US2256896A - Lifter - Google Patents

Description

Sept. 23, 1941 E. V. 'CULLEN LIFTER 3 Sheets-Sheet i Filed July 8, 1938 Eda/arc! Vfczzzzem p 1941- E. v. CULLEN 2,256,896

LIFTER I Filed July 8 1958 3 Sheets-Sheet 2 17. Z@f 2 I 9 J5 I :51 I F i J6 I Q] Sept. 23, 1941. v, CULLEN LIFTER 5 Sheets-Sheet 5 Filed. July 8, 1938 I Jkmehfr dwarc/VCzz// Patented Sept. 23, 1941 2,256,895 LIFTER Edward V. CullenpC hicago, 111., assignor to Gullen-Friestedt Company, Chicago, 111., a, corporation of Illinois Application July 8, 1938, Serial No. 218,118

9 Claims. (c1.

.ing device on the operating end of the crane or hoist with which the lifter is used; a pair of opposed horizontally elongated complemental V jaws which are carried by the supporting element so that they are shiftable to and from one another into and out of engagement with the side margins of the sheets; and gearing which is associated with and carried by the supporting element and operates when driven in one direction to shift the jaws apart and when driven in the opposite or reverse direction to shift the jaws together into gripping relation with the sheets or other articles to be carried by the lifter.

One object of the invention is to provide a lifter of this type which is an improvement upon previously designed lifters of the same general character and is so designed and constructed that it is more efficient in operation and is capable of being handled more expeditiously and with greater facility.

Another object of the invention is to provide a lifter of the type and character under consideration which includes a lost motion spring type driving connection in the gearing whereby shock or impact resulting from contact of the jaws with the sheets to be lifted or accidental locking of the jaws during inward and outward movement thereof is so absorbed that it is not transmitted to the electric motor or the portion of the gearing which is between the motor and the lost motion connection.

'Another object of the invention is to provide a lifter of the last mentioned character in which the lost motion spring type driving connection embodies a pair of springs, one of which serves to absorb shock and form a cushion when the jaws strike against adjacent objects or are accidentally locked in connection with outward shift thereof, and the other of which serves to absorb shock and to form a cushion when the jaws strike against the sheets or other articles to be lifted during inward movement thereof and in addition operates when the lifter is raised or hoisted in connection with {lifting of the sheets to swing the jaws inwards as far as permitted by the connection in order to compensate for the sag in the sheets.

A further object of the invention is to provide a lifter of the aforementioned type and character in which the gearing between the reversible electric motor and the jaws has associated therewith a differential band brake which operates to stop or prevent over-run of the motor when the switch therefor is opened and in addition serves automatically so to hold or lock the jaws so that they are prevented from swinging inwardly in response to the action of gravity.

A still further object of the invention is to provide a lifter which isgenerally of new and improved design and may be manufactured at a comparatively low and reason-able cost.

Other objects of the invention and the various advantages and characteristics of the present lifter will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features whichare hereinafter set forth and are more particularly defined by claims at the conclusion hereof.

In the drawings which accompany and form a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views:

Figure 1 is a side view of a lifter embodying the invention;

Figure 2 is an enlarged fragmentary vertical longitudinal sectional View illustrating in detail the construction and design of the portion of jaw actuating gearing that is between the reversible electric motor and the lost motion spring type driving connection;

Figure 3 is a vertical transverse sectional View taken on the line 33 of Figure 2 and showing the construction and design of the lost motion spring type driving, connection whereby impact or shock is absorbed when the jaws accidentally or otherwise are locked against inward or outward shift during drive of the electric motor;

Figure 4 is a fragmentary sectional view taken on the line 44 of Figure 3 and further illustrating the structure and design of the lost motion driving connection;

Figure 5 is a vertical transverse sectional view taken on the line 55 of Figure 2 and illustrating the arrangement and design of the differential band brake for holding the jaws against inward swing by gravity upon stoppage of the electric motor;

