US1148232A - Ammunition-hoist control. - Google Patents

Description

J. D. IHLDER 61. W. D. LUTZ.

AMMUNITION HOIST CONTROL.

APPLICATION FILED AUG-l8. 1909.

1,148,232. Patented July 27, 1915.

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J. D. IHLDER & W. D. LUTZ.

AMMUNITION HOIST CONTROL.

APPLICATION HLED AUG.I8. 1909.

Patented July 27, 1915.

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JOHN D. IHLDER, on NEW YO K, Y., AND WILLIAM n. LU'rz, or ALLENDALE nonouen, NEW JERSEY, ASSIGNOBS T0 OTIS ELEVATOR COMPANY, or JERSEY CITY, NEW JERSEY, A conronn'rron on NEW JERSEY.

AMMUNITION-HOIST CONTROL.

Specification of Letters Patent.

Patented July 2'7,

i 0 all whom it may concern:

Be it known that we, JOHN D. IHLDER and WILLIAM D. LUTZ, citizens of the United States, and residing in New York, in the county of New York and State of New York, and the borough of Allendale, county of Bergen, State of New Jersey, respectively, have invented new and useful Improvements in Ammunition Hoist Control, of which the following is a specification.

Our invention relates to motor-controlling apparatus, and more particularly to motorcontrolling apparatus used in connection with ammunition hoisting mechanism similar to those disclosed in Patent No. 897,537, and #879,387,-issued to J. DJ Ihlder September 1, 1908 and February 18, 1908.

Our present invention relates to that type of ammunition hoists in which the ammunition is raised by a carrier to a position opposite the breech of the gun, and the "carrier is held in its elevated position by means of a reduced current supplied to the hoisting motor.

One of the objects of the invention is to provide means for varying the amount of current applied to the hoisting motor in HCCK I'ClQILJQ *ith the movernentof the gun up or down.

Another object of the invention is automatic'ally to vary the balancing current for the hoisting motor. 7

A further object is to provide means de pendent for operation upon the simultaneous operation of 'the' gun elevating motor and the hoisting motor, for introducing resistance in the hoisting motor circuit.-

For the attainment of these ends and the accomplishment of other new and useful objects, our invention consists in the features of novelty in the combination and arrangement of the several parts, hereinafter more completely described and claimed in the appended claims.

In the accompanying drawings, Figure 1 is a cross section of a turret containing the essential devices of our invention; Fig. 2 is a diagrammatic view of the electrical svstem of control for the motors showing the dependent action of one motor upon the other. 1

Eur invention will be described as in connection with a gun on a war vessel, similar to the disclosure of the patents above referred to. It is necessary to avoid the difiiculty which presents itself in the following manner: After a full load has been raised by the ammunition hoisting motor to the breech of the gun, and is held at the breech by a reduced current in the ammunition hoisting motor, it may become necessary to lower the breech of the gun by means of the gun hoisting motor before the load is transferred to the gun. The position of the buffer which determines the height to which the ammunition hoisting motor raises its carrier is varied by means of a direct connection with the gun hoisting motor. Therefore in the above condition, when it is desired to lower the breech of the gun, it would be necessary for the gun elevating motor to exert sufficient power not only to move the gun but also to overcome the torque of the ammunition hoisting motor which. is holding the load at the breech of the gun with suiiicient surplus torque to enable it to follow up when the breech of the gun is to be raised. It is obvious that this would demand a gun elevating motor of larger size than would ordinarily be re quired to move the gun, and in order to avoid this condition, we provide means, by which, when the controller of the gun elevating m0- tor is moved to'depress the breech of the gun, the holding current of the ammunition hoisting motor is automatically reduced;

Our invention will be described in c011- nection with an ammunition hoist for a breech loading gun. In Fig. 1, such a gun l shown mounted in the gun turret T, and a hoistway I is provided to guide the carrier J from a lower floor 9 to a position opposite the breech of the gun 1. This position varies with the movement of the gun breech and is limited by the buffer 6 which moves in accordance with the said breech. butler (5 carries a catch 23 to engage the bracket 2-1. The gun motor N is provided with mechanical connections, such as the gears 7, 8, for raising and lowering the The breech of the gun 1 and the buffer device 6.

