US3064324A - Crane apparatus - Google Patents

Description

Nov. 20, 1962 D. w. SCHAPER CRANE APPARATUS 5 Sheets-Sheet 1 Filed June 29, 1961 ATTORNEYS Nov. 20, 1962 w, sc PE 3,064,324

CRANE APPARATUS 5 Sheets-SAaeet 2 Filed June 29, 1961 FIGZ INVENTOR.

. DONALD W. SCHAPER ATTORNEYS Nov. 20, 1962 D. w. SCHAPER CRANE APPARATUS Filed June 29, 1961 5 Sheets-Sheet 3 INVENTOR.

ATT ORN EYS Nov. 20, 1962 D. w. SCHAPER 3,064,324

CRANE APPARATUS Filed June 29, 1961 5 Sheets-Sheet 4 INVENTOR.

DONALD W. SCHAPER ATTORNEYS United States Patent f q ii.

3,064,324 CRANE APPARATUS Dennis. W. Schaper, Alliance, Ohio, assignor to Elie Morgan Engineering Company, a corporation of Ohio Filed June 29, 1961, Ser. No. 121,297 22 Claims. (Cl. 22-95) My invention relates to crane apparatus and particularly to stripper cranes utilized for separating metal ingots from the molds in which cast and for handling the ingots.

An object of my invention is to facilitate the rotation of the crane barrel in which a stripper plunger is axially movable for orienting the tongs carried by the barrel without rotating the vertically movable frame on which the barrel is supported.

Another object of my invention is to provide means for rotating the barrel of a stripper crane to orient the tongs carried by the barrel without relative motion between the barrel and a stripping plunger reciprocally movable axially of the barrel.

Another object is the provision for a unique driving arrangement for operating a stripper plunger, for rotating a barrel in which the plunger is reciprocal and for correlating the operation of the plunger and rotation of the barrel to obtain highly useful results.

Another object is the provision of a novel system for orienting the tongs carried by a rotatable barrel of a crane while maintaining the gripping position of the tongs actuated by reciprocation of the plunger relative to the barrel.

Another object is the provision of improved arrangement for rotating the tong-carrying barrel without rotation of the frame carrying the barrel.

Another object is the provision of a structural arrangement in a crane apparatus which permits the electric motor which rotates the tong-carrying barrel to be fixedly mounted on the vertically movable frame of the crane apparatus and without the motor housing being required to revolve relative to the frame.

Another object is the provision for simplifying and rendering more efficient the mechanism required for rotating the tong-carrying barrel of a stripper crane to orient the tongs.

Another object is the provision for utilizing the force of a stripper plunger to intensify the gripping action of a pair of tongs moved through an initial gripping movement by auxiliary power means.

Another object is the provision for operating a pair of tongs through a first movement by a motor carried by a stripper crane plunger and through a subsequent movement to gripping position by retracting motion of the plunger relative to the tong-carrying barrel.

Another object is the provision for actuating. a first pair of tongs by reciprocal motion of a stripper plunger relative to the barrel in which the plunger is axially movable, for actuating a second pair of tongs through an initial movement toward gripping position by an auxiliary source of power carried by the barrel and for actuating the second pair of tongs through a subsequent movement to final gripping position by additional reciprocal motion of the stripper plunger beyond the point of movement required for actuation of the first pair of tongs.

Another object is the provision for obtaining additional and useful functions with a stripper plunger reciprocal relative to the barrel of a stripper crane apparatus.

Another object is the combination of the above described features to obtain a novel and highly important combination of structural elements in a stripper crane.

Another object is the provision of a novel and unique arrangement of parts and relationship of functions to produce a. new and highly useful crane mechanism I edge portion of FIGURE 1,

F a large amount of space on the frame 3,664,324 Patented Nov. 20, 1962 "ice giving surprising and advantageous results in operation.

Other objects and a fuller understanding of the invention may be had by referring to following description and claims, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is an elevational view, partially in section, showing the upper portion of my improved apparatus mounted on a vertically movable frame supported by a crane trolley structure;

FIGURE 2 is an elevational view, partially in section, showing the lower portion of my improved apparatus mounted on such vertically mounted frame. The lower indicated by the letters AA, is to be considered as joined to the upper edge portion of FIGURE 2, indicated by the letters AA, so that FIGURES 1 and 2 together, upon such joining of these edge portions, compose a view of the entire improved apparatus. In FIGURES 1 and 2 the upper pair of the crane tongs are in a closed position and the lower pair of the crane tongs are in an open or widespread position;

FIGURE 3 is an elevational view of the lower portion of the apparatus shown in FIGURE 2 and in which the lower pair of tongs has been moved to an initial or preliminary position preceding the full gripping position;

FIGURE 4 is a view similar to that of FIGURE 3 and in which the lower pair of tongs has been moved through a subsequent range of movement to full gripping position;

FIGURE 5 is a view of the lower portion of the apparatus shown in FIGURE 2 and on the same side thereof and illustrates both the upper and lower tongs in open or widespread positions;

FIGURE 6 is a diagrammatical representation, in simplified form, of portions only of the electrical circuit arranged for upward movement of the electric motor that raises the plunger and of that part of the electrical circuit of the electric motor powering an auxiliary hydraulic mechanism during one stage only of its operation in a particular range of movement.

The stripping cranes to which my invention is directed are used in metallurgical plants, such as steel plants, for handling of molds in which metal ingots have been poured, for stripping or removing the ingots from the molds and for gripping and handling the ingots. Stripping cranes of this type are used for removing ingots from both the big-end-up type of mold and the big-enddown type of mold. It is sometimes diflicult to orient the tongs of the crane relative to the load or burden to be gripped and raised, that is, to have the tongs so directed as to be aligned with opposite, substantially parallel sides of the ingot and of the mold.

It has sometimes been attempted to have the whole frame, which is raised and lowered relative to an overhead trolley, rotate on the axis of the frame for obtaining this result. Other times, to obtain this rotation of the crane and orientation of the tongs, it has been necessary to so mount the motor which operates the stripping plunger of the crane as to revolve around relative to the vertically movable frame, and this has required a relatively large space for the motor to permit it to revolve and also has required slip rings and electrical brushes to provide electrical connections with the motor in its different positions of revolution. All this has required and special electrical structure for making and maintaining electrical connections with the motor which operates the stripping plunger in those cases wherein the whole housing of the motor is mounted to revolve.