Figure 6 is an enlarged sectional view taken on the line 66 of Figure 3 illustrating in detail the construction, arrangement and mounting of one of the springs of the 10st motion spring type driving connection in the jaw actuating gearing;

Figure '7 is an enlarged sectional View taken on the line 1--''! of Figure 2 and Figure 8 is an end elevational view of the lift- The lifter which is shown in the drawings constitutes the preferred embodiment of the invention. It is adapted in connection with a crane or overhead hoist (not shown) having a connecting device at its operating end to lift and move from one place to another a stack of lower jaw members 23.

metallic sheets or other articles and comprises as its main parts an elongated supporting elej'usted positions by means of a pair of horizontally extending lock bars 26. The latter are carried by and longitudinally slidable in slots in the lower ends of the upper jaw members l9 and are adapted to coact with tooth equipped sectorshaped elements 27 at the upper ends of the The elements 2? are disposed above the pivot pins 25 and fit between ment 9, a pair of opposed horizontal elongated v jaws ii] and II, a reversible electric motor 1-2, and gearing 13 between the motor and the jaws for conjointly shifting the latter to and from one another in response to drive or operation of the motor.

The supporting element 9 is adapted normally to extend horizontally. It carries the jaws I8 and H, the reversible electric motor l2, and the gearing l3, and is in the form of an I-beam. As shown in Figures 1', 3 and 8 of the drawings, the element 9 carries the jaws IO and II in a depending manner and comprises a web it, a horizontally extending top flange l5, and a horizontally extending bottom flange it. Inwardly of its ends the element 9 is provided with a pair I of upstanding loops ll. These loops are adapted to be attached to the connecting device at the operating end of the crane or hoist by means of a chain 18 and embody depending legs which extend through holes in the top flange l5 of the element and are welded or otherwise fixedly secured in straddled relation with the webid.

The opposed horizontally elongated complemental jaws ID and H are adapted, as hereinthe lower ends of the plate metal pieces 22 which constitute the upper jaw members id. The bars 25 are provided with notches 28 adjacent to the tooth equipped sector-shaped elements 21 and are adapted when slid longitudinally in one direction to have the notches brought into alignment with the elements 2? so that the latter together with thhe lower jaw members 20 are free to swing laterally into any desired adjusted position. When the bars are shifted in the opposite direction the notch defining portions of the bars are adapted to interlock with the elements 2? and lock the lower jaw members 29 against swinging movement relatively to the upper jaw members. Longitudinal shift of the lock bars 26 is efiected by means of handle equipped levers 29 which are carried by the lower ends of the upper jaw members l9. bars 26, the elements 2'! and the levers 29 constitute means for releasably locking the lower jaw members in their various adjusted positions after described, to be shifted and swung to and from one another in response to actuation of the gearing l3 by the reversible electric motor :2. They extend lengthwise of the supporting element 9 and comprise upper members i9, lower members 26, and horizontally extending angle iron bars 2!. The upper members :9 have inturned or inwardly extending upper ends, as shown in Figure 8, and each comprises a pair of laterally spaced plate-metal pieces 22. The upper ends of the members IQ of the jaws'are piv- I '1 otally connected by way of pivot pins 2-3to laterally extending pivot lugs 24 on the elongated supporting element e. The upper members of the jaw Ill are transversely aligned with the upper members of the jaw H, as shown in- Figure 23;:

