US1340240A - Hoist control - Google Patents

Description

A. 1. NIGHT; JR.

HOISICONTROL.

APPLICATION FILED JAN. 30, I914.

Patented May 18, 1920.

3 SHEETSSHEET 1.

QVAY/mmaao A. I. NICHT, JR.

HOIST CONTROL.

APPLICATION FILED JAN. 30, 1914- 0 2. 92 1. 9: 8H 14 8 Wm M 8 d3 m A. J. NICHT, In.

HOIST CONTROL.

nmcmou FILED JAN. 30. 1914.

1,340,240. a ented May 18,1920.

3 SHEETS-SHEET 3.

UNITED STATES r ENT oEEIcE.

ALEXANDER J. NIGHT, JR, 0F MILNAUKEE, WISCONSIN, ASSIGNOR TO ALLIS- CHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A.

CORPORATION OF DELAWARE.

HOIST CONTROL.

Application filed January 30, 1914.

To all whom it may concern.-

Be it known that I, ALEXANDER J. NIGHT, Jr., a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented a certain new and useful Improvement in Hoist Control, of which the following is a specification.

This invention relates in general to motor control apparatus and has particular relation to the control of electric motors for use in connection with hoisting apparatus.

In hoisting installations, considerable damage may be done if the skip or car is allowed to approach the limit of its travel when moving at a comparatively high speed, or if the hoist motor is operated in the wrong direction when the hoist is at either of its limits of travel.

An object of this invention is to provide devices for insuring the slowing down of the hoist-operating motor prior to bringing the hoist to rest at either limit of its travel, for preventing over-winding of said hoist and for insuring the operation of the hoist motor in the proper direction at either limit of the hoist travel.

A further object of this invention is to provide an improved control system for electric hoisting apparatus, which permits ordinary control of the hoist motor by an operator and, further, insures that no damage will result in case the operator neglects the proper control of the motor at any time.

A further object'is the provision, in connection with manually operated means, for causing the insertion of resistance in the circuit of the hoist operating motor, of improved automatic devices for controlling the insertion of such resistance and the opening of the motor circuit.

-A further object is the provision of a controlling rheostat of improved construction and capable of manual operation or of being automatically operated in response to predetermined conditions.

These and other objects are attained by this invention, thevarious novel features of which will be apparent from the description and drawings forming part of this application, which disclose one embodiment of such invention, and will. be particularly pointed out in the claims.-

Specification of Letters Patent.

Patented May 18, 1920.

Serial No. 815,841.

The novel rheostat, per .96, forming an element of the control system disclosed in the present application is claimed in application Serial No. 78,047, filed Feb. 11, 1916, the latter being a division of the present application.

In the accompanying drawings:

Figure 1 is a diagrannnatic view, with parts in elevation, showing a motor operated hoisting system, embodying the invention, the motor being capable of manual control and of being controlled automatically by the hoist.

Fig. 2 is an elevational view, partly in section, of a resistance device used for controlling the speed of the hoist motor.

Fig. 3 is a fragmentary elevational view, showing an automatically operated valve and latch means therefor, forming a detail of the resistance device of Fig. 2.

Fig. at is a view in elevation of a cam forming part of the hoist operating means shown in Fig. 1.

Fig. 5 is a diagrammatic view, with parts in elevation, showing a modification of the resistance device and other controlling parts shown in Figs. 1 and Fig. 6 is a view in elevation of a movable weir or gate forming a part of the resistance device shown in Fig. 5.

Fig. 7 represents a fragmentary section on the line 7-7 of Fig. 5. but with the weir or gate in its upper position.

As shown in Fig. 1, a motor M, having a resistance device R adapted to be included in its circuit, the motor being here shown as of the induction type and having the resistance device included in its secondary circuit, operates one or more hoisting drums D, E, through any suitable driving connection, which may be, as shown, a reduction gearing F, H, the parts of which are mounted on the motor shaft and drum shaft, respectively. A convenient and economical way of operating the hoist is to provide a plurality of skips, one of whih is raised as the other is lowered, the weight of one balancing that of the other, but it is to be understood that the particular typeof hoisting apparatus and number of skips or cars used is immaterial in so far as the control apparatus of this invention is concerned.

The primary of the motor M is supplied with current from the supply circuit 1, 2, 3,

pipe 21.

the switch S, between the motor and the sup- .ply means, acting to complete the primary circuit for operation of the motor in either direction.