It has also been found that upon rotation of a barrel member of a crane to orient the tongs carried by the barrel member, and which tongs are actuated by recipro- U cal movement of a plunger relative to the barrel member, that during relative rotation between the rotative shaft and the barrel there is actuation of the tongs when such actuation is not desired. For example, when the tongs have gripped and raised an ingot, the tongs should not release and drop the ingot when the barrel member is being rotated to orient the tOngs about the axis of the barrel member. It is desired to be able to hold the load carried by the tongs of the crane in full gripping action upon rotation of the barrel member so as to obtain orientation by rotation of the barrel member. The overcoming of these and other problems has been accomplished by the presently described and disclosed invention.

In the composite view made up of the FIGURES l and 2, wherein FIGURE 1 represents the upper portion of the crane structure to which my invention is applied and FIGURE 2 represents the lower portions of that structure, a guide frame which is supported by the overhead trolley structure is denoted by the reference character 11. Slidably mounted in this guide frame 11 so as to be vertically movable up and down along the guide frame is a movable frame 12. Upon this vertically movable frame 12 are mounted and supported the parts of the apparatus embodying my invention.

A barrel member 13 mounted vertically to the frame 12 is supported on a journal support 14 riding on a trackw-ay or bushing positioned substantially centrally of the frame 12. By this journal mounting 14, the barrel 13 and parts carried thereby may be rotated on the axis of the barrel member. As seen in the lower portion of FIG- URE 1 and in FIGURE 2, the barrel member 13 at its lower end portion has an outer wall portion 16 welded thereto so as to leave an annular space between the wall portion 16 and the barrel member 13. There is a bushing or cylindrical bearing 18 around the upper portion of the wall portion 16 and another bushing or bearing 19 around a location of the wall portion 16 at a lower transverse portion of the frame 12. These bushings or bearings 18 and 19 provide a bearing guidance for the rotation of the barrel member about its axis in the frame 12.

A plurality of pulleys 15 carried on axles, in turn supported by the frame 12, are reeved with pulleys on a hoist in the overhead trolley structure, not shown. For purposes of simplicity of illustration, the steel cables reeved about the pulleys 15 and extending to the pulleys of the overhead trolley have not been shown. As is well known in the operation of such cranes, the vertically movable frame and the parts carried thereon are raised and lowered by the hoist on the trolley in cooperation with the cables reeved around the pulleys 15 of the movable frame.

Carried by the frame 12 and mounted concentrically around the wall portion 16 of the barrel member 13 is a casing 17 which is fixed to the frame and is non-rotatively connected to the frame. This casing 17 acts as a shield or protection around the barrel member at its location intermediate the several pulleys 15.

Disposed axially of the barrel member 13 Within the upper portion thereof is a rotatable shaft 21, the upper end of the shaft 21 extending upwardly from above the top of the barrel member 13. The lower end 21a of the rotatable shaft 21 is splined so a to provide an elongated non-circular cross-section at the lower end of the shaft 21.

Keyed to this splined end 21a of the shaft 21 is a screw mechanism 22 which is in the form of a sleeve having both internal and external threads formed thereon. The external threads on the screw mechanism 22 are thre'adably interengaged with the lower threaded end por tion 13a of the barrel member 13. The upper end portion of the screw mechanism 22 is so mounted on the splined end 21a of the shaft that relative axial movement may be had between the screw mechanism 22 and the shaft 21 on rotation of the shaft 21. The internal threads on the screw mechanism 22 are threadably engaged with external threads on the threaded end portion 23a of a plunger 23 axially aligned with the shaft 21.

The interaction of the screw mechanism 22 with the threaded portion of the barrel member 13 and the threaded portion of the plunger 23 is such that the mechanism 22 acts as a motion-translating device whereby rotative movement of the shaft 21 is translated or changed to axial movement of the plunger 23 along the axis of the barrel member.

The plunger 23 has a nose portion 25 at its lowermost end and secured thereto by means of a threaded head as. The plunger 23 with its nose portion 25v and the head 24 are so connected as. to be movable axially together as a unit and are here referred to jointly as a plunger and more usually as a stripping plunger.

Welded to the top of the head 24 around the periphery thereof is a guide sleeve 26 of cylindrical shape which is slida'ble in the cylindrical space provided between the inner wall of the barrel 13 and the outer wall portion 16. This sleeve 26 reciprocates in the annular space provided by the barrel member 13 and the wall portion 16 in such manner as to provide guidance to the reciprocal movement of the plunger, the guide sleeve 26 moving with the plunger as a part of the assembly thereof.

Carried by the upper end portion of the sleeve 2% and extending radially therefrom is a key or projection 27. This key 27 is movable in a longitudinal keyway or slot 28 provided in the wall portion 16. Thus the plunger, including the parts 23, 24, 25 and 26, may reciprocate but may not rotate relative to the barrel member 13.

On a diametrically opposite side of the wall portion 16, there is a keyway or slot 29 which extends upwardly from the lower end of the wall portion 16. An abutting projection or key 24a is carried by the head 24 and slides along in the keyway or slot 29 upon reciprocation of the head 24.

Carried by the barrel member 13 in such manner as to rotate with the barrel member are two pairs of tongs, the first or upper pair of tongs 32 and the lower or second pair of tongs 37. A first yoke member 31 is so mounted near the lower portion of the barrel member 13 as to be slidably movable up and down relative to the barrel member 13. The first yoke member 31 has two diagonally disposed or slanted slots 31]) positioned on opposite sides of the barrel 13. Slidably mounted on these slots 31b are cross-pins 33 which are arranged to move up and down in the slots 31b and as so moving up and down to be moved toward and away from the axis of the barrel member. Thus when the cross-pins 33 are disposed at the upper ends of the slots 31b, the cross-pins 33 have been moved radially inward toward the axis of the barrel member 13. When the cross-pins 33 are in the lower ends of the slots 315, then the cross-pins 33 have been moved radially outward from the axis of the barrel member 13.

' These cross-pins 33 are mounted to and extend from the upper ends of the tongs 32, respectively. Thus the upper ends of the tongs 32 are moved radially inwardly and outwardly in accordance with the position of the crosspins 33 in the slots 31]).

A cross-link 34 carries at its opposite ends pivot pins 35 upon which are pivotally mounted the tongs 32 at points intermediate their respective ends. These pins 35 provide pivot mountings about which the tongs 32 may rock in and out of gripping position. The cross-link 34 carrying the pins 35 may move upwardly and downwardly relative to the barrel member so as to permit the tongs 32 to move upwardly and downwardly relative to the first yoke member 31 as the pins 33 move in the slots 31b.

Shown in broken lines directly below the nose portion 25 of the plunger and in a position to be gripped is the top or upper portion of an ingot denoted by the reference character 36. The ingot 36, of which the top portion is shown, may be protruding upwardly from a mold or it may in some instances have been removed from the mold and be standing alone ready to be gripped, raised and moved to another location.