l. The pivot lugs 2 fit between and are welded to the top and bottom flanges i5 and E8 of the element 9. They are also welded to the web of the element and project into thespaces between the upper ends of the pairs of pieces 22 which form or constitute the upper jaw members I9. The pins 23' extend through aligned holes in the pivot lugs and the upper ends of the pieces 22 and together with the lugs so pivotally support the jaws Ill and II that the latter are free to swing to and from one another into and, out of gripping relation with the stack ofsheetsj The lower members 20 of the jaws extend substantially vertically and carry at their lower ends the horizontally extending angle bars 2!. The upper ends of the members 20 project into the spaces between the lower ends of the pairs of plate metal pieces 22 and are pivotally supported by pins 25 in such manner that the lower Jaw members may be swung into different'angular positions with respect to the upper members in order to adapt the lifter for use in connection with stacks of wide sheetsfas well as narrow or small sheets. releasably held or locked in their various ad- The lower jaw members 20 are 1 and such means forms the subject matter of an application for United States Letters Patent filed May 13, 1938, by Erard J. Shaughnessy, Serial No. 207,682. Reference may be had to this application or the patent to issue thereon for a more detailed description of the construction and design of the lock bars 26, the elements 21 and the levers 29. The angle iron bars 21 consist of substantially vertical legs 39 and substantially horizontal legs 3|. The vertical legs are welded or otherwise fixedly secured to the inner faces of the lower ends of the lower jaw members 20 and'are adapted when the jaws are shifted towards one another, as hereinafter described, into hoisting relation with a stack of sheets, to abut against the side edges of the lowermost sheets. The horizontal legs 3| are formed integrally with, and project. inwardly from, the bottom margins of the legs 30 and are adapted-to underlie the side margins of the sheets, as shown in Figure 8. a

The motor i 2 is disposed'beneath the central portion of the elongated supporting element 9. It is connected to the horizontally extending bottom flange it of the element 9 by way of a pair of brackets 32 and is arranged so that the armature shaft thereof extends parallel to the element 9. Current or electrical energy is supplied to the motor by way of a switch equipped conductor (not shown). The switch is of such design that it may be manipulated to cause the motor to run in either direction or to shut off the supply of current to the motor. The motor is adapted when driven in one direction to drive the gearing in such manner as to cause the jaws to swing apart and when driven or operated in the reverse direction operates through the medium of the gearing is to swing the jaws in- [wardly into gripping relation with the sheets or other articles to be lifted.

The gearing I3 for conjointly swinging or shifting the jaws 9-and Ito and from one another in response to drive or operation of the electric motor l2, underlies the elongated supporting element 9 and comp-rises a gear type The lock speed reducing unit 33, a shaft 34, a pinion 35, a gear segment 36, a horizontally extending shaft 31, sets of arms 38 and 39 between the shaft 3'! and the jaws, and a lost motion driving qconnection it! between the gear segment 36 and the shaft 31. The speed reducing unit 33 is located beneath the central portion of the elongated supporting element 9 and is disposed directly opposite to the electric motor 12. It is connected to the bottom flange 16 of the element 9 by a bracket ll and comprises a cylindrical gear enclosing housing 42, a horizontal drive shaft 43, and a horizontal driven shaft 44. The drive shaft 43 extends through one end of the housing 42 and is coaxially positioned with respect to the armature shaft of the electric motor l2. It is connected through the medium of gearing within the housing 42 to drive at slow speed the driven shaft 64 and has a drum 45 keyed or otherwise fixedly secured to the outer end thereof. The drum is cylindrical and, as shown in Figur 2, is driven by the armature shaft of the motor by way of a friction clutch 46. The latter comprises a driving arm 41 and a pair of arcuate shoes 48 and permits the motor l2 to run in the event thatthe jaws are accidentally locked during inward or outward swing thereof or the operator of the lifter fails to cut off the supply of current to the motor when the jaws reach the end of their inward 0r outward swing. The arm 41' is provided on the central portion thereof with a hub 39 and this hub is mounted on and fixedly secured to the contiguous end of the armature shaft of the motor. The

