US2943708A - Hoisting equipment - Google Patents

Description

July 5, 1960 M. F. SAISGEN noxsmc EQUIPMENT 2 Sheets-Sheet 1 Filed Feb. 9, 1959' INVENTOR. MATTHIAS F. SASGEN y y l Ma/m/M ATTORNEYS y 1960 M. F. SASGEN 2,943,708

HOIS'iING EQUIPMENT Filed Feb. 9, 1959 2 Sheets-Sheet 2 INVENTOR. MATTHlAS F. SASGEN ATTORNEY;

United States Patent HOISTING EQUIPMENT Matthias F. Sasgen, River Forest, 11]., assignor to Sasgen Derrick Company, Chicago, 11]., a corporation of Illinois Filed Feb. 9, 1959, Ser. No. 792,154

2 Claims. (Cl. 187-85) This invention relates to a safety device for hoisting equipment of the kind wherein the platform is arranged for up and down movement on a substantially upright frame, and the safety device is one which is adapted to hold the plaform in the event that the hoisting cable should break.

Safety devices of one kind or another are commonly employed in association with platform hoists wherein the platform is usually elevated by a cable, the safety taking over in the event that the hoist cable should break. In those instances where the frame which affords the vertical guide for the platform is of ferrous metal, the safety device usually takes the form of a toothed eccentric which is mechanically arranged to take a tight hold on the frame itself in the event the hoisting cable should break. In this instance, the toothed eccentric or other toothed holding device actually bites into the frame, but since the frame is of steel or the like there is very little likelihood of damage to the frame.

In recent years, however, resort has been had to frames constructed of aluminum for hoisting apparatus. Aluminum, in a manner of speaking, is relatively soft, and it is found that the conventional safety device mentioned above for use in connection with steel frames, is ineffective on aluminum. Thus, there is little or no assurance that the safety device which is intended to in efiect grasp the frame will be effective on an aluminum frame, and in fact it is very likely that such a safety will slip rather than grab on aluminum, turning and twisting the aluminum frame.

In view of the foregoing it is an object of the present invention to devise a safety specifically adapted to grab a safety cable rather than the frame of hoisting apparatus fabricated primarily from aluminum. Thus, a safety in the present instance is one that comprises an eccentric disposed on one side of a safety cable, and a back-up member disposed on the other side of thecable. Both the eccentric and the back-up member are carried by the platform, and the cable is at least anchored near the top of the aluminum frame. A crank is afforded, for the eccentric, this crank being normally effective to position the eccentric with a low part thereof presented to the safety cable so long as the hoisting cable or other flexible lifting element is eifective to raise or hold the platform. In the event that the flexible lifting element should break, means are effective to operate the crank to present a high part of the eccentric to the cable, causing the cable to be squeezed between the eccentric and the back-up member. When this initial safety condition is established, any further drop of the platform is instantaneously characterized by a servo-action of the eccentric such that practically instantaneously the eccentric is effective in cooperation with the back-up member to tightly grab the safety cable, and this condition is maintained by the weight of the platform itself.

It has heretofore been proposed to construct a safety including a safety cable .and a cooperating eccentricand 2,943,708 Patented July 5, 1960 back-up member. However, prior constructions of this general kind have many deficiencies and are generally impractical in connection with heavy-duty hoisting apparatus of the kind presently under consideration. Accordingly, it is a specific object of the present invention to devise a safety of the general kind mentioned above having improved operating characteristics particularly in respect of the crank which is to operate the eccentric and the spring element which is to deliver the initial impulse for actuating the crank.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. l is a perspective view of hoisting apparatus of the kind contemplated by the present invention;

Fig. 2 is a fragmentary elevation of one form of safety link constructed in accordance with the present invention;

Fig. 3 is a fragmentary elevation of another form of safety link constructed in accordance with the present invention; and

Fig. 4 is a fragmentary elevation showing details of actuation of a clamping eccentric. 1

Hoisting apparatus of the kind contemplated is illustrated in Fig. 1. This particular hoist includes, in its operative position, a generally upright frame 10 having parallel guide members 11 and 12. The guide members 11 and 12 are of extruded aluminum, and these are braced and spaced by cross members as 13 in the usual fashion.

