US2529804A - Remote hoist control - Google Patents

Description

N V- 1950 w. HARNISCHFEGER ET AL 2,529,804

REMOTE HOIST CONTROL 4 Sheets-Sheet 1 Filed April 27, 1946 INVENTORS ATTO/P/VL X MQQQQ O 14, 1950 w. HARNISCHFEGER ETAL 2,529,804

REMOTE HOIST CONTROL Filed April 27, 1946 4 Sheets-Sheet 2 HOIST do QM BATTERY TEST W INENTORS Nov. 14, 1950 Filed April 27, '1946 W. HARNISCHFEGER ET AL REMOTE HOIST CONTROL 4 Sheets-Sheet 5 Alan/4% 1950 w. HARNISCHFEGER ETAL 2,529,804

REMOTE HOIST CONTROL 4 Sheets-Sheet 4 Filed April 27, 1946 INVENTORS Patented Nov. 14, 1950 OFFICE REMOTE HOIST CONTROL Walter Harnischfeger, Milwaukee, and Glenn Koehler, Madison, Wis.

Application April 27, 1946, Serial No. 665,362

6 Claims. 1

This invention relates to cranes, hoists and lifting devices adapted to be controlled from a distance and resides more specifically in an electrically driven hoist adapted to be raised, lowered or stopped through radiated impulses emitted by a portable control transmitter which may be carried to and operated at a point where a lift is to be made or at any other location in the vicinity of the hoist.

Many power driven hoists particularly that form thereof known as traveling overhead cranes are employed in locations where large and irregular periods of idleness occur. In such instances it is uneconomical to maintain an operator in constant attendance and it is also inconvenient for a temporary operator to have to climb to the operators cab "each time it is neccesary to use the crane. To avoid this difficulty efforts have been made to employ pendant mechanical or electrical control cords through which the crane maybe operated and controlled by a person situated on the floor who requires the services of the crane. For certain limited applications the pendant cord control is quite serviceable, but where large obstructions either temporary or permanent exist within the area served by the crane it is dangerous to depend upon pendant cord control. Also, with pendant cord control rates of traversing of the trolley and bridge must be kept below that of a walk in order to permit the person operating the crane to keep up with pendant cord.

In accordance with this invention means are provided by which an overhead crane may be controlled from any point on the floor by a control box or transmitter having no physical connection whatever with the traveling parts of the crane. In this way the dangers introduced by pendant cord control are avoided, eificient speeds are rendered feasible and the temporary operator need not climb to the control cab of the crane in order to put the same in use.

This invention is herein described by reference to the accompanying drawings forming a part hereof and in which there is set forth by Way of illustration and not of limitation one form in which the apparatus of this invention may be constructed.

In the drawings:

Fig. 1 is a circuit diagram of the receiving, control and power circuits for the three motors giving motion to the bridge, trolley and hoist of an overhead crane;

Fig. 2 is a circuit diagram of a transmitting control circuit adapted to activate the receiving control circuit of Fig. 1;

Fig. 3 is a front view in elevation of the transmitting control circuit housing; 7

Fig. 4 is a diagrammatic perspective view of the parts of one of the selector switch units which perform circuit selecting operations in response to received control pulses;

Fig. 5 is an end View in elevation of a remotely controllable crane with which the circuits and parts of the foregoing figures may be employed.

Fig. 6 is a circuit diagram of a control transmitter adapted for control of a slightly difierent form of apparatus of this invention; and

Fig. 7 is a circuit diagram of a control receiver adapted to be actuated by the control transmite ter of Fig. 6.

The form of the apparatus of this invention illustrated in the drawings comprises, as shown in Fig. 5, a bridge or girder I mouted on end trucks 2, arranged to travel on overhead runways 3. An electric driving motor or bridge motor 4 is mounted on the bridge I as shown and connected by transmission shafting, not shown, and gearing 5 with the wheels of the end trucks 2 so as to propel the bridge in known manner. Secured to the upper faces of the bridge I are trolley tracks Ii, only one of which is shown, which support a trolley I in rolling engagement therewith. Trolley I is furnished with an electric trolley driving motor 8 connected by gearing, not shown, with wheels of the trolley so as to propel the same upon the tracks 6 in known fashion. Also mounted on the trolley 1 is the usual hoisting drum 9 from which hoisting line I0 extends downwardly as shown. Drum 9 is arranged to be driven through gearing, not shown, by an electric hoist motor II. Each of the motors 4, 8 and I I are provided with brakes not shown which are automatically released upon admission of electric power to the motors and automatically applied upon discontinuance of electric power admission in accordance with well established practice.

For supply of electric power (in this case three phase alternating current) main trolley rails I2 and collector shoes I3 are provided at the left end of the bridge I. Power mains not shown extend from the shoes to a control receiving unit I4 (to be described in greater detail) mounted near the right hand end of the bridge I from whence power is distributed to motor 4 by leads not shown and to motor 8 by trolley wires I5, I6 and IT and to motor II by trolley wires I8, I9 and 2|] and by appropriate connections between '3 the respective motors, not shown, and the collector shoe assembly 2 I.