The second or lower pair of tongs 37 are pivotally carried on pivot pins 39 extending through ears 38 provided adjacent the lower end of the barrel member 13. Because the ears 38 are fixedly secured to the barrel member 13, they and the lower tongs 37 carried thereby revolve as the barrel member 13 is rotated. Each tong 37 is of a V-shape in configuration. The lower end portion of each tong 37 is denoted by the reference character 37e. The arms of each tong 37 extending upwardly from the lower end portion 372 where they join, are disposed on opposite sides of a tong 32 of the upper set of tongs.

Projecting inwardly toward the axis of the barrel member near the lowermost end of each tong 37 is a point 37a adapted for engaging and penetrating under pressure an ingot or other burden to be grasped by the tongs 37. Also directed radially inward but at a point somewhat higher on the tongs 37 are projections 37b. These projections 37b are adapted to engage over the top edge of a mold, such as a big-end-up mold, to hold the mold in a downward position upon extraction of an ingot from the mold by the tongs 32.

Also provided on the inner sides of the tongs 37 near the lower end thereof are opposed recesses 37c. These recesses 37c are adapted to receive and hold the ears or projections extending out from opposite sides of a mold, such as a big-end-down mold, to raise and hold the mold upwardly upon pushing of an ingot from the big-end-down mold by the plunger nose 25.

Angularly extending from the upper ends of the tongs 37 are crank arm portions 37d which are integral with the main portion of the tongs 37 so that revolving of the crank arms 37d about the pivot pins 39 swings the tongs 37 toward and away from the axis of the barrel member 13. Thus upon upward movement of the crank arm portions 37d, the lower ends of the tongs 37 are moved radially inward toward the axis of the barrel member 13, and thus toward any burden, such as the ingot 36 partially illustrated in the drawing.

Pivotally connected to the outer or free ends of the crank arm portions 37d are pivot pins 40. These pivot pins 40 in turn are pivotally connected to the lower ends of vertically disposed rods 41 so that raising of the rods 41 raises the crank arm portions 37d and moves the lower tongs 37 toward each other, and lowering of the rods 41 conversely moves the lower ends of the tongs 37 away from each other.

The upper ends of the rods 41 extend through tubular bushings secured to and carried by a second yoke member 43 which is so mounted about the barrel member 13 as to be movable up and down relative to the barrel member 13. The upper ends of the rods 41 carry disc-type springs '46 and securing the springs 46 on the rods 41 are nuts 47. The springs 46 are so biased as to absorb shock and also to urge the rods 41 upwardly relative to the bushings 45 on the upper yoke 43. The resiliency of the springs 46 takes up any lag or delay otherwise occurring in the operation of the apparatus and slightly delays opening of the tongs 37 away from each other which is obtained through downward movement of the upper yoke 43 moving the bushings 45 downwardly.

Extending out from opposite sides and connected to the upper yoke 43 are brackets or ears 48. Secured to the brackets or ears 48 are the lower ends of piston stems 49 extending upwardly therefrom. These piston stems 49 extend into hydraulic cylinders 50 wherein the pistons are reciprocal by admission of hydraulic fluid under pressure to the opposite sides of the pistons in the cylinders 50. By operation of appropriate valves in a hydraulic system provided, the pistons in the cylinders 50 are reciprocated so as to move the piston stems upwardly or downwardly in accordance with the control of the hydraulic system of which the cylinders 50 are a part. The upper ends of the respective cylinders 50 are connected and carried by brackets or ears 51 which, in turn, are welded to a shoulder portion 16a of the outer wall portion 16 carried by the barrel member. Thus, the yoke member 43 is raised and lowered by the hydraulic piston and cylinder assemblies which are operated and controlled by a hydraulic system carried by the barrel.

A supporting bracket 83 is secured to, and supported by, the wall portion 16 of the barrel member 13 at a location adjacent the cylinders Stl. Mounted upon this bracket 83 is a pump and valve mechanism denoted by the reference character 76. An electric motor 77 is mounted upon the pump and valve mechanism 76 for operating the pump of the hydraulic system. The control of the operation of the motor 77 controls the operation of the pump and valve mechanism 76 so that the operator by the electric control of the motor 77 controls the operation of the hydraulic cylinders 50 and hence the raising and lowering of the upper yoke member 43.

An arm 82 is secured to the wall portion 16 0f the barrel member 13 so as to extend radially outward from the barrel member to revolve with the barrel member. This arm 82 carries a plurality of electric brush elements or contact members 78 which are disposed to be in contact with circular electric contact members or slip rings 84 mounted in fixed position on a bracket 81 carried by the frame 12. Thus the elements 78 are maintained in electrical connection with the slip rings 8% throughout rotation of the barrel member. Slip rings in turn are connected to the electrical circuit of the crane apparatus so that flow of current through the respective rings 80 and contact elements 78 is controlled by the operator of the crane apparatus by manipulation of switches in the operators cab of the crane. The cable shown extending from the motor 77 carries wires to the brush elements 78 so that the motor 77 and valve mechanism 76 are operated and controlled through the electrical circuit and connections maintained through the elements 78 and slip rings 80.

Secured to and projecting outwardly of the second yoke member 43 along the lower edge portion thereof is a projection or abutting member 44. This projection or abut ting member 44 is in alignment with the top portion of the first yoke member 31. The disposition of the parts is such that the yoke member 31 may not be moved upwardly beyond the projection or abutting member 44, but upon reaching the projection 44 engages and pushes upwardly upon the projection 44 and hence upon the second yoke member 43 carrying the projection 44. Thus the lower portion of the yoke member 43 and the upper portion of the yoke member 31 face each other in opposition so that raising of the yoke member 31 to the point of contacting the projection 44- and the continued raising of the yoke member 31 tends also to raise or move upwardly the yoke member 43. However, the yoke member 31 may be moved downwardly away from the yoke member 43 so as to disengage and be spaced from the projection 44.

Fixedly mounted upon the top of the frame 12 so as to be carried thereby is a motor 53, which because it powers the actuation of the stripping plunger is sometimes referred to as the stripper motor of the apparatus. The rotor shaft of the motor 53 carries a beveled gear 54, which is enmeshed with a beveled gear 55, which in turn is splined to an inner shaft is at right angles to the motor shaft. The arrangement is such that the motor drives the vertically disposed inner shaft 5a through the enmeshed beveled gears 54 and 55. The inner shaft 56 is rotatable in a bushing 61 carried by the frame 12. Splined to the inner shaft 56 so as to be rotatable therewith is a gear 57. This gear 57 in turn is enmeshed with an intermediate idler gear 58, which is enmeshed with a gear 5-9 splined on the upper end of the shaft 21. The idler gear 53 is rotatably mounted on a shaft 79 supported in bushings carried by the frame. It is thus seen that by the power of the motor 53 and the gear train described, the shaft 21 is rotated in accordance with the direction of the 7 rotation of the rotor of the motor 53. The cable shown extending from the motor 53 carries wires connected to the electrical circuit of the crane which includes switches in the operators cab of the crane so that the operator may control the operation of the motor 53 as todirection of rotation and of speed.

