US2060722A - Hoist grab - Google Patents

Description

NOV. 10, 1935. ,J BRESLAV 2,6@,7Z2

HOIST GRAB Filed April 11, 1935 INVENTOF! MW um Wu ATTORNEY Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to improvements in grabs for power-hoists and the like including those suspended from over-head traveling cranes. Such grabs in use commonly are suspended from 5 a hoist-hook traveling over-head and the crane is controlled and the hoist raised and lowered by an operator in a cab traveling with the crane; and ordinarily a second operator, located in a seat at the hoist-hook suspended from the crane, or

l on the floor, attends to local operations of the grab. No second operator is required in using the invention hereof, altho an operator at the grab may be employed occasionally.

The object of the invention is to improve the construction and operation of such grabs in the various respects described below and resulting in the advantages there stated.

The invention consists of the new and useful features of mechanical construction which are pointed out in the claims; examples of these features being shown in the drawing of which Fig. 1 is a broadside elevation of a practical embodiment of the invention; this figure showing a load on the floor, the grab partially suspended from a hoist and astride the load and partially resting on it.

Fig. 2 is an elevation of the right end of Fig. 1.

Fig. 3 is a broadside elevation like Fig. l, partly in section, and showing the load held elevated slightly above the floor by the grab; with the grab-arms E in powerful grasping engagement with the sides of the load, and ready by the hoist to either lower the load to the floor or lift it further above the floor.

Fig. 4 is a somewhat diagrammatic perspective, showing the movable operating parts of the grab, and from which the central stationary part F of Figs. 1 and 3 and partially concealing them is omitted for clearness to show the locking mechanism L and the over-lapping of arm-carriers Y, and in this Fig. 4 the grasping members S, S, are moved outwardly away from engagement with load Z, and temporarily locked securely in such relations.

The upper end of the grab is shown as provided with a clevis or ball C, by which the grab is hung from the hook H of a hoist. A king-pin K is supported in clevis C. A pivoted linkage system is pivoted at its top to king-pin K below bail C, and thereby pivotally suspended from the means by which the grab as a whole is suspended from a hoist; and the lower portion of this linkage system is pivotally connected at P, P to a strong support F whereby the latter is pivotally suspended from the linkage system. Thus the linkage system is suspended from the hoist, and support F is suspended from the linkage system.

The grasping hands or fingers S, S, on the facing sides of lower portions of depending grabarms E, E, are shown diagrammatically and may 5 be of any desired nature for any desired cooperation with the means for operating loadgrasping drop-arms E. S, S may be adapted for grasping loads having any particular character of surface or shape to be frictionally grasped or otherwise supported by the grab hands or fingers. The load-grasping portions of arms E, E, as S, S, may extend the entire vertical length of the insides of the non-pivoted arms E, because according to the invention these arms preferably extend straight down vertically with uniform operating angles in all operations; but on the other hand the grasping portions of arms E may be special grasping hands for use alternatively with the linkages disclosed herein.

The invention hereof relates more particularly to means for supporting the non-pivoted grabarms E and for carrying them inwardly toward and outwardly from one another to adapt the grab to use of S, S and non-pivoted arms E in load-grasping, and yet preserve ample grasping power for safety in handling loads of various weights and widths. The invention also relates to means for employing the weight of the load to determine the power which is applied in operating the means which supports and carries the non-pivoted, constant-angle grab-arms, (as distinguished from pivoted arms), so that the grasping pressure against the load (when a friction grip is employed as commonly), is high and in general proportional to the weight of the load itself.

Grab-arms E, E are supported at upper portions at or relatively near their upper ends, by movable horizontal carriers or cantilevers Y which extend inwardly fromthe upper ends of the respective arms E. Said movable carriers Y are longitudinally reciprocable, inwardly and outwardly, simultaneously in either direction, carrying the two arms E simultaneously in either direction, i. e., alternately toward one another and away from one another, to cause the grab to engage the load Z preparatory to lifting it and so as to be disengaged from the load after its lowering and deposition in a new location onthe 5 floor or other support.

Arm-carriers Y so longitudinally movable, move horizontally thru a relatively stationary central box-like support F suspended from the linkages. The means for such suspension of support F may be of any desired nature so far as concerns carriers Y; but the illustrated suspension by a power increasing leverage linkage is preferred, as inthe example shown and to be described, because such linkage very greatly increases the effect of the gravity which may be employed in the example shown to control the grab operation in place of a motor. Support F sustains both 'the weight of both the movable carriers Y, Y

" they can be lowered by hoist H straight down to positions straddling the load, and between the load and other loads close alongside it, with only.

sumcient space between them to allow for the downward passage of each of straight arms E, for carriers Y, Y preferably do not extend out beyond E, E.