The uprights 11 and 12 constitute guides for a platform 15 which includes a pallet 16 supported by arms 17 that are disposed in a generally horizontal plane and project outward substantially at right angles from the upright guides 11 and 12. The platform 15 additionally includes a pair of vertical arms as 18, and these arms are provided with guide rollers 19 which fit in outside channels formed in the uprights 11 and 12. It will be noted that the rollers 19 turn on axes that are generally parallel to the pallet support arms 117. It should be mentioned that the arms 18 have other rollers (not shown) which rotate on axes that are normal to the axes for the rollers 19, and these other rollers fit neatly within the outside channels in the uprights 11 and 12 so as to be substantially in engagement with the inside faces of the flanges F of the uprights. Thus, it will be recognized that the rollers mentioned stabilize the platform on the frame 10 and at the same time provide for anti-friction movement of the platform on the frame.

The platform 15 is raised and lowered by a flexible lift element in the form of a hoist cable 20. This cable is wound and unwound from a cable winder 21 which is anchored in place on a motor base 22 which in turn is anchored to a horizontal relatively expansive stabilizing base 25 which is the primary stabilizer for the frame 10. The winder 21 is powered by an internal combustion engine 30. The hoisting cable 20 extends upward along the length of the frame 10 and is played over a pulley 31 which is supported at the top of the frame 10. The hoist cable 20 is connected to a sheave or block 32, and this sheave or connector in turn is attached to the lift head v35.01:.the platforr'nlS, tDifferent .pounections can -of 'In this connection it will be noted that the hoisting apparatus illustrated in Fig. 1 includes a pair of elongated arms 40 and 41 which are attached at their upper ends to the guide members 11 and 12, the points of attachment being somewhat below the top of the frame. These arms extend downward from their points of attachment at a divergent angle relative to the guides 11 and 12, and the lower ends of the arms 40 and 41 are joined to the primary stabilizing base 25 by connectors as 42 and 43. The arms 40 and 41, and the connectors 42 and 43 are placed relative one to another and are also placed against the guides 11 and 12.

An axle 45 is supported by the connectors as 42, and wheels 46 in turn are supported by the axle 45. A conventional hitch 47 is attached to the top of the frame 10. Pivotally attached to the arms 40 and 41 are a pair of auxiliary stabilizer arms 47 and 48. These auxiliarystabilizers have ground engaging pads 47F and 48F. The manner of pivotally attaching the auxiliary stabilizers 47 and 48 to the arms 40 and 41 is such as to enable the stabilizers 47 and 48 to be turned upward in a counterclockwise direction as viewed in Fig. ;l*to a folded state substantially parallel'with the arms 40 and 41, and means (not shown) are employed to enable the stabilizers to be releasably secured in their'folded state. When so folded,

the stabilizers '47 and 48 enable the holdingapparatus to be turned clockwise as viewed in Fig. 1 about the connectors 43, and it should be mentioned that these connectors are located in a plane that is inclined upwardly 'out of the plane of the primary stabilizer base 25, and

this facilitates tilting of the apparatus. Once tilted, the

-wheels 46 eventually are effective to support the apparatus forconvenient towing through the hitch 47.

It will be appreciated that the platform 15 will'be used to raise materials or equipment to an elevated position 'when the hoisting apparatus is in use, and of course a workman may also ride on the platform 15. In any event it becomes important to provide some form of safety in the event that the hoisting cable should break. In accordance with the present invention such safety feature is represented by an'eccentric clamp, the details of operation of which will be explained hereinafter, and which cooperates with a safety cable ,50 which is conveniently anchored at its upper end near the top of the frame 10. The lower end of the safety cable 50 can be conveniently secured to the lower base mounting 22.

It will be observed-in Fig. 1 that safety cable 50 is located adjacent one side of the lift head 35 that is includedas a part of the platform 15, and of course it will be realized that the safety cable is stationary and that the platform 15 moves up and down relative thereto. In accordance with the present invention, a clamping disc 53, Fig. 4, is mounted for rotation on an eccentric axis, and this axis is represented by a ,pin 54, Fig. 4, which in turn is supported by a mounting bracket 55, which in turn is fixed on the upper end of the platform lift head 35. Thus, the bracket 55 includes a rectangular vertical leg 56 which is welded or otherwise secured to the lift head 35, and the bracket 55 is formed with a horizontal leg 57 which extends slightly over the eccentric 53 so as in effect to constitute a protective cover therefor. The horizontal leg 56 is formed with an aperture 57A, and the safety cable 50 is passed therethrough. Thus, it will be seen that the eccentric 53 and its mounting bracket 55 move with the lift head 35. It ought also to be pointed out that the bracket 55 includes a back-up plate 59 which is disposed in vertical relationship with the bracket 55 and which lies near the safety cable 50. The back-up plate 59 represents an important element of the safety clamp as will be explained hereinafter. It