' sprocket chain U and theregulator C is rotated in accordance with the movement of the drum 2. The arm V which controls the positions of the contacts'of the regulator C' is automatically adjusted by means of a ing in accordance with the breech thereof. The function of the regulator C is automatically to control the operationof the carrier motor M in. raising and lowering the carrier J.

Referring to Fig. 2, P designates a combination main line and automatic" circuit breaking switch with its overload coil 10, which is adapted to connect the apparatusto the source of current supply indicated by *the character and L' The gunelevating motor N is provided with the manual switch R which is operable to effect the rotation ofthe motor N in either in the same direction. The electro-respon' sive device D is 'so arranged in respect to the 'main wire 1e and the gun elevating motor lead connections, thatthewinding 17 receives current only when the motor N is energized to'lower the breech of the gun, thereby separating the contacts 15 and accomplishing a result that will be subsequently set forth.

The ammunition hoisting motor M is controlled by means of the car switch K and the automatic controller device C,-.both of which are referred'toin'the patents above referred to, and in the pending application of John D. Ihlder for ammunition hoist control, Serial No. 438,080, filed June 12,

i 1908. The shunt'lield 20, together with the additional shunt resistance 19, are connected to the leads 13 and 21. An electro-magnetic brake B is connected to the controlling apparatus for the motor M, and is released or applied at predetermined times, according to the'operation of the controlling apparatus.

Various magnets and resistances are shown for controlling the operation of the ammunition hoisting motor M, the line magnet L, load magnets G and H, balancing curv rentmagnet BC, slow-speed magnet S, fastspeed magnet F, magnet E, and the accelerating magnet AM, which also short-circuits the series field SF; and also the locking device magnet LM which locks the ammunition carrier or the car in its position opposite the breech of the gun. This locking device LM comprises a catch 23 adapted to engage a bracket 24 attached to the ammunition carrier. The catch 23 is released by en ergizing the solenoid 25. The locking magnet LM is not absolutely necessary in this exemplification, as the operation of the apparatus may be satisfactorily accomplished .without the use of the locking magnet. flexible-cable 4: attached to the gun, and mov- Blowoutcoils 22 are provided: to protect the apparatus, in the ordinary well known manner.

In Fig. 2, the hand lever 26 of the car i switch K is shown in the up position, and the controller C inthe position assumed at itsnormal upper limit of travel. The operation of the motor -M in raising the ammunition carrier to this position from the lowest position will be'explained. As soon as the hand lever 26 of the car switch K is vturned to the up position, asshown in the drawing, the contact plate 27 makes connections with the contacts 28, 29, 30, 31, 32. This establishes the following circuits From the positive. supply main (designated through the'switch P to the main lead 13; from lead 13, through conductor 33,

contact 28, contact plate 27, contact 29, to conductor 34 where the current divides, part proceeding by way of conductor 34: through the main line magnet spool, conductors 36, 37, to the main lead 21, and thence through the switch P to the negative supply main, (designated and the other part of the current is carried through the conductor 73, contacts 15, conductor 74, magnet spool 75, and conductor 76 to the main lead 21.. Closing thisparallel circuit will cause the magnets E and L to be energized, thereby joining the contacts 77 and 38 respectively, and establishing a motor circuit from the main lead 13 to the armature brush 39, through armature brush 40, conductor 41', series field SF, resistances 42, 43, 14, 45, conductor 84, contacts 7 7 conductor 48, contacts 38, to the negative main lead 21. Another circuit is made from the plate-27 which is connected with the positive main lead 13, through contacts 30, conductor L9, brake magnet winding 50, conductors 51, 37, to the negative main lead 21, thereby energizing the brake magnet and releasing the brake. A connection is also made from the contact plate 27, through contact 31, conductor 68, contactbrush 59, contact ring or spiral 55 of the automatic controller or stop device C, contact brush 61, conductors 69, 70, fast speed magnet winding 71, conductors 36, 37,

