US2838336A

US2838336A - Rope sling

Info

Publication number: US2838336A
Application number: US480404A
Authority: US
Inventors: Archer Jean Francois
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-01-12
Filing date: 1955-01-07
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10
Also published as: FR70273E; GB805264A; FR1098184A; FR65648E; FR69162E; NL193933A

Description

Jun 10, 1-958 J. F. ARCHER ROPE SLING 2 Sheets-Sheet 1 Filed Jan. 7, 1955 a M I v June 10, 1958 ARCHER 2,838,336

ROPE SLING Filed Jan. 7, 1955 2 Sheets-Sheet 2 ROPE SLING Jean Francois Archer, La Celle Saint Cloud, France Application January 7, 1955, Serial No. 480,404

Claims priority appiicatlon France January 12, 1954 4 Claims. (Cl. 294-78) f This invention relates to lifting slings and more particularly to a sling capable of lifting a load substantially vertically and without lateral displacement regardless of the position of the center of gravity of the load with respect to the apex of the sling spans.

7 .It is known to provide an adjustable sling of the kind which comprises a pulley or pulley element over which a rope is passed with means for immobilising the-rope relative to the pulley or pulley element. When a sling of this kind is to be used, both ends of the rope are fixed tothe article to be raised, the pulley is moved until it is inthe'position which ensures that the article will be raised straight up vertically without lateral displacement whereupon lifting is commenced and causes the. rope to be held stationary or immobilised relative to the pulley or pulley element.

The principal object of the present invention is to provide a new and improved sling of the above-mentioned kind, whichv is of simpler construction and is more elicient in operation than the known types. 7 J

jln accordance with the invention, the sling comprises ajline guide and support member which is so formed as to enable it to' be engaged directly by a hooked member, for example the hook of a lifting apparatus, and means forprejventingrotation of the support relative to the said hooked member, the arrangement being such that, when the line is supporting a load, it is immobilised relative to the support. It will be understood that the term line is used in the generic sense to indicate a rope, cable or chain. i

Preferably the means for preventing the relative dis placement comprises a stop which is provided on the support and is adapted to abut the lifting hook.

If desired, the said stop may be also adapted to immobilise the rope or cable by virtue of the fact that it is caused to move into contact with and press the latter against the support, the latter may consist of a pulley or an arcuate or rounded member.

For example, the support may comprise a pulley to which the stop is fixed in such a position that upon loading a rope or chain preferably being so wound around the pulley as to provide at least one complete or dead turn so that when the said tape or chain is not taut it may be moved around the pulley to enable the sling, to be ad justed upon the hook member, but is immobilised automatically by the friction created between it and the throat of the pulley, upon commencing to lift an article.

Alternatively, the stop may be movably mounted upon the rope, chain or cable support, and its path of movement may extend at least to the rope or chain being displaced into contact with the hooked member automatically as the hoist is operated to lift a load; in such circumstances; the support'need not consist of a complete pulley and the rope or chain need only be passed over the sup port since the former is gripped between the stop and the support, and is thereby immobilised, when the stopis brought into contact and engagement therewith. 7 Before States Patent the rope 'orchain is loaded it is movable relative' to the support to permit. adjustment of the sling; however, whether the stop is fixed to or movable upon the support, means may be provided so that when, for example, a succession of identical or substantially identical articles are to be lifted, the rope or chain may be immobilised permanently.

The stop may comprise at least one pivotal member which is mounted on the support and is adapted to abut the hooked member so as to immobilise the support relative to the said member, the said pivotal member being engageable bythe hooked member and having, at least in its hook-engaged part, a curved area of a radius less than the radius of that part of the support over which the rope or chain is passed, the sling comprising means operable by realtive movement between the pivoted memher and the support, for immobilising the rope or chain and comprising, for example, one or more rope-gripping fingers or shoes.

Also the rope or chain support may be formed with an opening through which the hook passes and at least the hook-contacting portion of which is curved, its center of curvature being situated below the center of curvature of the support portion over which the rope or chain is passed. I

The rope or chain immobilising means, may comprise a flexible or articulated helical member through which the said rope or chain may be passed.

In order that the invention may be more readily understood and carried into practice, reference will now be made to the accompanying drawings illustrating various different sling constructions and wherein:

'Fig. 1 is a front elevation view of a sling constructed according to the invention.

Fig. 2 is a side elevation view of the sling shown in Fig. 1.

Fig. 3 is a diagram illustrative of the manner in which the sling functions when lifting a load.