arcuate shoes 45, 48 are positioned adjacent to the ends of the arm ll and are provided with clutch linings 58 which engage frictiohally the drum 45. They are connected for drive by the arm 4'! through the medium of a pair of pin and slot connections El and are connected together for conjoint rotation or drive by a pair of bolts 52. The latter extend through holes in outwardly extending lugs 53 on the ends of the shoes and permit radial movement of the shoes with respect to the drum. Compression springs 54 surround the outer ends of the bolts and serve to urge the shoes towards one another into gripping relation with the drum 45. These springs extend between and abut against the outwardly extending lugs 53 on the ends of the shoes and nuts 55 on the outer ends of the bolts. The pin and slot connections 5| constitute a driving connection between the arm 4'! and the arcuate shoes 68 and comprise a pair of pins 56 and a pair of pin receiving slots 51. The pins 56 are fixedly secured to the ends of the arm 41 and project toward the speed reducing unit 33 and in overlying relation with the contiguous end of the drum 45. The slots 51 are formed in a pair of outwardly extending lugs 58 on the central portions of the shoes and extend axially with respect to the drum in order that the shoes are free to move radially. The connections 5i effect rotation of the shoes with the arm in response to drive or operation of the electric motor l2 and at the same time permit the shoes to move outwards. The springs 56 urge the shoes inwards and maintain adriving connection between the arm 41 and the drum. When during outward or inward shift of the jaws I8 and H an'obstruction is encountered so that the jaws are locked against further outward or inward movement, the clutch it permits of slippage of the -motorwith respect to the gearing 13. When the motor is operating at full speed the shoes are ets 6i.

subject to the action of centrifugal force and tend to move outwards against the force of the compression springs 54. Such action on the part of the shoes decreases the frictional grip between the clutch linings 59 of the shoes and the drum t5 and hence ready slippage between the motor and the gearing is permitted in the event of looking or stoppage of the jaws during outward or inward shift. When the motor is started and the rotative speed thereof is hence comparatively low, the shoes grip with greater force the drum 35 and hence there is an efiicient or effective driving connection between the motor and the gearing. The clutch 46 is adjusted by tightening or loosening the nuts 55. When the nuts are tightened, the springs 54 are placed under greater compression and hence effect greater frictional grip of the drum &5. When the nuts 55 are loosened, the springs are placed under less compression and hence the shoes grip the drum with less force. The clutch linings so on the shoes 48, as shown in Figure 2, fit within an annular groove 59 in the outer end of the drum 45, that is, the end which is farther removed from the housing 62 of the speed reducing unit 33. The driven shaft it of said unit is axially aligned with the drive shaft 43 and is journaled in a bearing in, and projects through the rear end of, the cylindrical housing of the unit. The shaft 34 of the gearing [3 extends horizontally and is positioned in coaxial relation with the driven shaft 44 of the speed reducing unit 33. It is disposed beneath and extends parallel to the elongated supporting element 9 and is journaled in a pair of bearings 65. The latter, as shown in Figure 2, are mounted in the central portion of a pair of brackets 6i which are spaced apart and depend from the bottom flange it of the element 9. The end of the shaft 3 which is adjacent to the driven shaft 54 of the speed reducing unit is connected to the projecting end of the last mentioned shaft by means of a coupling 52. The latter consists of a pair of complemental coupling memberstZ-i which are keyed or otherwise fixedly secured to the contiguous or adjoin ing ends of the shafts 3t and id and have interfitting lugs which form a driving connection between the two members. By employing the coupling 62 a positive driving connection is maintained between the shafts 3 3 and filteven though one of the shafts is not truly coaxial with the other shaft. The pinion 35 is fixed to the shaft 34 so that it is driven by the latter. It is disposed between the brackets El and is in mesh with, and serves to drive, the gear segment 3-6.

The latter embodies a hub t l and operates through the medium of the lost motion driving connection 58 to drive the shaft 3? in onedirection or the other depending upon the direction of rotation of the reversible electric motor H2. The shaft 3? underlies and extends parallel to the elongated supporting element 9, and is journaled at one end thereof in a bearing 65, which as shown in Figure 1, is connected to the lower end of a bracket 66. As shown in Figure 1, this bracket is secured to and depends from the elongated supporting element 9. The other end of the shaft is journaled in a pair of bearings 65 which are secured to the lower ends of the brack- The arms 38 of the gearing it are fixed to and radiate from the end of the shaft 37 and are transversely aligned with the upper jaw members 59. They are connected to the upper members of the jaw ill by way of links 6'! and operate in response to rocking or rotation of the counterclockwise manner.

