US2894610A - Chain hoist - Google Patents

Description

A J. AT HARRINGTCN 2,894,610

July. 14, 1959' f CHAIN HQIST 2 Sheets-Sheet 1A FiledvJune 5, 1957 INVEN'roR:

HARRINGTON `vJOHN A.

ATTYS.

July 14, 19.59 J. A. HARRINGTON 2,894,610

' CHAINVHOIST l Filed June '5, 1957 2 Sheets-Sheet 2 FIL-3.5. 4

`J'oHN A. HARRINGTON ATTYS.

INVENTOR'.

Uite

CHAIN HOIST John A. Harrington, Whitemarsh, Pa., assignor to The Harrington Company, Plymouth Meeting, Pa., a corporation of Pennsylvania Application June 5, 1957, Serial No. 663,727

6 Claims. (Cl. 192--16) The present invention relates to new and useful improvements in chain hoists and more particularly to new and useful improvements in the load lowering and raising mechanism in a manually operated chain hoist.

Prior to the present invention, when a manually operated chain hoist was used to lower a load, the load was dropped in a series of short sudden jerks or steps by releasing the brake mechanism which maintained the load .in its elevated position and then causing the brake mechanism to be applied to stop downward movement fof the load.

In these prior chain hoists, the brake mechanism could only be released and applied suddenly thereby causing the sudden stopping and starting of the t downward movement of the load. This frequently i would cause damage to the structure supporting the hoist or to the load itself and was one of the major disadvantages of a manually operated chain hoist of this type.

According to the present invention, mechanism is pro- `vided to cause pressure to be gradually applied to and i released from the brake of the chai-n hoist so that when s the load is lowered in the conventional manner sudden starts and stops of the load are eliminated and the hoist -f operates in a much smoother manner than prior hoists of this type.

With the foregoing in mind, the principal object of the j present invention is to provide a novel chain hoist of the above stated type wherein the load may ,be lowered in a series of steps `Without any sudden stopping or starting of the movement of the load during the lowering operation.

Another object of the present invention is to provide c a novel chain hoist which is of relatively compact construction and wherein all of the operating parts of the .f chain hoist are mounted directly about the main drive t shaft of the hoist.

A still further object of the present invention is to j provide a novel chain hoist having the features and characteristics set forth above which is of relatively simplified construction, may be manufactured easily and cheaply,

and is entirely efficient and effective in operation and use.

These and other objects of lthe present invention and the various features and details of the operation and conf. struction thereof, are hereinafter more fully set forth and described with reference to the accompanying drawings, in which:

Y parts of the hoist in the position they assume during raising of the load and while maintaining the load in the 'elevatcd position;

Patent the load wheel.

Fig. 6 is a fragmentary elevational view of the chain hoist in the position of Fig. 5;

Fig. 7 is an enlarged fragmentary transverse sectional view similar to Fig. 5 with the operating parts of the hoist in the position they assume during lowering of the load;

Fig. 8 is a fragmentary end elevational view similar to Fig. 6 with the hoist in the position of Fig. 7; and

Fig. 9 is an exploded perspective view illustrating the various operating parts of the chain hoist removed from `the main drive shaft of the hoist.

Referring more specifically to the drawings and particularly Figs. l, 2 and 3 thereof, the chain hoist of the present invention comprises essentially an inclosed housing 10 having an intergal boss 11 formed on the top portion -thereof within which a conventional mounting hook 12 is secured, as indicated at 13. A Ibase plate 14 closes the lower end of the housing 10 and has a pair of guide openings 15 and 16 therein through which a load chain 17 passes. The load end of the chain 17 extends downwardly beneath the housing 10 at the left hand side of the housing, relative to Fig. l through the chain guide opening 15, and has a conventional load hook 18 or other load lifting member secured thereto, as shown in Fig. 2. The free end of the chain 17 passes downwardly through the chain guide opening 16 at the right hand side of the housing 10, relative to Fig. 1, and hangs in spaced parallel relation with the load end of the chain, in the conventional manner. As shown in the drawings, the mounting hook 12 is offset from the vertical axis of the housing 10 yto Ithe same side as the load end of the chain 17 to prevent twisting of the chain hoist while in use.