Since the horizontal broadside, constant angled movements of straight non-pivoted arms E in opposite directions toward one another and the load, and alternately in opposite directions away from one another and the load, and always at the same angle, are caused by corresponding movements of arm-carriers Y, therefore the over-all width of this grab as a whole varies according to the width of the load, as Z, i. e., there is no need of any outward extension of the carriers Y horizontally beyond arms E; the result being for example that the straight arms can pick up a load from the bottom of a deep narrow pit which is very little wider than the load, as well as a load on a floor from a location close to other loads alongside it. The above relations of horizontally movable carriers Y and their straight drop-arms E provide for straight-line movements of the parallel arms broadside toward and away from one another and to and from the sides of the load, in addition to up and down movements of the vertically straight arms; that is, the dependent arms E at all times are parallel to one another, 1. e., their angular positions are constant, in both their vertical and horizontal movements, whether or not they extend exactly straight down as preferred; and in addition, the horizontal mobility of arm-carriers Y independently of one another provides for both great and little separation of arms E from one another, so as to adapt the grab to handle loads of widely varying widths. The load-widths may be either as great as the combined effective lengths of the two movable carriers Y; or on the other hand the load-widths may be as narrow as the width of central carriersupport F, all as the result of the following construction permitted by the independent mobility of the arm-carriers Y, i. e., independent of F. Preferably, in order to accommodate wide loads, carriers Y are long enough horizontally, and of shapes and locations over-lapping one another, Fig. 4, so as to extend horizontally parallel to one another, at least at said over-lapping portions. Thus the two carriers Y, from their relative positions supporting the two arms E in positions much closer together than in Figs. 1 and 4, (as in Fig. 3), can be moved outwardly so as to cause arms E to be moved much, further apart than even in Fig. 4, as by suitable operations of the rack-and-pinion arrangements to be described, for operating carriers Y by the power of gravity as shown and to be described.

Carriers Y can be moved inwardly, toward very narrow loads, to the inner limit where the insides of the tops of more or less vertical grab-arms E abut against the ends of the bottom FB, Fig. 2, of central carrier-support F. Since said support F for carriers Y is very narrow horizontally, the carriers Y when constructed as above for overlapping relations of their inner ends, Fig. 4 can be moved far inwardly to move arms E to and against very narrow loads, altho at the same time the over-lapping arrangement of carriers Y permits them to be of great horizontal length providing for large. extents of their outward movements to move arms E to positions far enough apart to straddle very wide loads.

As to the extent of possible inward movements of carriers Y, when their central support F for their over-lapping, parallel inner ends is sufflciently narrow, and when carriers Y themselves throughout their lengths are movable in paths generally parallel to one another as shown, then carriers Y can be moved so far inwardly, in extreme cases of exceptionally narrow loads, that the inner end of either carrier Y may extend outwardly beyond the arm E carried by the other carrier Y. But with a given construction of the grab and in the cases of most loads, even of narrow widths, handled by the grab, the inherent advantage of the over-lapping arrangement of carriers Y is that it provides for handling quite narrow loads without any projection of either carrier Y horizontally beyond the vertical arm E carried by the other carrier Y, so that there are no projections laterally beyond the arms E to interfere with load-handling operations, and so that the grab when not in use can be collapsed inwardly laterally and therefore stored in a small space, which is an important practical feature.

As to the extent of outward movements of carriers Y with over-lapping construction, when their over-lapping inner portions are of suillcient length, then the carriers can be moved outwardly to move arms E to positions far enough apart to engage very wide loads, up to the limit of the means which may be provided for moving carriers Y, and up to the limit of the ability of the grab to withstand the weight of a load of extremely great width up to the strength of the grab, obtained by suitable mechanical design of the mechanical combination of arms E, carriers Y, carrier-support F and of whatever means may be employed to suspend support F from hoisthook H. When a load is held up off the floor, Fig. 3, by engagement with it of the grasping hands or fingers S, S, then the over-lapping ends of carriers Y in central support F have a tendency to be forced downward in support F by the weight of the load, as against the bottom wall P3 of F, Fig. 2; and at the same time, the weight of the load tends to cause carriers Y to move inwardly inside their support F, as by way of the rack and pinion arrangement El, GT.

As the result of the above preferred straightline broadside movements of non-pivoted droparms E toward one another caused by movable carriers Y, to cause engagement of the grab with a load to be lifted, and regardless of the space between arms E for any particular load-width, the space between adjacent loads in a row of loads, to allow load-straddling by the grab-arms, is not necessarily any greater than the horizontal thickness of the respective vertically straight grasping hands or fingers as S. The constantangle movements of non-pivoted arms E to and from one another is important in general as above, and is of particular importance in relation to the particular means which may be used in the grab in combination with movable carriers Y, for the purpose of causing gravity to move non-pivoted arms E, in the ordinary cases where grasping friction with the load is to be relied on as the means of providing a safe nonslipping grasp of the grab-hands on the load; as follows.

