US2898083A

US2898083A - Hoist with chain takeup

Info

Publication number: US2898083A
Application number: US619461A
Authority: US
Inventors: Elmer R Kresl
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-10-31
Filing date: 1956-10-31
Publication date: 1959-08-04
Anticipated expiration: 1976-08-04

Description

Aug. 4, 1959 E. R. KRESL HOIST wrm cam: TAKEUP 2 Sheets-Sheet 1 Filed Oct. 31, 1956 i a fi Q M M ii mr i i N w. d \FW 1 F M \M/HLS W I i w m 1 W w 1%,

Aug. 1959 E. R. KRESL 2,898,083

HOIST WITH CHAIN TAKEUP Filed Oct. 31, 1956 2 Sheets-Sheet 2 s figgzzerfa i 32225 m 45 4M1 2,898,083 Patented Aug. 4, 1959 HOIST WITH CHAIN TAKEUP Elmer R. Kresl, Warrenville, Ill.

Application October 31, 1956, Serial No. 619,461

4 Claims. (01. 254-173 This invention pertains to a hoist with chain takeup, the hoist being more particularly of the portable type in which a roller chain is entrained over a drive sprocket from an electric motor reducer, the end of the chain on one side of the sprocket being referred to as the load engaging end, and the other end of the chain, on the other side of the sprocket, being referred to as the tail end, which later it is desirable to take up or retrieve during upward movement of the load engaging end.

An important object of the present invention is the provision of improved means for taking up the tail end of the chain as the load engaging end of the chain is drawn up by the motor reducer, such means being contrived to dispose the tail end of the chain in orderly and compact form so as to prevent interference by the chain with other objects and also to prevent jamming or kinking of the chain when the load engaging end is descend- 111g.

A further object of the invention is the provision of yieldable means responsive to the slack in the chain between the drive sprocket and the first mentioned takeup means to shut off the current to the motor when the chain is fully payed out to prevent breakage.

These and other objects and advantages will be apparent from the following description, taken together with the accompanying drawings, of an illustrative embodiment of the invention, and in which drawings Figure 1 isa side elevational view of an electric hoist with the present invention applied thereto;

Figure 2 is a fragmentary section taken on the line 22 of Fig. 1;

Figure 3 is a view of the structure of Fig. 1 looking at the right-hand side of the latter, but showing the chain further payedout;

Figure 4 is an enlarged fragmentary vertical section taken on the line 44 of Fig. 3;

Figure 5 is an axial section still further enlarged of the spring barrel, taken on the line 5-5 of Fig. 4; and

Figure 6 is an axial section of the drum and spring barrel on a smaller scale than Fig. 5 and omitting the chain and other parts for clearness of description.

Referring in detail to the illustrative construction shown in the drawings, the numeral 11 indicates a frame of a portable electric hoist of the type herein referred to, which may be suspended from any suitable support by an overhead hook 12 swivelly connected to the frame 11. The frame 11 carries a motor housing 13 on one side thereof and a reduction gear casing 14 on the other side, the drive sprocket 15 being located between the housing and the casing and adapted to be driven by the mechanism thereof for raising or lowering the load engaging end 16 of a roller chain 17, the chain end 16 terminating at its lower end in a load engaging hook 18. The chainend 16, below the sprocket 15, may pass in front of gear case 19 and the two spaced parallel members of a double ended control lever 20 that is intermediately pivoted at 21 on a hanger depending from the frame 11 which may be a part of chain stripper 22. The

nitedStates Patent O fice control lever 20 is manually operable by having connected with its ends pull cords 23 and 24 respectively for moving the control lever to one of two extreme positions to place the motor in circuit and to an intermediate position to discontinue the current thereto, the pull cord 23 in this instance being pulled upon, as indicated, to move the left-hand end of the control lever downwardly to cause upward or hoisting movement of the chain end 16 and the pull cord 24 being arranged to pull the right-hand end of the control lever downwardly to cause downward movement of the chain end 16. The horizontal position of control lever 20 is the neutral position shutting off current to the motor. It will be understood that a suitable switch mechanism (not shown) will be carried, for example, within case 19 or attached thereto for actuation by control lever 20 and linkage 2017 as need not be further described.