to thenegative main 21. The spacingof the contact brushes 59, 61, with respect to the contact ring 55, is so arranged that current i is supplied to the fast speed magnetwinding 71, by means of the circuit above traced, and

this circuit is preferably opened at some dis- 7 tance before the upper limit of travel of the ammunition carrier, is reached. understood that the automatic controlling device C is rotated by means of some mechanical connection with the moving mecha- It is to benism. The brush carrier 67 is adapted to move in accordance with the movement of the gun, thereby altering the position of the brushes to effect the stopping of the ammunition carrier at the proper position, as described in the other specifications above re ferred to. A circuit is also closed from the main 13 through the path already traced to contact plate 27, thence through contact 32, conductor 78, brush 58, contact ring 54, brush 57, conductor 79, accelerating magnet spool 80, conductor 81, to conductor 41, thereby connecting the accelerating magnet AM around the motor armature, so that the said magnet will operate after the motor M has attained sufficient speed to increase the counterelectro-motive force of the motor M to a predetermined amount. As soon as contact plate 27 on switch K has made connection with contact 31, the fast speed magnet F is operated to close the contacts 72, thereby leading the current around resistances 44 and 45, and through the conductor 82, series winding 85, conductor 83, to conductor 84. As the motor M speeds up, the accelerating magnet is operated to close the contacts 86, 87, 88, and the path of the motor current taken When the resistance is entirely out out may be traced from the positive lead 13, through armature brush 39, armature of motor M, brush 40, conductor 41, contacts 88, conductors 90, 89, 84, contacts 77, conductor 48, contacts 38, to the negative lead 21. When the ammunition carrier nears the top limit of travel, the circuits through the accelerating magnet winding 80 and the fast speed winding 71 are automatically opened by means of the controller C, the resistances 42, 43, 44, and the series field SF are reinsorted in the armature circuit. As long as contact 72 is closed, the balancing magnet BO will be energized, the current being lead around resistances 44 and 45 by means of contacts 72 and 92, conductor 82, winding 85, conductor 83 to conductor 84. This balancing current magnet BC is so constructed that when the load to be lifted by the ammunition hoisting motor M and held at the breech of the gun, is large, the current through the winding 85 is suflicient to hold the contacts 92 in connection, but when the load is light, the contacts will not be held in connection with each other, the circuit through the winding 85 will be broken, and the resistance 45 will be inserted in the motor circuit, thus further reducing the current through the hoisting motor M. It is obvious that the va riation of the balancing current to hold the load at the breech of the gun may be carried to any desired degree of refinement although only one balancing magnet BC is shown in this exemplification of our invention. WVith the ammunition carrier at the upper limit of travel, the motor will receive a current which is reduced by the various resistances,

and which is sufficient to hold the carrier in position and to follow up any upward movement of the gun. During this time, the line magnet L is closed, the brake is energized, the locking device catch 23 has engaged the carrier 24, the magnet E is energized and the contacts 77 connected, the car switch K and the controller C are in the positions indicated.

lVhen the ammunition hoisting motor M is holding the carrier at the breech of the gun, as above explained, and in readiness to follow up any upward movement of the gun breech, it may become necessary to lower the breech of the gun, and then the gun elevating motor N will be started in the proper direction by means of the manual switch R or other convenient means. Opcrating the gun motor N to lower the breech of the gun, energizes the electro-responsive device D, causing the contacts 15 to be sepa rated and the circuit through the winding 75 of the magnet E is broken. This causes the contacts 77 to be separated, and the resistance 46 is inserted in the circuit of the motor M, reducing the current through the said motor M, and reducing the upward torque of this motor. The motor circuit through the motor M is then traced from the main lead 13, through the motor, conductor 41, series field SF, resistances 42, 43, 44, 45, conductors 84, 93, resistance 46, conductor 48, contacts 38, to the main lead 21. Thus it is seen that when the gun motor N is operated to depress the breech of the gun, the balancing or holding current in the am munition hoisting motor M is so cut down that the upward torque of this latter motor is materially reduced, enabling the gun elevating motor N to perform its work in lowering the breech of the gun with the least opposition from the ammunition hoisting motor. It is evident that a much smaller gun elevating motor may thus be employed than if it were necessary to overcome the full torque of the ammunition hoisting motor.