' Fig. 4 is a front elevation view of another embodiment of the sling according to the invention.

Fig. 5 is a side elevation view of the sling shown in Fig. 3.

Fig. 6 is a plan view, partly in section, of the sling shown in Fig. 3. V

Fig, 7 is a front elevation view of a variant of the sling according to the invention.

the sling according to the invention.

Fig. 9 isa front elevation view of still another variant of the sling according to the invention.

f The sling shown in Figs. 1 and 2- comprises an annular pulley 1 of which, as indicated, the eye is adapted to be engaged by a hook 2 or a lifting apparatus and around the hub of which a rope 3 is so wound as to form one complete or dead turn as shown. The flanges or cheeks of the pulley are transversed by arod 4 which is adapted to abut across the hook 2 as shown when the pulley turns or rotates about the hook while lifting a load; the rod therefore acts as a stop which prevents the pulley from continuing its rotational movement.

When the. rope or line is slack, it is capable of turning freely around the pulley hub to enable the sling tobe adjusted or set preparatory to lifting an article or load in a manner which ensures that the article remains up right andis kept from swinging horizontally so as to be to an articles (Fig. 3) to be lifted. I As the lifting operation commences, the rope is made taut and tightens around the pulley; thefriction of the rope on thepulley' automatically prevents the rope from turning about the.

latter. a On the other hand, as shownin Fig. 3, the posi- Ptitented June 10, 1958 tion of the sling from which the article is suspended in a horizontal position, may not correspond to that in which the pulley 1 is so located that the center of the pulley, the center of gravity of the article, and the point of con tact between the pulley and hook are in the same vertical plane. In such circumstances a couple is applied to the pulley so that the latter tends to turn about its point of contact with the book 2 and move the article from the desired horizontal and upright position. However, this turning movement is prevented by the stop 4 coming into abutment with the side of the hook as soon as any such relative movement is set up between the pulley and hook. The rope 3 is therefore immobilised and the article 5 remains upright.

It is to be understood that, before the sling is adjusted or set, by turning the rope about the pulley hub, the direction in which the pulley will tend to turn as the rope is loaded at the beginning of the lifting operation will be known; consequently, no difficulty will arise in positioning the pulley in such a manner that the stop 4 will prevent the said turning movement by abutment with the hook. V

A single stop is therefore sufiicient. Nevertheless, two stops may be provided and may be spaced apart by an angular distance of, for example, 45 to 90, the hook being engaged with the pulley between the said stops.

When a number of identical or substantially identical articles are to be raised in succession, it is advantageous to provide means for immobilising the rope relative to the pulley even before the rope is loaded so that it is not necessary after an initial adjustment has been made to readjust the sling each time a fresh article is to be lifted.

In the sling shown in Figs. 1 and 2, this permanent rope-inunobilising means consist of a bolt 6 which is screwed into one of the pulley flanges or checks so that it immobilises the rope by gripping the latter between the shank of the bolt and the other flange or check. A nut 7 is provided so that the bolt may be locked.

When the rope 3 is no longer taut and the bolt has been slackened, it is again possible to turn the rope due to its inherent elasticity, about the pulley.

In the sling construction shown in Figs. 4-6, two bellcrank levers 14 are pivoted between the pulley flanges about axes 15; the upper or free end of one arm of each lever consists of a rope-immobilising shoe 17. By varying the relative lengths of the arms of each lever, it is possible to increase or decrease the force exerted on the rope by the shoe 17 when in its immobilising position.

Since the lifting hook is invariably of a much smaller cross section in the vicinity of its tip or nose than in the vicinity of its shank or heel, it is also advantageous that the stops should be adapted to assume positions which are inclined relatively to the plane of the book when brought into abutment with the latter, at the same time assuring that they remain normal to the plane of the pulley so that there is no risk that they will escape abutting the hook in the vicinity of the said nose.

For this purpose, in the construction shown in Figs. 4-6, each stop 16 is of strip-like form and extends through an opening 18 formed in the upper part of the corresponding lever arm, the said opening being of a width greater than the width of the stop but of a depth sub stantially equal to the thickness of the said stop. The stops are therefore maintained in positions normal to the plane of the pulley but may be inclined, as indicated in Fig. 6, relatively to the vertical plane of the hook. Pins 19 provided on the stops on the opposite sides of their respective levers, prevent the said stops from removal from the openings.