Mounted concentrically of the inner shaft 56 and enclosing the lower portion thereof is a tubular shaft 61. The axes of the inner shaft 56 and of the tubular shaft 61 around the inner shaft 56 coincide. A supporting housing 62 secured to the frame 12 of the crane apparatus encloses and supports through suitable bearings the tubular shaft 61. The arrangement is such that the tubular shaft 61 may rotate on its axis within the housing support 62. At the lower end of the concentric inner shaft 56 and tubular shaft 61 there is an electromagnetic clutch device 64. This clutch device 64 has a clutch part 6-5 carried by a flanged portion 63 which is keyed to the lower end of the tubular shaft 61 so as to rotate therewith. Thus, rotation of the tubular shaft 61 rotates the clutch part 65 of the electromagnetic clutch device 64. Keyed to the lower end of the inner shaft 56 is a clutch part 66 of the electromagnetic device 64. The clutch part 66 rotates with the inner shaft 56. The structure and arrangement of the electromagnetic device 64 is such that by a spring bias applied to the parts thereof, the clutch parts 65 and 66 are disengaged when the motor 53 is electrically energ led. The electric cable shown extending from the electromagnetic device 64 carries wires connected to the electrical circuit of the crane apparatus, of which the controlling switches are in the operators cab and the arrangem nt of the circuit is such that when the electric motor 53 is electrically energized, the electromagnet device 64 is in a disengaged arrangement so that the inner shaft 56 and the tubular shaft 61 are not operatively connected. However, on the de-energization of the motor 53, the flow of electric current is terminated to the electromagnetic device 64 so as to cause the clutch parts 65 and 66 to become engaged by spring action and thus to operatively connect the tubular shaft 61 and the inner shaft 56 so as to rotate together as a unit.

Fixedly mounted upon the frame 12 is another motor 68 which because it is used for turning the barrel member 13 on its axis is often referred to as a turning motor. This motor 68 has shown extending therefrom an eiectric cable carrying wires which are connected to the electrical circuit of the crane apparatus, including the control switches in the operators cab. A shaft 69 rotated by the motor 68 extends therefrom and carries splined on its outer end a worm gear 71 which is enmeshed with a pinion gear 72, which in turn is splined to the tubular shaft 61 so as to rotate therewith. Rotation of the shaft 69 by the motor 63 through the described gear train rotates the tubular shaft 61 in accordance with the direction of rotation of the rotor of the motor 68. Embracing the shaft 69 is an electromagnetic brake 79. An electric cable shown extending from the brake 7t? carries wires which are connected to the electrical circuit of the crane apparatus and to the switches in the operators cab. The arrangement is such that when the motor 68 is de-energized, then the electromagnetic brake 79 is actuated so as to brake or stop the rotation of the shaft 69 and hence to brake or stop the rotation of the tubular shaft 61. Upon the operative connection of the tubular shaft 61 and inner shaft 56, the brake 7% upon stopping rotation of the tubular shaft 61 also stops rotation of the inner shaft 56.

Splined to the upper end of the tubular shaft 61 is a gear '73 which in turn is enmeshed with an idler gear 74 carried on a supporting shaft 79. The gear 7 is in turn enmeshed with a gear 75 splined to the upper end of the barrel member 13. Thus rotation of the tubular shaft 61 through the described gear train rotates the barrel member 13 in accordance with the direction and speed of the rotation of the tubular shaft 61.

It is to be noted that the gear ratios of the upper gear train 57, 5S and 59 are the same as those of the lower gear train made up of gears '73, 7 and 75. Thus the speed and direction of rotation of the shaft 21 in the barrel member 13 by the inner shaft 56 are the same as the speed and direction of rotation of the barrel member 13 by the tubular shaft 61. Thus, aiso upon rotation of the inner shaft 56 and the outer or tubular shaft 61 together, that is, as a unit, by their operative connection through the clutch device 64, the shaft 21 and the barrel member 13 rotate together and Without any relative motion therebetween. Although the barrel member 13 may rotate with the shaft member 21, there is no reciprocal movement of the plunger 23 because there is no relative rotation between the shaft 21 and the barrel member 13 when the inner shaft 56 and the tubular shaft of are operatively connected to rotate together as a unit by the clutch device 64-. The clutch device thus acts as coupling means for operatively connecting the two power-transmitting means described.

The upper or first pair of tongs 32, sometimes referred to as the extractor tongs, are actuated by power derived from the reciprocation of the stripping plunger 23. As seen in FIGURE 2, the abutting projection 24a of the head 24 carried by the stripping plunger extending out into the keyway 2? extends under and abuts a key portions 31a of the yoke member 3 which key portion 31a also is movable in the keyway 29. Thus raising of the plunger 23 and the head 24 carried thereby raises the yoke member 31 and the tongs 32 and cross-link 34 which are carried thereby. This raising of the tongs 32 raises a burden, such as the ingot 36, engaged by the points 32a embracing or pressing into the sides of the ingot. By reason of the inclination of the slots 3112, the raising of the yoke member tends to force the points 32a on the lower end of the tongs 32 inwardly toward the axis of the plunger and hence into firm gripping engagement with a burden, such as a steel ingot. In the pulling of an ingot from a mold, such as a big-end-up mold, to prevent the mold from moving upwardly when the ingot is being extracted therefrom, the lower tongs 37 are moved inwardly so that the projection 37b engaging the top of the mold holds the mold downwardly while the tongs 32 pull the ingot upwardly therefrom.

in the ordinary use of the lower tongs 37, for merely bringing them in together to a position to hold a mold downwardly (for big-end-up molds) or raised (for bigend-down molds), and where no great gripping action is required, the tongs 37 are actuated by normal operation of the hydraulic piston and cylinder assemblies 50. The electric controls of a hydraulic motor and valve mechanism are so controlled that a normal stroke of the pistons and cylinders 50 are obtained so as to bring the lower ends of the tongs 37 downwardly in an initial or normal position, such as in the position for merely positioning projections 3715 over a mold. The force required for merely manipulating the lower tongs 37 into this initial or normal position is not great as compared with the force required for lifting an ingot, for example.