There may be provided a circuit breaker 5, biased to open position by a spring pressed toggle 6, and normally held in closed position by a latch 7. This latch is responsive to an overload magnet 8 and a no-voltage magnet 9, either of which may trip the latch when abnormal circuit conditions of a predetermined degree exist.

An operating lever 11 is pivoted in a position where it can be easily manipulated, and is connected, through a linkage or otherwise, with a ivoted gear segment 12. This gear segment meshes with a pinion 13, integral with or rigidly secured to a :am memberl provided with cam grooves 15 and 10 on opposite sides. A pivoted lever 17 has a portion or roller en aging in the groove 16, and actuation of this lever through the cam member let operates a multiway valve 18 to automatically connect a servo-motor 19 with a pressure receiver 20 or with an exhaust The servo-motor 19 operates a crank 22 on a shaft 23 carrying a bevel gear 21. A portion or roller on a pivoted lever 25 engages in the groove 15 of the cam member 14, and the lever 25 is operated through this engagement to shift a sleeve 20, carrying oppositely disposed and spaced beveled gears 21 and 28 and splmed on the operating spindle 29 of the switch 9. Movement of the sleeve 26 meshes one or the other of the gears 27, 28, with the gear 2-1, so that, on rotation of the shaft 23, the switch 3 is operated by the servo-motor, in accordance with the desired direction of rotation of the motor M.

The engagement between the cam member let and the lever 17 is such that this lever is operated to connect the under side of the piston of the servo-motor to the pressure receiver during the first portion of the movement of the lever 11 in either direction from its neutral position, and. during the last portion of the movement of lever 11 toward neutral position, lever 17 is operated to connect the u er side of the piston of the servomotor to the pressure receiver. The engagement between the lever 25 and the cam member 14 is such that this lever is operated to mesh either gear 27 or gear 28 with gear 21. depending on the direction of operation. of lever 11, during the first part of the movement of the lever 11 from its neutral position, and to unmesh said gears during the last part of reverse movement of lever 11 in either direction toward neutral position. The shape of the cam grooves 15 and 16 and the neutral positions of the rolls on the levers 17 and 25 is clearly shown in Fig. 4.

A stop is provided to prevent the operation of the lever 11 from forward on position to reverse on position without stopping in off or neutral position. Spring pressed, pivoted dogs 101, 102, on the lever 103 are moved by the lever 22, through the connecting rod 105, or otherwise, into the path of a linger 104 on the gear segment 12, when the latter is operated in one or the other direction. The full movement of the lever 22, due to the action of the piston of the servo-motor 19, being subsequent to that of the finger 101, the pivoted dogs are free to move into the pathv of the finger, when the latter has been moved from neutral position. Stops 100, 107. are provuded on the lever 103 to prevent the movement of the dog 101 in an anti-clockwise direction and the movement of the dog 102 in a clockwise direction, respectively. If the operating movement of the segment 12 and finger 104 has been in a clockwise direction, and it is then attempted to move the lever 11 in an opposite direction through neutral position. the dog 102, through engagement with the linger 10%., will prevent such operation beyond neutral position, until the lever 22 has been actuated sufiiciently to move the switch bi to off position. Vhen. the lever 11 is In its other extreme position, movement thereof in a backward direction through neutral. position will be prevented by the engagement of the finger 10 1 with the dog 101, until the switch S has been moved to off position.

In the embodiment of the invention disclosed, the resistance device R, in the secondary circuit of the motor M, comprises a (3215- 100 ing 30 divided by the partition 31, into two compartments 32 and 33. Tt is obvious that, instead of providing a single casing divided into a plurality of compartments, two separate casings might be used. The upper 105 compartment or casing 32 is designed to contain electrodes 34-, 35, 30, in series with the secondary circuit of motor M. These electrodes may be of any suitable form, but each preferably consists of one or more metal 110 plates spaced apart and rigidly secured in position. These electrodes are immersed in a body of resistance liquid, preferably slightly acidulated water.

The lower compartment of the casing 115 30 acts as a reservoir for liquid resistance material. A pump 37 driven by a motor 38, or any other suitable means, acts to force the resistance fluid through the pipe 39 to the upper compartment 32.

It is obvious that the resistance in series with the secondary of the motor M varies inversely as the amount of resistance fluid in contact with the electrodes in the upper compartment. For varying the amount of 125 such fluid and thus varying the secondary resistance, one or more movable weirs 40, passing through the partition 31. are provided. which act as overflow passages to discharge fluid from the up per compartment 130 to the lower supply compartment, the weirs being adjustable through the partition 31 to vary the level at which the resistance fluid in the com artment 32 overflows, and, in their lowermost position, maintaining such a level of fluid that the electrodes are slightly immersed.

