US2663865A - Signal for lifting apparatus - Google Patents

Description

Dec. 22, 1953 R. H. wlLLrAMs SIGNAL FOR LIFTING APPARATUS Filed Nov. 14, 1949 INVENTOR RICHARD H. WILLIAMS BYH/Ck ATTORNEY Patented Dec. 22, 1953 SIGNAL FOR LIFTIN G APPARATUS Richard H. Williams, Amsterdam, Ohio, assignor to National Delaware Steel Corporation, a corporation of Application November 14, 1949, Serial N0. 126,980

2 Claims. 1

The present invention relates to apparatus for lifting articles and is primarily concerned with preventing the accidental dropping of the article or articles being lifted. The present inventon relates more particularly to improve ments in lifting cranes of the type used to lift ladles of molten metal or to the lifting of other1 articles, the dropping of which would constitute a danger to the workmen and is primarily concerned with the provision of means for signalling to the crane operator when the crane hooks are properly in place for lifting the ladle.

Relatively large overhead cranes are used in steel mills and other plants for lifting and transporting iadles containing molten iron or steel from one location to another location in the steel mill. For example, cranes are used to transport ladies of molten iron from the mixer to thel open hearth furnace and to transport ladles of molten steel from the open hearth furnace to the ingot molds. The molten metal may be discharged from the ladle while the ladle is supported by the crane or the 'crane may deposit the ladle on a suitable support. The crane customarily is' provided with a pair of depending hooks which engage a pair of laterally extending trunnions mounted on the sides of the ladle. The crane operator, while located in a cab mounted on the crane far above the mill door, lowers the crane hooks and moves them into position to lift the ladle. When the hooks are in engagement with the trunnions, the crane operator by "means of a suitable control mechanism actuate's the crane to lift the ladle and to then move the crane and the ladle to the new location. Giften, the ladle containing hot molten metal is lifted from the floor of the mill to a relatively great height. At times, the ladle of hot metal will slip from the crane hooks and fall to the mill floor scattering the molten metal over the' surrounding area. Such a ladle may contain, for example, 65 tons of molten .metal and may be lifted about 60 feet above the mill floor. If the lifted ladle drops, the molten metal will severely burn anyone in the immediate area, and the ladle and its contents will severely damage any equipment they may strike. While a ladle of molten metal is only infrequently dropped. the lifted ladle does constitute a potentiel hazard to the workmen.

4It is an object of the present invention to pre vent the raising or lifting of an. article when the raising or lifting apparatus and the article to be raised are not in lifting engagement with each other so as to preclude dropping of the article.

It is an object of the present invention to provide a lifting crane which includes a signal that automatically will indicate when the crane hooks are in correct lifting engagement with the ladle trunnions so that the crane operator will not operate the crane to lift the ladle when the hooks are not in the proper position and thereby prevent dropping of the lifted ladle.

In accordance With the present invention, the lifting apparatus is provided with a signalling means which indicates when the article to be lifted is properly engaged by the lifting appara tus so that the operator will not lift the article when improperly engaged to prevent dropping of the article. In a preferred embodiment of the present invention, a crane is provided With a signal light and means for turning on the light only when the lifting hooks are in correct lifting engagement with the ladle trunnions. This prevents the crane operator from lifting the crane hooks and the ladle when the hooks are not in fixed engagement with the trunnions. This prevents lifting of the ladle in such a manner that it can be subsequently dropped. The means for signalling the operator may be readily and inexpensively installed to prevent the dropping of a ladle of molten metal with subsequent injury to the workmen and equipment in the mill.

These and other objects and advantages will become more readily apparent when considering the following description, taken with the accompanying drawings, in which:

Figure 1 is a view in elevation of a crane lifting a ladle of hot metal;

Figure 2 is an enlarged fragmentary view in end elevation illustrating a portion of the crane and the ladle shown in Figure 1;

Figure 3 ls a side view in elevation of the apparatus shown in Figure 2;

Figure 4 is an enlarged, fragmentary sectional view taken along line 4--4 of Figure 2, and

Figure 5 is a circuit diagram of the signaling apparatus provided by the present invention.

