because the cor responding system and apparatus for the motor 4 are almost identical therewith, a portion of the shaft 21a which is controlled by the motor 4 is illustrated, to show the interconnection between the two motors. The shafts 21 and 21a are illustrated as driven from the motors by belts. In practice, the motors are gear-connected to the respective shafts. The switch 16 creates a holding circuit'for the actuating coil of the switch 13. The switch 17 controls circuits for the actuating coils of the switches 14 and 15. The switch 117 is adapted to establish a circuit for the actuating coil 110 of the switch 13. The switch 18 is adapted to establish the circuit of the actuating coil of a set-up relay 22. The switch 19 controls the circuit of the actuating coil of the switch 112. The switch 20, which is operable by the motor 3, controls the circuit of the other motor 4, and the switch 2066, which is operable by the motor 4, controls the circuit of the motor 3.

Skip hoists are usually provided with two skips one of which is lowered, empty, While the other is raised, loaded. Upon each skip reaching the end of its path of travel, a mechanism operated by the skip hoist is adapted to operate a limit switch 24 or a like switch 124 into engagement with the one or the other of two stationary contact mem bers and 71, depending upon whether the particular one of the two skips is being raised or lowered. The limit switches 24 and 124 may be operated by cams controlled by a shaft, like the shaft 21, that is operatively connected to the skip-hoist motor, or the'y'may be operated in any other desired manner. The contact members 70 and 71 are connected to the positive line conductor 1 through a master switch 508 which controls the skip-hoist motor, upon the master switch 508 being actuated into engagement with a contact member 506 or a contact member 507 to reverse the skip-hoist motor. The limit switches 24 and 124 close a circuit for the actuating coil of the relay 22 which controls the circuits of the small-bell motor 3.

The operation of the large-bell motor 4 is controlled by a sequence switch 26. The sequence switch 26 is illustrated diagrammatically only, as it forms the subject-matter of a co-pending application, by C. H. Hot gkins, Serial No. 281,505, filed Mar. 3, 1919, and assigned to the same assignee as this application. The sequence switch 26 comprises a disk 514 upon which are mounted rotatable cam members 27 for momentarily actuating a switch 28. The cam members 27 are adjustably,longitudinally arranged in radial sockets of the disk 514, so that they may occupy positions such as that illustrated, in which they extend beyond the circumference of the rotating disk 514, or they may occupy positions (not illustrated) within the said circumference. In the latter event, the

cam members 27 are inoperative to effect the operation of the switch 28. The switch 28 may be closed by such of the cam members 27 as occupy positions in which they extend beyond the circumference of the disk.

In the drawing, those cam members 27 only are illustrated which extend beyond the circumference and which, therefore, are operable to effect the closing of the switch 28. There are usually twenty cam members 27, the number twenty being chosen because it is desirable to operate the large-bell motor 4 after a series of operations of the smallbell motor 3, which series is usually a factor of 20. The magnitude of the factor is determined by the number of cam members 27 which are fixed in operative positions like those indicated in the drawing.

The sequence switch 26 is adapted to be driven from one end of the shaft21, which is rotatable with the small-bell motor 3, by a crank arm 29 which, through a crank or link 129, actuates a toggle or lever 30. A pawl 31 is pivotally attached to an intermediate point of the lever 30 to intermittently engage a ratchet member 32 that is rigidly connected to the disk 514 so as to rotate therewith. At each revolution of the shaft 21, which is driven by the small-bell motor 3, the crank 29 causes the advance of the pawl 31 to effect a partial rotation of the ratchet member 32, after which the pawl 31 is withdrawn from engagement with one of the ratchet teeth, on account of the return movement of the crank 29, and is placed in engagement with the next consecutive ratchet tooth. As the ratchet member 32 has as many teeth as there are cam members 27, preferably twenty in number, one completerevolution of the sequence member 26 willbeeffected after twenty complete revolutions of'the shaft 21., If, for example, every fourth cam member 27. is adjusted to the position shown in the drawing, there will be five operations of the motor 4 and twenty operations of the motor 3 during one complete revolution of the sequence switch 26. An accentuating device, not illustrated, is. provided for maintaining the sequence switch 26 in the exact position to which it is actuated by the pawl 31.