The brake B may be automatically applied if the ammunition carrier has been raised too high, so that the controller C has been rotated too far causing the contact brushes 64 and 66 to slip off from the contact rings .56 and 52, for in this event, the circuit 50 will through the brake magnet windin be opened.

In the present system, the downward movement of the ammunition carrier is offected by the weight ofthe carrier, the motor M is driven as a generator, and is provided with specially arranged circuits and electroresponsive devices to comprise an electro-dynamic brake. The hand lever 26 of the car switch K must be turned to the right of the central position in the down direction, making connections between the plate 27and the contacts 94, 95, 96, 97, 98,

99 to effect the movement of the ammunition carrier in the down direction. The carrier will not be released until the contact plate 27 has made connection with the contact 99, which closes an energizing circuit through the locking device winding 25, and releases the bracket 24 by lifting the catch 23. This circuit may be traced from the main lead 13, through conductors 33, 105,

"contact 96, contact plate 27,-contact .99, con

ductor 111, magnet winding 25 to the main 'lead 21. A" connection is also madefrom the contact plate 27, through contact '97, conductor 112, winding 113 of the load magnet H, conductor 106, to main 21. This connection energizes the down magnet H, and joins the contacts 114 to close a local or armature circuit for the motor M. As soon then as the magnet LM releases the ammuni- .tion hoist carxor carrier, and the saidcarrier commences to descend-by its own weight, the motorfM is caused to rotate in adirection opposite to that in therhoisting operation, and since the shunt field 20 is still excited by reason of the fixed connections with the main leads 13 and 21through the conductors 117 and 115, the motor M will become a generator which supplies current to the local or armature circuits. I closed by'the slow-speed magnet S canreadily be traced, and the local circuit closed by the load magnet H is traced from the armaslow-speed magnet S is deenergized, the contacts 102- are separated, and the armature current takes the path closed through the contacts 114. This latter path adds resistances 119, 120, 46, and 43 to the first path, thus decreasing the armature current and causing the motor M to have less braking effect upon thecarrier. When the hand lever 26 is moved still farther in the down direction, thecontact plate 27 will break connections with the contact 95, and the circuit through the fast speed magnet F will'be broken, thus introducing the resistances 45 and 44 into the armature circuit. Ifthe speed of the'motor is increased so that the generated electro-motive force is su'fliciently great, the load magnet G will be-energized, the magnet winding 121 being connected directly across the armature of the motor M by the con- The first local circuit and apply the brake B. Y m

If it is desired to arrest or stop the motion ductors 122 and 123; Energizing this magnet G will cause the contacts 116 to be joined,

thus cutting out the resistances 119, 120, 46, i

and aportion of the resistance 45 from the armature circuit. This magnet G is so designed and adjusted that when the electromotive "force applied is of a certain value, the magnet isoperated, but when the potential fallsbelow a definite limit, the contacts 116 are separated, and by meansof-this actionthe resistance which is inserted in the localcircuit of the motor M, is varied, so

that the braking effect on'the'motor acting as a generator, is increased or diminished in accordance with the downward motion of the ammunition carrier. T he electrodynamic braking effect may also be diminished by turning the contact plate 27 to connect with the contacts 95 and 94. YVhen the carrier nears the lower limit of travel, the contact plate 53 of the controller C comes in contact with the brushes 60 and 62', and a' circuit is automatically closed through the slow speed magnet S, thereby causing the'g'reatest electro-dynamicbraking effect. This circuit for the slow-speed magnet is traced from the main lead 13, t hrough conductors 33, 105, contact 96, contact plate 27, contact 97, conductor 124, contact brush 60, contactstrip 53, contact brush 62, conductors 125, 104, contacts 100, conductor 103, magnet winding 101, conductor'106, to the main lead21.