My invention includes means for obtaining greater and more intense grip on an object to be lifted, such as a steel ingot, wherein more than the normal inward movement of the tongs 37 is required. In order to raise a steel ingot, it is necessary to penetrate the ingot by an inward forcing of sharp points, such as the points 37a,

near the lower ends of the tongs 37. As the force exertable by the hydraulic cylinders 51 is not suflicient, I impart additional force for obtaining this greater or more intense gripping action through borrowing power from the reciprocal plunger 23 upon upward movement thereof.

In the position of both the upper tongs 32 and the lower tongs 37 illustrated in FZGURE 5, both sets of tongs are in their widespread or ungripping position. As seen in this view, the yoke member 31 is in its lowermost position by reason of the movement of the plunger 9 downwardly in the barrel member. Also the lower tongs 37 are in their open or most widespread position.

FIGURE 2 illustrates the position of the tongs 37 in their widespread position ready to grasp or grip an ingot, such as ingot 36. (The tongs 32 are shown closed but are not in use.) Upon actuation of the hydraulic piston piston and cylinder assembly 50, the yoke 43 is raised to raise the rods 41. The raising of the rods 41 in turn swing the lower tongs 37 to the initial or contacting position illustrated in FIGURE 3. Here the points 37a have contacted the ingot 36 but enough force has not yet been applied to cause penetration of the ingot 36 by the points 37a. The force of the hydraulic cylinders has been suflicient to swing the tongs 37 to this initial or preliminary position shown in FIGURE 3. It is to be noted that in this position, the top of the yoke 31 is in line with a location indicated by a broken line denoted by the letter A in FIGURE 3. The bottom of the projection or abutting member 44 on the yoke 43 is at the level indicated by a broken line denoted by the letter B in FIGURE 3.

In the ordinary operation of the crane apparatus wherein the tongs 32 are being utilized for extracting an ingot or for otherwise raising a burden, the electric controls are such that upon the top of the yoke member 31 reaching the level indicated by the broken line A, a limit switch is engaged and actuated so as to break the circuit to the motor 53 and thus to prevent further upward movement of the plunger 23 raising the yoke member 31. Thus in such normal operation as in the use of the tongs 32, FIG- URE 3 illustrates the uppermost limit reached by the yoke member 31. Upon reaching this position, the limit switch in the electrical circuit prevents further upward movement of the yoke member 31. To impart additional gripping force to the lower tongs 37, the limit switch is by-passed by the operator pressing a by-pass circuit switch so as to cause the yoke member 31 to continue to be raised upwardly by the raising of the plunger by continuing the energization of the stripping motor 53 so that the top of the yoke member 31 engages and abuts the lower surface of the projection 44 at the level indicated by the broken line marked with letter B in FIG- URE 3.

Also at the level indicated by the broken line marked with the letter A in FIGURE 3, the electrical circuit energizing the motor '7 7 of the hydraulic system of which the cylinders d are a part, is also disconnected by the limit switch. However, this disconnection is also bypassed by the operator simultaneously pressing a by-pass circuit switch so as to make ineffective the said limit switch so that the cylinders 59 may continue to raise and pull upwardly on the yoke member 43.

Upon the top surface of the yoke member 31 engaging the projection id and pressing upwardly thereon so .as to raise the yoke 43 through the additional force imparted by the raising of the plunger 23, which lifts the yoke member 31, a greater and additional force is applied to raise the rods il. This additional force helps move the tongs 37 toward each other so as to cause the points 37a to penetrate the ingot as illustrated in FiGURE 4. This additional force applied through borrowing the force derived from the plunger actuated by the stripping motor 53 imparts an intense gripping action on the lower tongs 37 so as to apply a greater inward force on the points 37a than could be obtained by the hydraulic piston and cylinder assemblies 50. The by-passing of the limit switch which ordinarily de-energizes the motor 77 of the hydraulic pump and valve mechanism allows the hydraulic piston and cylinder assemblies to assist rather than oppose the upward movement of the yoke member 43. Without including this feature of this continued actuation of the motor 77 so as to cause the piston and cylinder assemblies 54) to continue upward operation, it is necessary to provide relief or by-pass valve means so that upward movement of the pistons in the respective cylinders would not After the ingot has been id be opposed by the fluid therein and thus cause rupture or breakage in the hydraulic system.

After the upper yoke member 43 has been raised sufficiently to cause the penetration of the points 3711 in the ingot by reason of this intensified or additional gripping action obtainable through the borrowing of power from the upwardly moving plunger, then the top of the yoke member 31 reaches the level or location indicated by the broken lines marked with the letter C in FIGURE 3. At this level or location, a second limit switch is engaged and automatically open so as ,to tie-energize the motor 53 and prevent additional raising of the stripping plunger and thus prevent breakage of the parts beyond the point tolerated by the design and dimensions of the several parts. firmly grasped by this intensified action, such as in the relative position of the parts shown in FIGURE 4, the frame 12 may be raised by means of the hoisting cables so as to lift and move the ingot to a desired location. Thus, the lower tongs 37 .are utilized for the function of gripping and raising objects, such as ingots, and which is a function in addition to their other uses, previously described.

It is an important feature of the invention that the barrel member and tongs carried thereby may be rotated so that the tongs, such as tongs 37, may be oriented, that is, swung around relative to a fixed reference location. For example, it may be desired to partially rotate the ingot 36 after it has been gripped and raised by the tongs 37. To maintain the firm and intense grip on the ingot by the tongs 37, it is necessary that there be no relative rotative motion between the shaft 21 and the barrel member 13 If, for example, there were such relative rotation so as to cause the stripping plunger to move downwardly in the barrel member 13, the removal of the intensified grip on the ingot borrowed through the plunger would permit the tongs 37 to loosen their gripon the ingot 36 The grip on the ingot would be lost and the ingot would drop from the tongs 37. However, by having the barrel member 13 and the shaft 21 rotate together in the same direction and .at the same speed when the barrel member 13 is rotated on its axis to orient the tongs 37, the firm and intense gripping action of the tongs 37 is uniformly maintained.

To rotate the barrel member 13, the turn motor 68 is energized, the brake 70 is released, and the electromagnetic clutch device 64 is so operated as to operatively connect the inner shaft 56 and the tubular shaft 61 to rotate together and thus assure the shaft 21 rotates in unison with the barrel member 13.

There has been illustrated in FIGURE 6, an elementary and diagrammatic showing of a simple arrangement for the operation of the switch for by-oassing the limit switches. For purposes of simplicity only two power lines and 86 are illustrated, these lines 85 and 86 being in the electrical circuit of the apparatus and being connected to a source of electrical energy. Connected to and leading from the power line 85 is a connection 87 which in turn is electrically connected with the motor 53. A line 88 connected to the motor 53 is connected to a limit switch 89. The limit switch 89 is connected by a wire 90 to another limit switch 91. This limit switch 91 is electrically connected by a line 92 to the other power line 86.