Extending longitudinally of the housing 10` between opposite side walls thereof is a drive shaft 21 which mounts the various operating parts of the hoist of the present invention. The drive shaft 21 is formed as illustrated in Figs. 5, 7 and 9 of the drawings and has an enlarged hub 22 at the left hand end thereof, relative to the above figures, which provides a bearing mount for one end of the shaft in the housing. Extending outwardly from the hub 22 beyond one side wall of the housing is a boss 23 having a squared opening 24 -therein within which a conventional ratchet wrench 25 may be received. The opposite end portion of the drive shaft 21 is 4threaded as indicated at 26 and terminates in a hexagonal shaped end portion 27, more fully described hereinafter, extending outwardly beyond the opposite side wall ofthe housing 10.

In accordance with the present invention a load wheel 28 is mounted about the drive shaft within the housing and has one end thereof threaded as indicated at 31 to receive the threads 26 of the drive shaft 21. A boss 32 extends outwardly from the load wheel about the threads 31 and beyond the side wall of the housing 10, as illustrat'ed in Figs. 5 and 7, and provides a bearing mount for the opposite end of the shaft in the housing 10. The load wheel 28 has a series of pockets 33 therein about its outer periphery which are adapted to receive lthe links of the load chain 17. The load chain 17 is positioned about the load wheel with alternate links of the chain received in the pockets 33 so that upon rotation of the load wheel 28 the load chain 17 is positively driven.

Positioned adjacent the opposite side of the load wheel from the hub 32, within the housing 10 and about the drive shaft 21 is the friction brake mechanism of the present invention which is operable to create a suflicient drag on the load wheel to maintain a load carried by the load chain in the elevated position or to stop downward movement of the load when the load is being lowered. This brake mechanism consists of a series of washers and disks which may be forced together axially, as more fully described hereinafter, to exert a braking effect on As illustrated in Figs. ,5, 7 and 9, the

Fatented July 14, 1959 brake mechanism consists of a hard friction washer 34 formed of woven asbestos or the like mounted about the drive shaft adjacent to the load wheel 28. Adjacent to the hard friction washer 34 is a ratchet disk 35 formed of steel or the like and having a series of ratchet teeth 36 about its peripheral edge. The ratchet teeth incline rearwardly relative to the clockwise direction in Fig. l and are engaged by a ratchet pawl 37 pivotally mounted within the lower end of the housing l as indicated at 38 in Fig. l, A pawl spring 41 mounted in engagement with the ratchet pawl and the base plate of the housing maintains the ratchet pawl in engagement with the teeth of the ratchet disk. One end of the ratchet pawl extends outwardly beyond the housing 1.0 through an opening 42 and the base ratchet pawl may be disengaged manually from the teeth of the ratchet disk by the user of the chain hoist when the hoist is not supporting a load to permit the load hook to be positioned relative to the housing 10.

Positioned adjacent to the ratchet disk 3S and mounted about the drive shaft 2i is a soft friction washer 43 formed of chrome friction leather, felt, or like material, and a metal friction disk 44 also positioned about the drive shaft is mounted in engagement with the soft friction washer 43. The friction disk 44 has a central opening 45 therein provided with a series of serrations which re mounted in engagement with a splined section 47 on the drive shaft 2l adjacent to the hub 22 to prevent relative rotation between the friction disk 4d and the drive shaft 2l yet permit the axial movement of the friction disk 44 relative to the drive shaft. the brake mechanism is a spring disk 48 which is generally dish-shaped and is positioned about the drive shaft intermediate the friction disk 44 and the enlarged hub portion 22 of the drive shaft. The spring disk 48 normally is in the position illustrated in Fig. 7 but may be compressed to a flattened position as shown in Fig. upon axial movement of the load wheel 28 to the left relative to Fig. 5.