The motor 8 is operatively connected to the small bell of a blast furnace and the motor 4 is operatively connected to the large bell.- The bells may be so designed as to be actuated to closed positions by counterweights, the motors 3 and 4 operating in opposition to the forces of the counterweights, to open the bells. The motors 3 and 4 are continuously operated at varying speeds to complete cycles of operation, each comprising an entire revolution, to effect or permit the successive opening and closing of the bells.

The motors are automatically operated through their cycles of operation when a control drum 75, shown in elevation in Fig.

2 and diagrammatically, in developed form,

in Fig. 1, occupies its illustrated position. The control drum 75 is adapted to be actuated to any one of five positions, respectively labeled Automatic, Overload reset, Off, Manual and Extra. A pointer upon the handle of the control drum 7 5 indicates which of the five positions the drum 75 is occupying. The small bell may be stopped in open position by actuating the drum 75 to the Manual position and then, when the small bell has reached the open position, to the Off position. The large bellmay be similarly controlled by its drum 75. Upon the drums being returned to their Automatic positions, the bells will be returned to their initial positions.

hen the drums occupy the Extra positions, their motors may be operated through extra cycles of operation. This is effected, as explained below, through the medium of the switches 24, 12A or 28, upon the drums reaching the Extra positions. The drums then immediately resume their Automatic positions. The immediate return of the drum to the Automatic position is effected by means of. a spring 7 5a which is secured to the lower portion of the drum 7 5 and which has a portion 7 5?) for engaging a stationary pin 750. When the drum 75, therefore, is actuated from. the Automatic position toward the Extra position, the portion 7 5b of the spring 7 5a engages the pin 7 to place the tension upon the spring 75a so. that, upon the operator releasing the handle of the-control. drum 75, the spring 75a will return the drum'75 to the Automatic position, in which it will be stopped by the usual .accentuating device.

The extra operation may be made without disturbing the sequence of operation of the motors because the pawl '31 is adapted to be actuated. to its inoperative position by a solenoid 160 when the interlocking drum 6O occupies one of the broken and-dotted-line positions of Fig. 2. The drum 75 is normally prevented from being actuated to the lvlanual or the Extra position by a projection 61 which ismaintained in operative relation to the drum '75 by the interlocking drum when the latter occupies the full line position of Fig. 2. Upon the interlocking drum 60 being actuated to one of its broken-and-dottedline positions, the projection 61 will be actuated out/of operative relation to thedrum by a spring 161a. The operating handle of the drum 7 5 (which handle is illustrated in its normal position, corresponding tothe Of position of the drum), is provided with a projection 260 which is adapted to engage a pin 261 upon the top of the cover member (not shown) of the controller. The pin. 261 is normally maintained, by a padlock 360, in such position as to engage the projection 260 on the handle, upon'the operation of the drum 75, in a clockwise direction, toward the Manual position. The key to the padlock may be retained by a foreman or other suitably authorized person, who alone may unlock the padlock, thus permitting the pin 261 to drop out of operative relation to the projection 260, permitting the actuation of the drum to its Manual position. The drum 7 5 may be actuated to the Overload reset position without in any way disturbingthe interlocking drum 60 or the pin 261. In the Overload reset position, the drum 75 is adapted to reset overload relays and 81.

The shunt field-magnet winding 7 is normally energized by a circuit extending from the positive line conductor 1, through a con-' trol switch 8-2, the actuating coil of the overload relay 80, the shunt field-magnet winding 7, the actuating coilof the field relay as, the actuating coil of the overload relay 81 and the switch 8%, to the negative line conductor 2. The field relay 42is thus normally closed.