The limit switch 91 is so located as to be engaged and opened at the level or location A indicated in FIGURE 3, upon upward movement of the yoke member 31. The limit switch 89 is located so as to be engaged and opened at the location or level indicated by the letter C in FIG- URE 3, upon upward movement of the yoke member 31. a

A by-pass of the first limit switch 91 is provided by a line 96 to electrical contact point and by a line 93 to electrical contact point 94. The line 96 is electrically connected with the line 92 and line 93 is electrically connected with the line 96. The lines 93 and 96 thus bypass the limit switch 9-1 except for the gap between the points 94 land 95.

aoeaaaa A line 97 also connected with the power line 85 is connected to a contact point 93. The motor 77 is connected through a line tilt) to the power line 86 and another wire or line lit/1 connects the motor 77 with a contact point 99 spaced from the contact point 98. A switch device made up of a push-button 193 biased in open position by a spring 104- has spaced double contact members Hi5 and 102. By pressing the button 163 inwardly against the bias of the spring 1%, the contact member 165 electrically connects the contact points 94 and 95 and at the same time the contact member fill electrically connects the contact points 98 and 99. Thus by pressing the switch button 193, the first limit switch 9 1 is effectively bypassed so that the motor '53 continues to be energized until the limit switch 89 is opened by reason of the top of the yoke member 31 reaching the level or location indicated by the line marked with the letter C in FIG- URE 3. Thus between the levels of the line B and of the line C, the intensified or greater gripping action is supplied to the tongs 37 through the borrowing of the additional power derived from the raising of the plunger and the power derived from the stripping motor 53. This intensified gripping action is considerably greater than that which could be obtained through the hydraulic piston and cylinder assemblies which are normally used for raising the yoke member 43 and hence swing the tongs 37 to their initial or preliminary position, such as that shown in FlGURE 3.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by Way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. In crane apparatus having a vertically movable frame guided in vertical non-rotative movement by a guide frame carried by a crane trolley and raised and lowered by hoisting mechanism carried by the trolley, the combination of a vertically disposed barrel member journaled on said movable frame to rotate on its axis relative to said movable frame, a pair of tongs arranged in opposition to each other to grasp an object therebetween upon actuation of the tongs, pivot connections carried by said barrel member for pivotal support of said tongs, respectively, the axes of said pivot connections being parallel to each other and disposed in a plane normal to the axis of the barrel member, a plunger shaft axially disposed in said barrel member and non-rotatively reciprocal therein to extend from said barrel member, tong-actuating means operatively interconnecting said plunger shaft and said tongs to actuate said tongs upon reciprocal movement of the plunger shaft relative to sad barrel member, screw mechanism in said barrel me aber and threadably engaging said barrel member and said plunger shaft to reciprocate the plunger shaft upon rotation of the screw mechanism relative to said barrel member, an electric motor mounted in fixed position on said movable frame movable therewith, driving connection means operatively connecting said electric motor and said screw mechanism for turning the same by the said electric motor to reciprocate said plunger shaft, powerdriven means carried by the movable frame and operatively connected to said barrel member for rotating said barrel member on its axis and revolving said tongs about said axis to orient the said tongs, and coupling means for operatively coupling said driving connection means and said power-driven means to cause rotation of the screw mechanism in accordance with the rotation of the barrel member upon rotation of said barrel member by said power-driven means o prevent relative rotative movement of screw mechanism relative to the barrel membe and to maintain the longitudinal position of the plunger shaft relative to the barrel member, said driving connection means and said power-driven means between said coupling means and said screw mechanism and between said. coupling means and said barrel member being proportioned to impart equal rotative speed to said screw mechanism and said barrel member upon the coupling of said driving connection means and said powerdriven means.

2. The combination defined in claim 1 and in which said power-driven means for rotating the barrel member includes another and separately controlled electric motor carried by said movable frame.

3. The combination defined in claim 1 and in which said power-driven means includes a brake for locking said power-driven means against movement to prevent rotation of the member upon independent operation of the drivin connection means to rotate the screw mechanism relative to said bar-rel member fo reciprocation of the plunger shaft.

4. in crane apparatus having a stripper plunger reciprocal in a vertically disposed barrel membe by rotation of a screw mechanism positioned in the barrel member concentrically therewith, a driving shaft extending axially of the barrel member and operatively connected in the barrel member to the screw mechanism to rotate the same, said barrel member being rotatively mounted on a vertically movable and non-rotatable frame to rotate on its axis relative to the said frame and to be raised and lowered with the frame relative to a supporting trolley, said barrel member carrying tongs journaled on pivots disposed in planes normal to the axis of the barrel member and having jaws movable toward and away from the axis of the barrel member upon reciprocal movement of the stripper plunger relative to the barrel member, the improvement comprising the combination of, an electric motor carried by said frame, power-transmitting means carried by said frame and operatively connecting said electric motor and said driving shaft to rotate the driving shaft and said screw mechanism by the said electric motor, said power-transmitting means including a first rotating member rotatable on an axis parallel to and spaced from the axis of said driving shaft, power-driven mean carried by the said frame and operatively connected to said barrel member for revolving said barrel member and the said tongs about the axis of said barrel member to orient the said tongs, said power-driven means including a second rotating member disposed concentrically with said first rotating member and rotatable on said axis parallel to the axis of the driving shaft, clutch means for operatively interengaging said first and second rotating members, said power-transmitting means and said power-driven means upon being interengaged by said clutch means being proportioned to rotate said driving shaft and said barrel member together at equal rotative speeds.

5. The improvement defined in claim 4 and in which said power-driven m ans includes another and separately controlled electric motor carried by said frame.

6. The improvement defined in claim 4 and in which said power-driven means includes a brake for locking said power-driven means against movement to prevent rotation of the barrel member upon independent operation of the power-transmitting means to rotate the driving shaft and screw mechanism relative to said barrel member for reciprocation of the stripper plunger.

7. In a stripper crane, the combination of a barrel member carried by a frame vertically movable relative to a crane trolley, tongs carried by the barrel member, a plunger mounted in said barrel member to reciprocate therein, said plunger being adapted to push an ingot from a mold upon protrusion of the plunger from said barrel member and adapted to actuate said tongs into ingot gripping action upon retracting motion relative to said barrel member, a shaft axially extending into said barrel member at the upper portion thereof, a screw mechanism in said barrel member threadably interengaged with said shaft and said plunger whereby rotation of said shaft relative to said barrel member causes reciprocation of said plunger relative to said barrel member, an electric motor mounted on said frame, a first gear concentrically mounted on said shaft and keyed thereto, a second gear concentrically mounted on said barrel member and keyed thereto, a first driven gear train operatively connecting said electric motor and said first gear for rotating said first gear and shaft upon operation of said first driving gear train, a second driving gear train operatively connected to said second gear for rotating said second gear and barrel member upon operation of the second driving gear train, and selectively actuatable coupling means for coupling said first and second driving gear trains in unison, said first and second driving gear trains and said first and second gears, respectively, being in such ratio that the said shaft and said barrel member are rotated at the same speed upon the coupling of said first and second driving gear trains to prevent relative rotation between the shaft and barrel member.

