US1674967A - Crane - Google Patents

Description

B. F. FITCH CRANE Filed March 30, 1925 7 Sheets-Sheet l W'MM'A a/J 79 b 1 June 26, 1928.

B. F. FITCH CRANE 7 Sheets-Sheet 2 Filed March 50, 1925 June 26, 1928. 1,674,967

I B. F. FITCH CRANE Filed March 50, 1925 7 Sheets-Sheet 3 FTC.- 4

June 26, 1928., 1,674,967

B. F. FITCH CRANE Filed March so, 1925 7 Sheets-Sheet 4 FIG. J

June 26, 1928.

B. F. FITCH CRANE Filed March 50, 1925 v 7 Sheets-Sheet 5 FIGJV FBG. 9

atfotucv z o t M u w 3 uFume 26, 1928 1,674,967

B. F. FITCH CRANE Filed March 50, 1925 7 Sheets-Sheet 6 Fm.- H

FIG.- 12.

. 1,674,967 B. F. FITCH CRANE 7 Sheets-Sheet 7 HM) M m d G M v M- w I W 4% I Q a L T- F e F 10M Mme v t A F a w) 1 June 26, 1928.

Filed March 30, 1925 Patented June 26, 11928.

. unrr BENJAMIN F. FITCH, OF GREENWICH, CONNECTICUT, ASSIGNOR T0 MOTOR TERMINALS COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

CRANE.

Application filed March 30, 1925.

This invention relates to hoisting and conveying, apparatus and is particularly concerned with the provision of a crane adapted to travel on overhead tracks. Such a crane is especially adapted for use in a system for handling freight wherein freight is stored in removable automobile bodies or containers.

In handling freight by such a system, it is desirable to adapt the apparatus to existing conditions without requiring extensive changes to be made in the structure of warehouses. platforms or runways adjacent thereto. The size of a removable container which has been found to give the most satisfactory results for handling freight is such, however, that the average warehouse or freight station is not constructed to receive a standard crane and to admit the container. Accordingly, extensive altering and shoring must be resorted to in order to strengthen the structures and to render them safe for handling loaded containers by means of an overhead crane. An additional characteristic frequent in existing structures is the lowshead room, which greatly hinder-s the use of standard size cranes.

A further problem which arises in the handling of freight by the use of removable automobile bodies as containers is the difficulty of positioning a motor vehicle'at right angles to a station platform. This difficulty arises on account of the fact that the street adjacent a platform is frequently very narrow and that the motor vehicles employed for conveying freight are too long to permit the normal flow of traffic along the street if the vehicles are disposed at right angles tothe platform. In order. therefore, to permit the handling of heavy loaded containcl's, it is desirable to use electrically operated overhead cranes which may raise a load. turn it and then transport it from one place to another. The size and weight of the containers. however, present a serlous problem in the designing of a crane which will have sufficient power to raise the load,

and to permit the turning thereof without making important and extensive changes in the construction of the building.

One of the objects of the present invention therefore, is the provision of a crane which while possessinga minimum depth still has sufficientpower to raise a loaded Serial No. 19,280.

along an overhead trackway. Further objects are to materially shorten the span required to support such an overhead crane, yet to permit the turning of the load through a complete revolution.-

To overcome the necessity for a skilled crane operator, I propose to provide means for automatically controlling the extent of travel of the hoisting mechanism so as to minimize the changes incident to the operation of such a crane. Moreover, I propose to so arrange the load receiving device, that the crane,'when once adjusted for a given location and a given sized container, functions automatically during the raising operation to engage a load, and during the low ering operation to release the load at the the part of the operator.

To carry out the above objects; I employ a crane which has a. main frame movable along an overhead trackway. The main frame carries a supplemental frame which embodies a turntable having hoisting mechanism mounted thereon. To permit the crane to have a minimum depth, the supplemental frame is disposed within planes which define the upper and lower surfaces of the main frame. The load engaging device as illustrated comprises a cradle which is adapted to extend over and engage the sides of a body. Suitable mechanism is provided for enabling the sides of the cradle to move inwardly for engaging the container during the upward movement of the cradle By arranging adjustable stop devices, the mechanism may be set to engage a given load automatically without requiring the services of a workman to effect engagement of the cradle with the container at the proper time. In

addition, I provide mechanism including ad services of the skilled crane operator may be may be accomplished in a minimum period of time.