Assuming that the ship-hoist mechanism has been operated to hoist one of the skips and to empty it, and that the master switch 508 has been actuated out of engagement with the contact member 506 and into engagement with the contact. member 507 to effect the reversal of the skip-hoist motor, the skip hoist will'begin to descend, .whereupon the limit switch 124k will be automati: cally actuated into engagement with the contact member 71. A circuit will then be established from the master switch 508, which is connected to the positive line conductor 1, through the contact member 507, the limit switch 124, and a contact segment 74 of the interlocking drum 60, by a conductor 76, through a switch 75a, which is mechanically connected to the relay 22, a limit switch 18 and the actuating coil of the relay 22, by way of conductors 176 and 78, and through a knife switch 79, which governs the control circuits of the motor 3, to the negative line conductor 2. The relay 22 will thereupon be closed by its actuating coil. It will appear that the relay 22 initiates the operation of the motor. It will be evident at this point, therefore that, unless the contact segment 74 occupies its illustrated position, the relay 22 cannot be closed and the motor cannot, therefore, be started. When the contact segment 74 occupies some other position than that illustrated, therefore, the skip hoist may be operated without the switches 24 and 124 setting the motor into operation. This feature is of particular importance in connection with Extra or Manual operations of the motor, for the skip hoist may then be operated without disturbing such Extra or Manual operations.

A holding circuit for the actuating coil of the relay 22 is established from the positive line conductor 1, through one blade of the control knife switch 79, by way of a conductor 82, through a contact member 182 of the control drum 75, by way of a conductor 88, through a switch 175, which is mechanically connected to the relay 22, the limit switch 18 and the actuating coil of the relay 22, by the conductors 176 and 78 and through the other blade of the switch 79, to the negative line conductor 2. This is really a transfer circuit, the switch 75a being adapted to remain closed until after the switch 175 closes. The switch 175 is, in practice, connected directly to the positive line conductor, and not through the switch 182.

A circuit may now be traced from the contact member 182, which is connected to the positive line conductor 1, by way of the conductor 88, through the relay 22 and the limit switch 20a which is controlled by the motor 4, by way of the conductor 150, through the overload relay 80, by way of the conductor 151, through the field relay 42, by way of the conductor 153 and through the limit switch 117, the actuating coil 110 of the switch 13, the overload relay 81 and the switch 79, to the negative line conductor 2. The switch 13 is thereupon closed by its actuating coil 110.

A second circuit is established from the relay 42 which, as above traced, is connected to the positive line conductor 1, by way of i a conductor 154, through the actuating coil of a brake relay 93, the overload relay 81 and the switch 79, to the negative line conductor 2. The brake relay 93 will thereby be actuated to close the circuit of the brake winding 94, which extends from the positive line conductor 1, through the switch 84, the actuating coil of the overload relay 80, the brake coil 94, the brake relay 93, the actuating coil of the overload relay 81 and the switch 84, to the negative line conductor 2. The coil 94 will, therefore, be energized to release the brake and to permit the motor 3 to operate.

The closing of the switch 13 effects the closing of the switch 114 which is mechanically connected thereto, whereby a circuit is closed which extends from the field relay 42, which is connected to the positive line conductor 1, through the switch 114, by Way of a conductor 156, through the actuating coil of a switch 14, the overload relay 81 and the switch 79, to the negative line conductor 2. The switch 14 will thereupon be closed, establishing a circuit from the con ductor 156, which, as just shown, is connected to the positive line conductor 1, through a switch 97 which is mechanically connected to the switch 14, the actuating coil of the switch 15, the overload relay 81 and switch 7 9, to the negative line conductor 2. The switch 15 is thereupon closed. A switch 98, which is also mechanically connected to the switch 14, establishes a holding circuit for the actuating coil of the switch 14.