Referring to the drawings and more partici larly to Figure l, steel mills and other plants customarily have a relatively large overhead crane l0 for moving a ladle l l of molten metal from one location to another in the plane. Various types of cranes may be used. The crane le is one type customarily used and includes a main motor driven ycarriage l2 movable along rails i3 carried by posts it located at opposite sides of the plant building. A second motor driven carriage I8 is mounted on rails ll carried by carriagelfZ. Thus, both carriages l2 and lil are movable along rails i3, and carriage ifi is transversely movable along rails l1. A bail i8 is suspended by cables I9 from 3 carriage I6, and the bail I8 carries a pair of hooks 20, 2l adapted to engage a pair of trunnions 23, 23 located on opposite sides of the ladle II.

In operation, the operator while located in an observation cab 25 carried beneath carriage I2 actuates the controls located in the cab 25 to move carriage I2 and carriage I8 to a position in which the bail I8 is above the ladle to be lifted. A drum (not shown) on carriage I3 is then caused to rotate to unwind the cables I8 and lower the bail I3. The crane and the bail are then maneuvered by the operator so that the hooks 28, 2l engage the trunnions 23, 24 and then the ladle is lifted. After the ladle has been lifted, the crane I8 is moved to transport the ladle II to a position above its new location, and the ladle is then lowered. All movements of the crane and the raising and lowering of the crane hooks is controlled by the crane operator located in cab 25 by means of suitable controls located in the cab.

The cab 25 is usually high above the mill floor and may, for example, be about 60 feet above the point where the ladle is located. The ladle is quite large and contains a large quantity of molten metal; for example, the ladle may contain 65 tons of metal. At times, and after the ladle has been raised, the ladle slips from the crane hooks and falls to the mill floor. In addition to damaging the mill equipment, a failing ladle of molten metal obviously is dangerous to the Workmen.

As described above in detail, the crane IE and ladle I I are of the type customarily in use around mills and form no part of the present invention.

In accordance with the present invention, the lifting apparatus or crane which includes a member or hook adapted to be arranged in lifting engagement with the article or ladle to be lifted is provided with an electrically operated signalling means for indicating tothe operator when 4 to the bulb 21.

the lifting member is in lifting engagement with Y the article to be lifted. Referring more particularly to Figures 2, 3 and 4, on the bail I8 which carries hooks 28, 2l there is mounted an electric light bulb 21 protected by a transparent cover- Y ing 23. The bulb 21 is mounted in a socket 29.

A battery 3&3 is mounted on bail I8, and one side of thegbattery 38 is'connected by an insulated wire 3i to one side ofy the socket and the bulb in the socket. The other side of 'socket 29 and bulb 21` is connected through wire 32 to the conductive metal bail IB. In other words, the other side of the bulb is grounded. To the other side of the battery 38, there is connected an insulated wire 33 that extends from the bail down through a protective conduit 34 mounted on hook 28 to post 36. A second post 31 is mounted on the side of hook 20, and a bare conductive wire 38 extends between posts 31 and 36 and is connected to wire 33. Each post insulates the wire 38 from the hook 2B. These posts are similar and only post'31 will be described in detail. Referring to Figure 4, post 31 comprises a stud 48 threaded into the side of hook 2t and a cylindrical insulator 4I formed of ceramic or other suitable material mounted on stud AG. The end of wire 38 is wrapped around insulator 4I so that the wire is insulated from the hook 28. The opposite end of wire 38 is similarly insulated from the hook 2l by post 31.

Wire 38 is mounted on the hook in position so that it is engaged by trunnion 23 only when the trunnion is positioned in the hook recess 42 in the lower portion of the hook member 20. Preferably, the wire 38 is resiliently mounted so that it will give and not break when engaged by trunnion 23. As shown, Va portion of wire 3B is coiled to form a spring 44 so that when the trunnion engages the wire, the wire will stretch. The spring 44 may be a separate spring. When the trunnion and the hook are in lifting engagement, the trunnion, which is metal and conductive, electrically connects wire 38 and hook 28 to close the electric circuit to bulb 21 so that bulb 21 lights up only when the trunnion and hook are in lifting engagement with each other.