The preferred means for carrying out my invention is illustrated in the drawings wherein Fig. 1 is a plan view of a crane embodying my invention; Fig. 2 is a vertical section taken longitudinally through the crane as illustrated by the line 22 in Fig. 1; Fig. 3 is an end view of the crane; Figs. 4 and 5 are sections taken on an enlarged scale along planes indicated by the lines 44 and 55 respectively in Fig. 1; Fig. 6 is a section taken on a plane indicated by the line 66 in Fig. 5 and showing some of the mechanism for actuating the crane; Figs. 7 and 8 are sections taken on an enlarged scale through planes indicated by the lines 77 and 8-8 respectively in Fig. 1;Fig. 9 is a section taken on a plane indicated by the line 9-9 in Fig. 8; Figs. 10, 11 and 12 are horizontal sections through a part of the automatic cradle operating mechanism illustrating three different positions of such-mechanism; and Figs. 13 to 16 inclusive are diagrams showin the electrical arrangement for effecting t e automatic control of the hoisting mechanism.

In Figs. 1 and 2 the crane embodying my invention is illustrated as supported upon overhead tracks 10 and 11 which are carried on columns 12 and 13 respectively. The crane embodies a main frame indicated in general at 15 and a supplemental frame indicated in general at 16 which is carried by the main frame and is arranged to be rotated through a complete revolution with reference thereto. Wheels 17 and 18' journaled in the" main frame, are arranged to travel on the tracks 10 and 11 respectively. These wheels as shown are slightly lessin diameter than the depth of the main frame. The main frame may have longitudinal beams 20' which are connected at the ends by transverse beams 21 and 22 respectively. The end members are arranged in pairs so as to support the wheels in a conventional manner.

To support the supplemental frame within the main frame, I have shown a plurality of spaced rollers 25, which are mounted radially and are arranged to engage the underside of the supplemental frame adjacent the periphery thereof. As shown in Fig. 7 each roller is supported upon an inwardly extending bracket comprising a horizontally disposed plate 26 and an inclined plate 27 which are rigidly secured to the frame work of the main frame.

The supplemental frame as shown embodies a circular frame having a periphery comprising an inwardly facing channel-shaped beam 30, the lower flange of which rests upon the rollers 25. The supplementalframe carries the hoisting mechanism which prefserene? erably includes a screw and nut couple as illustrated by a threaded shaft 32 and a nut 33. The nut is arranged to travel along the shaft whenever the shaft is rotated. The means for rotating the shaft is shown more particularly in Fig. 4 as embodying an electric motor 35 which drives a shaft 36 through the medium of gears 37 and 38. A worm 39 on the shaft 36 meshes with a worm wheel 40 which is rigidly secured to a shaft 41. A coupling 42 indicated in general in Fig. 1 may then connect the shaft 11 with the threaded shaft 32. In Fig. 4 thrust bearings 13 and 4 1 are shown associated with the worm 39.

To effect engagement with a load I have shown a cradle in the nature of a foldable frame comprising longitudinal bars 50 and transverse end/ bars 51. As shown in Fig. 3 the end bars are hinged at 52 adjacent the mid-portion of the frame so that vertical movement of the hinge portion will cause the longitudinal bars to move either inwardly or outwardly with reference to a load. The cradle is indicated as being supported by four cables 55, each of which has one end thereof attached to the nut 33, wherefore the cables are simultaneously operated to raise or lower a load. Horizontally disposed guide sheaves 56 at one end of the frame and vertically disposed guide sheaves 57 function to lead the cables out wardly and then downwardly with respect to the supplemental frame.