To complete the apparatus a portable control transmitting unit 22 (to be described in greater detail) is provided which is capable of radiating pulses to be received by control receiving unit It which will cause the starting, stopping and reversing of the several motors 8 and II. From this it may be seen that an operator may command the operations of the crane through manipulation of the control transmitting unit 22 from any convenient location within the vicinity of the area served by the crane with all of the advantages previously described.

The power and control receiving circuits of the crane and the control receiving unit [4 are shown in greater detail in Fig. 1 where the bridge, trolley and hoist motors i, 8 and Ii respectively are diagrammatically indicated. Within the control receiving unit It is situated a master maintainer receiver 23 so designated on the drawing. The receiver 23 is made up of a tuned loop antenna unit 24, a first stage of tuned radio frequency amplification 25, a second stage of tuned radio frequency amplification 26 and a hot cathode gaseous discharge tube and associated circuit 21.

To provide power for the operation of the receiver 23, a power pack unit 28 having a transformer primary winding 34 is arranged to be supplied with current through lead 25 joined with main 1211, switch 3?), lead 3|, lead 52 and lead 33 joined with main 12b. Plate current for the amplifiers 25 and 26 is furnished by secondary winding 35 joined through rectifier 36 and filter elements 37 to ground and plate current supply lead 38 as shown. Current for supply of the cathode heaters of amplifiers 25 and 26 is supplied by secondary winding 39 as indicated. For heating of the filament of tube 21, secondary winding 53 is connected as shown, while bias for the grid of tube 21 is created by secondary winding 54. Bias for the grids of amplifiers 25 and 26 is provided for through grounding of voltage divider resistor 55 shown at 56. The output of amplifier 26 is applied to the grid of gas discharge tube 21 and when of sufficient intensity causes the tube 2'! to break down and become conducting completing a circuit from main 52a through leads 29, 40, 4!, tube 27, lead 42, choke 43 and lead 44 to the coil of sensitive relay 45 and thence through leads 46 and 47 back to main I21). Relay 45 is of the normally-open, delayed-release type being capable of remaining closed for about one second after excitation ceases. Upon closure of relay 45 a circuit is established extending from main 120, through lead 48, coil 49 of magnetic contactor master switch lead 5!], contacts of relay 45, lead 52 and thence through lead 4i back to main i2b. This causes the closure of master switch 5! and prepares the system for response to commands issued to it.

From the foregoing it will be understood that unless a nearly completely uninterrupted signal of sufficient strength is continuously received by the receiver 23 master switch 5| will not be closed and none of the motors 4i, 8 or H, supplied therethrough, can be operated. Receiver 23 is tuned to a specific frequency, for example, 410 kc. or other suitable frequency and is responsive to no other. Provision for its nearly steady excitation when needed by a signal of this frequency is made through means contained within the control transmitting unit 22 to be more fully described hereinafter.

For reception of commands directed to the hoist motor ll another receiver generally designated 57 is also mounted in the control receiving unit I4. The receiver 57 in manner analogous to receiver 23 is provided as shown with a tuned loop antenna unit 58, tuned radio frequency amplifier units 59 and 50 and a hot cathode gaseous discharge tube ill and associated circuit elements. These parts are supplied with power from the power pack 28 by connecting leads 38, Q! and 51 as previously described in the case of receiver 23.

The output of gaseous discharge tube 6| is confined to a circuit starting with main l2a and passing through leads 40 and ii to the filament of tube 6|. From thence the circuit passes to the plate of tube ti and then through lead 62, choke 53, lead 54, the two windings 55 and 10 of step-by-step unit 65, leads 66 and 5'? and then through lead 47 back to main l2b.

Receiver 5? is tuned to a specific frequency different from that of receiver 23, for example, 350 kc. or other suitable frequency and is responsive to no other. Provision for excitation of receiver 51 in pulses of controlled frequency, spacing, duration and number is made through means contained within the control transmitting unit 22, to be more fully described hereinafter.

Pulses delivered through the two windings B9 and it of step-by-step unit 55, cause the sweep contact 58 thereof to be shifted to one or another of the three possible positions thereof as more fully indicated in Fig. 4. As there shown the unit 55 comprises a pivotally mounted pawl support ll, normally held in the position shown, against the stop 72 by a spring l3. Attached to the support ll intermediate the ends thereof by means of an armature link 55 is an armature M positioned to be drawn into coil 59- upon excitation thereof. At the lower end of support H a pawl 76 is pivotally attached and normally held in the position shown by a spring ll.

Located so as to be engaged by the pawl 76 upon its actuation by coil 59 and armature M is that part of the toothed periphery of a ratchet segment is which is designated l9 and which constitutes the driving ratchet of unit 65. Ratchet segment 78 is secured to a rotatable shaft 36 normally held in and urged to return to the position shown by means of a spiral return spring 8!.