Energization of the actuating coils of the switches 14 and 15 and the consequent closing of those switches efi ccts the closing of the motor circuit, which extends from the positive line conductor 1, through the switch 84, the actuating coil of the overload relay and the switch 14, by way of conductors 198 and 99, through the armature 5, the series field-magnet winding 6, the resistor 9, the actuating coil of a relay 49, which is mechanically connected to the switch 15, the switch 15, the actuating coil of the overload rclay 81 and the switch 84, to the negative line conductor 2.

It will be noted that, though the switches 13, 14 and 15 are all closed, the switch 13 does not, at this time, control the motor circuit, but the closing of this switch is essential to the operation of the switch 114, which is mechanically connected thereto and which controls the circuits of the actuating coils of the switches 14 and 15, these, in turn, closing the motor circuit. The switch 13, however, performs a function described hereinafter, which is dependent upon its occupying its closed position. If the switches 14 and 15 were arranged to be closed before the switch 13, a dynamicbraking circuit would be closed through the switch 113 which would prevent the clos- All ing' of the switch 13. It is essential, therefore, that this switch 13 bclosed before the switches 14 and 15 operate.

Upon establishing the above-traced circuit of the motor, the motor 3 will commence to operate at slow speed, the resistor 9 being in series with the armature 5. The motor will thereupon commence to rotate the shaft 21, whereby the switch 16 will b come closed to establish a circuit for the coil 110 independent of the relay 22. This circuit extends from the contact member 182, which is connected to the positive line conductor 1, through a contact member 157, by way of a conductor 158, and through the limit switch 16, to the limit switch 20a which is controlled by the motor 4, the circuit for the actuating coil 110 of the switch 13 being otherwise the same as above described. The relay 22 is thus shunted by the switch 16, so that the opening of the relay 22 will not interf re with the operation of the motor during the remainder of its cycle. Upon continued operation of the shaft 21, the limit switch 18 will be opened to break the holding circuit for the actuating coil of therelay 22, whereby the relay will drop open by gravity, to remain open until the relay 22 becomes closed again by the limit switch 24 or the limit switch 124 to effect again the starting operation of the motor.

In my above-mentioned application, the relay 22 is replaced by a relay of the same type as the overload relays 80 and 81, so that the relay will be maintained closed by gravity instead of depending upon its actuating coilv The system of the said application is preferable for the reason that, should a failure of voltage take place between the time when the relay 22 is first closed and the limit switch 16 becomes closed to maintain the circuit which is initially established by the relay the motor 3 would fail to operate through one cycle of operation and the sequence of operation between the motors 3 and 4 would be thereby disturbed. The system of my above-referred-to application is a little more complicated than the present system and, since it is seldom that voltage failure takes place at the very time between the closing of the relay 22 and the closing}; of the limit switch 16, the system of the present application is usually suiiicient to guard against the disadvantages flowing from voltage failure. The system of my abovementioned application is designed to guard aeainst disturbance of the cycle of operation between the motors 3 and 4 which might be caused. by voltage failure at any time. present system is designed to guard at voltage failure at all times exce t between the closing of the relay 22 and the closin of the limit switch 16. This will be evident from the fact that an additional controllinrr circuit for the actuatinq coils ot the switches 1 and 15 is ontrolled by the limit switch 17 toward the end ot the of operation. The holdins" circuit for the actuating coil of the switch 14 may be traced from the limit switch 20a, which is controlled by the motor 4, and which, as above explained, is connected to the positive line conductor 1, by way of the conductor 150, through the overload relay 80, by way of the conductor 151, through the relay 42, by the conductor 153, through the limit switch 17, by way of the conductor 156, and through the actuating coil of the switch 14, the overload relay 81 and the switch 7 9, to the negative line conductor The switch 17 thus shunts the switch 114 when the switch 117 is open, so that, after voltage failure at this time, the switches 14 and 15 may be closed to complete thecycle. The switch 97, which is mechanically connected to the switch 14, normally (that is, except after voltage failure) controls the circuit of the actuating coil of the switch 15. The switches 14 and 15, being controlled by the limit switch, will, therefore, remain closed until the motor 3 has completed its cycle of operation. The advantage of the above-described circuits for the actuating coils of the switches 14 and 15 is that, toward the end of the cycle of operation of the motor 3, after the switch 13 has become opened, as by voltage failure, it would be impossible to restart the motor so as to complete the cycle (because it would be impossible to reclose the switch 13, the relay 22 being open) unless some'method were provided for energizing the coils l4 and 15 in some manner other than through the switch 114, which is mechanically connected to the switch 13. In the final position, the switch 16 will open to cause the opening of the switch 14.