The arrangement of rack-teeth El, El over the tops of carriers Y, the co-meshing gear or pinion-teeth GT formed on pinion-segments SG, and removable pinion-axles P, provide for adjustments of non-pivoted arms E to adapt the grab to use with loads of very different widths without varying the grasping pressure on the'load. In,

the particular embodiment of the invention illustrated as an example, this rack and pinion arrangement also provides for the automatic establishing of lifting grasping pressure of nonpivoted arms E on the load by means of the weight of the grab itself, and provides for increase of such pressure by 'the coming on of the load; and in the construction of the grab as a whole in any embodiment of the invention, whenever desired, the grasping pressure on the load always is the same for a given load-weight re.- gardless of any particular load-width or adjustment of arms E by means of the rack and pinion arrangement to adapt the grab to loads of different widths.

The linkage system above the rack and pinionteeth arrangement is the particular means disclosed by way of example herein, for obtaining the maximum uniform grasping pressure, high and proportionate to load-weight, on loads of given weights regardless of the widths of such loads, after the grasping members, S, S have been engaged with the load, Fig. 3.

The provision of the desired adjustment or setting of arms E to adapt them to use with loads of varying widths without variation of grasping pressure, is as follows. The segment pinions SG are journaled in the front and rear vertical walls of box-like support F, by way of axles or short shafts P, P extending thru said walls and thru the centers of the pinions SG located between said walls, i. e., inside box-like support F. In order to change the setting of non-pivoted arms E, the shafts or axles P, P readily are removed by the operator, (most readily when as in Fig. 1 support F itself is supported as on the load itself). The pinions SG then are lifted up from engagement with the rack-teeth El, El on the tops of carriers Y, Y, and then said carriers are moved inwardly or outwardly as desired, manually, either to decrease or increase the spacing between arms E from both their two operating positions of Figs. 1 and 3, so as to adapt the grab to loads respectively narrower or wider than load Z in those figures. Then the pinions SG are lowered (swinging on pivots U, U) into reengagement with the racks on carriers Y, and the axles P are replaced, leaving the linkages above carriers Y exactly as before. The grab then is ready to commence operations on loads having a new range of operation on loads of a narrower or wider range of widths, within which new range the grab-arms E will be moved automatically the same distances as before, upon operation of hoist H, by means of the gravity of the grab itself, to or from the sides of the load, the power of gravity acting automatically by way of the linkages below hoist-hook Hbetweenl I the sides of the load automatically will be greatly increased to a safety-grip, by thelinkages'operated by the weight of the grab plus the now added weight as the load, upon the raising of hoist H, j

the grab and the load. These automatic op'erations are independent of the width of loads which are within the adjusted-range of arms E. In Fig. 1, arms .E are locked in their positions shown, by mechanism L, Fig. 4; and before the resetting by manual horizontal movements of arms E, said mechanism is operated to unlock arms E, as has been done in Fig. 3 by hoist-op eration.

In the above adjustment or resetting of arms E, no change is made. in the leverage-linkage system above the racks and pinionsfand said linkages thereafter and at all times act the same for all ranges of operation of arms E. It is for this purpose of obtainingthe desired ranges of operation of arms E for different ranges of loadwidths, without making any change in the conditions of the linkages, that segmental pinions SG are lifted up from the racks to allow independent rack-adjustment, instead of turning the pinions on their axes P while enmeshed with the racks. After a new setting of arms E by this adjustment is made, and in the further operations of the grab, carriers Y are moved in and out by pinionturning while enmeshed with the racks, respectively, at different stages of operation, first by the power of gravity of the grab alone, and sec- 0nd by the' power of the gravity of the grab plus the gravity of the load. For all different widths of loads of the same weight, the grasping pressure will be substantially the same, vi. e., in general proportion to the weight of the load. In other words, while arms E are adjustable to different load-widths yet the linkages which support them are not adjustable but always are operated in the same way by a given gravitational force, and with the result of causing greater gravitational forces to cause higher load-graspings by arms E, irrespective of the width of a load and of the arm-spacing adapted to such width.

Any desired type of linkage for suspending the grab including parts F, Y and E, from the hoist may be employed; but means having the gravity-power-increasing leverage such as that shown is preferred in order to cause the power from gravity to be effective in very greatly increasing the arm-pressure against the load both before and after the coming on of the load. However, the arrangement of movable carriers Y, with or without a multiplying linkage, provides for higher inward grasping pressure of arms E on the load after the load-weight is added to the weight of the grab alone, i. e., after the grab-weight has caused initial arm-grasping of the load.

After a given resetting of arms E has been effected, as above, and after the racks and pinions again are enmeshed in the same relations of thelinkages as before, (the pinion shafts P occupying the same positions in support F as before), then it is not necessary again to reset arms E until it may be desired to adapt the grab to loads of a different range of loadwidths; and meanwhile carriers Y are reciprocated as by the power of gravity in the successive several waysdescribed below.