To rotate the supplemental frame with reference to the main frame, I have shown the supplemental frame as having an annular rack 60 which isarranged to be engaged by a pinion 61 on a shaft 62. A motor 63, shown more particularly in Fig. 6 may be used for selectively actuating the shaft 62 to rotate the supplemental frame or to rotate one of the wheels 17 for propelling the frame along the overhead trackway. I

The mechanism illustrated in Figs. 5 and 6 embodies a worm 65 on the armature shaft 64 for actuating a worm wheel 66 on a shaft 67. Thrust bearings 68 adjacent the worm, and thrust bearings 69 adjacent the worm wheel function to absorb working stresses in the usual manner.. One'end of shaft 67 carries one member 70 of a clutch which is adapted to engage a coacting member 71 for effecting rotation of shaft 72, and through the medium of the double gears 73 and 74, for effecting rotation of the pinion 61. The opposite end of the shaft 67 is indicated as having a clutch member 75 which is arranged to engage a coasting member 76 for effecting rotation of shaft 77.. Bevel gears 78 and 79 function to transmit rotation of shaft 77 to shaft 80, while pinions 81 and 82 at opposite ends of the shaft mesh with gears 83 and 84 respectively, for eifecting simultaneous operation of one traction wheel 17' and one traction wheel 18 on the I tracks and 11 respectively.

To edect movement of the crane along the overhead trackway, I have shown a slide 85 which is slidably mounted on a bearing block 86 and which carries shipper levers 87 and 88 respectively. A flexible member 89 may have the ends thereof attached to the shipper rod and may extend downwardly so as to be accessible beneath the crane. If the operator desires to move the main frame along the overhead traekway, the slide is moved to effect engagement of the clutch members 75 and 76 whereupon a direct connection is made between the armature shaft of the motor 63 and the traction wheels on the main frame. If it is desired to rotate the supplemental frame, then the slide is moved to effect engagement between the clutch members 70 and 71 whereupon the pinion 61 isicaused to rotate. The shipper levers 87 and 88 alerigidly mounted upon the slide in such manner that when one of the clutches is connected with the motor, the other clutch is disconnect-ed from the motor. Thus the supplemental -frame can be turned only while the main frame is stationary, while the main frame can be propelled along the trackway only when the supplemental frame is stationary.

One of the operations which has required considerable time in the handling of freight by removable containers is the positioning of the load engaging elements so as to efiect simultaneous engagement with the load at four points. If individually actuated members are used, the workmen must hold the members in contact with the load while the cables are being raised. This not only requires considerable skill to avoid injury, but also necessitates the presence of the workmen each time a load is engaged and hence adds materially to the cost of handling the freight.

I propose to obviate the necessity for workmen being present to assist in positioning the load engaging elements and to this end I have devised automatic mechanism which may be adjusted for enabling a container to be automatically engaged during the hoisting operation and to be automatically released when a load is deposited at the proper level. Moreover, I provide safety features which will prevent the load from being released before it is deposited on the support, as will be hereinafter set forth.

I accomplish the automatic load engaging feature by employing a cradle which is sufficiently large to extend around the container as indicated in Figs. 2 and 3. By employing weighted arms 51' hinged at 52 when the cradle is suspended by the cables 55, the normal tendency of the weight is to move the cradle to the position shown by the gage the load. Such engagement can be effected only when the hinge of the end barsof the cradle is raised vertically so as to bring the books on the cradle into the position shown by the full lines in Fig. 3, where they may engage downwardly facing members 91 on a load indicated at 92.

'The vertical shifting of the hinge connection may be accomplished by the use of cables 93, the lower ends of which are attached to the cradle, adjacent the hinge connection and the upper ends of which are arranged to be actuated whenever the nut 33 is in a predetermined position on the shaft 32. The mechanism employed to carry out this motion is shown more specifically in Figs. 8 to 12, wherein the cables 93 are attached to an arm 94 which is pivotally mounted as at 95 to an adjustable bracket 96. The bracket may be longitudinally positioned with reference to the shaft 32 by a set screw 97 which engages a lower flange of a guide beam 98. The position of the bracket 96 with reference to the guide beam is dependent upon the size of the con- 100 is pivotally mounted at 101 to the hub portion at the arm 94, and has a rounded shoulder 102 which permits it to be swung in one direction with reference to the arm 94. A squared shoulder 103, however, limits the swing of the latch in the opposite dircction with reference to the arm. It results from this arrangement that the pin 99 may move in one driection and engage the latch 100 without actuating the arm 94, but cannot move in the opposite direction without doing so.