For temporary retention of segment 18 and shaft 80 in any position to which it may be advanced by the action of pawl 16 a pivotally mounted locking pawl 32 having a spring retaining finger 83 is provided and mounted as shown to engage that part of the toothed periphery of segment '58 constituting the temporary retaining ratchet designated Attached to the looking pawl 82Joy an armature link 84 is an armature 85 positioned within coil iii so as to be drawn to the left when the latter is excited. To restrain immediate return of armature 85 and associated parts under the influence of spring 85 when excitation of coil iii is terminated, pneumatic dash pct 87 is attached to the armature 85. Dash potfl'l is provided with sufficient ventage or leakage between the piston and cylinder wall thereof so that after an elapse of about 2 seconds following termination of excitation of coil iii, spring 86 will have taken charge to an extent necessary to cause disengagement of finger 83 from ratchet 83'. p g

By reason of. the structure of step-by-step unit 65 so far described upon simultaneous excitation of windings 69 and 10 in pulses of sufllcient intensity and spaced from one another by intervals less than 2 seconds but more than the brief interval required for return movement of pawl 16, segment 18 and associated shaft 80 are advanced clockwise in discrete steps against the action of spring 8|. As soon as properly spaced pulses cease for a longer interval than 2 seconds segment 18 and shaft 80 are released'to return to normal position against the stop 88. The interval of 2 seconds is given by way of example only and may be made longer or shorter as desired depending upon conditions to be fulfilled.-

.Secured to the end of shaft 80 opposite the segment 18 is an arm carrying an advancing pin 89 and an arm carrying a clearing lever 90. Advancing pin 89 is so located axially with respect to radial follower pin 9I as to come into contact therewith and to rotate the same and the independent sweep support shaft 92 upon which it is mounted whenever shaft 80 is sufficiently rotated. In like fashion clearing lever 90 is so positioned as to come into contact with and displace cam finger 93 and final holding pawl 94 to which the cam finger 93 is secured.

The sweep supporting shaft 92 is separate from the shaft 80 and rotatably mounted so as to carry the sweep contact arm 68 through an arc bringing the same into engagement with stationary step-by- step contacts 95 and 96. A spiral spring 91 secured to the shaft 92 operates to return the shaft 92 and arm 68 to and hold them against the stop 98. Also secured to the shaft 92 is a holding segment having a toothed ratchet portion 99 positioned to be engaged by the tip of holding pawl 94, the two notches thereon corresponding to the two angular positions in which sweep contact 68 is in contact with the stationary contacts 95 and 96.

In order to permit a single pulse series to produce either a net clockwise or counter-clockwise shifting of sweep contacts 68, advancing pin 89 and follower pin 9I are so related angularly, when the apparatus is in normal position, that 3 pulses or advancing steps of segment 18 are necessary to bring them into engagement with one another. Also clearing lever 90 and cam finger 93 are so related angularly that engagement thereof andrelease of holding segment 99 only takes place during movement of segment 18 from the second to the third step from the normal or starting position thereof. By reason of this a pulse series of less than .3 pulses will cause no change to take place in the position of sweep contact 68. A pulse series of 3 pulses will not move sweep contact if in the position shown in Fig. 4 or will cause it to be returned thereto from' either of its other two possible positions. A pulse series of 4 pulses will cause return of sweep contact 68 from any position occupied by it to normal position and will then move it into contact with stationary contact 95. In doing so clearing lever 99 passes beyond cam finger 93 and to avoid release of holding pawl 94 during return movement, clearing lever 90 is pivotally attached to the clearing arm at I 50 as to be free to lag by displacement of spring IOI during return movement without displacement of cam finger 93' and holding pawl .94. In similar fashion a pulse series of 5 pulses will carry the sweep contact 68 to and leave it in engagement with stationary contact 96 regardless of the position occupied at the start of the'pulse series.

While a pulse series of more or less than 3 pulses may be employed as a clearing or preliminary pulse series by simply varying the number of notches or steps inthe segment 18 and appropriately relating the angular positions of the other parts a three pulse clearing series is preferred. The reason for this preference is that the apparatus will ignore a spurious radiation having two accidental peaks spaced in a manner corresponding to the delay interval necessary and will stop safe in the rather improbable case of 3'such peaks being properly spaced. The apparatus will only be dangerously responsive to the very improbable coincidence of 4 or more such peaks occurring in properly spaced intervals. To provide a greater number of preliminary clearing steps is to introduce an undue lag in the response of the apparatus. To provide a smaller number is to unduly increase the possibility of response to spurious radiations.

Stationary contacts and 96 are employed as means by which selection is made of either forward or reverse driving of the hoist motor II. To this end contact 95 will complete a circuit from main I2b, through lead 41, lead 61, sweep contact 88, contact 95, coil of relay I02, lead I03, and lead I04 back to main I20. Relay I02 is of the normally-open, delayed-engagement type so that it will not respond to contacts made between contact 95 and sweep contact 68 when the latter is merely passing to and from a position of engagement with contact 96. However, when contacts 68 and 95 remain in engagement for an appreciable interval relay I02 closes and completes a circuit from main I2c through lead I04, lead I05, the contacts of relay I02, lead I06 to coil I01 of switch I08 and then through lead I09 back to power main I2a. This causes switch I08 to close for forward driving of hoist motor II to cause a lifting motion of hoisting line I0. In similar fashion engagement of contacts 68 and 96 causes closure of relay H0 and through lead III the energization of coil N2 of switch I08 to cause it to close for reverse or lowering driving of the hoist motor II.