The pinion shafts P, P constitute the pivots of two bell-crank levers having relatively long lever-arms G, and relatively short lever-arms 56 on which the segment-pinion gear-teeth GT are cut. The relatively long and short respective lever-arms G and SG are the controlling elements for the above multiplication of gravity power for ultimate eflfect on the load-grasping pressure of arms E. Longer lever-arms G depend from pivotal connections U, U with the lower ends of links T, T, suspended from kingpin K in clevis C. It is said excess length of G over shorter lever-arm SG which provides the leverage to increase the effect of gravity on non-pivoted, constant-angle arms E. The leverage-increase in these linkages is useful in both the above successive operations of increasing the gravity power, i. e., respectively before and after the load comes on.

Pins PN, PN, Fig. 1, left and right are provided to prevent reduction of the desired efliciency of the linkages in causing the weight of the load to increase the initial grasping pressure of arms E first effected by the gravity of the grab without the load-gravity. These pins PN extend across the path of circular movements of the edge of each pinion-segment SG inside box-like support F. They prevent excessive upward movement of lever-arms G, Fig. 3. The ends of pins PN are supported in the front and rear walls of box-like support F. They are permanently secured in place, as by welding in support F. They act as stops for undesired amplitude of movements of the bellcranks, and prevent longer lever-arms G from being moved so far toward vertical positions as to unduly reduce the desired leverage for increasing the load-gravity effect in increasing the grasping pressure on the load by arms E. In the case of loads too narrow to be within the load-range-widths for a given manual setting of spacing of arms E, then pins PN prevent arms E from even initially engaging the sides of the load; and such condition indicates to the operator that there is need, with loads of such range of narrow widths, of manual re-setting of arms E. But if the load is wide enough to permit the grab to engage the load by the time pins PN have stopped undesired movements of the bell-cranks, then the positions of longer leverarms G will be sufliciently near the horizontal to provide the high leverage to multiply the effect of the weight of the load to increase the grasping pressure to the desired maximum of safety-grip. But also, and before the turnings of pinion-segments SG in grab-operation cause their edges to engage pins PN to check further inward movement of arms E toward a load, the manual setting of the spacing of arms E is such as to cause arms E to go astride of substantially wider loads within the range of load-widths established by a given manual setting or adjustment. Thus, the narrower the range of loadwidths for any given manual setting of arms E, the smaller will be the variation of final safe grasping pressures on a load within that range of widths and of a given weight; but pins PN limit the range of movement of arms E inwardly so that there always will be ample grasping pressure on the narrowest loads within the range-setting, as the result of their weight, so that regardless of load-width the grasping pressure always is at least generally proportionate to the weight of the load, and it is immaterial if the grasping pressure be somewhat higher on wider loads within the range of widths. If pins PN be not employed, it would be possible for a load of given width and weight to be lifted off the floor by a grasping pressure which (altho it might be higher than that 01' initial engagement) might not be as safely secure as desirable, as the result of movements of bellcrank arms G undesirably far outwardly toward vertical positions. Thus pins PN automatically provide for operation of the grab within limits of grasping pressure as high as may be desirable, and insure against all chances of more or less lifting a. load by grasping pressure not abundantly safe.

with such manual adjustment or re-setting of movable carriers Y and grab-arms E, as above, it is possible to handle only a small range of load-widths relative to the total grab-range; but abundantly safe grasping-arm pressure is applied to the load throughout each and all such relatively small ranges. Since such safe grasping pressure is the same for all such manual range-adjustments (owing to the fact that the linkages always possess the same relations to carriers Y irrespective of the settings of arms E), therefore the safe grasping pressure is provided over the entire load-width range of the grab, (which is made very great by the central over-lapping of arms E), regardless of the width of any particular load, and controlled by the weight of the load in all cases hereof.

When this grab is not in use, it can be removed from hoist H, and stored in compact form occupying little storage space, with carriers Y and arms E moved far inwardly to the extreme limit permitted by the narrowness of central carrier-support F; the re-setting of Y and E for that purpose being effected by means of the separable rack and pinion arrangement. When the grab is needed again for use, and is removed from storage, all that is necessary is to manually re-adjust Y and E by the same arrangement to the desired condition for limited range of loadwidths. This involves manual adjustment from the extreme narrowest conditions of the grab, by longitudinal horizontal outward movements of carriers Y; but ordinarily in use, when adjustments of carriers Y and arms E occasionally may be made for adaptation to loads of comparatively slight width-difi'erences, the adjustments may be of only slight movements of the carriers, down to a minimum of only one rack-tooth El or portion thereof.

