US394952A - Overloading and slack cable-stop for electrical hoisting-machines - Google Patents

Description

(No Model.) 3 sheets-sheet 1. W. BAXTER, Jr. OVBRLOADINGANDSLAGKGABLESTOPEORBLEGTRIGALHQISTING MACHINES.

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CVEELOADING AND SLACK CABLE STOP FOR ELECTRICAL HOISTING MACHINES.

No. 394,952. Patented Dec. 25, 1888.

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, W. BAXTER, J1. CVEE'LCADINC AND SLACK CABLE STCE ECE ELECTRICAL ECISTINC. MACHINESE No. 394,952. Patented DCC. 25, 1888.

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XVUATIAM BAXTER, JR., OF BJJITDORE COVNTY, MARYLAND.

OVERLOADING AND SLACK CABLE-STOP FOR ELECTRICAL HOISTING-MACHlNES.

SPECIFICATION forming part of Letters Patent No. 394,952, dated ecember 25, 1888.

To all whom it' may concern.' l

Be it known that l, \\.'ILLIAM BAXTER, J r., a citizen ot' the United States, residing in the county of Baltimore, State of Maryland, l have invented certain new and useful lmprovements in Overloading and Slack Cable- Stops for Electrical l-loisting-Machines, ful-ly i described and represented in the following l specification and the accompanying draw` ings, forming a part of the saine.

rlhis invention relates to that class of hoistl ing-machines in which an electric motor used for actuating the hoisting mechanism, and the hoisting car or platform is elevated t (by such mechanism) ina vertical or inclined hoistway; and the object of this invention is to provide any such hoistingmechanism with means for stopping the electric motor automatically when, on the one hand, the car is overloaded, or, on the other hand, when the y car or its eouiiter-balance is obstructed, so that the hoisting-rope becomes slack or overstrained.

It is well known that in electric motors operated at a constant potential the current passing' through the motor increases with the I resistance opposed to .its rotations, and the overloading` of the hoisting mechanism, which would impose upon the motor a resistance greater than its normal capacity, would therefore tend to increase the current to such an extent as to burn out the armature and to 5 thus ruin the machine.

My present invention provides an electric switch which is operated automatically by the movement of some support which sustains the weight or pressure oi' the ear, and which is adapted to yield when the car is either overloaded or obstructed.

My invention also includes an automatic indicator, as a bell, operated by a yielding connection with the car when overloaded, to warn the conductor that a portion oli' the load 1 must be removed, an electric circuit being derived from the main motor-circuitor from a local battery carried upon the moving' ear i or platform to actuate the indieatonif a magl netic device be used. The yieldingI support, aifected by the variable load in the car, must l ot' necessity be located between the hoisting device and the car-platform, and may therefore be combined with a pulley-bearing, over ry 28,1888. Serial No.265,575. (No modela which the hoisting-ropeis conducted, with an elastic connection between the car and its l suspemling-rope, or with. any other element of the hoisting device which is affected by the load imposed. It' the hoisting mechanl ism continues to pay out the suspending-rope when the car is obstructed in its downward motion, such rope is liable to be greatly deranged when again wound up, or is liable to rupture it the obstruction to the car be suddenly removed and the car allowed by the slack in the rope to fall a considerable distance. Then a counter-balance is used and connected with the car by a rope, the evils arising' from an obstruction of the counterbalance are nearly as great as those affecting the car, and my appliances are equally applicable for automatically stopping the electric motor when the counter-balance is obstructed in its movement, so as to slaeken or tighten its suspending-rope.

My improvements will be undcrstmid by reference to the annexed drawings, in which- Figure l is a diagram of an electric motor actuating a hoisting apparatus, the drum of which is connected by a rope with a suspended ear, and the motor-circuit conveyed to the car by a cable to actuate an electric indicator therein. The circuit in this ligure is arranged to operate with constant potential y an independent battery with a local circuit,

also indicated in dotted lines within the car. Fig. 2 is a diagram showing a yielding bearing for the counterbalance-pullcy, a motorcircuit adapted to operate with constant current, and an electric switch actuated by the y movement of the yielding bearing to shortcircuit such motorwhcn the car is overlmnled. l, l-, and 5 show constructions lfor the yielding-car connection. Fig. o is a diagram of the constant potential switch with circuit opened.