To use the chain hoist of the present invention the housing is secured to a support by the mounting hook 12 and the load hook 18 is attached to the load to be elevated. A ratchet wrench or similar tool is inserted within the squared opening 24 in the end of the drive shaft and the drive shaft is rotated in the clockwise direction relative to Fig. 1 by means of the wrench. During rotation of the drive shaft in the clockwise direction the load wheel 28 is urged to rotate in the counterclockwise direction relative to Fig. 1 by virtue of the pull exerted on the load end of the load chain 17. This causes the load wheel 28 to be moved axially of the drive shaft 2l by the drive shaft threaded section 26 to the left relative to Fig. 5 thereby exerting axial pressure on the various disks and washers of the brake mechanism. When a sucient axial pressure is exerted on the brake mechanism the load wheel is locked to the drive shaft by the brake mechanism and is caused to rotate in the clockwise direction along with the drive shaft. lf a ratchet wrench is used to raise the load, the drive shaft will be driven intermittently in the clockwise direction and the load will be raised intermittently, the load wheel being maintained in the locked position on the drive shaft during the entire raising operation. When the drive shaft is not being rotated engagement of the ratchet pawl 37 with the ratchet disk will prevent the load wheel from rotating in the counterclockwise direction to lower the load.

in order to lower the load carried by the chain hoist, the drive shaft 21 is rotated in the eounterclockwise direction relative to Fig. 1. During the initial portion of the counterclockwise rotation of the drive shaft 21, the load wheel 28 will be maintained stationary by virtue of inertia forces and because of the action of the brake mechanism. During this portion of rotation of the drive shaft 21 the load wheel will be moved axially to the right to Fig. 7 to the position shown in Fig. 7 wherein axial pressure is removed from the brake mechanism. The brake mechanism will then release the load wheel and permit the The final element of 1 load wheel to be rotated in the counterclockwise direction because of the force exerted on the load wheel by the load chain and permit the load to lower.

During lowering of the load the load wheel is rotated in the counterclockwise direction relative to Fig. 1 at a more rapid rate than the drive shaft 2l and will thus be moved axially to the left relative to Fig. 7 on the drive shaft 2l thereby exerting axial pressure on the brake mechanism, stopping rotation of the load wheel and also stopping the downward movement of the load.

Upon continued rotation of the drive shaft 2l in the counterclockwise direction relative to Fig. 1, the load wheel is again moved axially to the right relative to Fig. 7 thereby releasing axial pressure on the brake mechanism and permitting the load wheel to repeat the above described operation. Thus, the load is lowered in a series of steps by the chain hoist of the present invention.

Means are provided to limit the loosening of the brake movement of the load wheel 28 axially of the drive shaft 2l, as viewed in Figs. 2, 5, and 6, to prevent the load wheel from exerting an outwardly directed force on the housing l0. This will only happen when the chain is being lowered with no load or when the drive shaft 2l is being rotated in a direction to lower the chain and the hook of the chain is run out to its extreme position with the stop on the free end of the chain in contact with the base of the hoist. Under these conditions, when the drive shaft is rotated in a direction to lower the load, the load wheel 28 is prevented from rotating with the drive shaft and thus will be moved to the right relative to the drive shaft, as viewed in Fig. 7, toward the side of the housing l0. According to the present invention, this movement of the load wheel relative to the drive shaft is limited by means of a check washer 52 positioned on the hexagonal shaped end portion 27 of the drive shaft. The check washer has an outwardly extending lug portion thereon operable to engage a stop member 5l, which in the present instance is illustrated in the form of a bolt, extending outwardly from the face of the load wheel 28. Upon counterclockwise rotation of the drive shaft, relative to Fig. 1, or clockwise rotation, relative to Figs. 6 and 8, the check washer 52 engages the stop member 51 preventing further relative rotation in this direction between the drive shaft and load wheel and limiting axial movement of the load wheel relative to the drive shaft. The position of the check washer may be adjusted about the hexagonal shaped end portion of the drive shaft in the conventional manner to limit the axial movement of the load wheel relative to the drive shaft and prevent the load wheel from exerting pressure on the inner side of the housing.