When sweep contact 68 engages neither of the contacts 95 or 96 neither of the coils I01 or H2 is energized and switch I08 remains open so tha motor II is stopped.

For control of the trolley motor 8 and the bridge motor 4 control receiving unit I4 also contains receivers H3 and H4 identical in make up with receiver 51 with the exception that receivers H3 and H4 are tuned to respond, each to its own individual frequency. For example, receiver II3 may be tuned to respond to a frequency of 370 kc. and receiver I I4 to a frequency of 390 kc.

By reason of the identity of circuit and of parts in the receivers 51, H3 and II4 detailed description of the latter two is unnecessary and separate designating numerals for the parts thereof have therefor been omitted to avoid unnecessary confusion. It is sufiicient to point out that reversing switch I I5 under control of receiver II3 causes the stopping, starting and reversing of trolley motor 8 while reversing switch I I6 in like manner responds to receiver II4 to control bridge motor 4.

For excitation of receivers 23, 51, H3 and I I4 control transmitting unit 22 previously referred to is provided. The unit 22 as appears more clearly in Figs. 2 and 3 is made up of a three element vacuum tube II6 capable of driving an oscillating circuit with an output of limited Wat tage. The plate of tube I I6 is connected by lead II1 with the midpoint of a loop antenna II8 "7 which forms with capacitor I I Ban oscillating circuit'tuned'tothe frequency of the master main- -.taiiner'receiver-'23.- Inductively related to the loop I I8' is-coil I connected to the grid of tube 116 so as to maintain oscillation. Battery I2I "connected incircuitwith the filament of tube for heating-thesam'e is controlled by a switch or start stop button I22. For supply of plate currentibattery I22 shuntedby condenser I22 is provided and connected as shown. Upon closure of start button I22 which is self maintaining in either open or closed position antenna II8 begins to emit a steady radiation at its tuned frequencyggiven for-example as 410 kc. If at the same-time switch 38 in the control receiving unit I4"isclosed, master switch 5| promptly closes placing thecr'ane in readiness for use.

Connected as shown in Fig. 2 so as to augment the capacity of capacitor I it upon closure of dial switch I25'is a supplementary capacitor I26 of such capacity as to alter the frequency of oscillation in antenna I I3 to that of receiver I I4, for -=example, from 410 kc. to 390 kc. Dial switch I25 is of conventionalconstruction and therefor shown diagrammatically only, being of the type which makes contact on return-movement only, which return movement is accomplished at a regulated rate. By reason of this a series of pulses of 390 kc. frequency is interposed in the steady emission of 410 kc. frequency each time dial switch I25 is actuated. Dial switch I25 is so adjusted as to its return rate that the duration of each of the 390 kc. pulses is less than the interval during which relay will maintain itself in closed position. switch 5I isnot disturbed by any regular manipulation of dial switch I25.

In like manner capacitor I21 is arranged to augment the capacity of capacitor IIQ upon actuation of dial switch I28 to such an extent as .to alter the transmitter frequency to that of receiver H3 while capacitor I29 will accomplish a similar function upon actuation of dial switch I32 so as to alter the transmitter frequency to that of receiver 51.

For convenience there may be housed in the unit 22 a meter I3I for indicating the condition of batteries I2I and I23 upon closure of buttons I32 or I33 through connections not shown. A

meter IS I may also be provided for indicating plate current connected in circuit in well know manner not shown.

It maybe observed that the relationship between transmitting unit 22' and receiving unit It is such that a command issued to the crane can remain under execution only so long as the transmitting unit 22 is properly functioning. If .unit 22 fails from any cause receiver 23 is no longer excited and master switch 5I drops open. .In this way it is impossible for the crane to run away beyond the control of the transmitting unit 22. V

In. operation a person intending to use the crane carries the unit 22 to the location where supervision of the lift is most convenient. Switch 3'0 is assumed to be closed. The operator then pushes the start button I22 and dials either north or south on dial switch I25 to bring the bridge I over'the lift. Before, after or during movement of the bridge the operator may dial either east or west on the dial switch I28 to bring the trolley I to the desired position. Upon arrival of the bridge I at the desired location "stop is dialed on switch I25 and upon arrival of trolley I in the desired location stop By reason of this master ascgsoc is'dialed on the switch I33. Hoisting line I 6 at any time either before, during or after these motions-may be manipulated as desired by similar dialing of switch I39. Lifting, traversing and lowering of the load is accomplished in similar fashion. At any time all functions of the crane can be brought to a stop simultaneously by pushing'the stop-button of switch I22. Upon again pushing the start'button of switch I22 the crane will resume the execution of any pre-existing commands. v

In order to permit the clearing of pre-existing commands and to permit the placement of suspended advance commands without activation of receiver 23 inductance I35 and mechanically interlocked switches I35 and I3? are provided and connected as shown in Fig; 2. When the latter switches are moved from the position shown to a-position where I 36 and I3! are open, dial switches I25, I28 and I 36 may be actuated to move the step-by-step units of their respective receivers H4, I I3 and 5? to and from any of their three positions but without any of these commands being executed; When the switches I36 andIB'I are returned to the position shown in Fig. 2 execution of any existing command will then be brought about by reason of the activation of receiver 23. Itis preferred that a single mechanical actua'tor for the interlocked switches ISG and I3! be'provided as shown at I38 in Fig. 3.