The motor circuit, as above shown, comprises the energizing coil of the currentlimit relay 49 which is mechanically connected to the switch 15. So lone as the current traversing the motor exceeds a predetermined value, the relay 49 will be maintained open, though it becomes mechanically released upon the closing of the switch 15. As soon as the current traversing the motor falls to a predetermined value, the relay 49 will becomeclosed by gravity, whereupon a circuit will be established for ciiiectingr the actuation of the switch 10, this circuit extending; from the positive line con ductor 1., through the switch 79, by way of conductor 82.v through a- .switch 103, which is mechanically connected to the switch 112 and which closed when the switch 112 is open, the relay 49, a switch 104, which is mechanically connected to the switch 12 and which is closed when the switch 12 is open,

and the actuating coil of the switch 10, by way of a conductor 78, through the switch '79, to the negative line conductor The switch 10 will thereupon be closed by its coil to effect the short-circuiting oi a portion of the resistor 9.

The circuit for the motor will now extend from the positive line conductor 1, through the switch 8%, the actuating coil of the overload relay 80, the switch 14, by way of conductors 9S and 99, through the armature 5, the series field-magnet winding 6, a large portion of the resistor 9, the energizing coil of a relay which is mehanically connected to the switch 10, and the said switch by way of a conductor 106, through the switches 13 and 15, the actuating coil of the overload relay 81 and the switch 84, to the negative line conductor 2. The switch 13 thus performs a useful function in connection with the short-circuiting operation of the resistor 9, that is, it serves to insert the starting resistor during dynamic braking, when the switch 113 is closed. It is necessary but to open the switch 12, because the switches 10 and 11 are opened by the switch 1041; upon the closing of the switch 12. In similar fashion, upon the closing of the relay which is mechanically connected to the switch 10, in accordance with the value of current traversing the motor circuit, the switch 11 will become energized and, upon the closing of this switch, an additional portion of the resistor 9 will become short-circuited. Similarly, the switch 12 will be closed upon the closing of a relay which is mechanically connected to the switch 11. Upon the closing of the switch 12, the resistor 9 will be entirely short-circuited.

The closing of the switch 12 effects the opening 01? the switch 104 and this, in turn, breaks the circuit of the actuating coil of the switch 10. Upon the switch 10 becoming opened, the current-limit relay, which is mechanically connected thereto, will also be opened to effect the opening of the circuit of the actuating coil of the switch 11. This, in turn, will break the above-traced circuit for the actuating coil of the switch 12. A holding circuit for this coil is first, however, established by a switch 107 which is mechanically connected to the switch 12. This holding circuit comprises the switch 108 and the relay 49. Although the switches 10 and 11 will thus be opened, the switch 12 will be maintained closed to maintain the resistor 9 short-:ircuited. The motor 3 will consequently operate at normal speed.