Turning now to the expedients of the present invention, and by way of example with one typical hoist structure, there is here shown, carried on frame 11, and pivoted at 25 thereon, yoke arms 26 and 2611 between which is arbored, on spindle 27, a relatively large drum 28 having the

side walls

29 and 29a through which the spindle 27 (Fig. 5) passes, the drum being rotatable on the spindle. Welded, as at 27b, or otherwise permanently affixed to each end of the spindle 27 is a threaded nut 27a which fits into a correspondingly broached hole in each of the yoke arms. Large headed screws 30 threaded in the nuts 27a retain the spindle and yoke structures in assembled position. Bushings 42 may be provided in hub bores 40 and 41 for bearing purposes. As shown, clearance is provided at the hub of the drum so it can turn freely on spindle 27. Flexible elements such as chains 31 are fastened at their upper ends 32 to a clevis 33 surrounding the hook 12 and at their other ends 34 to the

yoke arms

26 and 26a to support the drum 28 with respect to the hoist so that the drum is capable of swinging upwardly in the event that it is struck by an ascending load carried by the hook 18, thus avoiding damage to the drum.

Following the present invention, the drum 28 includes a spring barrel 35 that functions somewhat like a window shade roller and comprises coil spring 36 that is anchored, as by means of one or more screws 44, at one end 37 to the spindle 27, and at its other end 38 is anchored to the rotatable barrel 35 as by means of a bolt 45 passing through a hole 43. It will be understood that the barrel 35 and drum walls 29-29a rotate as a unit, wall 29a being welded to barrel 35, as at 39 (Fig. 6), and wall 29 being secured to the barrel by means of a flange or ears 35a (Fig. 5), carried by the barrel, and bolts 39a. As stated above, the drum assembly is free to rotate on spindle 27. a

The spring 36 is desirably of the coiled band type, as best seen in Figs. 4 and 5, its outer end 38 being anchored to rotate with the drum structure, its inner end being stationary with spindle 27.

As best seen in Fig. 4, terminal link 46 of the tail end 47 of the roller chain 17 is resiliently connected to the barrel 35 as by being fixed to one end 48 of a spiral spring 49 the other end 50 of which is bent into the form of a hook or loop and fastened to the outside of barrel 35 by means of bolt 45.

It will be understood that the chain 17 is wound around the barrel 35 between the walls of the drum 28 in a plurality of convolutions (that may be more numerous for example than shown in Figs. 3 and 4). In assemblying the chain takeup device with the hoist structure, the drum is rotated in a direction to wind up the spring 36 prior to attachment of the hoist chain 17 to the drum and suificiently to maintain a takeup pull on the chain even when all available chain is wound upon the drum, after which link 46 of the chain is attached to spiral spring 49 and the drum released to wind all slack chain upon the drum. Then, in operation of the hoist, when the chain is payed out, as by the lowering of the hook 18, the drum and barrel are rotated counterclockwise (Fig. 4) thereby winding the spring 36. When the load hook 18 rises, the tail end of the chain is wound upon the drum by clockwise rotation of the drum and spring barrel, driven in clockwise direction by spring 36, thus retrieving what would otherwise be slack chain.

Normally, in this rotation of the drum and spring barrel, the spiral spring 49, connecting the end of the chain to the barrel of the drum, is inactive, but in the event that the chain is fully payed out as by lowering a load without manually stopping the hoist before the lowermost position of the load hook is reached, spring 49 then provides a resilient connection between the chain and the barrel that guards against breakage. Breakage is further prevented by the safety stop device indicated generally by the numeral 51. This comprises, in this instance a bell crank lever 52 intermediately pivoted at 53 on a triangulated sub-frame 54 depending integrally from the yoke arm 26 of the drum. One end 55, that is, the outer end, of the bell crank lever 52 is normally retracted upwardly by a relatively heavy spiral tension spring 56 that is hooked as at 57 at one end to stud 57a on the lever end 55 and at its other end is hooked as at 58 to stud y on the outer end of the yoke arm 26 that extends beyond the pivot 27 of the drum. Alternatively, the spring may be hooked into holes provided at the ends of

members

55 and 26. The other or inner end 60 of the bell crank lever 52 carries an idler roller 62 on a spindle 61. That portion of the tail end 47 of the chain 17 be tween the drive sprocket 15 and the drum 28 passes first downwardly and then upwardly around the idler roller 62, guided by a pair of chain guides 60a. The spring 56, by pulling up on the outer end 55 of the bell crank lever 52, urges its end 60 carrying the idler roller 62 downwardly to maintain a predetermined amount of a slack in the tail end of the chain between the drive sprocket and the drum to permit unobstructed movement of control lever 20 except when necessary to function to stop the hoist. The amount of slack is determined by the position of a stop stud 63 projecting laterally from the frame element- 54 spaced from the bell crank lever pivot 53.