8. The combination defined in claim 7 and in which a second electric motor is operatively connected to said second driving gear train for powering said second driving gear train independently of said first driving gear train.

9. The combination defined in claim 7 and including braking means carried by said frame and operatively connected to said second driving gear train, said braking means being arranged for automatically preventing the rotation of said second gear and barrel member upon discontinuance of operation of said second driving gear train.

10. The combination of an upright barrel member, a plunger axially mounted therein adjacent a lower end of the barrel member, a shaft axially mounted therein adjacent an upper end of the barrel member, a motiontranslating member in said barrel member and interengaging said plunger and shaft to translate rotative movement of the shaft relative to the barrel member to reciprocal movement of the plunger relative to the barrel member, crane tongs carried by the barrel member revolvable about the axis of the barrel member upon rotation of the barrel member, means operatively interengaging said plunger and tongs for actuation of the tongs by reciprocal movement of the plunger, a first power-transmitting mechanism operatively connected to said shaft for rotating the same relative to the barrel member, a second powertransmitting mechanism operatively connected to said barrel member for rotating the same and revolving the tongs about the axis of the barrel member, said first and second power-transmitting mechanisms having concent rically disposed portions, and selectively actuatable clutch means adapted to connect operatively said concentrically disposed portions to rotate said shaft and barrel member simultaneously, said first and second power-transmitting means upon being connected being arranged to rotate the shaft and barrel member at uniform speed and direction to assure maintenance of the relative positions of said plunger and barrel member upon rotation of the barrel member.

11. The combination defined in claim 10 and including a first electric motor operatively connected to said first power-transmitting mechanism for delivering power thereto and an independently controlled second electric motor operatively connected to said second power-transmitting mechanism for delivering power thereto.

12. The combination defined in claim 19 and including a brake operatively connected to said second powertransmitting mechanism to brake the same and prevent rotation of the barrel member upon termination of trans- 1% mission of power through the second power-transmitting mechanism to the barrel member.

13. In stripper crane apparatus having a supporting frame vertically movable relative to an overhead crane structure, a vertically disposed barrel member journalled on said frame for rotation about its axis, a stripping plunger axially mounted in said barrel member and reciprocal relative to said barrel member, a shaft axially mounted in said barrel member and axially aligned with said stripping plunger, screw mechanism mounted in said barrel member and threadably engaged to said shaft and said plunger to translate rotative motion of the shaft relative to the barrel member to reciprocal motion of the plunger relative to the barrel member, the combina tion of a first electric motor carried by said frame, a spindle member rotated by said electric motor, a tubular member concentrically mounted on said spindle member, electro-magnetic actuatable clutch mechanism positioned to operatively couple said spindle member and tubular member, said electro-magnetic clutch mechanism being controlled by supply of electric current to said first electric motor to actuate the electro-magnetic clutch mechanism so as to disconnect the spindle member and tubular member upon electrical energization of said first electric motor, a second electric motor carried by said frame operatively connected to said tubular member to rotate the same upon electrical energization of said second electric motor, an electro-magnctic brake mechanism operatively connected to said tubular member, said electro-magnetic brake mechanism being controlled by supply of electric current to said second electric motor to actuate the electro-magnetic brake mechanism to break the rotation of the tubular member upon electrical de-energization of said second electric motor, first connecting means operatively connecting said spindle member and said shaft for rotating the shaft, second connecting means operatively connecting said barrel member for rotating the barrel member, the rotation of the tubular member by the second electric motor during coupling of the tubular member and spindle member by the electro-magnetic clutch mechanism causing the barrel member and shaft to rotate in unison, the said first and second connecting means being so proportioned and arranged that upon such rotation in unison the shaft and barrel rotate at the same speed and direction.

14. Apparatus for rotating the tong-carrying barrel of a stripper crane without reciprocal movement of a tongactuating stripper plunger relative to the barrel, the plunger being carried by and reciprocal relative to the barrel by rotation of a screw mechanism relative to the barrel, said barrel and plunger being in axial alignment and operatively interconnected by said screw mechanism, said screw mechanism being at least partially within said barrel, comprising first driving means for rotating the screw mechanism, second driving means for rotating the barrel member, selectively actuatable coupling means for coupling said first driving means and second driving means to rotate said screw mechanism and barrel member at such speeds and direction as to prevent reciprocal movement of the plunger relative to the barrel, and brake means operatively connected to said second driving means for braking rotation of the barrel member by the second 7 driving means upon uncoupling of the first and second driving means and independent rotating of the screw mechanism by the first driving means.

15. In stripper crane apparatus, the combination of a barrel member, a stripping plunger reciprocal in said barrel member, first power means for raising said plunger relative to said barrel member, a first set of tongs pivotably carried by said barrel member, a first yoke member carried by said barrel member to be moved therealong and operatively connected to said first set of tongs to actuate the same to gripping position upon upward movement of the first yoke member relative to said barrel member, said plunger and said first yoke member having first abutting portions disposed in oppositon to each other to interengage upon upward movement of said plunger to a first limit point for raising said first yoke member by the upward movement of the plunger beyond said first limit point, a second set of tongs pivotally carried said barrel member, a second yoke member carried by said barrel member to be moved therealong and operatively connected to said second set of tongs to actuate the same in a motion toward gripping position upon upward movement of the second yoke member relative to the barrel member, second power means carried by said barrel member and operatively connected to said second yoke member for raising said second yoke member a first distance relative to said barrel member for actuating said second set of tongs through an initial stage of said motion toward gripping position, said first yoke member and second yoke member having second abutting portions disposed in oppositon to each other to interengage upon the upward movement of the first yoke member to a second limit point for raising said second yoke member a second distance additional to said first distance by the upward movement of the first yoke member beyond said second limit point, said upward movement of the second yoke member through said second distance actuating said second set of tongs through a subsequent stage of said motion toward gripping position.