Upon the motor 3 approaching the end of the first half of its cycle of operation, the

limit switch 19 will become closed to effect the closing of the switch 112. The limit switch 19 elfects the closing of a circuit which extends .lrom the contact member 182, which is CODHGCLGCl to the positive, line conductor 1, by way of the conductors 88 and 188, through the limit switch 19 and actuating-coil of the switch 112, by way of the conductor 78 and through the switch 7 9, to the negative line conductor 2. Upon the closing of the switch 112, the switch 103 and the switch which is mechanically connected thereto will become opened. The opening of the switch 103 will effect the opening of the circuit of the actuating coil of the switch 12, which switch will thereupon become opened by gravity to reinsert the resistor 9 into the armature circuit. The switch 112 establishes a dynamic-braking circuit for the motor which extends from one terminal of the armature 5, by way of conductors 99 and 108, through the switch 112, by way of a conductor 109 and through the dynamic-braking resistor 51, to the other terminal of the armature 5. The motor is thus brought to a gradual stop by dynamic braking as the small bell is brought to the limit of its downward movement.

The motor is not disconnected from the line at the end of the half cycle, where the switch 112 is closed. The closing of the switch 112 shunts the armature with the resistor 51, and the resistor 9 is inserted into the armature circuit, merely effecting a slowing down of the motor.

The motor continuing to operate, the limit switch 19 will again be opened, to break the circuit of the actuating coil 01' the switch 112, which switch will thereupon drop open by gravity to effect the opening of the above-described dynamic-braking circuit. The motor will thereupon start to operate once more with the resistor 9 in circuit with the armature The switches 10, 1.1 and 12 will again become closed, in the same manner as above described, in accordance with current conditions, to effect the automatic acceleration of the motor to normal speed. The small bell is actuated upwardly toward its closed position. WVhen the bell approaches the limit of its upward movement, the circuit of the actuating coil of the switch 110 will be broken by the limit switch 117, whereupon the switch 13 will fall open by gravity. A second dynamic-braking circuit will be established, the circuit extending from one terminal of the armature 5, by way of the conductor 99, through the switch 113, a coil 210 and the resistor 51, to the other terminal of the armature 5. coil 210 will operate to maintain the switch 13 open and the switch 113 closed so long as current of appreciable Value flows through the dynamic-braking circuit. The small bell, therefore, will be slowed down as it approaches its lower limit and will ultimately be brought to a stop.

During the above-described operation of the motor 3, the shaft 21 has been rotated throughout a complete revolution. The

The

crank mechanism 29 has accordingly operated to-actuate the toggle 30 so as to drive the pawl 31 to the right, as shown in Fig. 1. The pawl 31, engaging one of the teeth oi: the ratchet member 32, has rotated this ratchet memberthrough a small angle equal to1/20 of the circumference and the pawl 31has then been actuated to its initial position, where it engages a succeeding'tooth of the ratchet member 32. In this manner, after each complete operation of the motor 3 and a corresponding rotation of the shaft 21, there has been a partial rotation of the ratchet member 32 and the sequence switch 26 equal in angular value to'1/20of a circumference; I'Laiter each operation of the ratchet member 32 and of the sequence switch 26 connected thereto, the cam 27 which is inproximity to'the switch 28 occupies a position within the limits of the circumference of the sequence-switch disk 514:, theoperationof the sequence switch will be without effect to control the" motor 4. The skip li'oist mechanism will successively trip the limit switches 24* and 124: to effect complete operations of the motor 3 and of the sequence switch 26 controlled thereby, until anumber of operations of the small hell have been effected, equal in number to the number of operations desired as determined by the adjustment of the cam members 27 of the sequence switch 26;

