US2315942A - Luffing crane - Google Patents

Description

April 6, .1943, v J. w. DEIST 2,315,942

LUFFiNG CRANE Filed Sept. 29, 1942 5 Sheets-Sheet l M'AQ' YZZIZZ X77; w/Mwd April 6, 1943. w DElSTT 2,315,942

' LUFFING CRANE I Filed Sept; 29, 1942 5 Sheets-Sheet 2 INVEN'I'OR April 6, 1943.

J. w. DElST LUFFING CRANE Filed Sept. 29, 1942 5 Sheets-Sheet 5 III II 3" a INVENTOR QW'WMQMX April 6, 1943. J. w. DEIST 2,315,942

LUFFING CRANE Filed Sept. 29, 1942 Shee'ts-Sheet 4 I INVENTO April 6, 1943. w IDE|ST 2,315,942

' LUFFING CRANE Filed Sept. 29, 1942 5 Sheets-Sheet 5 6M1 day/Mat Patented Apr. 6, 1943 Joy Wendell Deist, Mount Lebanon, Pa., assignor Pittsburgh, Pa., a corto Dravo Corporation, poration of Pennsylvania Application September 29, 1942, Serial No. 460,051

1 Claim.

This invention relates to lufiing cranes and,

generally, to structures that include pivotally require to be swung P wermounted parts that fully. Such structures may, for example, be draw-bridges or the gates of locks. The invention, however, has been developed in the building of lufiing cranes, and in such specific association it will here be shown and described. The

objects in view are speed and accuracy in operation and durability.

In Letters Patent of the United States, No. 2,188,686, granted January 30, 1940, onthe application of Bernard H. Kersting and Hans Enard, means are described in association with a lufling crane for efiecting the lumng movement. The present invention consists in improvement on the lufiing means of the said patent.

In the accompanying drawings Fig. I is a view in side elevation of a gantry crane of turret type, mounted to travel upon rails, in which the luillng means of this invention are. employed; Fig. II is a fragmentary view to larger scale, showing in plan the lufiing-mechanism; Fig. III is .a fragmentary view in side elevation of the luiiing mechanism, the wall of the mechanism being broken away in part, and the structure beyond the wall shown in vertical section in the plane of the axis of one of the screws; Fig. IV is a fragmentary and sectional view to yet larger scale, on the plane IVIV, Fig. IH; Fig. V is, a view in section, on the plane indicated at V- V, Fig. IV (from the showing of Fig. V, however, certain details of structure are lacking); Fig. V1 is a sectional view to yet larger scale, on the plane indicated at VI-VI, Fig. II; Fig. VII is a view to yet larger scale, presenting in end elee vatlon the lumng mechanism that in Fig. II is shown in plan; Fig. VIII is a diagrammatic view in side elevation of a draw-bridge which includes a pivotally mounted element, and to which application is made of the swinging means of the invention. I

Referring, first, to Fig. I, the crane is mounted upon a base, in this instance a platform I mounted to rotate turret-like upon a derrick 2. The crane includes a jib 3 pivoted upon a horizontal axis to the base at 4 and adapted to swing vertically upon such pivotal mounting. Such vertical swinging is termed lufling. From a drum ("not shown, but rotatably mounted on platform I", as is usual) a hoist line 8 extends throughout the length of the jib and supports, in a suitably formed bight, a block I. Upon this block the load is hung.

screws 9 thus form a triangle (called The jib 3 of the' crane is, as in Fig. I it is shown to be, a truss structure, of general triangular outline, pivoted at one comer of the triangle at 4 upon the base I00. This triangular truss structure includes the basal chord memher 8.. A third member (in this case and for the purposes of invention a multiple member, consisting of duplicate screws 9, 8) is, througi intermediate parts, pivoted at one end (on a horizontal axis of pivoting) to the otherwise free end of member 8 of the truss-formed jib (at l0) and is, through intermediate parts, pivoted at the opposite end (and on a horizontal axis of pivoting) to the base I00 at the point ll, remote from the pivot point 4. The base Hill, the chord member 8, and the duplicate in the industry an A frame). Of this triangle of members, the effective length of one ,side (formed by .the duplicate screws 9) is variable; and,"by variation of the effective length of this member, the jib is'swung and lufiing is effected.