The automatic operation of the cables 93 may best be illustrated by reference to Figs. 10, 11 and 12 which show various positions of the pin 99 with reference to the pivotal connection 95. For example, in Fig. 10, the pin is shown as about to engage the latch 100 and is traveling in a direction indicated by the arrow. It will be noted that the arm. and latch are positioned at right angles to the path of travel of the pin. This is the normal position of the arm and latch. since a spring 104 tends to hold the arm in enga'gement with a stop 105 while a spring 106 tends to hold the latch in the position shown in Fig. 10.' While the arm is in the position indicated in Fig. 10, thenthe cradle is in the position shown by the broken lines 51 in Fig. 3. In other words, thecradle is .in extended position.

Now as the nut is advanced along the screw 32 to raise the cradle, then the pin 99" engages the latch and swings it together with the arm 94, as shown in Fig. 11, about the pivotal connection 95. As a result, the cables 93 are raised at a faster rate than the cables 55. This is evident from an inspection of Fig. 11 wherein the cables 55 are raised at a rate equal to the speed of the pin, while the cables 93 are raised at a rate equal to the speed at which the end 110 of the arm 94: is caused to travel. Y

The length of the cables 55 is so determined that when the pin is about to engage the latch during the raising movement, the cradle is in extended position with the hooks 49 slightly beneath the shoulders or hooks 91 on the load. Moreover, the cables 93 are so adjusted that they are taut just as the pin is about to engage the latch. Accordingly, as the latch is engaged, the load engaging hooks on the cradle move upwardly and inwardly simultaneously to effect an automatic connection with the load.

After the load is engaged and the weight thereof is assumed by the cables 55, and if the .pin 99 has not as yet cleared the end of the latch, then the spring 111 associated with the cables 93 will be extended so as to prevent such cables from breaking. As soon as the pin has cleared the latch, then spring 104 tends to return the arm and latch to the original position, at right angles to the shaft 32. In addition the weight of the springs 111, as well as the tension exerted thereby, assist to return the arm to the original position. As heretofore stated, the stop 105 functions to maintain the arm at right angles to the shaft 32. Thereafter continued movements of the nut along the shaft causes the load to be raised while the cables 93 are slackened as shown in Fig. 2.

Assuming now that the load is to be deposited upon a truck or upon a station plat- -form, then the nut is moved in the opposite direction so that the pin 99 engages the edge 112 of the latch. The rounded shoulder 102 permits the latch to be moved with the pin as shown in Fig.\12 and with reference to the arm, without causing the arm to swing about the pivotal connection 95.

As a result of thearrangement described the loadengaging hooks 011 the cradle are relieved of the load before the slack is taken out of-the cables 93. Accordingly, as soon as the load is supported by the stationed platform, an automobile truck or other support, the weight at the hinged connection of the cradle causes the connection to drop suddenly, so as to spread the cradle into the position shown by the broken lines 51' in Fig. 3. The impact of such downward movement is assumed by the springs 111.

As the nut is moved during the lowering operation so that the pin 99 clears the latch, then to prevent the cradle from closing during the succeeding raising movement, I have shown a cable 113 which is adapted to be manually actuated, and which may be employed to swing the latch about the pivotal connection 101 independently of the pin 99. Then on the next hoisting movement of the nut the cradle may be raised without engaging a load. This is useful whenever it is desired to deposit a load and then to raise the cradle for enabling the crane to be shifted to another position.