Vhen the ammunition carrier is in its lowermost position, the controller 0 has turned almost a complete revolution from that shown in the drawing and in a counterclockwise direction. 'In' this position, the contact brushes 60 and 62 will-rest ,on the contact ring 53, and the brushes 65 and 66 will rest on the contact ring 52. If for any reason the controller is moved too far, the brush 65 will break connection with plate 52 of the motor. M and the ammunition carrier at any time during the upward or down ward movement of the latter, the return of the hand lever 26 of the car switch K to its central position will cause the circuit through the armature of the motor to be broken, and thebrake B to be'applied.

A more detailed description of our invention is not deemed necessary. It is to be understood that we have not shown all of the contemplated refinements of the accelera tion, loading or "control of the motors, but

have indicated in a clear way, how-thesere sults may be accomplished. For example, only one balancing magnet BC is employed automatically tovary the current through the motor M when the ammunition carrier is at the upper limit of travel, when it is ob vious that any number of similar magnets might be employed to secure any desired degree of refinement. The position and spacing of the contacts of the car switch K and the arrangement and construction of the an? tomatic controller C may be varied to suit the exigencies of the case.

We wish not to be. limited to the eXact construction, combination, and arrangement of the several parts as herein disclosed, as various changes may be made by those skilled in the art without departing from the spirit and scope of the invention; also similar hoisting devices may be used in place of the ammunition hoist here described.

lVhat we claim as new and, desire to secure by Letters Patent of the United States, is

1. In the art of gun-loading, the combination of a hoist and a gun, two motors therefor, means for opposing the torque of the two motors, and means for reducing the torque of one motor when the other motor is in opposition.

2. In the art of gun-loading, the combination of an ammunition hoist and a movable gun, two motors therefor, means for causing the torque of the motors to be exerted both in the same direction and in opposite directions, andmeans whereby when the motors are operatedin opposite directions the torque of one of the motors is reduced.

3. In the art of gun-loading, the combination of an ammunition hoist and a movable gun, two motors therefor, means for supplementing the action of one motor by the action of the other, means for opposing the action of one of the motors by the action of the other, and means for reducing the opposition of one of the motors when the actions of the two are opposed.

a. In the art of gun loading, the combination of an ammunition hoist and .a movable gun, two motors therefor, means for causing one of the motors to supplement theaction of the other, means for opposing thev actions of the motors, and means whereby when the motors are opposed the opposition of one motor is reduced thereby freeing the other motor to that extent of the opposition.

In the art of gun loading, the combination of two, movable members comprising the breech of a gun and an ammunition, Carrier, two moving means thereforharranged to oppose each other, when operated in one direc'tionand to assist each other when operated in the opposite direction, and means whereby the opposition, of one of the moving means is automatically reduced to permit the other moving means to overcome the reduced opposition so that both members move together. V,

' 6. In the art of gun loading, the combinationwith an ammunition ho'ist,,o;f armovable gun, means for moving the hoist and gun, means for effecting a predetermined torque of the said hoist moving means, and

automatic means for lessening the said torque when the gun is moved in one direction.

7. In the art of gun loading, the combination with an ammunition hoist, of a movable gun, means for moving the hoist and gun, means for effecting a predetermined torque of the said hoist moving means, and automatic means for lessening the said torque when the breech of the gun is lowered by the gun moving means.

8. In the art of gun loading, the combination with an ammunition hoist, of a movable gun, means for moving the hoist and gun, means for controlling the said hoist moving means so as to resist the downward movement of the hoist, and means whereby in effecting a downward movement of the breech of the gun the resistance opposing the downward movement of the hoist is lessened.