should also be mentioned that the platform 15 is raised and lowered by a hoisting cable 20, and it will be, noted that this cable is also identified in Fig. 2. A connector of one kind or another is attached to the end of the cable 20 which is used to elevate the platform 15, and this connector serves as an intermediate member joining the hoisting cable to the lift head of the platform. Thus, in Fig. 2, a connector takes the form of an inactive sheave 61. The end of the sheave 61 opposite that joined to the hoisting cable is secured to an elongated eye bolt 62, and this bolt is passed down through an aperture formed in the horizontal flange 35H of the lift head 35, noting that the lift head 35 in the present invention is disclosed as being in the form of an angle bar. The threaded end of the eye bolt 62. extends to. a point displaced well below the lower edge of the lift head 35. A tubular sleeve 63 is arranged concentric to the portion of the shank of the eye bolt 62 which extends below the flange 35H of the lift head, and the coil spring 65 is arranged concentric to this portion of the eye bolt, shank in the space between the eye bolt shank and the sleeve '63. A of lock nuts as 67 are threadedly mounted on the lower end of the eye bolt 62, and a washer 70 is interposedibetween the nuts 67 and the lower end of the sleeve 63. Thus, the arrangement is one wherein the connectorrepresented by the sheave 61 and the eye bolt 62 is effective to raise the platform 35 through the spring 65', and under such circumstances the spring 65 will normally be substantially fully compressed so as in effect to con stitute a resilient block between the connector means and the lift head of the platform.

The clamping eccentric 53 is controlled by a crank structure which is carried between connector means. Thus, as shown in Fig. 2 a rigid horizontal arm 70 is welded to the portion of the eye bolt 62 which projects above the lift-head 35. The arm 70 extends toward the bracket 55 which carries the eccentric, but terminates short of the bracket 55. Referring to Fig. 4, a crank link 72 has its inner end firmly joined'to a point on the eccentric 53 below the axis pin 54. The opposite end of the crank link 72 extends free of the disc 53, and an intermediate operating link 74 is pivotally connected to the adjacent ends of the arm 70 and the crank link 72.

In the event that the hoisting cable 20 should break, lifting forces otherwise effective on the cable 20are dissipated insofar as the platform is concerned, and hence the platform 15 will undergo normally a free fall; however, and at the same time, a coil spring 65 which was previously under compression will now expand to the dotted line compression shown in Fig. 2. Concurrently with this, arm 70 drops, and because of the angular relationships involved between the links 72 and 74, the operating link 74 tends to assume a horizontal position, and the resultant forces are translated into counter-clockwise rotary motion of the disc 53. Accordingly, instead of a low part of the eccentric being presented to the safety cable as under normal or ordinary circumstances, a high part of the eccentric is turned into engagement with the safety cable 50, pushing the safety cable against the backup plate 59. It should be mentioned that the spring 65 -or other resilient starting element, simply initiates the operation of the crank structure, because once there is effective friction between the disc 53, the safety cable 50 and the back-up plate 59, the weight of the platform comes into play, and a servo force is established causing the eccentric 53 to grip the safety cable 50 tighter and tighter. The final holding force really becomes the weight of the platform. In an actual test, wherein the hoisting cable was burned through by a torch, the platform 15 dropped only three inches during the time that the above servo action was taking place.

Various forms of construction can be resorted to insofar as an effective relationship is concerned between the connector means and the spring means used to start operation of-the clamping eccentric. Thus, referring to Fig.

3 a doubled hoisting line 20A is utilized in connection with the completely effective sheave 61A. In other words, the hoisting cable 20A in this instance is conventionally associated with the pulley 61A. The horizontal arm of the crank operating structure is of somewhat longer length and is indicated at 70A in Fig. 3. Plate 80 is secured to the sheave 61A, and this plate has an end projecting below the sheave 61A, and a bolt 81 is used to join the arm 70A to the plate 80. A pair of conventional bolts 82 and 83 are inserted in corresponding apertures in the arm 7 0A with the heads thereof reposing on the upper surfaces of the arm 70A. The bolts 82, 83 are centered in either side of the arm 70A and the plate 80, and the shanks thereof are passed through a pair of apertures in the horizontal flange of the lift head 35. The tube, coil spring and lock nut arrangement described above in connection with Fig. 2 is repeated for each of the bolts 82 and 83, but instead of a washer 70 there is used a common crosshead 90 interposed between the two sets of lock nuts and the two sleeves 83.