The wire 3l constitutes one side of an electric circuit, and the wire 33, wire 38, hook 28, bail I8 and wire 32 constitute the other side of a normally open circuit for supplying electric current The wire 33 and the hook 20 which are insulated from each other in effect constitute means for closing the circuit only when the hook and trunnion are in lifting engagement with each other. If, for example, the end e3 of the hook 28 engages the bottom of the trunnion so that the trunnion is balanced on the end of the hook, then the fact that the light bulb does not light will indicate that the hook is not in proper engagement with the trunnion and the operator will not actuate the crane to lift the ladle. The

crane operator in cab 25 is often so far from the ladle that it may appear that hook 28 engages trunnion 23 when actually the hook `is not in lifting engagement with the trunnion. The signal light visually indicates when the hook is in lifting engagement, and the ladle will not be lifted improperly and then dropped.'

A signal light bulb 41 and a battery i8 are electrically connected to hook 2i the .same as.4

described in connection with hook 28. v The bulb is connected by wire i8 to battery 38 and.

grounded through wire 58 to the conductive metal bail IS. insulated wire 5I to the exposed wire 52. Wire 52 is mounted on hook 2I in the same manner as wire 38 is mounted on hook 23. When the hook 2| is in lifting engagement with trunnion 24, the trunnion 2li engages wire 52 and hook 2I to close the circuit to bulb 3l. The wire 52 and hook 2I constitute an open switch that is closed only when the hook is in lifting engagement with the trunnion. A signal light is preferably provided for each hook as it is possible to have one hook in lifting engagement without having the other hook being in lifting engagement.

A circuit diagram for either signal light is illustrated in Figure 5. As shown, one terminal of the battery 30 is connected to a terminal of f the light 21 through a lead 3l, while the other' terminal of the battery and of the light are connected together through conductor 83, switch 6I and conductor 32. The switch 5I includes terminals 63 and Sli and a switching member 65 which is movable into contact with the terminals`r to form an electrical connection therebetween. The conductor 38 corresponds to the wire 33, and

the switch contact 63 corresponds toA the wire 38. The other switch contact 5d corresponds to the end 46 of the hook while the conductor 62 represents the hook 28 and the bail I8. The switching member 65 corresponds to the trunnion 24.

hooks properly engage the trunnions when the hooks do not.

Battery 139 is connected through I claim:

1. In a crane for lifting an article, the bination comprising, a lifting hook having a recess for receiving a portion of the article to be lifted when arranged in lifting engagement with an article to be lifted, electrically operated signal means, and a normally open electric circuit means for connecting the signal means to a source of electric current, said circuit means including a normally closed rst conductor means for connecting one side of the signal means to a source of electric current and a normally open second conductor means including the lifting hook for connecting the signal means to the other side of a source of electric current. and said second conductor means including conductive means carried by the lifting hook in position to be engaged by said portion and complete the electric circuit through the lifting hook to the signal means only upon said portion of the article to be lifted being in the hook recess.

2. In a crane for lifting a ladle having a pair of electrically conductive trunnions, the combination comprising, a bail, means for lifting the bail, a pair of hooks carried by the bail for engaging the pair of ladle trunnions, each hook having a recess for receiving the corresponding trunnion when the hook is arranged in lifting engagement with the trunnion, an electrically operated signal means carried by the bail for each hook, and an electric circuit for supplying electric current to each signal means, each circuit including a rst conductor means for connecting one of the signal means to one side of a source of electric current and a normally open second conductor means for connecting the same signal means to the other side of the source of electric current, each of the second conductor means including one of the hooks and an exposed conductor member mounted on and insulated from the hook in position to be engaged by a trunnion upon the hook being in lifting engagement with the trunnion whereby the electric circuit for each signal means is closed only upon a trunnion being positioned in the recess of the corresponding hook.

RICHARD H. WILLIAMS.

References Cited in the le of this patent UNITED STATES PATENTS Number N ame Date 327,919 Burmann Oct. 16, 1885 2,337,625 Walther Oct. 23, 1945 2,510,115 Jakosky June 6, 1950 OTHER REFERENCES American Merchant, pg. 99, Feb. 3, 1944.

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