While the apparatus as above described is embodied in the familiar form of an overhead traveling crane having three functions or movements, it is evident that the apparatus may be adapted to cranes or hoists having either more or less than three functions. It also is feasible if desired 7 to employ step-by-step units having more than three positions, controlled by appropriate dial switches in the transmitting unit 22, by which more than one forward or reverse driving speed may be selected.

In Figs. 6 and 7 is shown another form of the apparatus of this invention in which the control pulses are in the form of interruptions in the otherwise continuously emitted radiation produced by the control transmitter. As shown in Fig. 6 the control transmitter is made up of the 'threee lement tube I39 connected as shown in an oscillating circuit including an antenna I40 supplied by the plate current source MI through a dial switch M2. The dial switch I42 as shown is provided with an interrupted contact ring I43 over which the self-returning contact arm I44 may pass so as to cause interruptions in the plate circuit thus producing interruptions in the emitted radiation. In normal position the arm I 44 remains in contact with the contact surface I43 as shown. Filament current is supplied from the sourceI I5 and is arranged to be interrupted by the manual switch I45 when the apparatus is not in use. The signal emitted by the transmitter shown in Fig. 6 is adapted to be received by a receiver I tI having an antenna I23. The receiver I II may be of well known form and so constructed as to close' the circuit between leads I 49 and I 50 so long as asignal is being received from the transmitter shown in Fig. 6 and in so doing to energize the relay I5I with current supplied through control-current supply leads I52 and I53. The'relay I5 I is-of the rapidly operating type and is biased by a spring I54 away from the position shown in Fig. 7 but is held in the position there shown so long' as the transmitter 6 is emitting a signal.

Upon dialing of the switch I42 the several impulses in the form of signal interruptions which occur cause the relay I I to move from the position shown in Fig. '7 to the position to which it is biased by the spring I54 and to return therefrom each time an interruption impulse occurs. In the position shown in Fig. 7 contact I 55 of relay I5I being joined through lead I56 with control current supply lead I52 establishes a circuit through contact I51 and lead I58 with relay I59 and thence through lead I 60 back to control current supply lead I53. The relay I59 is of the normally open, rapidly closing, delayed release type and it acts through its contacts and leads I6I and I62 to close and maintain the closure of main power switch I63. When a pulse occurs and contact I55 leaves contact I51 momentarily, relay I59 remains undisturbed because of its delay characteristics thus maintaining the closure of main power switch I63.

The dropping of contact I55 due to an impulse also causes it to momentarily engage contact I64 which through a lead I65 momentarily energizes relay I 66 which is provided with a return connection through the lead I60. The relay I66 is also of the normally open, rapidly closing, delayed release type the amount of delay being sufficient to overlap at least two impulses caused by the contact arm I44 traveling at its normal rate. The closure of relay I66 is without immediate effect although a circuit from lead I60 through a relay I61, lead I68 and lead I69 is established in part up to a contact I 10. Upon termination of the first impulse contact I1I engages contact I10 thus completing the circuit referred to by reason of connection of contact I1I with lead I56, the effect of which will be more fully described hereinafter.

During each impulse including the first the contact I1I also momentarily engages the contact I12 but on the first impulse contact I12 connected through lead I13 with contacts of relay I61 finds the relay I61 open and, therefore, perfforms no function. The relay I5I is provided with an additional set of contacts I14, I15 and- I16 which likewise for reasons to be more fully ex lained hereinafter are idle during the first impulse.

At the end of the first impulse re-closure of contacts I and I 51 recharges relay I59 to insure maintenance of closure of main powerswitch I63. Also at the end of the first impulse contact I55 leaves contact I64, but relay I66 being of the delayed release type remains closed temporarily. At the end of the first impulse also, contacts I1! and I1?) close thus completing the circuit which su plies relay I61 which then closes. A single impulse such as this, however, does not operate to ca u e the execution of any control function which is felt by power elements of the circuit to be more fully described and if but a single impulse is received, relays I66 and I61 will again open.