In the normal operation of the hoisting apparatus, it is intended that the pump 37 be continuously operated to circulate the resistance fluid between the lower and upper compartments. The rate at which this circulation takes place may be varied. by adjusting the valve ll, here shown as of the butterfly type,in the communicating passage 39. lVith such a system as is here described, fluid that becomes heated through use as a resistance element in the upper compartment 32 passes oft" at its upper level and is discharged into the lower compartment The lower compartment may be provided with a plurality of cooling pipes 42 through which air or other cooling fluid may circulate to assist in cooling the liquid. I

\Vhen the motor M is not in operation, only the lower ends of the electrodes at, 3 36, are immersed in the fluid resistance, the level of the fluid being lowest and the overflow weirs 40 being at their lowest point. lVith this condition existing, the resistance of the secondary circuit of the motor is a maximum. When the motor is started, the weirs are lifted to their upper level and the pump 37 forces liquid into the compartment 32., gracually filling the same and decreasing the secondary resistance, until the level reaches the weir outlet, when the secondary is practically short circuited. The motor then operates at its maximum speed. To stop the motor, resistance is first inserted in. the secondary circuit by moving the weirs to their lower level and allowing the liquid to discharge to the lower compartment. l/Vhen the liquid is at its lower level, the primary switch may be opened, and, as little current is flowing therein, practically no ar ing results.

The weirs are operated by a pivoted lever d3, which in turn is operated by the cam member 14, through the connecting rod a l, secured to the cam member in such a manner that rotation of the cam member in either direction from its neutral position imparts movement to the rod 44 in the same geeral direction and thus causes the lever 43 to raise the weirs.

The system described is such as might be used where the control of the motor M is wholly manual. In such operation, the lever 11 is moved in one direction actuating the cam member 14 which in turn operates to mesh either gear 27 or gear 28 with gear 24, through the lever 25, and causes the servo-motor 19 to be actuated, through the lever 17 and valve 18, to cause the gear 24 to actuate the spindle 29 of the switch S in one direction or the other, depending on the desired direction of motor operation. The cam member 14 also actuates the rod 44: to cause the lever 43 to raise the weirs 40. The primary circuit of the motor being completed through the operation of the switch S, the motor starts and gradually increases in speed as the resistance of the secondary circuit is decreased through the admission of a greater volume of. fluid to the upper compartment of the resistance device R. The motor operates the skips at this maximum speed. until the latter approach the limit of their travel, at which time the lever 11 may be operated in a reverse direction to bring the same to its neutral position. This reverse operation causes the lowering of the weirs l0, thus increasing the resistance of the secondary circuit as the fluid level in the upper compartment lowers, and also causes the operation of the bevel gear 24, through servo-motor l9. and lever 17, to move the switch S back to neutral or oil position. The rod l4: is so connected to the cam member 14': that the raising and lowering of the weirs 40 is gradual and takes place throughout the whole angular move ment of the cam member 14.

In order to show the location of a skip or car at any time, indicators. 51, 52, corresponding to the ships L and N, respectively, are provided. In the present embodiment of the invention, each of these indicators consists of a dial 5 over which pointers travel. The pointer moves through less than 360 degrees during the entire travel of the skip and is an actual indication of the position of the ship at any time. The pointer 55 moves only during the latter part of the travel of the skip, probably during only the last one hundred feet, and it is intended that this pointer shall make approximately one revolution during a small predetermined fraction of the complete travel. These pointers may be driven through sprockets on the drum shaft and the jack shaft 56.

Provided the secondary resistance is inerted at such a time as to cause the skip to pproach its limit oi. travel at a comparaively slow speed, no damage can occur through overwinding. However, if the operator should fail to slow down the motor at the proper time, considerable damage may result on account of the high speed at which the cage or skip is traveling. In order to prevent such damage and to insure safe operation, automatic devices are pro vided to insure proper operation even though the operator 1S negligent.

irleans are provided for causing the discharge of fluid resistance from the upper compartment 32, independently of the weirs d0. This means comprises a by-pass 61 between the compartments, the passage through which is normally obstructed by a valve 62, biased to open position by a weighted lever 63 and normally held closed by a latch 64:, engaging a projection 65 on an operating handle 66 of the valve. The latch 64: is normally maintained in engagement with the projection to hold the valve 62 in closed position, by an electromagnet 67, the latch 64- being mounted on the armature of said magnet. An adjustable stop 68 engages the handle 66 when the valve is open to limit the size of discharge passage through the pipe 61. This by-pass outlet 61 may be so disposed as to empty the upper compartment to any desirable extent, depending on what final. slow-down speed is desired. It will be obvious that the final liquid level attained on the operation of the slow-down device may be changed to anything desirable by providing the inlet to the by-pass with an extension that will permit emptying the tank to only the desired level.