Support F may be of any suitable construction adapted to any desired form of rack and pinion arrangement or equivalent. In the practical example shown, support F is a sort of steel box or housing for movable arm-carriers Y and portions of pinions SG, with open ends for carriers Y to move inwardly and outwardly. Support F includes front and rear vertical steel plates and a bottom steel plate or fioor FB all welded together in a unit so as to provide the necessary strength. The floor FB must sustain not only the weight of carriers Y and the linkages above it and supported on it by axles P, but also arms E and the load Z which they grasp and sustain. The shorter toothed bell-crank arms SG, when employed, extend beyond the open ends of the box-housing F which are left open for that purpose and for the purpose of receiving carriers Y. As shown in Figs. 2 and 3, the central portion of support F intermediate its ends is closed at its top, and lever-arms G move up and down above such closed top. Carriers Y also are very strongly constructed as of sufliciently thick steel parts in order that they may sustain the mass of a heavy load in the widely spaced positions of arms E; and similarly, arms E are of strong steel construction so as to possess suflicient rigidity and strength to transmit the high grasping pressure to the load from carriers Y when the latter are given, as by gravity, powerful tendencies to more inwardly and force arms E against the load with high pressure. The linkages also are of strong steel construction, when used, because they sustain the entire weight of both the load and the grab-parts below them. The carrier-housing F between its front and rear portions, Fig. 2, preferably has dimensions large enough to permit it to receive the inner ends of both carriers Y in their preferred overlapping relations, Fig. 4, parallel to one another; and support F is adapted by interior width to allow for the simultaneous sliding movements of over-lapping carriers Y in opposite directions. The construction of support F internally and externally, may be of various different designs for the above purposes.

The scale of the drawing is one and one-half inches to the foot. Links T may be eight inches long on centers. The longer bell-crank leverarms G may be twelve inches long from shafts or studs P to pivot-pins U which connect G to T; while shorter arms SG as pinions are of substantially the same length as the diameter of a completely toothed pinion of the same tooth-construction. The pinion-teeth GT may be proportioned on the ratio of three teeth for each inch of pitch diameter, and this on a radius of two and one-sixth inches. That radius determines the arm-motion to or arm-pressure against the load (as the case may be) which is transmitted by pinions SG to the racks and movable carriers Y and thence to arms E. Studs P, P may be sixteen inches apart. Arms E may be extensible to twenty inches more or less. But allthe above dimensions may be very much greater.

Locking of arms E In Fig. 4 are shown arms E locked by mechanism L in their widest spacing of a given armsetting of relations of racks El to pinions GT. A vertical plunger-rod I is suspended from kingpin K, Fig. 4. The lower portion of the length of rod I is housed in a tube Fl, Fig. Lin which I is vertically slidable. Tube Fl is supported and carried by central box-like arm-support F as by being welded to a. side thereof. A latch-bolt B also is carried by tube F by extending horizontally thru two supports F2, F2 also secured to the same side of support F. Around bolt B is a helical spring J, located between a collar D secured to B and one of the fixed bolt-supports F2. Spring S tends to push collar D and bolt B, Fig. 1, thru an opening in the side of tube Fl, to the interior of the tube and interposed in the downward path of rod I in the tube. In these conditions a bevel 0, Fig. 4, on the lower end of plunger-rod I is in engagement, Fig. 3, with a bevel Bl on the adjacent or detent end of bolt B. In these conditions, lowering of hoist H will permit a gravity collapse of the linkages below king-pin K which will cause outward movements of arms E and simultaneous downward movement of king-pin K, and of plunger-rod I down in tube Fl facing bolt B, Fig. 1, out of the interior of tube Fl against spring J and compressing spring S. Further downward movement of rod I, down below bolt B will cause a recess B2, Fig. 4, in rod I to come in registry with the detent end Bl of bolt 13, whereupon spring J will shoot bolt B into locking relations with rod I, thereby locking arms E in their positions of wider spacing, because the locking together of I and Fl holds K and F together so that no raising of hoist H can move the linkages toward the straightened out condition of vertical elongationsshown in Fig. 3, such straightening out being necessary for inward movements of arms E. The proportioning of the grab-parts is such as to cause this arm-locking tooccur at the end of the outward arm-movements of any given arm-setting. As long as arms E are locked, the grab can be moved freely by the hoist in any direction without inward arm-movements be cause bolt B prevents all changes in the condition of the linkages which necessarily accompany in- I ward arm-movements.

Re-setting of arms E Fig. 1 also illustrates a favorable condition for readily re-setting arms E, on the infrequent occasions when re-setting may be necessary to adapt the grab to loads of a different width from those previously hoisted. This favorable condition is due to the facts that in Fig. 1 there is no pressure on rack-teeth El by pinion-teeth GT or between lever-arms SG and their axles P, because hoist H is holding up the weight of the linkages altho not of F, Y, E. Thus the manual operations can be easily executed, of removing axles P, P, lifting pinions GT from off racks El; and, after the manual re-setting of arms E by sliding them along the floor of box-like support F, the manual operation can be easily executed, of replacing pinions GT in mesh with racks El in their new settings, and of replacing axles P in the journals of the pinions thru the same holes in support F as before. The condition and operation of the linkages always are the same for all arm-settings, and the range of horizontal movement of arms E always is the same for all arm-settings.