If a succession of two impulses is transmitted and received, as soon as the second impulseinterruption starts relay I66 still under retention is recharged but without effect since relay I6! is still. under retention. The closure of contact I1 with contact I12, however, brings into play a new circuit since the contacts of relay I61 are now closed causing relay I11 which also is of the normally open, rapidly closed, delayed release type to become energized and to close contacts I11A' and I11B. Closure of contact I 11B is without immediate effect since it is joinedby lead I18 with contact I15 which at the start of the impulse is open; The function of contact I11B, however, is

.layed release characteristics of relay I11.

delayed, but briefly, since at the termination of the second impulse contact I 15 is engaged by contact I14 with a result to be described hereinafter. The closure of contact I11A, however, may be of immediate effect since it is interposed in a circuit extending from supply lead I52 through leads I56 and I19 through a ratchet release magnet I and thence through lead I8I,

contact I11A, lead I82, contact I83, lead I84, clearing switch I and lead I86 back to supply lead I53.

Clearing switch I85 is a part of a stepper switch mechanism 236 having a pivotally mounted control arm I 81 mounted on a shaft be attracted by the magnet I88 previously re-' ferred to. If the contact arm I 61 is found in any position other than that shown in Fig. '7 at the moment of starting of the second impulse switch I85 will be in closed position and the closure of relay I11 will result in the energizing of magnet I80 and the lifting of the retaining pawl I93 from the ratchet wheel I88 thus permitting the spring I89 to cause return of the arm I81 to the position shown in Fig. '7. By' reason of this any series of two pulses or the first two pulses of any series having a greater number of pulses than two will cause the arm I81 to return to the position shown in Fig. '1 regardless of where the same may be located.

At the end of the second pulse interruption contact I55 engages contact I51 maintaining retention of relay I59 and continued' closure of switch I63. The separation of contact I55 from contact I64 is without immediate efiect because of the delayed release characteristics of relay I66. At the same time contact I1I re-engages contact I10 insuring retention of relay I61. The separation of contact I1I from contact I12 is without immediate effect because of the de- The engagement of contact I14 with contact I15 now sets up a circuit through lead I18, contact H113 and relay I95 normally biased to the position shown which will be called the open position which is of the quickly attracted, delayed release type. This closes contact [95A for a purpose to be hereinafter described and opens the contact I83 so as to permit the retaining pawl I93 to return to retainingposition. On commencement of a third interruption impulse relays I59, I 61 and I95 maintain them selves temporarily while relays I66 and I11 are recharged so as to prolong the maintenance thereof. As a result all previously established circuits involving closure of the relays named are preserved and upon engagement of contact I14 with contact I16 a circuit is established for the first time through lead I96, contact I95A, lead I91, advancing magnet I92, lead I98 and lead I60 causing the advancing pawl I to move the arm I81 into contact with idle contact I99. As the third interruption impulse comes to a close relays I59, I61 and I are recharged to prolong the maintenance thereof temporarily and relays I66 and. I11 become self-maintained 11;. temporarily thus. preserving. circuits previously setup. through; these relays.

Ir-nofur-ther impulses occur, relays its. and H7. at the end of their delay period will drop open causing relays 16 i and i951- to follow at the end. of their delay period; Thearmlti'i will thus-be leftin contact with the idle contact 55353 Where it.v will remain: until 'anew pulse series of at least two pulses is applied. to cause arm I811 torreturnr to the position. shown in Fig. '7.

In a pulse series of more than three pulses at the commencement of the fourth interruption pulse, engagement of contact Il' 'i with contact I76 causes the motor magnet 52 to advance the-arm l8lto the segmentZilfi. At the end of the fourth interruption pulse contact arm it"? remains in contact. with segment are unless further pulses occur in the: series. For each pulse in the series in excess of four the arm I81. is successively. advanced to segments 25)! to 208, respectively, depending upon the number of pulses in the series. Atthe termination of any pulse series having more than two pulses contact arm 18? is leftin engagement with that segment last contacted in the manner described in connection with the termination of a three pulse series.

The segments 26% to 298 are connected shown soas to control a hoist motor 2%, a-

bridge motor 2m anda trolleymotor 2| i mounted as described in connection with previously described formsof the invention so-as to actuate the. three essential motions of an overhead traveling crane. a pulse series of sevenpulses willbring the arm I81 into engagementwith segment: 293- and if the pulse series there terminates such. engagement will be retained. In doing so a. circuit isestablished. through lead 2i2 extending from control current supply lead E52 through spring I89 and arm [8? to segment 2G3 and thence through lead 2|3 to reversing switch magnet- 2l4- and thence throughlead 2Hi-and the contacts 229 of relay 215 to the lead- 2-H which joins with control current supply lead E53. Magnet- 214 is of the delayed attraction type so that it will not respond to the passage ofarmit! across the segment 203- in movingto and from other segmentsbut only responds when the arm I8! is allowedto dwell for a substantial interval in contact with segment 203. Upon sufficient energization of magnet 2 Miorward driving contacts 2l8 are closed, thus supplying current.