The circuit of the latch-holding magnet 67 is normally closed by the switches 71 and 71, secured on or adjacent to the indicators 51 and 52, respectively, and urged to closed position by springs or otherwise. Each switch has a projection which extends into the path of projection on one of the pointers 5 1, so that, at a certain point in the movement of this pointer, one or the other of the switches 71, 71 will be opened, to open the circuit of the holding magnet 67. The circuit of the holding magnet 67 and switches 71, 71 may be supplied from one phase of the supply mains 1, 2, 3. The connection between the switches 71, 71 and the magnet 67 may be direct, or may be, as shown, through a double throw switch 121, the particular utility of which will be referred to later.

Connected to the supply mains and the circuit of the holding magnet 67, in parallel with the switches 71 and 71, a switch '76, having fixed contacts 77 and 7S, and a movable bridging contact 79. This switch is operated by a speed responsive governor 12% that is driven from the motor shaft through the gearing 125. lVhile the motor is operating at full speed, an insulating portion 80 on the switch 76 bridges the fixed contacts 77 and 7 8, thus opening the circuit through the switch. If the speed of the motor drops to a certain point, the governor 124 actuates the switch to move the bridging contact 79 into engagement with contact 77 and 78 and thus establish a circuit for the holding magnet 67. Switches 72 and 72' are provided in the vicinity of the indicators 51 and 52, respectively, in such position that projections on such switches may be operated by projections on the pointers 55, either directly or through the pivoted levers 73. when these pointers reach a certain position, correspond ing to the approximate end of travel of the hoist. These switches are normally closed, and one or the other of them is always in circuit with the no-voltage coil 9, which circuit may be completed through the auxiliary switch T, having fixed contacts 81, 82, 83, and a movable contact 84. The fixed contacts 82 and 83 may be connected directly to the sides of the circuit of the no-voltage magnet 9, or, as shown in Fig. 1, they may be connected with the circuit of magnet 9, through the double-throw switch 121, when the latter is in one of its operative positions. In the position of the switch S that causes movement oi the motor M to lower the skip L, the switch T is in such position that it completes the circuit of the no-voltage magnet 9 through the switch 72, independent j of switch 7 2. lVhen the motor is operated in a reverse direction, as to lower the skip N,

the switch T is in such position as to complete the circuit of the no-voltage magnet 9 through the switch 7 2", independently of the switch 72. Theoperating means of the switch T may be so connected to the operating means of the switch S that the desired operation of the former will be secured with a corresponding operation of the latter.

In case the operator should neglect to slow down the motor at such point in its travel as will insure the skip coming to rest from a slow speed of travel, the switch 71 or 71" will be opened by the pointer 54:, at a certain point in the travel of the hoist, and, as the speed of the motor at this time is such as to maintain the switch 76 in open position, the circuit of the holding magnet 67 will be interru i ted and the latch 6% will be tripped to allow the weighted lever 63 to open the valve 62. Opening of this valve allows the discharge of electrolyte from the upper compartment and thus inserts resistance into the secondary circuit of the motor, slowing down the same. The motor will run at a gradually decreasing speed until the end of travel is reached, when a projection on the pointer 55 will cause the opening of one or the other of the switches 72, 72, to open the circuit of the no-voltage magnet 9, thus tripping the latch 7 and allowing the circuit breaker 5 to open.

When the motor circuit has been automatically opened in this manner, it will be impossible to manually operate the lever 11 in such a direction as to cause further operation of the motor M in the previous direction, for the reason that the switch 72 or 72 is maintained open and a closed circuit through the switch T is impossible in an operative position of switch S, thus preventing a closed circuit through the no-voltage magnet 9, and rendering it impossible to hold the circuit breaker 5 closed and latched. It will. be obvious that the only manual operation that can be accomplished is the closing of the motor circuit so as to cause a reversal of the direction of rotation of the motor, this operation causing the switch T to complete the circuit of the no-voltage coil 9 through the other one of the switches 72, 72 I It is to be noted that the automatic stopping devices are wholly independent of the manual control, that is, these automatic devices will not operate in case the operator attends to the slowing down of the motor at the proper point. In this case, if the motor speed is decreased through the operation of the lever 11, the speed responsive governor 81 is actuated to cause the contact 79 to bridge the fixed contacts 77 and 78, thus closing one of the supply circuits of the holding magnet 67. Then, when the pointer 54 opens the switch 71 or 71, the circuit of the holding magnet 67 is not interrupted for the reason that a shunt circuit is completed through the switch 76.