ln Fig. l, ll is a ln)isting-machiiic actuated by electric motor 3l. P are the posts of the hoistway; P', a beam across the top, supporting` a countei-balaiice-pulley, l, and two guidepulleys, .l and K, leading the hoisting-rope L from the hoister-drum to the car A counter-balance, (f, is connected with the car by a rope, C2, passed over the pulley I. A pulley, N, is arranged below the level of the hoisting-drum to guide the rope L downward TOO 2 v scesa from the la-tter to illustrate the application ot' a yielding bearing to sustain an upward pull. The motor is connected with an electric circuit by wires w i', the current being connected with switches s, s', and s?, which are actuated, respectively, by thc bearings ot' the pulleys K, N, and I. The conductors r 1c are also connected through a iiexible cable, Q, to a switch, S3, inside the car, which is actuated when the car is overloaded to operate a suitable indicator and notify the attendant that it would be injurious to start the motor. Such switch is moved by a yielding connection between the car and its suspending-rope, and is thus affected by the load placed upon the car-platform. The yielding connection consists in a sliding` bolt, l), fitted through the roof of the car, with a head, d, upon its inner end and a spring, b, inserted between the head and the car-beam b. The rope being attached to the outer end ot the bolt, it is evident that the load placed upon the car-platform p would operate to compress the spring and move the head d toward the top of the car. A bell, g, is shown fixed within the car, with a magnet, G, to actuate its hammer g electrically.

e e are the terminals of the circuit-wires, conducted to the car through the cable Q, and are formed as springs, one of which is arranged in the path of the bolt-head d, to be moved when the spring l) is abnormally compressed.

The springs@ c are mounted upon a switchbase, s3, to adjust the spring c in such relation to the bolt-head (l that when the proper load upon the platform of the car is exceeded it will be pressed against the spring e and the circuit closed through the bell-magnet G to operate the alarm as desired.

The use of a bell serves to call the operators attention more vforcibly than an inde-.vhand upon a dial; but it is obvious that any form of annunciator may be operated by the circuit, when closed, through the springs c e. It is also obvious that a local battery carried within the car maybe used instead of abranch of the motor-circuit, and such battery is indicated at q, with dotted connections 102 and w3, leading, respectively, to the magnet G and the spring c, like the terminals of the wires it w.

Three different forms of yielding bearing are shown in connection with the pulleys l, K, and N, that for the pulley l consisting in a pedestal, B, having one end of its foot resting upon a spring, t, adapted to yield when the normal pressure upon the pulley-shaft B is varied. The other end of the pedestal-foot is connected with its supporting-beam P by a hinge, B2, and the movable end of the foot is connected by a pin, c, with a switch-lever, c. The switch-lever is actuated by the movement of the foot to open the circuit and stop the motor when the counter-balance is obstructed in its movement, so as to sufficiently vary the pressure upon the .bearing B.

The movable end of the switch operates normally to imite two contacts, d", to maintain a closed circuit, as shown in l, and the weight of the car and counter-balance operate normally to compress the spring t to the point at which the switch is adjusted to close the circuit. The switch is therefore adapted to open the circuit and stop the motor ii' moved ineither direction, and an obstruction to the counter-balance in its downward movement, which would tend to slacken the pressure upon the bearing li, thus permits the spring t to raise the movable end of its 'toot and move the switch with the same effect as when the pressure upon the bearing was increased. As the ropes pass over the pulley K in a horizontal and vertical direction, the resultant pressure is at an angle with both ropes, and the boxf, supporting the pulley-axle K', is shown guided in an inclined socket provided with a pin to actuate a switch-lever, c', as just described. To sustain the box against the pressure ot the rope, a bent lever, j", is pivoted upon the pulley-stand and coupled with the box by link Z. rlhe lever is provided with sliding weight f2, which' is adjusted to balance the proper load, so as to hold the switch in its neutral position to close the circuit between the contacts d. The metallic connection c'2 between the blocks d is lapped upon each far enough to permit a normal movement of the bearing f and B within the limits ot an ordinary load without breaking the connection between the blocks and stopping' the motor; but an obstruction to the car in its downward movement would diminish the pressure upon the bearing and break the circuit by moving the switch in one direction, while an overload upon the car would cause the breaking of the circuit by moving the switch in the opposite direction, as described for the bearing i3.

The bearing for the pulley il is formed at the end of a hinged arm, N,witha spring, n2, above the bearingI to allow ot its vi elding like those last described.

The switch c is connected with the bearing by a pin, as in the other constructions, and the circuit through the motor is connected in series with its contact-blocks d', so that the circuit may be broken by a suitable movement of the switch.

ln Fig. 2 is shown the construction for the switches to operate with constant current, and a cut-out switch is shown. within the carto be actuated by the bolt-head d with either a slack-cable or overload for cutting out the motor and stopping the hoisting mechanism automatically. The switch is the same as that shown at the upper part of the figure, actuated by the yielding pulley bearing over which the suspending-rope is carried, and the motor for operating the hoisting mechanism is merely indicated with its operative circuit, as my improvement relates only to the electrical connections. The motor circuit is shown in the wires at d5, connected with the positive and negative line-wires, and the? two IOO IIO

switches are adapted to make a connection in a loop ot' the said circuit, and to thereby short-circuit the motor and cause its immed iate stoppage when either switch is operated. The switeh-lever in the car is shown actuated by a pin7 d, upon the bolt-head d, so that the movement of the. bolt-head will actuate the switch-lever the same as the movement ot the yielding-bearings heretofore described.