In the use of the invention, arms E are automatically spaced apart and simultaneously automatically looked, as above, and in the condition shown in Fig. 4, before the grab is lowered to position astride a load to be hoisted.

Operation of grab as a whole The following description of the several operations involved in use is based on the above assumption that in Fig. l the load L is about to be lifted and that arms E are widely spaced and looked as in Fig. 4.

The several operations include the cycle beginning and ending with such assumed conditions, as follows:

1. Unlocking of arms E by remote-control A.

2. Hoisting of grab causing automatic gravity movement of arms E from wide spacing into initial engagement of arms E with the load. The entire weight of the grab is available for the gravity operation, as distinguished from operation 6.

3. Continuation of hoist-lifting of grab after initial engagement with load, causing automatic gravity increase of arm-grasping pressure on load.

4. Routine hoist-operations as with ordinary grabs, up to and before deposition of load in different place.

5. Deposition of the load, freeing grab of weight of load thereby causing automatic gravity release of load from the higher grasping pressure of arms E.

6. The operations of automatic gravity withdrawal of arms E from the load and automatic gravity arm-locking, caused by the over-lowering of the hoist after load-deposition which is characteristic of the new grab. In this armwithdrawal operation the entire grab-weight is not needed, and is not available as in above loadgrasping operation No. 2 above where the partlcipation of the entire grab-weight is very useful in preparation for initial load-lifting adding the load weight to increase the arm-grasping pressure.

The above unlocking operation, No. 1, is the only operation which the new grab requires of the crane-operator additional to his ordinary duties in operating crane and hoist H; and the need of a second man or a motor, for location at the grab, is avoided by the grab-construction which causes the several automatic gravity operations of arms E, i. e., above Nos. 2, 3, 5, and 6; so that in fact, the arm-unlocking is the only non-automatic operation (save the relatively infrequent re-setting of arms E) which is involved in the use of the new grab which is operated exclusively by the hoist and the gravity of the grab itself, notwithstanding that its arms E do not operate on the ice-tongs principle but require power to hold them to the load and move them in and out as an accompaniment of their advantages of constant angle operation taking up small operating space at the sides of the load, as distinguished from the swinging operation of the pivoted ice-tongs principle. The re-setting of arms E is so relatively infrequent that it can be done by the hoist-operator, going, for that purpose from hoist-control to grab. The new grab therefore is a one-man grab, which in pre-- ferred form is a no-motor grab. The lockingmeans not only avoids need of a workman locally at the grab but also avoids the handling delays involved in manually moving grasping arms away from, and holding them away from, the load. The distant hoist-operator in the crane-cab effects the arm-unlocking by remote control, for example, an ordinary cord or rope A connected to the hook-end of bolt B and extending to the distant location of the hoist-operator to pull bolt B out of notch B2 in plunger-rod I and permit the automatic gravity operation of above operation No. 2.

Operation No.1-Un1ocking This is done by the crane-operator preferably before he has started grab-hoisting preparatory to load-grasping, especially when initially, the support F is resting on the load as in Fig. 1. He maintains the pull on cord A for an instant for assurance that king-pin K has raised plungerrod I so that its recess B2 is up out of registry with detent B.

Operation No. 2Arms E to load This starts as soon as the hoist starts raising the grab while the latter is in arm-unlocked condition. It may start while support F rests on the load, or when arms E rest on the floor. To hoist a load, it is not necessary to first lower the hoist so far as to cause F to rest on the load; all that is necessary being to lower the grab far enough so that when arms E reach the load, that will be at a proper height of the load. If the hoisting is started, under conditions when arms E are off the floor and support F of! the load, then the entire weight of the grab, from the commencement of hoisting will be exerted on the linkages; and that will cause the quickest movement of arms E to the load by the entire weight of the grab including arms E themselves, which pull down on the linkages exerting pressure by pinion-teeth GT on the racks El to push arms E to the load.

In this operation, the lower end 0, of plungerrod Fl is raised to a position, Fig. 3, above detent Bi.