In the 'Kersting and Enard patent alluded to the screw 9 is a single tension member and the stresses of' service are centered in the axis of the screw. ,The trussed jib 3 is a three-dimensional structure, of substantial extent in the direction perpendicular to the plane of the side elevation, Fig. I. Referring to Fig. 11, the truss of the jib 3 will be seen to include, not the member 8 only, nor even the pair of members 8, 8,-but a second pair 8*, 8 and a duplicate and more widely distant set of members 8', 8 and 8, 8. The invention consists in an elaboration of the lufiing means of the Kersting and Enard patent and an organization of the elaborated parts, by which the three-dimensional jib may be more effectively luiIed.

I have prepared duplicate screws 9, one for each of the two sets of truss members 8, 8 8, 8 and 8 8, 8, 8, and have centered the screws, one in each of the two groups, as sufilciently illustrated in Fig. II. The two screws, so severally centered, are geared to an interconnecting cross-shaft, whereby simultaneity in rotation and at equal speed is insured. And by such means the assembled structure is re-enforced, 'to'resist racking strains, and security, accuracy of operation, and durability are enhanced.- I have used the term duplicate screws 9, and the word duplicate will not be misunderstood. With such interconnection as that shown in Fig. II, the two screws, to be effective in the manner described (cf. Fig. VII), will be oppositely threaded. Subject to this detail of |6 a motor trated in Fig. VI, the shaft 9 couplings I 6!, 05

oppositely directedthreads, thescrews are duplicates.

Each of the two screws 9 is oppositely threaded at its two ends, and each carriesxupon its oppositely threaded ends two "oppositely threaded nuts, l2 and II. The nuts are pivotally mounted in pairs of links, l4, l4 and i6, I6. that move in runways 26 in two duplicate frames l6, l6, and in their mountings are secured against rotation. The links are pivoted-the links I4 at one end of the screws 6 to the paired truss members 6, 8, 6, 8' etc., and the links ii are pivoted to a correspondingly elaborated anchorage in base I (note in Fig. IV the elaboration I, I I, I). It is manifest, then, that; as the screws '9, 9 are rotated in one direction or the other and the pairs of links drawn together or spread apart, the eflective length of the paired screws as a member of the A frame is diminished or increased, and the jib 3 is swung upward or downward.

As appears in Fig. VI, each of the screws 6 may conveniently -be formed oftwo severally formed andessentially duplicate halves placed end to end and bolted together and carrying bolted to them a gear wheel 9 l. Upon each frame I6 is mounted, and from the driven shaft I80 of ing includes a pinion 92, whose shaft carries a bevel gear 93; and the duplicate bevel gears so associated, one with each of tus of the two shafts 9, are in mesh with duplicate complementary bevel gears, both borne by a single, transversely extending shaft 94. For purposes of assembly and adjustment, separable and 96 are conveniently provided. By such provision the two motors [6 cooperate in rotating the two screws 9, 0 in simultaneity.

It will be understood that, even though the direct loads on the duplicate screws 9, 9 ,are substantially equal, the power required to drive one of the screws may be different from the power required to drive the other. This is due to inequalities in the frictional resistance between the relatively moving parts of the two screw assem blies, caused particularly by unavoidable variations in the lubrication of the parts, and by minute variations in the contours of the threads of the screws. The cross-shaft 94 operates, manifestly, to equalize the work imposed upon the two motors, and thus it is possible to construct the shafts and the lufllng mechanisms muc lighter and at less cost than otherwise. r

The duplicate frames l6, s0 assembled with links l4, l4, l5, l afford a floating runway and a tension-resisting member for the links and support for the motors IS. The frames are formed of steel plate and are of the general troughshape shown. The two frames are interconnected by a walkway I63. In the ensuing claimthe term frame will be employed to include such a multiple part. Screws 6 are prolonged in shaftlike extensions 90 of reduced diameter that turn in frame-borne bearing-blocks I62. And upon these blocks the bodies of the screws make endwise abutment. Manifestly, it is only the reaches of screws 9 between the nuts l2 and I8 that are subject to the tension stresses of the loaded crane; and, of course, if the screws break, they will break somewhere in the interval between the nuts. In the event of such screw failure, the