from the power mains Zia-to the hoist motor 289 tocause the same to travel in the hoist direction. Atthe same time a maintaining contact 220 is closed by energization of the magnet 2M thus providingfor maintenance of the magnet 254 even though the arm I8? is subsequently. moved from engagement with segment 2%. This maintaining circuit extends through lead 22! and normally closed contact 222 and lead 223 into connection with control current supply main i52.' In entirely analogous fashion segment 28 is connected through lead 22 5 with magnet 225 arranged to close power contacts 226 to cause hoist motor 209 to travel in the lowering direction. Upon shifting of contact arm l8! from contact 283 to 2ilt'the maintaining circuit of magnet 21 3 becomes broken by opening of contact 222. At the same time contact 22? closes to establish a maintaining circuit for magnet 225 which will cause it to re-- main energized even though the arm It] is subsequently moved out of engagement with seg- In the casev of hoist motor 2t: 9

the-segment wills-required. to cause the magnet 2m to open the normally closed. contact 229 upon-which magnets225 and 2M. both depend. fortheirenergization. 'ilhusa four pulseseries will. cause stoppageiof. the hoist. motor 2694. re.--

garolless of. the direction iirwhich. it is traveling.

In-an entirely analogous mannera pulse series. of nine interruption pulses will through. switch.

assembly 2-30 cause, driving of bridgemotor 21.0. in one direction while a pulse seri-esof. tenpulses will cause driving of the same in the opposite direction throughv operation of. switch 23!. order: to. bring about stoppagev of bridge motor 2H segmentzu-l andrelay 235are brought into.

play-bya pulse series-of five pulses. Similarly. through pulse series of- 11. or 12 pulses trolley motor 2-Hv can be. operated. in. either direction.

through the operation. of switches. 232. and 233. stoppage of. trolley. travel. is brought about by a pulse seriesof six pulses. bringing into opera.- tion.. segment202 and relay 234:

By. reason of the arrangement above described anqoperator. through actuation of the transmitter. shown; inFig; 6 may dialso as;to bring intoplay ;;any. one or moreof. the cranefunctions which.

may all, proceed simultaneously. and v.may. at. any. time cause. stoppage. of. any of. such functions selectivelyor. in the-caseof emergencymay. cause stoppage simultaneouslyv of. all functions by open.- ing the manual. switch. M6.

in Fig. 6. shouldfailrelay I51 will move to the position opposite-that .shownin Fig. 7.. thus causing. main power. switch. Hi3v to open. Further- ;more, the apparatus of thisinventionas-set forth "in Figs. 6-and4 '7 isrelatively. insensitiveto accidental transients since it will not respond to.

cause any driving motion. of any motor unless a pulse. seriesv of at. least. five pulses shall. be. -impressed upon the receiverl i'l and it is very. unlikely that atransient will occur insuch a way as to. imitate such a five pulse series. Furthermore; in. the form of, apparatus described. in

connection withFigs. 6 and. '7 but a single re- ..ceiver IA! is required, the structure. of which may be'substantially as shown in the'caseof.

master maintainer receiver 2.3shown in'Fig. 1-

although any other. suitable form of. receiver.

may be used for the purpose.

We claim:

1. In a, remotely. controllable power unit a: transmitter adapted to transmit acontinuoussignal subject to. manually selected series of pulse-interruptions of predetermined duration,..

spacing, and. number. ofpulses; an electricdr-iving motor for said power, unit; power mains for supplying power thereto; switch means in said power mains. for establishing. and. interrupting,v

the supply of power to said motor; a receiver responsive. to the signal. transmitted by. said...

transmitter; means connected to-and activated by said receiver responsive to the continuousv signal emitted. by said. transmitter adapted to. cause. closure of. said switch. means during per-.

, sistence of saidsignal. and toretainsaid switch.

Inv

It. is furthermore apparent that if. for any. reasonthetransmitter.

means closed thereafter for an interval not less than the duration of a pulse-interruption of said continuous signal; selector means adapted to occupy a plurality of selective positions, connected to said receiver and adapted to respond to a series of pulse-interruptions delivered therefrom to move to a predetermined selective position dependent upon the number of pulse-interruptions in said pulse series; and means in circuit with said motor adapted to alter the operating condition thereof and adapted to respond to the position assumed by said selector means to interpose a difierent operating condition upon said motor for each selective position assumed by said selector means.

2. In a remotely controllable crane having a power unit for operation thereof a transmitter adapted to transmit a continuous signal subject to manually selected series of pulse-interruptions of predetermined duration, spacing, and number of pulses; an electric driving motor for said power unit; power mains for supplying power thereto; switch means in said power mains for establishing and interrupting the supply of power tosaid motor; a receiver responsive to the signal transmitted by said transmitter; means connected to and activated by said receiver when responding to the continuous signal emitted by said transmitter adapted to cause closure of said switch means during persistence of said signal and to retain said switch means closed thereafter for an interval not less than the duration of a pulse-interruption of said continuous signal; selector means adapted to occupy a plurality of selective positions, connected to said receiver and adapted to respond thereto upon occurrence of a series of pulse-interruptions to move to a predetermined selective position dependent upon the number of pulse-interruptions in said pulseseries; and means in circuit with said motor adapted to alter the operating condition thereof and adapted to respond to the position assumed by said selector means to interpose a different operating condition upon said motor for each selective position assumed by said selector means.