shaft 31 in one direction to swing the jaw I 8 outwards and in response to reverse rotation of the shaft to shift said jaw Ed inwards. The links 87 extend between and are pivotally connected by brackets 68 on the plate metal pieces 22 of the upper members of the jaw H3. The arms 39 are formed integrally with, and project radially from, the inner ends of the arms 38 and are con nected by means of links it to the upper members E9 of the jaw H in such manner that the jaw ll is swung outwards in response to rotation of the shaft 3-? in one direction and is swung inwards in response to reverse rotation of the shaft. The arms 38 and 39 are soarranged and connected to the upper members of their respective jaws that the jaws move or swing con-- jointly to and from one another in response to rock or rotation of the shaft 37. The links 69 are pivotally connected at the inner ends thereof to the outer or distal ends of the arms 39. The outer ends of the links 69 extend between and are connected by pivot brackets '10 to the plate metal pieces 22 which constitute the upper members of the jaw l l.

The lost motion driving connection 40 serves,

as hereinafter described, to absorb shock resulting from contact of the jaws with the sheets to be lifted or accidental locking of the jaws during inward or outward movement thereof in such manner that no damage is done to, or load or stress placed upon, the electric motor or the portion of the gearing which is between the motor and the connection 49. Said connection comprises a torque arm H, and a pair of springs '12 and 73. The torque arm comprises a central hub 74 which, as shown in Figure 4 of the drawings, extends around, and is drivably connected by way of a key to, the shaft 31. Said hub fits between the bearings 65 on the lower ends of the brackets 6i and forms a journal or a rotatable mount for the hub 55 of the gear segment 36. The hub 66, as shown in Figure 2, is confined n the hub l i against axial displacement by means of the torque arm proper at one end of the hub and a collar 75 at the other end of the hub. The i arm H is positioned in side by side relation with the gear segment and embodies at its ends a pair of lugs iii and H. The spring 12 is of the compression variety and extends between the lug 16 of the torque arm and a laterally extending lug 18 at one corner or end of the gear segment. A stud i9 is secured by a bolt 80 to the lug 78. This stud fits within and serves to prevent lateral displacement of the spring 12. It is, however, shorter than the spring and is only adapted to engage the lug 16 after compression of the spring. When the shaft 37 is driven in a counterclockwise direction, as viewed in Figure 3, the jaws l0 and H as a result of the arrangement of the arms 38 and 39 are swung inwards. When the electric motor i2 is driven so as to rotate the pinion in a clockwise direction, as viewed in Figure 3, the gear segment 36 is driven in a During such drive of the gear segment the spring 12 forms a driving connection between the lug 18 on the gear segment and the lug is on the torque arm and effects a counterclockwise drive or rotation of the torque arm and resultant closing of the jaws. Should the jaws during inward movement become locked or jammed as the result of contact with the sheets or articles to be lifted, the spring 12 is compressed and thus relieves the motor and the parts of the gearing between the motor and the connection M] from any damaging strains or load. When the spring 12 is compressed to such an extent that the stud 19 comes into contact with the lug 16 on the torque arm a direct or positive driving connection is effected between the gear segment and the torque arm and the shaft 31 is hence subjected to direct counterclockwise drive by the shaft 34. In the event that the angle iron bars 2! in connection with inward swing of the jaws into gripping relation with a stack of sheets to be lifted should bind as a result of initial contact with the sheets, the spring 12 relieves the gearing and motor of the initial shock due to locking of the jaws. As soon as the spring is compressed to such an extent that th stud 19 engages the lug 16 a direct driving connection is effected between the gear segment and the torque arm and further rotation of the motor acts to shift the jaws l0 and l I inwards until they are in their proper position with respect to the sheets. When the lifter is hoisted after being brought into gripping relation with a stack of sheets, the sheets tend to sag, as shown in dotted lines in Figure 8. Because the spring 12 is under compression as the result of effecting counterclockwise drive of the torque arm from the gear segment, such spring tends to expand into its normal position and thus automatically swings the jaws inwards and compensates for the sag in the sheets. From the foregoing it is manifest that the spring 12 has a two fold function in that it operates to prevent shock to the motor and the major portion of the gearing when the jaws are jammed or locked in connection with inward shift thereof and in addition operates automatically after inward swin of the jaws into contact with a stack of sheets to swing the jaws a further distance inwards upon hoist of the lifter. Th spring 73 extends between the lug 71 at the other end of the torque arm and a laterally extending lug 81 at the other end corner of the gear segment.- It is of the compression variety and extends around and is held in place by means of a stud 82 which is .secured to the lug 8| by a bolt 83 and is shorter than the spring 13 so that it doesnot engage the lug 77 until after partial collapse or compression of such spring. When the shaft 37 is driven in a clockwise direction, as viewed in Figure 3, the jaws i9 and H due to the arrangement and design of the arms 38 and 39 are swung apart. When the pinion 35 is driven in a counter-clockwise direction as viewed in Figure 3, the gear segment 36 is driven in a clockwise direction. During such drive of the gear segment, the spring 13 which is under compression between the lugs BI and TI forms a driving connection between the gear segment and the torque arm and causes the torque arm to rotate in a clockwise direction and thus to effect opening of the jaws. When during opening of the jaws in connection with release thereof from a stack of sheets the jaws tend to stick to the sheets, the spring 73 compresses in response to clockwise rotation or drive of the gear segment 35 until the stud 82 comes into engagement with the lug 71. As soon as the stud engages the lug a direct driving connection is effected between the gear segment and the torque arm and further rotation of the motor thus causes outward swing of the jaws l6 and H. When during normal outward swing of the jaws; the jaws as the result of contact with obstacles at the sides of the lifter are prevented from further outward movement, the spring 13 compresses and absorbs the shock so that it is not transmitted to the speed reducing unit 33 on the motor.