ends of the broken screw become compression the motor, through the gearing .illusis driven. The gearthe driving apparamembers and transfer through the blocks I02 to the body of the frame II the load-sustaining tension. Thus the frames I6, normally serving as runways and motor supports, are. adapted in emergency to become effective load-sustaining members, preventing undue harm to the apparatusc and guarding workmen from serious danger. Provision is made between nut and screw. tions upon the-degree of in the preparation of material and the fabrication of parts give value to this provision. The nut has gimbal mounting in the pairs of;,links; and, according y, underthe stress transmitted between screw and link, the nut adjusts itself upon the screw, and stress that otherwise might The practical limitabe concentrated at onepoint is distributed gears of the duplicate around the circumfere be of the interengaged threads. The gimbal mounting is found in a cylindrical cup 22 with-a bottom orifice through which, in the assembly, the screw I extends, and within which the nut is arranged. Externally, the cup is provided with trunnions 24, by which it is pivotally mounted in the associated pair of links (l4, l4 or l6, l6). Internally, the cup is provided with transversely extending cylindrical biisses. conveniently formed as pins 26, welded in orifices in the cup walls. The axes of trunnions 24 and of pins-2| are angularly displaced at a angle, with respect to the axis of the cup (and of shaft 6) as a centre. Upon the bosses 26 the -nut makes thrust bearing, the bearing surface of the nut' being, correspondingly cylindrical in shape. Elsewhere than over the thrust surfaces specified, the nut has clearance, from the surfaces of the cup.

The nut is compound, and consists of the con-- centrically arranged parts 20 and 21'. It is the outer of these two parts that engages the cup 23 over the cylindrical-bearing surfaces specifled; it is the inner part 20 that is the threaded part and that immediately engages the threaded stem 6. The inner tingzengagement with the outer 'over the shoulder Upon the part 20 a supplementary nut 36 is mounted. The supplementary nut is cut away in part, as indicated at 22 (Fig. IV), exposing the assembled threads of nut'and screw. threads within the part 26 are so proportioned as to fill the complementary threads of the screw: the threads in the space between the opposed'surfaces of nut and screw. When the parts the faces of the threads of the supplementary nut stand away from the faces of the threads of the screw. In consequence, it is the nut part 26 through which alone the stresses of service are normally transmitted. As in continued use the interengaged surfaces wear away. the spaces at which the surfaces oi the supplementary nut 26 stand away narrow. This narrowing of: space is visible through the cut-away'space I2. Thus a tell-tale is provided, by which determination may be made, when the nut part 20 is so far worn as to require replacement.

The nutpart 26 will ordinarily be formed of bronze; but the supplementary nut I6, serving the described purpose, not of tell-tale merely;

forthe distribution oflstress perfection attainable indicated at 26.

part makes stress-transmit- The supplementary nut 30 are so proportioned as normally to leave a small are initially assembled,

frame is diminished or increased; and arm 3 is raised or lowered. The provision of duplicate screws 9, arranged in parallelism and spaced apart in the direction of the breadth of the truss that constitutes the jib 3, adjustable to equality in effective length, and, when adjusted, adapted to be rotated in simultaneity and at equal speed, ailords an assembly that is rugged, braced against racking stress, and of notable rigidity and durability.

In Fig. VIII a draw-bridge is diagrammatically shown, consisting of two halves 40 severally mounted plvotally upon opposed bridge-heads ill; and adapted to be swung vertically between fullline and dotted-line positions. In this case, also, each bridge half is in structure a trussthat includes a chord member 80, and the truss has breadth: it extends in a third dimension, perpendicular to the plane of view of Fig. VIII. Between the distal end of chord 80 (the end remote from the point of pivoting) and a pivot to mountedon the bridge-head 50 at an interval from the pivot I0 0! the chord member 80, such a structure as that already described may be introduced. By means of such astructure the draw-bridge halves may be raised and lowered. By virtue of the duplication of the screws 8 o! the structure, connected to the relatively movable parts and spaced from one another across-the breadth of the structure, the ends already named of rigidity and durability are gained.

I The invention in like manner the swinging of single-span draw-bridges.- It is manifestly applicable to the swinging of the gates of canal locks; and generally to the swinging of pivotally mounted structures that require to be powerfully swung.

I claim as my invention: Means for swinging a structure pivotally mounted upon a support and having extension in the direction of the axis of pivoting, such means including a frame, two pairs of carriages mounted in the frame, the'carriages of each pair in 'alignment, and the two pairs arranged in succession in. the direction of the said axis of pivoting, the carriages mounted-for longitudinal movement in the frame, one carriage of each pair being pivoted to the swinging structure and the other carriage of each pair being pivoted to the support at points remote from the said axis of pivoting, two pairs of nuts mounted one pair in each of said carriages, two screws simultaneously engaging severally the two nuts of the two pairs and adapted on rotation to effect the drawing together and the separation of the so-engaged carriages, two motors, d iving connections from the motors severally to the two screws, and a crossshaft interconnecting the two screws, whereby the two motors co-operate in rotating the two screws and the load imposed upon the motors is equalized between them.

a JOY WENDELL DEIST.

is applicable to

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