The inward movement of arms E by gravity in this operation N0. 2, is greatly assisted by the preferred long lengths of long-arms G relative to the short arms SG of the bell-cranks, as follows. Links T are put under tension by the weight of the grab resisting hoisting, and such tension moves their lower ends closer together than in Fig. 1, toward their positions of Fig. 3. That moves up their pivots U with long arms G to their positions in Fig. 3. And that in turn moves long arms G thru a given angle on their pivots P in support F; and the longer the arms G are the greater will be their leverage in translating the weight of the grab to pinion-pressure on the racks, i. e., increasing the horizontal forces applied to arm-carriers Y by way of the teeth of the racks and pinions. In this operation the positions of long lever-arms G are changed from the more or less horizontal positions of Fig. 1 to their positions in Fig. 3 at angles of nearly forty-flve-degrees, on account of their lengths, thereby not only increasing the effect of the weight of the grab in moving arms E inwardly but providing for sufliciently wide amplitude of arm-movement by the angular turning of the pinions.

In this operation No. 2, as in the next operation No. 3, the above provisions for re-setting arms E while preserving the leverage condition of the linkages, is valuable in preserving the grasping power of the grab high substantially independent of differences in load-Widths, in addition to automatically causing that high grasping power to be higher for heavier loads.

In this operation No. 2, .the great leverage of the bell-cranks, acting only with the weight of the grab, is such as to cause powerful arm-grasping on the load, 1. e., sufilcient to start loadlifting, even before the weight of the load is added to the weight of the grab as a means for increasing the grasping-pressure.

Operation No. 3Incre'asing grasping pressure The picking up of the load, as in Fig. 3, does not cause any increase of amplitude of the movements of the grab parts which caused the inward movements of arms E to grasp the load initially, unless the load-surfaces yield to the arm-pressure on them. But it does increase the power of those parts, resulting in very greatly increasing the pressure of the pinion-teeth on the rack-teeth and therefore increasing the inward pressure of arms E on the load. This operation involves the static high leverage load-pressure efiectof long lever-arms G. As soon as the grab-weight, aided by arms G, has moved arms E against the load with sufficient pressure to cause the load to be raised by the hoist, then the lifting of the load is additionally resisted by frictional displacement, resulting in increased tension on links T, etc., causing, as an endresult, increased pressure of the pinion-teeth on the rack-teeth, with correspondingly increased pressure of arms E against the load. So, as the hoist and grab start to lift the load, there is instantaneous reaction between the grab and load which establishes equilibrium, with the ,load most securely grasped by the grab which assures abundance of safety in further load-lifting.

' Operation No. 4Handling load by arab The security of load-grasping, by the gravity of non-pivoted, constant-angle grasping arms E, is so great that the hoist-operator can control the new grab to move the load under the severest conditions tending to dislodge the load from the grab.

Operation No. 5--Depositing the load The ordinary deposition of the load on the floor, by freeing the grab of the load-weight, is the reverse of operation No. 3, and removes the high operating grasping pressure of arms E and thereby puts the grab in condition for the novel automatic gravity operations of withdrawing arms E from grasping engagement with the load and of locking the arms in such withdrawn locations.

Operation No.-6-Ovcr-lowefing the hoist This prepares the grab for hoisting from the deposited load and prepares the grab for grasping and hoisting the next load.

But the over-lowering of the hoist is performed with reference to the just deposited load, and for the initial purpose of gravity withdrawal of arms E therefrom.

In this operation No. 6, or last operation, as in operation No. 2, arms Eare operated by grabgravity; in operation No. 2 byhoisting the grab, and in this operation No. 6 by lowering it. But this operation No. 6 is not the exact reverse of operation No. 2 wherein the entire weight of the grab was used in moving arms E to the load, because here the grab is not only lowered instead 01 being raised, but is over-lowered after loaddeposition on the floor, so that even after the bottom of support F comes to rest on the load and therefore after the weight of support F and armsE is taken off from the rest of the grab, the linkages are free of support by the hoist and therefore can collapse by their own gravity so as to turn pinions GT, Fig. 1, and slide arms E outwardly along the floor of support F. And this operation involves the application of relatively slight gravity of the linkages, of amply sumcient power to slide arms E outwardly, largely by the leverage provided by long lever-arms G.

This operation No. 6, involving outward armmovement automatically by gravity, also involves the simultaneous arm-locking, also by the same linkage-collapse by gravity, and the operation is further described above in connection with such locking.

I claim:

1. A gravity-operated hoist-grab including hanging spaced load-grasping arms, a narrow support between them; movable grasping-arm carriers between the arms and carried by said support and respectively longer than the respective'spaces between the arms and said support, and extending inwardly from the arms substantial distances into the narrow support, and reciprocable inwardly and outwardly in said support along their lengths; rotatable operating mechanism moving said carriers respectively, simultaneously in opposite directions; means for suspending the grab from a hoist, and a power-increasing leverage-linkage system suspending the narrow support by way of connections to said support and said hoist-suspending means, and in conditions operating said linkage system, operating mechanism, arm-carriers, and grasping arms all by their own gravity as increased in effect by the leverage of the linkage system.

teeth; toothed rotatable devices carried by said support and engaging said carrier-racks; means for suspending the grab from a hoist; and a linkage-system suspending said narrow support by way of connections t said hoist-suspending means and the axles of said rotatable devices, and in conditions operating said linkage system, rotatable devices, rack-carriers and grasping-arms all by their own gravity.