The safety takeup device 51 comes into play when the chain 17 is payed out from the drum by lowering of the hoist load to an extent such that the spring 49 anchoring the chain to the drum begins to stretch as a result of the pull of the chain, this tension in the chain pulling upwardly on the idler roller 62 against the pull of the spring 56 connecting the other end of the bell crank lever to the yoke arm. Assuming the sprocket 15 is still rotating in a direction to lower the load, i.e., counterclockwise, the chain portion around the idler roller 62 raises the roller, bringing it into contact with cross pin 20a (Fig. 2) connecting the two control levers 20 and moving the lever 20 to bring the latter into the horizontal position, that is, from the position shown in full lines in Fig. l, which is the lowering position to the position shown in broken lines which is the stop position. The circuit to the motor is thus broken, bringing the movement of the chain to a stop. This happens practically instantaneously so that there is no overrun of the sprocket which would tend to carry the right-hand end of the control lever 20 farther upwardly to the hoist position.

It will be understood that clearance is provided between the idler roller and cross pin 20a, as shown in the drawings, to prevent interference with the normal manual control of the hoist switching mechanism. Contact between roller and cross pin is made only when the safety shut-off mechanism 51 is operating.

After the motor is stopped to prevent breakage of the equipment, the control lever 20 may be actuated to the hoist position (not indicated) by pulling upon the cord 23 and the hoist again put to normal use. As the tension on the spring 49 is relieved, the spiral tension spring 56, which is stronger than the barrel spring 36, again lowers the idler roller end of the bell crank lever 60 to the position shown in full lines in Fig. 1 out of the way of the control lever assembly.

It will be understood that the sprocket 15 is self-locking in the sense that the sprocket can move the chain but the chain cannot rotate the sprocket.

The invention is not intended to be limited to details of construction shown for purposes of illustration, and, furthermore, it may not be essential in all aspects of the invention to use all features thereof conjointly since various combinations and sub-combinations may at times be advantageously employed. Such changes may be made as fall within the scope of the appended claims Without departing from the invention.

What is here claimed is:

1. A hoist with chain takeup, comprising, an electric current operated motor mounted in the hoist, a frame carried by the hoist, a chain winding drum supported by said frame, said drum including retractable spring barrel mechanism urging the drum in rotation, a chain windable on said drum, the walls of said drum being spaced apart to guide the chain in a single spiral thereonto, means for anchoring one end of the chain on the spring barrel, the other end of the chain being trained over a hoisting sprocket on the hoist, said sprocket being drivingly connected to said motor, a spring urged idler takeup roller interposed between the hoist sprocket and said drum under which the chain is trained in a reverse bight, said roller being movable upwardly by action of the chain when the tension in the portion thereof between the sprocket and the anchored end thereof exceeds a predetermined magnitude, and means actuated by said upward movement of the roller to shut off the electric current to the motor, the arrangement being such that when said other end of the chain moves upwardly the tail end of the chain is wound on said drum by the action of said spring barrel mechanism, said spring barrel mechanism being wound up when said other end of the chain is moved downwardly rotating the drum in a direction counter to that in which the drum is urged by the spring barrel mechanism.

2. The structure of claim 1 wherein the roller is journalled in a rocker arm carried by the frame for the drum, the other end of the rocker arm being connected to a tension spring anchored on said frame biasing the roller end of the rocker arm downwardly.

3. In a hoist with chain takeup mechanism, the combination with a housing and a hoist driving mechanism including an electric current operated motor and a hoist sprocket and roller chain entrained thereover, said sprocket being drivingly connected to said motor, said chain having a load engaging end and a tail end, of a frame pivoted on said housing, a retriever drum for the tail end of the chain rotatably journaled' on said frame, said drumbeing spring biased in one direction of rotation to wind the chain on the drum, a bell crank lever pivoted intermediate its ends on said frame below the drum journal, an idler takeup roller carried by one end of the bell crank lever engaging the chain between said sprocket and said drum journal, spring means biasing said end of the bell crank lever downwardly, an intermediately pivoted control lever for the motor carried on the housing below said sprocket, a part of said control lever being in the path of movement of said roller on the end of said bell crank lever whereby upward movement of said roller actuates the control lever to shut off the current to the motor.

4. In an electric hoist with chain takeup mechanism an electric current operated motor mounted in the hoist, a control lever for controlling the fiow of current to the motor, a hoist sprocket drivingly connected to said motor and a roller chain entrained thereover, a spring biased References Cited in the file of this patent UNITED STATES PATENTS Golon Oct. 27, 1925 Stevens May 11, 1926 Whitcomb Feb. 24, 1942 Bostwick May 18, 1948 Lannen June 17, 1952