9. In the art of gun loading, the combination withan ammunition hoist, of a movable gun, means formoving the hoist, means for opposing the action of said hoist moving means, and for adjusting the vertical height of the breech of the gun, and means whereby in lowering the breech of the gun the opposingaction of the hoist moving means is reduced.

1 0. In the art of gun loading, the combination with an ammunition hoist, of a gun, mechanism for moving the ammunition hoist, a buffer device for limiting the upward movement of the ammunition hoist, means for raising and lowering the breech of the gun, means whereby said ammunition hoist can move up and down with the breech of the gun, and electromagnetic means for decreasing the power of said moving mecha nism and thereby reducing the resistance offered to the movement of the ammunition hoist when the gun breech is moved d0wnwardly.

11 In the art of gun-loading, the combination with a car, and a lifting motor, of

means for supplying current to the motor,

another motor to vary the limit of travel of the said car, and means in connection with the last named motor to vary the current supplied to the lifting motor.

12. In the art of gun loading, the combination with a carrier, of a motor for lifting the carrier, means for supplying current to the motor, another motor cooperating with the first named motor, a controller for said seconcLnamed motor, and means dependent upon the operation of the said controller for varying the current supplied to the first motor. v I

13. In the artof gun-loading, the combi nation with a .car, of an electric motor, power transmittingconnections between the car and, motor, means for supplying current to the motor in a direction to lift the car, another electric motor operative to limit the upward movement of the car, and means in connection with the last named motor for i V reducing the current supplied to the first named motor.

14L. In the art of gun-loading, the combiregulating the height to which the car should be raised, controlling means for said second motor and an electro-responsive device cotiperating with the said controlling means to efiect a reduction of current in the i first named motor when the second motor is energized. w

16. In the art of gun-loading, the combination with a carrier and a lifting motor, of means forsupplying current to the motor, another motor cotiperating with the first operating means for limiting the rise of the carrier, and an electro-responsive device operable to insert resistance in the circuit of the first named motor when circuit is supplied to thesecond motor.

17. In the art of'gun-loading, the combination with a car and a lifting motor therefor, of means for supplying current to produce an upward torque in the 1notor,'a limiting bufferfor the car, a second motor operative to vary the positionof the buffer, and an electro-responsive device in connection with the second motor for reducing the torque of the lifting motor.

18. In the art of gun-loading, the combination with a car and a lifting motor there for, of means-for supplying current to produce an upward torque in the motor, a limiting buffer for the car, a second motor op- 'erative to vary the position of the buffer, controlling means for saidisecojnd motor, and an electro-respon'sive "device cooperating with the said controlling means to efi'ect a reduction of the upward torque of the lift ing'motor at a predetermined time- '19. In the art of gun-loading, the combination with a carrier, of a hoisting'mo'tor therefor, means for supplying current to the motor to produce an upward torque, means i:'or automatically reducing the upward torque when the upper limit of traveloii th'e car 1s reached, a second motor, means for limiting the height to which the carrier s raised, and an electro-responsive device operated'in connection with'the second motor to effect the further reduction of the upward fies torque of the hoisting motor:

nation with a carrier and a hoisting motor,

of means for supplying'current to the motor to raise the carrier, a bufi'er device for limiting the upward movement of the carrier, sectional resistance,means for automatically inserting theresistance to restrict the current in the motor, a second motor, means for moving the buffer device inaccordance with the movement of thesecond motor, and an electro-magnetic device for inserting addi: tional resistance in the hoisting motor circuit when the second motor is operated in a certain direction. 7

21. In the art of gun-loading, the combination of a carrier, a hoistingmotor, means for supplying current to the motor to raise the carrier, means for automatically reducing the current when the carrier is raised, electro-responsive means for varying the current to correspond with the load, a gun elevating motor, and means associated. with the gun elevating motor for automatically reducing the current in the hoisting motor.