Each switch is provided with two contacts, o', both connected with the same circuitwires o?, and the other circuit-wire7 (ri, is connected with a metalli e piece, o, upon the switch-lever c. The piece or block o. is normalty Separated from the contacts o with a space between Such parts sut'tieient to allow the movement of the lever e within the normal variations ot the load, while any variations above or below the normal would move the block u desired.

It is obvious that either ot' the switches i illustrated would etteet the desired object, l

and that both would not be required in the lsame construction, the drawings being;l t'urnished with both the switches mel'elyto illus trate a variety ot' applimitiions.

The circuitis conveyed to the car through two conductors, d"e and di", shown, t'or convenience, fixed at opposite sides ot the carin the hoistway, with brushes or contacts dl sliding' over them with the movement of the car, and the circuit-wires u? and u connecting' such brushes with the contacts u in the earswitch.

it; is obvious that the current could be coitveyed to the ear by a cable, as shown in Ifig. l, or by any other suitable means. The indicator or bell (shown `in Fie'. l) would pret"- erably be set to give its alarm with a somewhat lighter load than that required to oper-i ate any ot the motor-switches shown applied to the yielding' bearings, so as to give warning' to the operator in time toavoid the actul ation ot sueh switches.

lt an automatic motor-switch were not ear or contiter-balance when ascending' would l not operate directly to stop the motor, but it would continue its revolution until its t'oree l were balanced bythe strain on the ropes, and this strain might be sut'licient to do serious damage lo the mechanism.

VWhere iron orsteel ropes are used their entang'lement or winding' over oneanother upon the drum causes short bends and intlicts serions injury ttpon them; but such injuries may be wholly avoided by a suitable adjustmentot the devices shown herein to etiect the stoppage ot the motor betore the ropes become slack enough to leave the grooves in the drum.

lt is obviously immaterial what means are employed to balance the tension upon the` yielding' bearing' orsuspemlinir-riuie, provided the pressure or weight ot' the car be sustained into contact with one ot." the pieces o', and thus short-eireuit the motor, as

Y provided, any obstruction to the nit'ivement ot' the at some point between the hoisting' device and car-platform by a yielding' support adapted to move an electric switch in the manner set forth.

The operation oit' the switches with j-onstant1 current and constant potential cireuits is substantially opposite, as is common with such i circuits, the motor being' stopped in the one l ease by short-circuitingI and in the other b v opening the circuit; but the automatic switches may be made ot' any etmstrtn-tion adapted to control the movements ot' the eleotrie motor and hoisting' nteeltanism. as desired.

. It is obviously immaterial how the power of the motor be applied to move the load. as g the connection between the motor and the carf plattform would in any case at'tord an oppori tunity for the insertion ot a yielding' support to aetuate a switch, as required in my inven l tion. l It will be noticed, although several ditlierent constructions for the automat ic swit eh are "shown in Fie'. i, that in practice a single switch at any convenient point in the circuitV is all that would be required. and the arrangement ot the several swit '-hes in series in the diagram is shown only to illustrate their mode of operation and would not be required in practice. lt will be also understood that the particular construction t'or the yielding' bearing' is immaterial, and that a weight, a spring', or any other suitable resistance may be opposed to the load upon the rope to hold the bearing' and switch normally in a position to operate, as desirial. lt is also immaterial how the yielding' connection to the earbe constructed, and I have shown in ldig's. il. -t, and 5 a variety ot' such constructions to illustrati'A the scope ot` my invention. llaeh otI these yielding' connections is shown operating' a switch conneeted with the terminals ot an electric circuit, and sneh circuit may be em i ployed either to stop the motor or to operate a bell or indicator, as may be desired.

lu liir. if) the rope l'. isattaehed to the short arm ot a lever, L', pivoted upon the top ot' 1 the car, and a weight is eonnmft'ed with the long' artn ol the lever to eounterlalanee the pull on the rope to a certain limit. 'lhe end ot` the lever is linked to a multpIyng-lever, el, connected with a pneumatic bell-push, e", the bell c being' `shown just below it, and the f excessive load upon the ear would operate to move the leverand aetuate the bell-push and i bell, as desired. l in Fig'. -t the rope 'l'. is shown passed bet two guide-pulleys, Il, which are pivoted upon a t'rame, m, adapted to turn upon the top ot the ear and to strain the suspending-rope out ot its normal vertical position. The tension upon the pulleys is produced by a springt/1, l t

attached to the top ot the car and to the i, trame nl, and operates normally to bend the rope in a certain degree until the load upon I the car becomes excessive. rThe frame is linked to a switch, c', and such excessive load lOO llO

y of a yielding' support sustaining the pressure device operated thereby, and a moving car is shown operating, by straining the rope L, to tip the frame against the tension of the spring and to shift the switch as desired.