If under such circumstances the motor 12 is not stopped by closing the switch therefor, the armature shaft continues to rotate due to the slippage that is afforded by th friction clutch 46. In order to limit outward and inward swing of the jaws I and II a stop member 84 is provided. This member is in the form of a bolt and is carried by one of th brackets 6|. As shown in Figure 2 of the drawings one end of this member overlies the torque arm H and coacts with the lugs 16 and Ti. When the shaft 31 is rotated in a clockwise direction as viewed in Figur 3 so as to efiect opening of the jaws, the lug TI is adapted at the end of the full or complete swing of the jaws to abut against the member and thus limit further outward swing of the jaws. When the shaft 3! is rotated in a counterclockwise direction as viewed in Figure 3 so as to close the jaws the lug 16 at the end of the full inward stroke of the jaws is adapted to abut against the member 8% and thus lock the jaws against any further movement. The member 84 together with the lugs at the ends of the torque arm, constitutes simple means for limiting or restricting outward and inward swing of the arms.

In addition to the supporting element 9, the jaws i9 and H, the motor I2 and the gearing IS, the lifter comprises a differential band brake 85. This brake surrounds and grips frictionally the end of the drum d5 that is in close proximity to the speed reducing unit l3. One end of the brake is anchored by way of a bolt 86 to the bottom flange it of the elongated supporting element 9. The other end of the brake constitutes what may be termed the live brake end and is provided with a vertically extending bolt 8?. The latter as shown in Figure 5 extends loosely through a hole in the bottom flange it of the member 9 so that it, together with the live end of the band, is free to move vertically. A compression spring 83 is mounted on the upper end of the bolt 87 and extends between and abuts against the top face of said flange l8 and a pair of nuts 39 at the extreme upper end of the bolt 87. This spring serves to take up any slack in the band and causes the band to grip frictionally the drum 35. The brake E55, by reason of the fact that it grips frictionally the drum 45, operates to prevent over-run of the armature of the electric motor 12 when the current for the latter is cut off and in addition serves to hold or look the jaws Ill and H so that they are prevented from swinging inwardly in response to the action of gravity. As shown in Figure 5 the brake is arranged so that the drum works against the dead end of the brake when it is rotated in connection with closing of the jaws and works against the live end of the brake, that is, the end with the bolt 81 and the compression spring 88, when it is rotated in the opposite direction in connection with opening of the jaws. By so arranging the brake little resistance by the brake is encountered when the jaws are swung apart against the force of gravity. A greater amount of resistance is encountered when the jaws are swung inwardly and are hence subjected to gravity. Because of the foregoing, the load on the motor is substantially the same when the motor is driven to close the jaws as it is when it is driven in the reverse direction to open the jaws. If it is desired to adjust the force of the brake, it is only necessary to tighten or loosen the nuts 89. When the nuts are tightened the spring 88 is 45 as hereinbeforepointed out.