To obviate the necessity for employing a skilled crane operator. I employ an electrical control system including adjustable cut-out switches for limiting the vertical movement of the cradle in either direction. To carry out this plan I have shown in Figs. 13 to 16, wiring diagrams wherein the electric motor 35 is shown at M and is a reversible type of motor. In Fig. 13 for instance the nut 33 is about to travel back after reaching one end of the travel in one direction. In such position the cut-out limit switch 151 has been opened by the nut just as the end of the stroke was reached. A similar limit switch 152 is adapted to be engaged by the nut when it reaches the opposite end of the stroke. These limit switches may each have a spring associated therewith as indicated at 153 and 154. respectively, so as normally to close the switch when the nut is out of contact therewith.

The source of current for operating the motor is indicated at S, while a hand controller having two positions is indicated as having a set of stationary contact fingers 1 to 6 inclusive and two sets of movable contact plates, which are so arranged that when one set is in engagement with some of the stationary contact fingers, the other set is out of engagement with all of the contact fingers. In Figs. 13 to 15, one set of movable contact plates is illustrated at 7. 8 and 9,,

while Fig. 16 the other set of plates is indicated at 160 to 163. inclusive.

Referring now to Fig. 13 the current flow is as follows :-Source of power S line 170, contact 8, where the current divides. part flowing through contact 4. .line 171 to energize the field 172. thence line 173. contact 3, contact 7, line 174 and back to the source of power. The rest of the current which is divided at contact 8 flows through contact 5. line 175, switch 152. line 176, armature motor M. line 177, contact'fi, contact 9. line 178, and thence back through 'line 174 to the source of power.

The result of this arrangement is that the motoris energized to drive the hoisting aerate? mechanism in such manner that the nut 32 is caused to travel along the supplemental frame in the raising direction until it engages the limit switch 152 and to then interrupt the Current flowing therethrough.

This automatically stops the motor.

In Fig. 14, the current is shown as flowing through the connections illustrated in Fig. 13, while the nut is approximately midway between the two limit switches. In Fig. 15 the nut has reached the end of the stroke and has broken the connection to the motor through the switch 152. In this figure the position of the controller is the same as that shown in Figs. 13 and 14, wherefore, the direction of motor rotation cannot be reversed, even though the switch 151 is closed until the controller position is changed.

In Fig. 16 the controller osition is changed so as to reverse the direction of motor rotation, even though the switch 152 is open. The current flow as shown by the connection in Fig. 16 is as follows: source of power S, line 180, where the current divides, part flowing through contact plate 163 to energize the field winding, a'part flowing through contact 161 to energize the armature winding. The current for energiz' ing the field winding flows through contact finger 4, then through line 171, field windings 172, line 173, contact. 3, cont-act 162, 1ines 181 and 182 and back to the source of power. The current flowing through the armature windings passes through contact 161, contact 2, line 183, switch 151, line 184, motor armature, line 185, contact 1, contact 160, line 182 back to the source of power.

An inspection of the arrows and comparison of Figs. 13 and 16 will show that the direction of current flowing through the field winding remains the same while the direction of current flowing through the armature winding is reversed, whenever the controller is moved from the position shown in Fig. 13 to the position shown in Fi 16.

The result of the arrangement of win ings and connections as illustrated in Fig.16 is such that the nut may continue to travel until it engages the limit switch 151 and interrupts the flow of current to the armature winding.

Assuming that a motor vehicle having a loaded body is brou ht to a station p atform, then the main flame is caused to travel along the overhead trackway until it is disposed 'over, the load, thereupon, the supplemental frame is turned if required with reference to the main frame until the cradle is in such position that when the hoistin cables are lowered, the cradle will extend around the load. The downward movement of the cradle is efiectedby placing the controller or resetting devices to the position shown in Fig. 16. The position of the switch 151 with reference to the main frame is previously so determined that the lowering operation is automatically stopped when the hooks 49 on the cradle are beneath the hooks or shoulders 91 on the load. Now to engage the load, all that the operator need do is to change the position of the controller to that shown in Fig. 13, thereupon the motor 35 is caused to be rotated to raise the cradle. As heretofore explained, the cradle is in extended position when in the lowermost position while the nut is so positioned on the shaft 32 that the pin 99 carried by the nut is disposed on the side of the latch 100 engaged in Fig. 10. Accordingly, as soon as the pin engages the latch, the arm 94 is caused to move simultaneously with the latch, as shown in Fig. 11. This motion continues until the pin clears the end of the latch, whereupon the spring 104 tends to return the arm and latch to the original position. As the arm 94 is moved into the position shown in Fig. 11, the cables 93 which are attached to the arm are moved at a faster rate than the cables 55, whereupon the cradle is buckled inwardly to effect automatic engagement with the load.