An important feature of the present invention is the provision of the spring disk 48 which permits axial pressure to be gradually applied to and released from the brake mechanism thereby causing the brake to be released gradually and applied gradually so that each step of the downward movement of the load will start and stop gradually. This prevents sudden shock stresses from being exerted on the supporting structure :for the chain hoist or on the load itself.

From the foregoing it will be apparent that the present invention provides a novel chain hoist in which pressure may be gradually applied to and released from the brake mechanism of the chain hoist, so that when the load is lowered in the conventional manner sudden starts and stops of the load are eliminated. In addition, it Will be apparent that the present invention provides a novel chain hoist which is of relatively compact construction, and wherein all of the operating parts of the chain hoist are mounted directly about the drive shaft to provide a relatively simplified construction.

While a particular embodiment of the present invention has been illustrated and described herein it is not intended to limit the invention to such a disclosure, and

changes and modifications may be incorporated and embodied therein within the scope of the following claims.

I claim:

l. A chain hoist to lift and lower a load comprising a housing, a drive shaft rotatably mounted within said housing, a load Wheel mounted on said drive shaft -for rotatable movement with and relative to said drive shaft, brake mechanism within said housing in engagement with said load wheel and actuatable to an on position to prevent rotation of said load wheel, brake actuating mechanism operable upon relative rotation of said load wheel in one direction with respect to said drive shaft to actuate said brake to said on position and upon relative rotation of said load Wheel in the opposite direction with respect to said drive shaft to actuate said brake mechanism to an off position, load supporting and lifting means carried by said load wheel operable to no-rmally urge said load wheel to rotate in said one direction relative to said drive shaft, drive means operable to rotate said drive shaft and said load wheel in a direction opposite to said one direction of rotation of the load wheel to lift the load and to rotate said drive shaft in the same direction as said one direction of rotation of the load wheel to release said brake actuating means, and resilient means interconnected with said brake mechanism and said brake actuating mechanism operable to resiliently exert pressure on said brake mechanism and resiliently urge said brake mechanism to said on position to cause said brake mechanism to be actuated to its on and off positions gradually and cause said load wheel to stop and start rotation in said one direction gradually.

2. A chain hoist to lift and lower a load comprising a housing, a drive shaft rotatably mounted transversely of said housing, a load wheel mounted on said drive shaft for rotatable movement with and relative to said drive shaft, brake mechanism within said housing in engagement with said load wheel and actuatable to an on position to prevent rotation of said load wheel, brake actuating means operable to move said load wheel axially of said drive shaft in one direction upon relative rotation of said load wheel in one direction with respect to said drive shaft to actuate said brake mechanism to said on position and upon relative rotation of said load wheel in the opposite direction with respect to said drive shaft to move said load wheel axially of said drive shaft in the opposite direction to actuate said brake mechanism to an off position, load supporting and lifting means carried by said load wheel operable to normally urge said load wheel to rotate in said one direction relative to said drive shaft, drive means operable to rotate said drive shaft and said load wheel in a direction opposite to said one direction of rotation of the load wheel to lift the load and to rotate said drive shaft in the same direction as said one direction of rotation of said load wheel to release said brake mechanism actuating means and permit said load wheel to be rotated in said `one direction to lower the load, and resilient means interconnected with said brake mechanism and said brake actuating mechanism operable to resiliently exert pressure on said brake mechanism and resiliently urge said brake mechanism to said on position to cause said brake mechanism to be actuated to its on and off positions gradually and cause said load wheel to stop and start rotation in said one direction gradually.