3. A gravity-operated hoist-grab including hanging spaced load-grasping arms, a narrow support between them; movable grasping-arm carriers between the arms and carried by said support and respectively longer than the respective spaces between the arms and said support, and extending inwardly from the arms and substantial distances into the support, and reciprocable in the support along their lengths inwardly and outwardly, and carrying upwardly projecting rack-teeth; means for suspending the grab from a hoist; a pivoted linkage-system suspended from said means; segment-pinions constituting the ends of lower links of said system and engaging said upwardly-projecting rack-teeth; and removable pinion-axles carried by said narrow support and by which the latter is suspended from the linkage system.

4. A hoist-grab including gravity-operated load-grasping arms, a narrow support between them, segment-pinions having their axles mounted in said support; bell-crank levers connected to said support by way of said pinion-axles, the segment-pinions being constituted of toothed ends of the shorter arms of the bell-cranks, the movements of the bell-cranks turning the pinions; movable grasping-arm carriers between said grasping-arms and carried by said support and respectively longer than the respective spaces between said arms and the narrow support between the arms and said support, and extending inwardly from said arms and substantial distances into said intermediate support and reciprocable inwardly and outwardly in said support along their lengths, said arm-carriers carrying upwardly extending rack-teeth engaging said pinions; and means carried by the narrow support and limiting the movements of said bell-cranks.

5. A gravity-operated hoist-grab including hanging spaced load-grasping arms, a narrow support between them; movable grasping-arm carriers respectively carrying said arms and extending between the arms and carried by said support, and respectively longer than the respective spaces between the arms and said support, and extending from the arms inwardly into the support and reciprocable along their lengths in the support inwardly and outwardly; means for connecting the grab to the hoist; links pivotally a narrow support between them; movable grasping-arm carriers between the arms and carried by said support, and respectively longer than the respective spaces between the arms and said support, and extending inwardly from the arms toward and into the narrow support and movable in the support in a direction carrying the arms at constant angles toward the load; means for suspending the grab from a hoist and mechanism translating the gravity of the grasped load into inward load-grasping pressure by the arms, said mechanism for that purpose including carrier-operating means suspended from said grab-suspending means, connected with and supporting said narrow support, and movable relative thereto and having operating connections with said carriers.

7. A gravity-operated hoist-grab including hanging spaced load-grasping arms, means for suspending the grab from a hoist; a linkage system from which said support is suspended; a narrow support between said arms; movable grasping-arm carriers between said arms and carried by said support and extending from inner portions of the arms to the support and substantial distances into the support and reciprocable therein inwardly and outwardly along their lengths; gravity carrier-operating means having connection with the carriers moving them outwardly; said means being connected with said linkage system and operated by the weight thereof by way of said connection therewith;- gravity-operated mechanism between and connected to said arms and carrier support for locking the arms in their outer positions; and remote-control means for operating said locking mechanism at will and unlocking said arms freeing them for inward loadgrasping movements by said gravity-operated carrier-operating mechanism.

8. A hoist-grab including gravity-operated load-grasping arms of the constant-angle type, reciprocable slidable arm-carriers and a support therefor in which they slide, and wherein the arms are held in load-grasping positions by corinections to the movable carriers; means for suspending the grab from a hoist; and a linkage moving the arms inwardly and outwardly in said support by the gravity of the grab itself, said linkage for that purpose being supported between said grab-suspending means and the carrier-support, and suspending the latter, and having operating connections with said arm-carriers which cause the gravity of the grab to move the arms respectively toward and away from the load.

9. A hoist-grab including gravity-operated load-grasping arms of the constant-angle-type, inwardly slidable reciprocating arm-carriers and a support therefor in which they slide, and wherein the arms hang from the outer ends of the reciprocable arm-carriers providing for arm-grasping pressure against the sides of the load; means for suspending the grab from a hoist; and a linkage forcing the arms securely against the load by the gravity of the load independently of the width of the load, said linkage for that purpose being connected to and between said grab-suspending means and said carrier-support, and having operating connections with said arm-carriers which cause the gravity of the load to force the arms securely against the load.

10. A hoist-grab including means for suspending it from a hoist, a linkage-system suspended from said suspending means and including bell- 1 crank levers; segment-pinions constituted of toothed ends of the shorter arms of the bellcranks; a support in which are mounted axles for said segment pinions, said support being suspended from said axles, and said axles constituting the pivots of said bell-cranks; gravity-operated load-grasping arms; and carriers for said arms, connected thereto and supported by said support for longitudinal movement therein; said carriers having rack-teeth for meshing with said segment-pinions.

JACK BRESLAV.

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