Continued motion of the hoisting mechanism places the load upon the lifting cables 55, which prevents the cradle from opening and allows the cables 93 to become slackened as shown in Fig. 2. The raising motion is continued until the nut engages the limit switch 152 as indicated in Fig. 15. This interrupts the flow of current through the motor and stops the raising motion. The main frame may then be trolleyed along the trackway until the location is reached for depositing the load.

After the main frame has reached the desired location, then if necessary the shipper rod 85 is moved to effect an operative connection between the motor 63 and the rack I on the turntable, whereby the load may be turned to the desired position. Thereafter, the controller is actuated to bring the contacts into the position shown in Fig. 16 and the load is lowered until the nut engages the limit switch 151. Before such limit switch is reached, however, the load engaging hooks on the cradle will have been released from the hooks on the load and the cradle will have opened automatically to the extended position as shown by the broken lines. 51 in Fig. 3. Preferably the position of the limit switch 151 is such that the hoisting motor is stopped shortl after the cradle is released from the loa If it is now desired to raise the cradle and to transport the crane to another location without raising the load, then the controller is moved back to the position shown in Fig. 13 and the cable 133 is drawn taut so as to bring the latch 100 out of the path of the pin 99. The latch is, so held until the pin has passed beyond the normal position of the latch, wherefore the cradle is raised while maintained in extended position. This revents the automatic engagement of the oad.

This arrangement of electrical connections just described permits the limit switches to be adjusted upon the supplemental frame so as to be engaged by the nut at predetermined points in thepath of travel. Obviously, the position of such limit switches is determined by the height of the lift de sired, and the distance of the load from the supplemental frame when such load is depositedupon' a support. Moreover the controller may be suspended from the crane and may have actuating member, such as acable,

- extending downwardly within reach of an operator, to permit the control to be shifted from one position to another in an expeditious manner. After the controller is once actuated, however, it'need not be shifted until the limit switch is actuated to stop the motor automatically at the desired point.

The automatic feature embodying the electrical control combined with the automatic gripping and releasing feature of the load engaging device, provides a crane which may be easily operated and which eliminates the danger which is largely incident to the personal element in the operation thereof. Moreover, a crane construct ed in accordance with my invention has a low overall depth which enables it to be installed in buildings of low height, yet permits a load to be engaged, raised and turned and transported from one position to another. This permits the use of the crane in connection with station platforms along narrow streets, without requiring an automobile truck to stand at right angles to the station platform.

The claims in the present application are confined to a load engaging device per se and the combination of a load engaging de vice with a crane. Claims on the electric crane structure shown are in m divisional application, Serial No. 85,877 led F ebruary 4, 1926; claimson the power stop per se, and on the power stop in combinationwith a hoist, Serial No. 85,878 filed February I claim 1. In a crane, the combination with a frame, of a load. engaging cradle depending therefrom, mechanism for raising the cradle and means for automatically actuating the cradle to buckle it inwardly for engaging a load during the raising movement.

2. In a crane, the combination with 'a frame, of a collapsible load engaging cradle carried thereby and movable relatively thereto, and means for automatically manipulating the cradle during the raising or ewes? lowering movement to engage or release a frame of flexible members depending therefrom, a. cradle carried by the members and arranged to extend around a load, means for raising said members, and mechanism placed in operative condition by movement of said means for controlling the raising movement to effect automatic engagement of the load.

4. In a crane, the combination with a frame, of a cradle, hinged intermediately and depending from the frame, and means associated with the frame for automatically moving one portion of the cradle at a faster rate than another portion, whereby the cradle is caused toengage a load during the raising movement thereof.