While the system described will operate in the manner set forth, when the contacts 82 and 83 of switch T are connected directly to the sides of the circuit of the no-voltage magnet 9, and the electrical connection between the switches ?1, 71= and the holding magnet 67 is direct, nevertheless, under certain unusual conditions, the operation of such a system may not be all that is desired. 1V ith such a system as has been described, it, through inexperience or carelessness, an operator should move the control lever 11 to off position some time after the automatic slow-down device had begun to operate and before the end of the hoist travel, the switch T, in which the contacts 82 and 83 are di rectly connected to the sides of the circuit oi the novoltage magnet 9, would be moved to a position in which it closed the circuit of magnet 9, independently of the switches 72, *2. Under such circumstances, the opening of the overwind switch 72 or 72 would not open the circuit of the no;voltage magnet 9 to trip the main circuit-breaker, and the cage or skip might not come to a stop without causing more or less damage.

To prevent any such occurrence, the con.- tacts 82 and 83 are connected to the sides of the circuit of the no-voltage magnet 9 through the switch 121, when it is in one of its operative positions. This position of the switch 121 is not the normal one, and it is moved to such position only when the automatic slow-down has operated and the circuit of the magnet 9 is opened at the switch 72 or 72. The normal position of the switch 121 being as shown in Fig. 1, it will be obvious that the operation of the lever 11, after the automatic slow-down has begun to operate and the operation of the switches S and T to neutral position. will not close a shunt circuit for the magnet 9, and the slowdown device will properly check the skip.

It will be impossible to start the motor for operation in either direction now, until the switch 121 has been moved to its other closed position, thus completing a circuit for the no-voltage magnet 9 through the switches T and 121. Even with the switch 121 in this new position, it will be impossible to operate the motor in the same direction as it was operating before, for the circuit of the magnet 9 will be immediately opened at the switch T. The motor will operate in the reverse direction until the cage or skip has moved suificiently to allow the switch 7 2, or 72 to close, thus completing a circuit for the magnet 9, independently of the switch T.

The operator will be warned that this is not the intended operating position of the switch 121, in which position the circuit of the holding magnet 67 through the switches 71, 71 is interrupted, by the slow speed of the motor, the speed-controlled switch 76 operating to open position at a certain point to open valve 62 and prevent immersion of the electrodes, necessitating the operation of the hoist motor at its slowest speed. i ihen the switch 121 is operated to normal position, and the valve 62 is set, if the same has been tripped, the motor can be operated at full speed, the circuit of the holding magnet 67 being now made through the switches '71, 71, and the switch 121, independently of the speed-controlled switch 76.

In order to hasten the insertion of rece in the secondary circuit of the when the by-pass valve 62 is opened, the pump motor 38 may be caused to stop by breaking its circuit. A switch may be provided on the shaft of the valve 62, or arranged in any manner, to open when the valve opens. As shown in Fig. 2, a drum 135, having bridging contacts 132 and 133, is adapted to close two sides of a threephase pump-n1otor circuit by suitably bri ging terminals of this circuit. This switch may be operated by a chain, belt or gearing connection between the shaft of valve 62 and the spindle 134 of the switch, the connections being such as to render the pump 3'? inactive when the valve 62 is open.

in 5, is disclosed a modification of the invention, as illustrated in Figs. 1, 2, 3 and e, the primary switch and the secondary resistance device being directly ed by the control lever 11, and the 1*" :e device B being of modified constru t on to better adapt the same for the quick insertion of resistance in the secondary circuit of the motor The resistance device R, in this case, comprises a casing 130, divided by a traylilIn partition 131, into upper and lower compartments 32 and 33, respectively. The tr .y 131. is secured to the casino at three sides and the upper compartment is formed by the tray and the side walls of the casing; and is closed at the fourth side by a movable partition or weir 90, which is separated from the fourth side of the casing. This weir or gate is provided with rollers 91 operating in guide ways 92, 93, secured to opposite sides of the casing. In its upper position, the weir 90 is adapted to close the upper compartment so that the same may contain resistance fluid to such a height as will provide the best running conditions of the motor, at which time the lower edge of the weir is adjacent the upper edge of the partition tray 131. The upper edge of the weir and the side walls of the easing, with which the weir is in contact in its movement, may be provided with packing devices to prevent leakage from the up per compartment, while the weir is in any of its operative positions.