placed under. greater compression and hence the brake'grips the drum 45 more securely. When the nuts are loosened the compression of the spring 88 is reduced with the result that the brake grips the drum less securely.

The operation of the lifter is as follows: when it is desired to lift a stack of sheets the electric motor I2 is driven so as to open the jaws. Thereafter the lifter is lowered by the crane or hoist so as to'bring the jaws l0 and H into straddled relation with the sheets. After this operation the operator of the lifter causes the motor l2 to rotate in the reverse or opposite direction in order to swing the jaws l0 and H inwardly into gripping relation with the bottom sheets. As soon as the angle-bars 21 at the lower ends of the jaws are brought into engagement with the adjacent side margins of the sheets the motor is stopped. Thereafter, the crane or hoist with which the lifter is associated is manipulated so as to raise'the lifter and the sheets. In the event that the sheets tend to sag the spring 12 which as hereinbefore pointed out is under compression as the result of inward swing of the jaws, expands and swings the jaws inwardly so as to compensate for the sag (see dotted line position of jaws IE and. in Figure 8 of the drawings). When the sheets have been brought to their destination by the crane or hoist the lifter is lowered and then the motor is operated so as to open the jaws and disengage them from the sheets. If, during operation of the lifter the motor is not stopped before the jaws reach the end of their inward. or outwardswing, slippage of the armature of the motor with respect to the gearing i3 is permitted by the friction clutch If, during inward swing of the 'jaws, the jaws are brought abruptly into contact with the sheets or other articles to be lifted without stoppage of the motor, the'spring I2 of the lost motion connection 40 absorbs shock and thus prevents any damage to the portion of the gearing l3 between it and the motor.

The herein described lifter is capable of withstanding hard usage in View of the fact that it includes the spring type lost motion connection til and the safety type friction clutch 46. It is extremely eificient in operation and may be manufactured at a low and reasonable cost due to its simplicity.

Whereas the lifter has been described in connection with the lifting of sheets, it is to be understood that it may be used in connection with other articles, such as molds and the like, merely by changing the shape or character of the angle iron bars 2! at the lower ends of the jaws. It is also .to be understood that the invention is not to be restricted to the details set forth since these -may be modified within the scope of the appended claims without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. A lifter adapted for use in handling sheets and like articles and to be attached to a crane or hoist and comprising a pair of oppositely facing complemental jaws mounted to move to and from one another, driving means associated with the jaws, and gearing between the driving means and the jaws for conjointly shifting the jaws apart in response to drive of the means in one direction and conjointly shifting the jaws toward one another in response to reverse drive of said means, said gearing including a lost motion connection for permitting limited inward and outward shift of the jaws when the driving means is at rest, together with spring means associated with said connection and adapted when the jaws are shifted inwardly into gripping relation with the sheets to be so loaded that when the lifter is raised it urges the jaws inwardly to a limited extent to take up or compensate for any sag in the sheets.