3. In a remotely controllable crane having a power unit for operation thereof a transmitter adapted to transmit a continuous electromagnetically radiated signal subject to manually selected series of pulse-interruptions of predetermined duration, spacing, and number of pulses; electric driving motors for said power unit; power mains for supplying power to said motors; switch means in said power mains for establishing and interrupting the supply of power to said motors; a receiver responsive to the electromagnetically radiated signal transmitted by said transmitter; means connected and activated by said receiver when responding to the continuous signal emitted by said transmitter adapted to cause closure of said switch means during persistence of said signal and to retain said switch means closed thereafter for an interval not less than the duration of a pulse-interruption of said continuous signal; selector means adapted to occupy a plurality of selective positions connected to said receiver and adapted to respond thereto upon occurrence of a series of pulse-interruptions to move to a predetermined selective position dependent upon the number of pulse-interruptions in said pulse series; and means in circuit with said motors adapted to alter the operating conditions thereof and adapted to respond to the position assumed by said selector means to interpose different operating conditions upon said motors for each selective position assumed by said selector means.

4. In a remotely controllable power unit a transmitter adapted to transmit 'a continuous sigtacts and having a contact closed when said signal contact is closed said second relay being adapted to remain closed for an interval not less than the duration of a pulse interruption; a main power switch activated by said second relay contact adapted to close a power circuit to an operating unit as long as said second relay contact is closed; a third relay in circuit with one of said pulse contacts and having a contact which is closed when said pulse contact is closed said third relay being adapted to remain closed for an interval exceeding the spacing between pulse interruptions; a fourth relay in circuit with another of said signal contacts and with the contact of said third relay and having a contact which is closed when said signal contact is closed and said third relay is closed said fourth relay being adapted to remain closed for an interval not less than a pulse interruption; a fifth relay in circuit with the contact of said fourth relay and with another of said pulse contacts and having a clearing contact and an advancing contact both of which are closed when said fourth relay is closed and said pulse contacts are closed said fifth relay being adapted to remain closed for an interval exceeding the spacing between pulse interruptions; a sixth relay in circuit with the advancing contact of said fifth relay and with the third signal contact adapted to be excited position; circuit connections adapted to complete a circuit through the third of said pulse contacts,

the advancing contact of said sixth relay and the advancing magnet of said selector switch; circuit connections adapted to complete a circuit when said selector switch is in a position away from home position through the clearing contacts of said fifth and sixth relays and said clearing magnet; a plurality of control circuits adapted to be selectively completed by said selector switch; and an operating unit connected to be supplied with power through said main power switch and adapted to be controlled as to its operating condition by the selective action of said selector switch upon said control circuits.

5 In a remotely controllable power unit a transmitter adapted to transmit a continuous signal subject to manually selected series of interruption pulses of predetermined duration, spacing, and number of pulses; a receiver responsive to the signal transmitted by said transmitter; a receiver operated relay means; a main power switch 1 activated by said relay means adapted to complete a power circuit to an operatingflunitas long as a signal is being transmitted and received; a selector switch having means for selectively completing a plurality of circuits, an advancing magnet, retaining means and a cleartngmagnet'adaptedto act upon said retaining means to cause said selector switch to return to a home position; circuit connections between said relay means and said selector switch magnets adapted to cause said selector switch to move to complete predetermined circuits in response to series of predetermined numbers of pulse interruptions; a plurality of control circuits adapted to be selectively completed by said selector switch; and an operating unit connected to be supplied with power through said main power switch and adapted to be controlled as to its operating condition by said control circuits completed by said selector switch.

6. Ina remotely controllable hoist having an electric motor for driving the same, a main power control switch for said motor, an electro-magnetic radiation responsive receiver including switch operating means operative to close said main power control switch upon excitation, a second switch having a plurality of positions corresponding to driving conditions of said motor in circuit with said motor, a second receiver including switch operating means operative to alter the position of said second switch upon excitation by a predetermined pulse radiation,

and a transmitter including means forming an oscillatable circuit containing an antenna, means for driving said oscillatable circuit to cause said antenna to emit a steady radiation capable of excitation of said first receiver, and means adapted to interrupt said steady radiation and to cause said antenna to emit control pulses of such pre-determined spacing and duration as to excite said second receiver.

WALTER HARNISCHFEGER.

GLENN KOEHLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,188,202 Perry et al. June 20, 1916 1,597,416 Mirick Aug. 24, 1926 1,635,779 Carter July 12, 1927 1,760,479 Colman May 27, 1930 1,805,167 Fitzgerald May 12, 1931 2,052,708 Hammond Sept. 1, 1936 2,325,829 Boswau Aug. 3, 1943 2,388,595 Boyajian Nov. 6, 1945 2,388,748 Kipetzky Nov. 13, 1945 2,391,881 Clay Jan. 1, 1946 2,393,892 De Ganahl Jan. 29, 1946 2,396,091 De Bey Mar. 5, 1946 2,397,088 Clay Mar. 26, 1946 2,397,475 Dinga Apr. 2, 1946

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