The weir or gate 90 is secured to a piv oted lever 94 to be operated thereby. This lever 94 is operated, through a rod 95, by a pivoted lever 96, which is connected, through a rod 97, to the operating lever 11. The normal position of the lever 96 is such, relatively to the operating lever 11, that movement of the lever 11 in either direction from its neutral position, causes the lever 96 to operate the lever 94 to raise the weir or gate 90, allowing the liquid that is forced into the upper compartment through the pipe 39, by the pump 37, to accumulate, and thus reduce the secondary resistance of the motor and permit the same to pick up in speed.

The depth of the tray 131 is such that there is an appreciable amount of liquid retained in the tray and in contactwith the lower ends of the electrodes 34, 35, 36, which project into the tray and always dip into the liquid contained therein. This construction also maintains the secondary circuit of the motor in closed condition, although the resistance of this circuit is quite high, when the weir 90 is lowered so that the only resistance liquid in the upper compartment is contained in the tray, as at starting.

Connected to the lever 96 through the rod 98 is a beveled gear segment 99, an integral extension on the segment being connected with the rod 98. Meshing with the segment 99 is beveled pinion 100 on the shaft Q9 of the primary switch S. The mechanical connection between the operating lever 11 and the switch S is such that. in the neutral position of the lever 11, the switch S is open, and that the switch S may be closed to cause rotation of the motor in one or the other direction when the switch 11 is operated in one or the other direction from its neutral position.

The levers 94, 96 and 11, and the pivoted gear segment 99 are so relatively arranged that, during the first part of the movement of the lever 11 in either direction from its neutral position, the switch S is operated and the weir 90 is moved but slightly, continued movement of the lever 11 in the same direction causing the further operation of the weir. In the backward movement of the lever 11 toward neutral position, the weir is more or less quickly operated during the first part of this returning movement, and the switch S is returned to open position during the latter part of this movement, at which time the weir 90 is so lowered that the resistance of the secondary circuit is approximately maximum, the discharge opening from the upper compartment being sufficiently large to allow the liquid to pass off in a very short time.

The advantage of the control apparatus disclosed in Fig. 5 is that both the primary switch S and the resistance device R are positively operated and it is possible to so relatively time the operations that the switch S is operated to closed position before the secondary resistance decreases appreciably, and is opened only after the secondary resistance has increased to approximately maximum. It will be apparent that the resistance device of this figure may be used in connection with the manual control means illustrated in Fig. 1.

This type of resistance device may be provided with the same automatic discharge as is shown in connection with the resistance device illustrated in Fig. 1, in which a bypass 61 is provided with a valve 62, normally held closed by a latch 64 controlled by a no-voltage magnet 67; and a switch may be provided to open the circuit of the pump motor when the valve 62 is opened.

It will be apparent that, in case other than electrical means are used for driving the pump motor, suitable cut-oil means may be provided to operate in response to movement of the valve 62.

It will be obvious that the operation of the automatic devices shown in Fig. 1, for stopping the hoist motor, in case the operator neglects the manual control thereof, may be the same, no matter which form of resistance device or manual control means is used.

Vhile the means for indicating the positions of the hoists is disclosed as comprising a plurality of pointers on the same dial, it will, of course, be apparent that a single pointer may sufiice, and that this single pointer may, in different positions, operate both switches 71 and 72.

l hile the means for causing the slowdown of the motor, on the failure of the operator to act, is described as comprising a separate outlet from the upper compartment, nevertheless, any apparatus capable of providing for the filling and emptying of this compartment in response to manual control and of providing for the emptying of such compartment in response to the opoperative if the speed of said motor is eration of the automatic slowdown device, would accomplish the desired results; and, accordingly, is to be considered as within the scope of this invention.

It will be seen that, in accordance with this invention, a motor control system is provided that is capable of purely manual operation, or of operation in response to automatic devices in case the manual control means is not actuated at the proper time.

It should be understood that it is not desired to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the. art.

It is claimed and desired to secure by Let ters Patent:

1. In a motor control system, a liquid rheostat in the circuit of the motor to be controlled and comprising a casing, and electrodes adapted to be immersed in liquid in said casing, the immersion of said electrodes in the liquid being variable in response to manual control of said motor and in response to the speed of the motor under predetermined conditions.