3. A chain hoist to lift and lower a load comprising a housing, a drive shaft rotatably mounted within said housing, a load wheel mounted on said drive shaft for rotatable movement with and relative to said drive shaft, brake mechanism positioned within said housing about said drive shaft in engagement with said load wheel and operable upon exertion of pressure on the brake mechanism in one direction axially of said drive shaft to be actuated to an on position to prevent rotation of said load wheel, brake actuating means interconnecting said load wheel and said drive shaft operable to move said load wheel in said one direction axially of said drive shaft applying pressure on said brake mechanism and actuating the same to said on position upon rotation of said load wheel in one direction relative to said drive shaft and to move said load wheel axially of said drive shaft in the oppositel direction upon rotation of said load wheel in the other' direction relative to said drive shaft, means to limit rotation of said load wheel in said other direction relative to said drive shaft, load supporting and lifting means carried by said load wheel operable to normally urge said load wheel to rotate in said one direction relative to said drive shaft, drive means operable to rotate said drive shaft and said load wheel in a direction opposite to said one direction of rotation of the load wheel to lift the load and to rotate said drive shaft in the same direction as said one direction of said load wheel to move said load wheel axially of the drive shaft in said other direction to release said brake mechanism and permit said load wheel to rotate in said one direction, and resilient means interconnected with said brake mechanism operable to exert resilient axial pressure on said brake mechanism during operation of said brake actuating means to cause said brake mechanism to be actuated to its on and off positions gradually and cause said load wheel to stop and start rotation in said one direction gradually.

4. A chain hoist to lift and lower a load comprising a housing, a drive shaft rotatably mounted transversely within said housing, a load wheel rotatably mounted within said housing about said drive shaft for rotary movement with and relative to said drive shaft, a threaded connection between said load wheel and said drive shaft to move said load wheel axially of said drive shaft in one direction during rotary movement of said load wheel relative to said drive shaft in one direction and in the opposite direction during rotary movement of said load wheel relative to said drive shaft in the opposite direction, a series of friction disks positioned about said drive shaft adjacent one side of said load wheel, operable to be engaged by said load wheel during axial movement of said load wheel in said one direction and upon exertion of axial pressure thereon by said load wheel to stop rotation of said load wheel, releasable ratchet means interconnecting one of said friction disks with said housing to prevent rotation thereof in one direction, another of said friction disks being mounted for-axial movement relative to said drive shaft and rotatable with said drive shaft, load supporting and lifting means carried by said load wheel operable to normally urge said load Wheel to rotate in said one direction relative to said drive shaft and thereby be moved axially in said one direction relative to said drive shaft to exert axial pressure on said friction disks, drive means interconnected with said drive shaft operable to rotate said drive shaft in opposite directions, said drive means being actuatable to rotate said drive shaft in the direction opposite to said one direction of rotation of the load wheel to lift the load and actuatable to rotate said drive shaft in the direction opposite to said other direction of rotation of the load wheel to move said load wheel in said opposite direction axially relative to said drive shaft and release axial pressure on said friction disks thereby permitting said load Wheel to rotate in said one direction relative to said drive shaft to lower the load, and resilient means interconnected with said friction disks operable to exert axial pressure on said friction disks to thereby cause the axial pressure applied to said friction disks by said load wheel to be released and applied gradually and cause said load wheel to start and stop rotation in said one direction gradually.