5. In a crane, the combination with a frame, of flexible members depending therefrom, means associated with the lower end of said members for engaging a load, and mechanism on the frame for actuating said means and for effecting automatic engagementwith a load during the raising move ment of said members.

6. In a crane, the combination with a frame, of cables depending therefrom and spaced apart, means on the frame for winding in or paying out said cables, a hinged cradle having load engaging hooks carried by the cables adjacent the lower end thereof, and mechanism on the frame for moving the hooks simultaneously inwardly and upwardly to effect automatic engagement with a load while the cables are being wound in.

7. In a crane, the combination with a plurality of cables depending therefrom, means carried by the cables for engaging a load, and mechanism associated with the frame for automatically moving some of said cables faster than other of said cables, whereby said means is caused automatically to engage a load when the cables are raised.

8. In a crane, the combination with a frame, of cables'depending therefrom, means carried by the cables for engaging a load,

and mechanism on the frame for automatically moving some of the cables simultaneously with the remaining cables and then at a different rate, during a part of the raising movement, whereby said means is caused to engage the load.

In a crane, the combination with a frame, of a screw and nut couple mounted thereon," means for rotating one member of said couple, and means actuated by movement of one of said members for effecting automatic engagement of a load.

10. In a crane, the combination with a frame, of a screw and nut couple mounted thereon, four load lifting cables attached to said nut, means for rotating the screw to advance the nut along the frame, a foldable aerate load engaging cradle carried b said cradles,

an arm mounted to swing wit reference to said frame and having a cable attached thereto for buckling the cradle when the arm is swungin one direction, means associated with the arm and adapted to be moved by said nut when the nut is moved in one direction, said means functioning to effect simultaneous 'movement of the arm, whereby the buckling cables move at a faster rate-than the load cable to cause automatic engagement of the cradle with the load, and said means functioning to permit the arm to remain idle when the nut is moved in the opposite direction.

11. The combination with a frame, of a screw and nut coup-1e mounted thereon, means for rotating one member of said couple, cables attached to the other member of'sa-id couple, sheaves for directing said cables outwardly and downwardly with reference to the couple, a load engaging member carried by said cables, and means actuated by one member of the couple and operativelyconnected to the loadengaging member for causing said member to automatically engage a load, and to suspend it during the raising movement of said cables.

12. In a crane, the combination with a frame, of a screw and nut couple mounted thereon, means for rotating one member of saidcouple, a foldable load engaging cradle operatively connected to the other member of said couple, and means actuated by said last mentioned member for actuating the cradle to cause automatic engagement of "a load during the hoisting operation.

13. In a crane, the combination with a frame, of a plurality of load lifting cables depending therefrom, a load engaging foldable cradle carried by said cables, a screw and nut couple on said frame for actuating said cables simultaneously, a buckling cable having one end attached to the cradle, and a shift device mounted on the frame and attached to the other end of said buckling cable, said device being actuated by one member of said couple to buckle the cradle.

14:. In a crane, the combination with a frame, of a screw and nut couple mounted thereon, means for rotating one member of said couple, cables attached to the other member of said couple, a cradle carried by said cables, and means interposed in the path of said last mentioned member for buckling the cradle at a predetermined time whereby the cradle may be caused toengage a load automatically during the hoisting operation.

15. In a crane, the combination with a frame, of a screw and nut couple carried therebyfmeans for rotating the screw member of said couple whereby the nut is caused to travel along said frame, a plurality of cables attached to the nut member of the couple, a cradle carried by said cables, a lever pivotally mounted on the frame and adapted to be actuated by said' nut during a portion of the stroke, and means actuated by said lever for bucklin the cradle and for causing it to grip: a loaduring the hoisting operation. a

16. In a crane, the combination with a frame, of a plurality of cables carried thereby, a load engaging cradle carried by the cables, a slide having an arm pivotally mounted thereon, said slide being adjustably positioned on said frame, means for raising and lowering said cables, said means being adaptedto actuate said arm during the cable raising operation, and said arm being operatively connected with the cradle for causing the cradle to automaticall grip a load. In testimony whereof, I ereunto afiix my signature.

. BENJAMIN F. FITCH.

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