2. In combination, a motor, controlling means for said motor comprising a liquid rheostat in the circuit or" said motor, said liquid rheostat including a compartment containing resistance material in which electrodes are adapted to be immersed, means for varying tie degree of immersion of said electrodes, a normally closed outlet from said compartment, and means operable independently of said immersion varying means for opening said outlet in response to predetermined conditions in the operation of said motor.

In combination, a motor, controlling means therefor comprising a liquid rheostat, electrodes for said rhecstat, means for vaying the degree of immersion of said electrodes in the liquid of said rheostat, and means responsive to the speed of the motor under predetermined conditions for automatically decreasing the degree of immersion of said electrodes.

l. In combination, a hoist, means for indicating the position of said hoist, a motor for operating'said hoist, and means operable by said indicating means for controlling said motor, said controlling means being inbelow a predetermined value.

5. In combination, a hoist, means for indicating the position of said hoist in its travel, a motor for operating said hoist, means for controlling said motor, and means successively operative by said indicating means when said hoist is at a predetermined point in its travel for causing the slowing down and stoppage of saidmotor.

6. In combination, a hoist, a motor for op-' crating said hoist, controlling means for said motor comprising a variable resistance and a switch in the circuit of said motor, means responsive to the speed and position of the hoist for causing the slowing down and stoppage of said motor, and means for insuring that the succeeding operation of the motor will be in a certain direction.

7. In combination, a hoist, a motor for operating said hoist, automatic overwindpreventive means for said motor operative on the occurrence of predetermined o tions, and means operative on the actuat. of said overWind-preventive means to prevent the succeeding operation oi' said motor from being in the same direction, and perinitting the succeeding operation of said motor without interruption of the motor circuit.

8. In combination, a hoist, means :torin- 85 dicating the position of said hoist, a motor for operating said hoist, means operated by said indicating means for causing the d ual stoppage of said motor, and meal s for insuring a certain succeeding operation of said motor.

9. In combination, .a hoist, a motor for operating said hoist, means for indicating the position 0t said hoist, and automatic slow-down and overwind preventive means rendered operative successively by said in dicating means.

10. In combination, a hoist, a motor for operating said hoist, means for indicating the position oi said hoist and including a plurality of indicating devices, and automatic slow-down and overwind preventive means, said slow-down actuating means being rendered operative by one of said indicating devices, and said overwind-p ntive means being rendered opera... other of said indi devices.

11. In combination, a hoist, an in motor for operating said hois-.. the primary and a variable i 11o secondary of said motor, umeans for actuating said prim and varying said secondary rcsi independently actuated means operat response to the posi'ion and speed hoist for varying the secondary re, and opening the primary circuit of sa. tor.

12. In a motor control system, a liouid rheostat in the circuit of the motor to be controlled, a pump for forcing resistance material into electrode partment of said rheostat, erated means for controlh" of resistance mate ment, and means o ted bv s; controlling means for rendering sci-: inactive. (I

13. In a motor control rheostat in the circuit of L I 83 8:2121 P. p, a.

the motor to be 139 controlled, a motor-driven pump for torcing liquid resistance material into an electrode containing compartment of said rheostat, a switch in the circuit of said pumpdriving motor, and means "for permitting the discharge of resistance material from said compartment, said switch and said dis charge means being operatively connected to cause the actuation of said switch as a result of the actuation of said discharge means to render said pump-driving motor inactive when said discharge means is operated to permit discharge of resistance material from said compartment.

14. In combination, a hoist, an induction v motor for operating said hoist, a liquid rheostat in the secondary circuit of said motor, said rheostat comprising a receptacle, electrodes within said receptacle, and means for varying=the degree of immersion of said electrodes in liquid resistance material in said receptacle, and means normally inop erative and operative in response to an abnormal operating condition of said hoist tor decreasing the degree of immersion of said electrodes and stopping said motor.

15. In combination, a hoist, an induction motor for operating said hoist, a liquid rheostat in the secondary circuit of said motor, aid rheostat comprising a receptacle, electrodes within said receptacle, and means for varying the level of liquid resistance material in said receptacle, a normally obstructed outlet from said receptacle. and means normally inoperative and operative in response to an abnormal operating condition of said hoist for causing the disch of liquid resistance material from said receptacle through said outlet.

16. In combination, a hoist, an induction motor for operating said hoist, a liquid rheostat in the secondary circuit of said motor, said rheostat comprising a receptacle, electrodes within said receptacle, means for circulating liquid resistance material through said receptacle, said latter means including a device for insuring the maintenance of level of said resistance material at varying heights in said receptacle, and means operative in response to an abnormal operating condition of said hoist for causing the discharge of resistance material from said receptacle.