2. A lifter adapted for use in handling sheets and like articles and to be attached to a crane or hoist and comprising in combination a pair of oppositely facing complemental jaws pivotally mounted to swing to and from one another, a reversible electric motor associated with the jaws, and gearing between the motor and the jaws for conjointly swinging the jaws apart in response to drive of the motor in one direction and for conjointly swinging the jaws toward one another in response to reverse drive of the motor, said gearing including a lost motion connection for permitting limited inward and outward swing of the jaws when the motor is at rest together with a compression type spring associated with said connection and adapted when the jaws are swung inwardly into gripping relation with the sheets to be so compressed that when the lifter is raised it swings the jaws inwardly to a limited extent to take up or compensate for any sagging in the sheets.

3. A lifter of the character described comprismg in combination a pair of oppositely facing complemental jaws mounted to move to and from one another, driving means associated with the jaws, and gearing between the driving means and the jaws operative conjointly to shift the jaws apart in response to the drive of the means in one direction and conjointly to shift the jaws toward one another in response to reverse drive of said means and including a lost motion driving connection with oppositely acting take-up springs as a part thereof.

4. A lifter of the character described comprising in combination an elongated supporting element, a pair of oppositely facing complemental jaws depending from the element and connected with the latter to swing to and from one another, a reversible electric motor carried by the element, and gearing between the motor and the jaws operative conjointly to swing the jaws apart in response to drive of the motor in one direction and conjointly to swing the jaws toward one another in response to reverse drive of said motor and including a lost motion connection with oppositely acting take-up springs of the compression variety as a part thereof.

5. A lifter of the character described comprismg in combination a pair of oppositely facing complemental jaws mounted to move to and from one another, driving means associated with the jaws, and gearing between the driving means and the jaws operative conjointly to shift the jaws apart in response to drive of the means in one direction and conjointly to shift the jaws together in response to reverse drive of said means and including as a part thereof a driving connection embodying a gear part and a torque arm part and a spring between the two parts adapted to drive one part from the other during reverse drive of the driving means.

6. A lifter of the character described comprising in combination a pair of oppositely facing complemental jaws mounted to move to and from one another, driving means associated with the jaws, and gearing between the driving means and the jaws operative conjointly to shift the jaws apart in response to drive of the means in one direction and conjointly to shift the jaws together in response to reverse drive of said means and including as a part thereof a driving connection embodying a gear part and a torque arm part and a pair of compression springs between the two parts whereby one part is driven from the other in response to drive of the other part during drive of the driving means in either direction.

'7. A lifter of the character described comprising in combination a pair of oppositely facing complemental jaws mounted to move to and from one another, driving means associated with the jaws, and gearing between the driving means and the jaws operative conjointly to shift the jaws apart in response to drive of the means in one direction and conjointly to shift the jaws together in response to reverse drive of said means and including as a part thereof a driving connection comprising a gear part and a torque arm part, a compression spring between the two parts for driving one part from the other in response to drive of the driving means in one direction and means associated with said spring for positively driving said one part from the other during drive of the driving means in said one direction after limited compression of said spring.

8. A lifter of the character described comprising in combination a pair of oppositely facing complemental jaws mounted to move to and from one another, driving means associated with the jaws, and gearing between the driving means and the jaws operative conjointly to shift the jaws apart in response to drive of the means in one direction and conjointly to shift the jaws together in response to reverse drive of said means and including as a part thereof a driving connection comprising a gear part, a torque arm part, compression springs between the two parts for driving one part from the other in response to drive of the driving means in either direction, and means associated with the springs for effecting positive drive of said one part from the other after limited compression of either of the springs.

9. A lifter of the character described comprising in combination an elongated supporting element, a pair of oppositely facing complemental jaws depending from the element and pivotally connected to the latter so that they are adapted to swing away from one another against the action of gravity and to swing toward one another in response to the action of gravity, a reversible electric motor carried by the element, gearing between the motor and the jaws for conjointly swinging the jaws apart in response to the drive of the motor in one direction and for conjointly swinging the jaws toward one another in response to reverse drive of the motor, and a differential band brake for holding the jaws against movement when the motor is at rest applied to said gearing and arranged so that the motor drives against the dead end thereof during closing of the jaws and against the live end thereof during opening of the jaws.

EDWARD V. CULLEN.

Images