It will be recognized that the operating principles for the structure illustrated in Fig. 3 are substantially the same as shown in Fig. 2. Thus, if the hoisting cable 20 should break, the two previously compressed coil springs associated with bolts 82, 83 will expand and concurrently the horizontal arm 70A is pulled down, causing the intermediate link 74 to move to a substantially horizontal position thereby efiectively driving the crank link and causing virtually instantaneous rotation of the eccentric 53 whereby a clamping force on the cable 50 is generated in the manner described above.

It will be seen from the foregoing that under the present invention there is afforded a safety clamp or hoisting apparatus of the kind using a main frame constructed from aluminum which is a relatively soft structural material compared to steel. Thus in the present instance the safety clamp is associated with a safety cable rather than one that is effective on the frame itself. Relatively few operating parts are involved, and for the most part advantage is taken of an essential structure that will of necessity already be present. Thus, the present arrangement takes advantage of a sheave or other connector that is already interposed between the flexible lifting cable and the lift head of the working platform of the hoisting apparatus. Moreover, there are but few parts required to render the eccentric effective, and these include the backup plate on one side of the safety clamp, two links for rotating the eccentric, and an arm which is fixed to the connector for actuating the links. The arm which actuates the links only comes into play in the event that the hoisting cable should break whereupon the connector and e the arm 70 or 70A associated therewith are pulled down by the coil spring undergoing expansion.

Hence, while I have illustrated preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. In hoisting apparatus of the kind described, means affording a frame adapted to be disposed in a substantially upright attitude, a platform mounted on the frame for up and down movement, said platform including a lift head, means to raise and lower said platform including a flexible lift element, a connector joined to said lift element to be lifted thereby, a coil spring having one end backed up by said lift head and having the other end thereof joined to said connector whereby lifting forces are imparted to said lift head by lost motion through said spring causing compression of the spring, a safety cable having an upper end anchored near the top of said frame and said cable extending downward toward the bottom of said frame, a rigid back-up member carried by said lift head and disposed on one side of said safety cable, a rotatable eccentric carried by said lift head and located on the other side of said safety cable, and a crank for the eccentric carried by said connector, said crank including a substantially horizontal arm having a portion rigidly secured to said connector and a crank link having a portion connected to said eccentric and an intermediate link pivotally interconnecting the horizontal arm and the crank link, and said crank having a stroke that rotates the eccentric to present a low part of the eccentric to the safety cable when said connector is efiective to compress said spring and which presents a high part of the eccentric to the safety cable, pressing the safety cable against said back-up member, when said spring expands.

2. In hoisting apparatus of the kind described, means affording a frame including aluminum guide members adapted to be disposed in a substantially upright attitude, a platform mounted on the guides for up and down movement, said platform including a lift head, means to raise and lower said platform including a flexible lift element, a connector joined to said lift element to be lifted thereby, said connector being projected through said lift head and terminating at an end disposed well below the lift head, a coil spring located under the lift head and having an upper end backed up by said lift head and having the lower end thereof joined to said end of said connector whereby lifting forces are imparted to said lift head by lost motion through said spring causing compression of the spring, a safety cable having an upper end anchored near the top of said frame and said cable extending downward toward the bottom of said frame, a rigid back-up member carried by said lift head at one side thereof and disposed on one side of said safety cable, a rotatable eccentric carried by said lift head and located on the other side of said safety cable, and a crank for the eccentric carried by said connector, said crank including a substantially horizontal arm anchored to said connector and extending toward but terminating short of said eccentric, a crank link connected to said eccentric for turning the eccentric, and an intermediate operating link pivotally interconnecting said arm and said crank link at an angle, whereby said angle is changed causing turning of the eccentric when said horizontal arm is raised or lowered with said connector relative to said lift head.

References Cited in the tile of this patent UNITED STATES PATENTS 592,698 Cox Oct. 26, 1897 922,452 Burgan May 25, 1909 1,015,137 Clark Jan. 16, 1912 1,038,961 Rivers Sept. 17, 1912 1,252,122 Jewell Jan. 1, 1918

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