1?. In combination, a hoist. a operating said hoist, means for indicating the position of said hoist, said indicating means comprising relatively slow and fast moving indicating members, said fast moving member being operative only dring the latter part of the travel of said hoist, and automatic slowdown and overwind-preventive means for controlling said motor, said slowdown means being rendered operative by said slow moving indicating member and said overwind-preventive means bemotor "for ing rendered operative by said fast moving indicating member.

18. In combination, a hoist, an induction motor for operating said hoist in either direction, a switch in the primary circuit of said motor, means for preventing overwind ing of said hoist, and means for insuring that the operation of said hoist is in the roper direct-ion subsequent to the stoppage ct said motor through operation of said orerwind-preventive means, said insuring means comprising a switch operatively associated with said primary switrh for actuation therewith.

19. In combination, a traveling member, means for indicating the position of said member, a motor for operating said mem ber, means responsive to the speed of said member, and means operative jointly only, by said indicating means and speed responsive means, to control said motor.

20. In a motor control. system, resistance varying means adapted to be connected in the circuit of the motor to be controlled, means adapted to gradually adjust the value oi? said resistance and maintain it at any of a plurality of gradations during such adjustment, means controlling the condition of said resistance varying means, circuit controlling means arranged to be held in closed position in the circuit or? said motor, and means arranged to control said holding means and said condition controlling means.

2 In motor control system, resistance r: rying means adapted to be connected in circuit of the motor to be controlled,

' motor, and means whereby the act of ing the circuit controlling means in normal closed position to supply current to 10 motor, changes the condition of the reistance varying means so that it cannot asume running position.

In a motor control system, liquid resistance varying means having means for draining the liquid adapted to be connected in the circuit of the motor to be controlled, means for holding tid draining means closed, a circuit controller in the circuit of 4 motor, including means for holding ler closed, and means for controlling both of said holding means.

In a motor control system, a liquid rheostat in the circuit of the motor to be con trolled, means for filling liquid into said eostat, an automatic circuit breaker in c circuit of said motor, and means for conditioning the circuit breaker for closure while rendering said filling means inefiective.

24. In a motor control system, a liquid rheostat in the circuit of the motor to be controlled, normally inoperative means for substantially draining said rheostat of liquid, an automatic circuit breaker in the circuit of said motor, and means for conditioning the circuit breaker for closure and at the same time rendering said draining means operative.

25. In a motor control system, a liquid rheostat in the circuit of the motor to be controlled, normally closed means for substantially draining said rheostat of liquid, a circuit breaker in the circuit of said motor, means responsive to abnormal conditions for operating said draining means and said circuit breaker, and means for conditioning the circuit breaker for reclosure and at the same time preventing operative resetting of said draining means.

26. In a motor control system, a rheostat having a starting and a running position in the circuit of said motor to be controlled, a circuit interrupter in the circuit of said motor, means for opening said circuit interrupter under abnormal conditions, means for rendering the aforesaid means temporarily ineffective so that the interrupter may be placed in normal closed position, and at the same time necessitating rendering the aforesaid means effective before the rheostat can be put in running position.

27. In combination, a motor, a control system for said motor including a liquid rheostat in a circuit of said motor, said liquid rheostat including a receptacle containing resistance material in which electrodes are adapted to be immersed, means for varying the degree of immersion of said electrodes, and means operable independently of said immersion-varying means for altering the degree of immersion of said electrodes in response to predetermined conditions in the operation of said motor.

28. In combination, a motor, a control system for said motor including a liquid rheostat in a circuit of said motor, said liquid rheostat including a receptacle containing resistance material in which electrodes are adapted to be immersed, means for varying the degree of immersion of said electrodes, and means operable independently of said immersion-varying means for altering the degree of immersion of said electrodes in response to predetermined electrical conditions in said control system.

29. In a motor control system comprising electrical circuits and connections, a liquid rheostat in the circuit of the motor to be controlled, said rheostat comprising an electrode-containing receptacle, means for supplying liquid resistance material to said receptacle, and instrumentalities for varying the degree of immersion of the electrodes in said receptacle and including an adjustable weir operative to maintain the level of said liquid resistance material at desired points and permit overflow thereof, and electro responsive means for causing a lowering of the level of the liquid resistance material in said receptacle independently of the position of said adjustable weir in response to predetermined electrical conditions in the circuits and connections of said control system.

In testimony whereof the signature of the inventor is aiiixed hereto in the presence of two witnesses.

ALEXANDER J. NIGHT, JR.

'lvitnessesz ROBERT E. STOLL, J. V. KANE.

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