Atter this predetermined number of op erations of the motor 3, a cam member 27 will close the switch 28, whereupon a circuit willbe established for the actuating coil of a relay (not shown) similar to the relay 22, but which controls the motor i. As the circuit connections are identical with those for the motor 3, save that the switch 28 replaces the switch or the switch 71, the circuit connections have been omitted in order not to complicate the drawings. It will be, understood, however, that the relay, corresponding to the relay 22, for the motor at will effect the closing of control circuits similar to those already described for the motor 3, whereupon the motor a will be aperated through a complete cycle of operation, A portion of the interconnecting control circuits between the motors 3 and 4 is illustrated in Fig. 1, the limit switch 16a, which is controlled bythe motor 4;, being connected by a conductor 35 to the limit 7 switch 20, which is controlled by the motor 3,- in a manner similar to that in which the limit switch 16, which is controlled by the motor 3, is connected to the other limit switch 20a, which is controlled by the motor 4. A controlling mechanism, similar to that shown in- Fig. 2 for the motor 3, is provided for the motor 4, the only difference between the two being that the contact segments 161 and 162, which are provided upon the interlocking drum 60 of the motor 3, for controlling the circuit of the coil 160, areomitted from the corresponding control mechanism for the motor 4:.

In case'the overload relays 80 and 81' of either motor are opened upon the occurrence otoverload conditions, they may be reclosed' by moving the control drum to such position that the pointer of thecontrollerhandle will be in the position marked Sverload reset. This will break the. engagementof the contact members 1 82- and 157 with the corresponding stationary contact members and will make contact between. stationary contact members and contact members 250 and 251. The above-described actuation of the control drum '75 will establish a circuit from the positive line conductor 1 through the switch 79, by way of the'condu'ctor 82, through the contact members 250, 157, 210 and 251, by way of a conductor 211, through the coils which actuate the latch mechanisms of the overload relays and 81' and" the switch 79, to the negative line conductor 2 The overload relays 80' and 81, which become latch-ed, in open position, upon overload conditions, thereupon' become released and become closed by gravity.

When it is desired to etl ect a manual control of the motor 3 without disturbing the sequence of the operation between the motors 3 and 4c, the interlocking drum 60 must be moved to the one or the other of its dotteddine positions so as to release the projection 61 from the illustrated position, in which it prevents the operation of the control drum 75, and the padlock- 360 must be removed so as to permit the pin 261 to fall out of the way of the projection The drum 75 may then be actuated to the Manual position. So long as the drum 75 is maintained in this position, the motor will continue to operate. The motor may be stopped in any position by actuating the drum 75 from the Manual to the Off position.

When the interlocking drum is operated to one of the broken-and-dotted-line positions a: circuit is established from the line conductor 1, through the control switch 79, by way of the conductor 82, through the contact member 161 or the member 162, as the case may be, by way of a conductor 814:, through the coil 160, by way of the conductors 176 and 78 and through the switch 79, to the negative line conductor 2. The pawl 31 is thereupon raised, so that the motor 3 may be operated without affecting the rotational position of the sequence switch 26.

Another circuit is established from the conductor 82, through contact members 215 and 216 of the control drum 7 5, y way of conductors 217 and 150, through the overload relay 80, by way of the conductor 151, through the field relay 42 the conductor 158, the limit switch 117, the actuating coil 110 of the switch 13, the overload relay 81 and the switch 79, to the negative line conductor 2. The coil 110 is thus energized independently of the relay 22. The opera tion of the motor 3 throughout the extra cycle will be the same as that above described.

It will be noted that the circuit, just traced, for the actuating coil 110 does not include the limit switch 20a which is controlled by the motor 4. The corresponding circuit, which is controlled by the drum 75 for the motor 4;, is independent of the limit switch 20' which is controlled by the motor 3. here as ordinarily, therefore, both motors 3 and l cannot be operated together, because the control circuit for starting either motor depends upon the limit switch .20 or the limit switch 205/. being controlled by the other motor occupying its closed position, when the two drums 75 are actuated to their Manual position, both motors 3 and i may be actuated together. It is thus possible, without disturbing the sequence of operation of the two motors, to operate either one independently of the other, or both simultaneously.