5. A chain hoist to lift and lower a load comprising a housing, a drive shaft rotatably mounted transversely within said housing, a load wheel rotatably mounted within said housing about said drive shaft for rotary movement with and relative to said drive shaft, means interconnecting said load wheel and said drive shaft to move said load wheel axially of said drive shaft in one direction during rotary movement of said load wheel relative to said drive shaft in one direction and in the opposite direction during rotary movement of said load wheel relative to said drive shaft in the opposite direction, a series of friction disks positioned about said drive shaft adjacent one side of said load wheel operable to be engaged by said load wheel during axial movement of said load wheel in said one direction and upon exertion of axial pressure thereon by said load wheel to stop rotation of said load wheel, a load chain positioned about said load wheel with the opposite ends of the load chain extending downwardly therefrom beyond said housing, means interconnecting said load wheel and said load chain to move said load chain upon rotation of said load wheel, means to interconnect one end of the load chain with the load to be moved by said chain hoist, the weight of the load upon said load chain being operable to normally urge said load wheel to rotate in said one direction relative to said drive shaft and thereby be moved axially in said one direction relative to said drive shaft to exert axial pressure on said friction disks, drive means interconnected with said drive shaft operable to rotate said drive shaft in opposite directions, said drive means being actuatable to rotate said drive shaft in the direction opposite to said one direction of rotation of the load wheel to lift the load and actuatable to rotate said drive shaft in the direction opposite said other direction of rotation of the load wheel to move said load wheel in said opposite direction axially relative to said drive shaft and release axial pressure on said friction disks thereby permitting said load wheel to rotate in said one direction relative to said drive shaft to lower the load, and resilient means interconnected with said friction disks operable to exert axial pressure on said friction disks to thereby cause the axial pressure applied to said friction disks by said load wheel to be released and applied gradually and cause said load wheel to start and stop rotation in said one direction gradually.

6. A chain hoist to lift and lower a load comprising a housing, a drive shaft rotatably mounted transversely Within said housing, a load wheel rotatably mounted within said housing about said drive shaft for rotary movement with and relative to said drive shaft, a threaded connection between said load wheel and said drive shaft to move said load wheel axially of said drive shaft in one direction during rotary movement of said load wheel relative to said drive shaft in one direction and in the opposite direction during rotary movement of said load wheel relative to said drive shaft in the opposite direction, a series of friction disks positioned about said drive shaft adjacent one side of said load wheel operable to be engaged by said load wheel during axial movement of said load wheel in said one direction, releasable ratchet means interconnecting one of said friction disks with said housing to prevent rotation thereof in one direction, another of said friction disks being mounted for axial movement relative to said drive shaft and rotatable with said drive shaft, said friction disks operable upon the exertion of axial pressure thereon by said load wheel to stop rotation of said load wheel, a load chain positioned about said load wheel with the opposite ends of the load chain extending downwardly therefrom beyond said housing, means interconnecting said load wheel and said load chain to move said load chain upon rotation of said load wheel, means to interconnect one end of the load chain with the load to be moved by said chain hoist, the weight of the load upon said load chain being operable to normally urge said load wheel to rotate in said one direction relative to said drive shaft and thereby be moved axially in said one direction relative to said drive shaft to exert axial pressure on said friction disks, drive means interconnected with said drive shaft operable to rotate said drive shaft in opposite directions, said drive means being actuatable to rotate said drive shaft in the direction opposite said one direction of rotation of the load wheel to lift the load and actuatable to rotate said drive shaft in the direction opposite said other direction of rotation of the load wheel to move said load wheel in said opposite direction axially relative to said drive shaft and release axial pressure on said friction disks thereby permitting said load wheel to rotate in said one direction relative to said drive shaft to lower the load, and resilient means interconnected with said friction disks operable to exert axial pressure on said friction disks to cause the axial pressure applied to said friction disks by said load wheel to be released and applied gradually and cause said load wheel to start and stop rotation in said one direction gradually.

References Cited in the le of this patent UNITED STATES PATENTS 1,526,806 Schurmann Feb. 17, 1925 2,453,581 Moore Nov. 9, 1948 2,494,738 Booth ian. 17, 1950 2,736,408 Coiiing Feb. 28, 1956 2,770,339 Dotson Nov. 13, 1956 FOREIGN PATENTS 503,709 Germany July 31, 1930

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