22.'In the art of gun-loading, the combination with a carrier and a hoisting motor,

oi means forsupp'lying current to themoing resistance in the motor; circuit'to protime as the gun elevating motor and effective to introduce res stance in the hoisting'motor circuit to further reduce the holdingcurrent ofsaid'motor. 1

23. In the art of nation witha carrier, of a hoisting motor, means for supplying current'to the motor in 7 a direction to raise the/carrier, means for re. ducmg the current to an amount sufficient to tor to raise the-carrier,'mea ns for introducgun-loading, the combii lot hold the carrier in its raised position, a gun elevating motor, a buffer device, means in connection with the gun elevating motor for automatically adjusting the position of the buffer-device, and an electro-res ponsive device energized when the gun elevating motor opposes the hoisting motor and effective thereupon to reduce the holding current in the hoisting motor. r V f 24; In the art of gun-loading, the combination with a motor, of means for supplying current to the motor to cause rotation 11113.

certain direction, means for automatically "reducing the current supplied to the motor at a predetermined period in theroperation 'ofthe motor-,2. second motorwhich acts with V or opposes the first named motor, and means whereby the current "supp'lied to the first named motor is decreased when the second motor opposes thefirst named motor.

25. In the art of gun-loading, the comhination of a carrier, a hoisting motor thereizs iso'

for, a gunelevating motor, means for sup plying current to both motors, means for automatically reducing the current in the hoisting motor when the carrier is at the upper limit of travel, and an electro-magnctic device in conjunction with the gun elevating motor for limiting the current supplied to the hoisting motor after the carrier is in its raised position.

26. In the art of. gLm-loading, the combination of a carrier, a hoisting motor, means for supplying current to the motor in a direction to raise the carrier, means for reducing the current in the motor still enabling the motor to exert an upward torque, means for automatically regulating the reduced current in accordance with the load, a gun elevating motor, means whereby the gun elevating motor permits the carrier to be still further elevated or opposes its torque to that of the hoisting motor, and means associated with the gun-elevating motor for further reducing the current in the hoisting motor to effect the movement of the carrier with a minimum of power consumption.

27. In the art of hoisting, the combination with a load carrying device, of a hoisting motor, means for supplying current to the motor in a direction to lift the carrying device, means for introducing resistance into the motor circuit when the carrying device nears the upper limit of travel, means for forcing the carrier downward to a lower position against the lifting tendency of the motor, and means for reducing the current in the motor when the carrier is thus forced downward.

28. In the art of hoisting, the combination with a hoisting motor, of means for supplying current to the motor, a second motor adapted to act in conjunction with the hoisting motor, and in opposition thereto, and an electro-responsive device energized when the motors are in opposition and thereupon operative to reduce the opposition of the first named motor.

29. In ammunition hoisting apparatus, the combination with an ammunition carrier and a hoisting motor, of a gun elevating motor, a device for regulating the height to which the carrier can be raised mechanically operated by the gun elevating motor, means for reducing the current supplied to tho hoisting motor when the ammunition carrier is at its upper limit and producing a torque in the motor suflicient to hold the carrier in its raised position and to follow up any upward movement of the said device, and an electro-magnet in conjunction with the gun elevating motor which is operative to reduce the upward torque of the hoisting motor when the gun elevating motor operates to lower the breech of the gun.

30. In ammunition hoisting apparatus, the combination with an ammunition carrier and its hoisting motor, of means for supplying current to the motor, a gun elevating motor, electrical contacts, an electromagnetic device operated when the gun elevating motor is energized to lower the breech of the gun and operative to separate the electrical contacts, and resistance inserted in the circuit of the hoisting motor whenever the electrical contacts are separated.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN D. IHLDER.

Witnesses:

C. BLINN, R. 0. SMITH, Jr.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM D. LUTZ. WVitnesses H. W. BURTON, J. R. FURMAN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G.

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