In Fig. 5 the rope l) is connected with the top of the car through the medium of a couple 1 of toggles, which are attached at their ends to the car and to the rope, a spring, n", being inserted between them to press their middle joints apart. Any excessive tension upon the rope operates to-comprcss the spring' and to move an arm, n, connected with one of the toggles and to a switch, f", snitablel'or a constant potential circuit.

ln any of these constructions a weight or spring may be used at pleasure, or any other suitable means may be employed to 4perform the same function.

Any of the yielding'bearings or connections shown herein may obviously be einployed to actnate the indicator or bell by other mechanical means than a pneumatic bell independently of an electro-magnet.

Having' thus set forth my invention, whatl cla-im herein is-d l. In an electrica-l elevator system, the combination, with an electric motor, a hoisting device operated thereby, and a moving' car suspended by a rope from a hoisting device,

of the rope between the hoisting' device and the car-platform and an electric switch in the motor-circuit actuated by the movement of such yielding support to stop the electric motor.

In an electrical elevator system, the combination, with an electric motor, a hoisting device operated thereby, and a moving` car suspended by a rope from the hoisting device, of a pulley sustaining the pressure of the rope, a movable or yielding' bearing` for supporting the pulley-axle, and an electric switch actuated by the movement of the bearing to stop the electric motor, as and for the purpose set forth.

3. In an electrical elevator system, the combination, with an electric motor, a hoisting' device operated thereby, and a moving car suspended by a rope from the hoisting device, l of a pulley sustaining the pressure of the rope, j a movable or yielding bearing' for sumiortingl l the pulley-axle, a springer weight adjusted to sustain the bearing under a given load, and an electric switch actuated by the movement of the bearing' to stop the electric motor when such load is exceeded.

i. In an electrical elevator system, the conibination, with an electric motor, a hoisting' suspended bya rope from the hoisting` device, of a pulley sustaining' the pressure of the rope, l a movable or yielding' bearing' forsupporting the pulley-axle, and an electric switch actuated by the movement of the bearing' to close i a short circuit around the motor, as and for the purpose set forth.

` 5. In an electrical ele va-tor system, the combination, with an electric motor, a hoisting device operated thereby, and a moving car suspended by a rope from the hoisting device, of a pulley sustaining` the pressure of the rope, a movable or yielding bearing for supporting' the pulley-axle, a counter-balance connected with the car by a suitable rope, a pulley with yielding' bearing' for sustaining said rope, and electric switches applied to both of said yielding' bearings for stopping' the motor, substantially as herein setforth.

o'. ln an electrical elevator system, the combination, with a suspended car, of a yielding' connection between the car and its suspendin g-rope, an electric circuit connecting' the car with the electric motor, and a switch in such circuit upon the car, actuated by said yielding connection to stop the motor when the car is obstructed in its movement.

7. The combination, with a hoisting device and a moving car suspended by a rope therefrom, of a yielding support sustaining' the pressure of the rope between the hoisting' device and the car-platform, and a bell or indicator actuated by the movement of such yielding support, as and for the purpose set forth.

8. In an electrical elevator system, the combination, with a suspended car, of a yielding' connection between the car and its suspending-rope, a magnetic bell or indicator, an electric circuit for operating the same, and a switch arranged in said circuit and actuated by the yielding rope-connection to operate the bell or indicator.

9. ln an electrical elevator system, the combination, with a suspended car, of a rope connected with the car by an adjustable springcoupling, a magnetic bell or indicator upon the car and an electric circuit for operating the same, and a switch arranged in said circuit and actuated by the spring-coupling', when the maximum load is imposed upon the car, to operate the bell or indicator, substantially as herein set forth.

l0. ln an electrical elevator system, the combination, with a suspended car, of a yielding connection between the car and its suspending-rope, a magnetic bell or indicator, and an electric circuit for operating the same, alocal battery carried by the car for operating such circuit, and a switch arranged in said circuit and actuated by the yielding rope-connection to operate the bell or indicator.

In testimony whereof l have hereunto set my hand in the presence of two subscribing witnesses.

WM. BAXTER, JR.

Vitnesses:

L. LEE, Tiros. s. CRANE.

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