The drum 7 5 is'automatically spring-returnable, as above described, when occupying a position between the Extra and the Automatic positions. The extra operation may be effected by the drum 7 5 being moved momentarily to the Extra position, the drum 75 being then immediately returned to the illustrated Automatic position (Fig. 2). The drum is obviously not spring-returnable from positions between the Automatic and the Manual positions. To effect an extra, complete operation, a momentary actuation of the drum 75 to the Extra position suffices; but as soon as the drum 75 is actuated from its Manual position, that moment the motor stops. The operator may obtain Extra operations at will; but Manual operation is prevented by the padlock. In this way, an extra skip load of any material may be dumped into the small bell without, however, altering the normal ratio between the number of operations of the large-bell and small-bell motors, as previously explained.

The spring-returnable feature, though preferable, is by no means necessary, because the circuit of the coil 110, after the relay 22 opens and the switch 16 closes, comprises the drum-contact member 157. If the drum 7 5 were to be left in the Extra position, therefore, the cycle would not be completed until the drum was returned to the Automatic position; hence the necessity of returning the drum to the Automatic position.

If another Extra operation is desired, the drum 75 must again be moved to the Extra position. This is because the switch 22 is shunted by the switch 16 and the contact segment 157. By the time that the switch 16 is closed and the switch 18 opened, the drum 75 must be returned to the Automatic position, or the cycle will not be completed.

In accordance with the requirements of the patent statutes, I have described my invention in connection with a specific embodiment thereof. It will be evident, however, that my invention is not limited to the details shown and described and I desire, therefore, that the appended claims be construed broadly except in so far as limitations may be specifically imposed therein.

I claim as my invention:

1. The combination with a machine and a controlling device therefor having two operative positions, of means for controlling said machine when said device occupies one of said positions, means for preventing the control of said machine under predetermined conditions and means for rendering said preventing means ineffective upon the operation of said device to said other position.

2. The combination with a machine and a controlling device therefor having two operative positions, of means for controlling said machine when said device occupies one of said positions, means for preventing the control of said machine under predetermined conditions, means for rendering said preventing means ineffective upon the operation of said device to said other position, and means for preventing the unauthorized actuation of said device to said one position.

The combination with a machine and a controlling device therefor having two operative positions, of means for controlling said machine when said device occupies one of said two positions, means for controlling said machine when said device occupies said other position and means normally biased toward an inoperative position for preventing the actuation of said device to said one position until said first-named means is inoperative.

4:. The combination with an electric motor and a controller therefor having three operative positions, of means for automatically controlling said motor when said controller occupies one of said positions, an overload relay adapted to close upon said controller being actuated to said second position, means for permitting the actuation of said controller to said third position to effect the manual control of said motor and means for preventing the unauthorized actuation of said controller to said third position.

5. The combination with an electric motor and a controller therefor having two operative positions, of contact means for manually controlling said motor when said controller occupies one of said positions, contact means for automatically controlling said motor when said controller occupies the other position, a second controller normally adapted to permit such automatic control. but having a position adapted to effect suspension thereof, and means for preventing the actuation of the first-named controller to the manual control position until said suspension has been effected.

6. The combination with an electric motor and a controller therefor having two operative positions, of contact means for manually controlling said motor When said controller occupies one of said positions, contact means for automatically controlling said motor When said controller occupies the other position, a second controller normally adapted to permit such automatic control-but having a position adapted to effect suspension thereof, and an interlocking lug associated With said controllers for permitting the actuation of the first-named controller to the manual control position only when said suspension is effective.

7. The combination With an electric motor and a controller therefor having two operative positions, of contact means for manually controlling said motor when said controller occupies one of its positions, a pawland-ratchet device, an actuating magnet therefor, contact means for automatically operating said device as a part of the automatic control of said motor when said controller occupies the other position, a second controller normally adapted to permit such automatic operation of said device but having a position adapted to energize said magnet and suspend the operation of said device, and means for preventing the operation of the first-named controller unless said device has been rendered inoperative.

In testimony whereof, I have hereunto subscribed my name this th day of April 1919.

EDWIN s. LAMMERS, JR.

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