In the embodiments shown in Figs. 4-6, it is not necessary that the rope make a complete or dead turn around the pulley hub because the sling is provided with means for. immobilising the pulley automatically as soon as the rope is loaded. It is possible therefore, in these cmbodiments or constructions, to replace the pulley 1 by any other rope support (not shown) comprising an arcuate rope-receiving surface at its hook-engaging portion.

In the construction shown in Fig. 7, the sling comprises a pulley 1 through the throat of which the rope passes and which is formed with an eccentric hook-rcceiving aperture 37. The rope is wound into a complete or dead turn around the pulley hub.

With such an arrangement, when a load is imposed on the rope, the friction created between the rope and hub causes the pulley to turn about the hook. The force exerted in the more heavily loaded span of the said rope determines the direction in which the pulley rotates and the turning movement continues until the couple exerted by the said force is balanced by the couple exerted by the force in the other and less heavily loaded rope span, which limits the movement. The pulley therefore automatically assumes a position of equilibrium in which a vertical line passing through its point of contact with the hook, passes through the junction between the two rope spans.

Referring to Fig. 8, wherein is shown an alternative construction having two members 39 releasably engaging the book as shown and pivotally connected by pivot pin 38 on opposite sides of a semi-circular or arcuate support member 42 replacing the pulley of the other embodiments.

The members 39 are provided with pins 40 extending between members 39 and overlying the rope 3 as shown. When the sling is loaded the member 42 tends to pivot about axis 38 whereupon one of the pins 40 makes contact with the rope releasably clamping the rope between -itself and support 42. The members 39, of course, preclude movement of the support member 42 relative to the lifting hook.

In the modification shown in Fig. 9, the rope support comprises two spaced and parallel side plates 67, which are interconnected by an intermediate portion 68 over which the rope is passed, and by a helical blade spring 69 through which the rope also passes; hence, when subjected to a load, the rope extends the spring and reduces the area of the coils thereof, so that the rope is immobilised relatively to the support.

The improved sling is simple in construction and eflicient in operation, and no height is lost since the hook of the lifting apparatus is adapted to be engaged in the rope support.

What I claim is:

1. A sling comprising a guide member for supporting and guiding a line having spans to be attached to a load to be lifted, said guide member having an aperture so as to be releasably engageable by a lifting hook, said aperture being arcuate in configuration and of a dimension permitting rotational movement between said hook and said line guide member, means on said guide member for releasably engaging said hook for keeping said guide member from rotating relative to the hook when lifting a load, means disposed on the guide member for engaging the line to releasably hold the line on said guide member so as to stop relative movement between the line and said guide member, said means for keeping the guide member from rotating relative to the hook being constructed and positioned on said guide member for precluding rotation of said guide member on the hook to be releasably engageable by a lifting hook, said aperture being afcuate in configuration and of a dimension permitting rotational movement between said hook. and said line guide member, means on said guide member for releasably engaging said hook and cooperating therewith to stop and keep said guide member from rotating relative to the hook when lifting a load, means on said guide member for releasably clamping the line between it and said guide member to preclude relative movement between the line and said guide member, said first mentioned means being positioned on said guide member in a selected position for defining a selected rotation of said guide member on the hook and said aperture being positioned beneath an apex formed by spans of said line, whereby the guide member may rotate a limited angle relative to the hook when a load is applied and the weight of the load is distributed on the spans of the line and the load can be picked up without substantial swinging laterally of said hook and in a selected upright position.

3. A sling in accordance with claim 2, in which said means to stop said guide member from rotating relative to the hook is fixed to said guide member and comprises a rod positioned parallel to the axis of rotation of said support member and the means for releasably clamping the line comprising a bolt positioned on said guide member normal to said line spans so as to hold the line between it and the guide member.

4. A sling comprising, a guide member having means defining a first arcuate surface for supporting and guiding a line having span to be attached to a load to be lifted and defining a second arcuate surface releasably 6 engageable by a lifting hook, the second arcuate surface having a configuration and a dimension permitting rotational movement between said hook and said line guide member, means on said guide member engaging said hook for stopping and keeping said guide member from rotating relative to the hook when lifting a load, means on said guide member for releasably holding the line on said guide member to preclude relative movement between the line and said guide member, said second arcuate surface releasably engageable by the hook being positioned beneath an apex formed by spans of said line, whereby when a load is applied the weight of the load is distributed on the spans of the line and the load can be picked up substantially without swinging laterally of said hook and in a selected upright position.

References Cited in the file of this patent UNITED STATES PATENTS