16. In stripper crane apparatus having a barrel member, a stripping plunger axially mounted to said barrel member and reciprocally movable thereto, first power means operatively connected through the barrel member to the plunger for upwardly moving the plunger relative to the barrel member, a first set of tongs carried by the barrel member and actuatable to gripping position by upward movement through a first distance of a first yoke member raised by said plunger, the upward movement of the first yoke member through said first distance by said plunger being terminable by limit means controlling said first power means to discontinue upward movement of the plunger by said first power means, a second set of tongs carried by the barrel member and actuatable to an initial gripping position by upward movement an initial distance of a second yoke member raised by second power means carried by the barrel member, the improvement of first abutting means carried by the first yoke member, second abutting means carried by the second yoke member and disposed to face said first abutting means in opposing relationship, said first and second abutting means being spaced from each other during movement of the second yoke member through said initial distance, and means for opposing said limit means to permit said first yoke member to move upwardly beyond said first distance and to cause said first and second abutting means to interengage, additional upward movement of the second yoke member by the first yoke member through said interengaged first and second abutting means actuating said second pair of tongs to a subsequent gripping position.

17. In crane apparatus having a first pair of tongs carried by a vertically disposed barrel member, a second pair of tongs carried by the barrel member, and a plunger reciprocally movable axially of said barrel member, the combination of first means for actuating the first pair of tongs by an upward movement of said plunger through an initial range of upward movement, second means independent of said first means for initially actuating said second pair of tongs to a first gripping condition of intensity, and third means operable subsequent to said initial actuation of the second pair of tongs by another upward movement of the plunger through a second range of upward movement following said initial range of upward movement to actuate the second pair of tongs to a second gripping condition of intensity greater than said first gripping condition.

18. In stripper crane apparatus having a frame vertically movable relative to a supporting guide structure, a

barrel member journaled on said frame to rotate on its axis, a plunger axially mounted in said barrel member and reciprocal relative thereto, first rotative drive means carried by the frame, motiorntranslating means carried by said barrel member and operatively connecting said first rotative drive means and said plunger for moving the plunger axially of the barrel member by rotation of said first rotative drive means, second rotative drive means carried by said frame operatively connected to said barrel member for rotating the barrel member, coupling means for selectively coupling said first and second rotative drive means to rotate said motion-translating means and barrel together without relative motion therebetween to hold the plunger against axial movement relative to the barrel member upon rotation of the barrel member, a first pair of tongs pivotally carried by the barrel member to move in gripping action toward the axis of the barrel member, a second pair of tongs pivotally carried by the barrel member to move in gripping action toward the axis of the barrel member, rotation of said barrel member providing orientation of said pairs of tongs carried thereby, first means driven by upward movement of said plunger to a reference point for actuating said first pair of tongs to move the same into gripping action by a first upward movement of said plunger, power means carried by said barrel member and operatively connected to said second pair of tongs for moving said second pair of tongs through an initial step of movement in gripping action, and second means driven by upward movement of the plunger beyond said reference point for actuating said second pair of tongs to move the same through a step of movement in gripping action subsequent to said initial step of movement, said initial step being greater in extent of the movement of the second pair of tongs and said subsequent step being greater in the force applied to the second pair of tongs for gripping action.

19. In a stripper crane, the combination of first rotative driving means for obtaining reciprocal movement of a stripping plunger along the axis of a rotative barrel member carrying said stripping plunger and operatively connected thereto, second rotative driving means for rotating the barrel member for orienting a first pair of tongs and a second pair of tongs pivotally carried by the barrel member to revolve the tongs around the axis of the barrel member, coupling means for selectively coupling said first and second driving means for operating the same together at speeds to avoid reciprocal movement of the plunger relative to the barrel member during rotation of the barrel member, first interengaging means operatively connecting the plunger and the said first pair of tongs for actuating said first pair of tongs by upward movement of the plunger through a first range of movement of the plunger, independent power means carried by the barrel member operatively connected to said second pair of tongs for moving the second pair of tongs an initial distance toward gripping position, and second interengaging means operatively connecting the plunger, through said first interengaging means, and the said second pair of tongs for moving the second pair of tongs a succeeding distance to final gripping position upon upward movement of the plunger through a subsequent range of movement of the plunger.

20. The combination claimed in claim 19 and in which said independent power means includes hydraulic piston and cylinder means, and in which the initial distance the second pair of tongs is moved by the independent power means is greater than said succeeding distance and in which the gripping force applied to the second pair of tongs by said second interengaging means is greater than the gripping force applied to the second pair of tongs by the independent power means during movement through said initial distance.

21. In stripper crane apparatus, the combination of a barrel member, a plunger carried by and reciprocal relative to said barrel member, first power means for raising said plunger relative to said barrel member, a first yoke member carried by said barrel member to be moved therealong, said plunger and said first yoke member having first abutting portions disposed in opposition to each other to interengage upon upward movement of said plunger to a first limit point for raising said first yoke member by the upward movement of the plunger beyond said first limit point, a pair of tongs pivotally carried by said barrel member, a second yoke member carried by said barrel member to be moved therealong and operatively connected to said pair of tongs to actuate the same in a motion toward gripping position upon upward movement of the second yoke member relative to the barrel member, second power means carried by the barrel member and operatively connected to said second yoke member for raising said second yoke member a first distance relative to said barrel member for actuating said pair of tongs through an initial stage of said motion toward gripping position, said first yoke member and said second yoke member having second abutting portions disposed in opposition to each other to interengage upon the upward movement of the first yoke member to a second limit point for raising said second yoke member a second distance additional to said first distance by the upward movement of the first yoke member beyond said second limit point, said upward movement of the second yoke member through said second distance actuating said pair of tongs through a subsequent stage of said motion toward gripping position.

22. In a stripper crane apparatus having a barrel memher, a stripping plunger axially mounted to said barrel member and reciprocally movable relative thereto, first power means operatively connected through the barrel 118 member to the plunger for upwardly moving the plunger relative to the barrel member, a first yoke member rais- -able by said plunger by upward movement of the plunger,

the upward movement of the first yoke member through a first distance by said plunger being terminable by limit means controlling said first power means to discontinue upward movement of the plunger by said first power means, a pair of tongs carried by the barrel member and actuatable to an initial gripping position by upward movement an initial distance of a second yoke member raised by second power means carried by the barrel member, the improvement of first abutting means carried by the first yoke member, second abutting means carried by the second yoke member and disposed to face said first abutting means in opposing relationship, said first and second abutting means being spaced from each other during movement of the second yoke member through said initial distance, and means for opposing said limit means to permit said first yoke member to move upwardly beyond said first distance and to cause said first and second abutting means to interengage, additional upward movement of the second yoke member by the first yoke member through said interengaged first and second abutting means actuating said pair of tongs to a subsequent gripping position.

References Cited in the file of this patent UNITED STATES PATENTS 2,302,631 Hively Nov. 17, 1942 2,009,219 Harry Nov. 21, 1961 FOREIGN PATENTS 1,092,773 France Nov. 10, 1954

Images