US3178218A

US3178218A - Lifting clamp

Info

Publication number: US3178218A
Application number: US264828A
Authority: US
Inventors: Raymond L Renfroe
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-03-13
Filing date: 1963-03-13
Publication date: 1965-04-13
Anticipated expiration: 1982-04-13

Description

April 13, 1965 R. RENFROE 3,178,218

LIFTING CLAMP Filed March 13, 1963 2 Sheets-Sheet 1 A Y@Iluminull-muuu! ORNEYS April 13, 1965 R. RENFROE LIFTING CLAMP 2 Sheets-Sheet 2 Filed March 13, 1965 INVENTOR RqyffwmiLRenf'rae United States Patent 3,178,218 LETENG CLAMP Raymond L. Renfroe, 1926 Spearing St., Jacksonville, Fla. Filed Mar. 13, 1963, Ser. No. 264,828 3 Claims. (Cl. 294-101) This invention relates to clamps, and more particularly to clamps for lifting articles such as structural steel beams. This is a continuation-in-part of my pending application Serial No. 134,378, tiled August 28, 1961.

My previous application describes a clamp which is particularly useful in lifting heavy structural members such as wide ilange beams, I-'beams and the like. Such clamp has a clamp body including a slot which may be placed over the flange of an I-beam so that opposed jaws of the clamp can grip the llange on opposite sides of the slot. Such clamp also includes a lever arm pivotally connected to the clamp body and extending outwardly from the body transversely of the slot. The outer end of the lever has a connection to which a lifting cable may be attached. When the clamp is positioned on the ilange to litt the beam, the lever arm extends outwardly over the web of the beam. Thus the lifting force acts substantially in line with the center of gravity of the beam. This location of the lifting force stabilizes the beam when it is being transported and keeps the web of the beam substantially horizontal in order that the beam can be placed readily upon a new supporting surface. The clamp of my earlier application also embodies a particularly arranged clevis which permits the gripping jaws to be releasably secured in an inactive position when the beam is placed upon a new supporting surface so that the clamp can be removed from the beam without the presence of an operator at the clamp when the lifting operation is completed. The present invention is not limited to the use of such a self-releasing feature.

The clamp as described in my earlier application also includes means to transmit the lifting force to the clamp jaws so that the jaws are forceably urged into a gripping relation. This invention is directed to an improvement in the linkage for transmitting such lifting force to the gripping jaws. More particularly, the present invention encompasses improved means providing a slack-free pivotal pinned connection between the clamp lever arm and a lmovable jaw of the clamp to transm-it the lifiting force to the gripping jaws.

This invention allows the gripping jaws to be directly and immediately responsive to the application and release of a lifting force acting upon the clamp. This improved pivotal. pinned connection also eliminates looseness or play in the clamp linkage and, in a preferred embodiment, eliminates or minimizes the necessity for relative motion between sliding surfaces.

Itis, therefore, an object of the invention to provide an improved lifting clamp of the character described substantially devoid of play between the moving parts and very dependable in operation.

Another object of the invention is to provide an improved stiuctural beam clamp in which the connections transmitting the lifting force to the gripping jaws produce a direct and immediate response of the jaws to variations of the load on the clamp.

A still further object of the invention is to provide such an improved structural beam clamp which enables a lifting 4force to .be applied along a line near the center of gravity of the beam with the web substantially horizontal.

The invention generally relates to a lifting clamp comprising a clamp vbody lincluding a slot to receive an article to be lifted, a pair of opposed jaws connected to said body on opposite sides of said slot, one of said jaws being movable laterally in said slot between an inactive and a gripping position relative to the other jaw, lever means pivotally connected to said body and extending outwardly from said body transversely yof said slot, and means providing a slack-free pivotal pinned connection between the inner end of said lever means and said movable jaw to bring said jaws into an inactive relation and a gripping relation when the outer end of said lever means is depressed `and raised respectively, said lever means having at its outer end connection means whereby a lifting force applied to said connection means exerts a substantial moment on said lever means to bring said jaws into said gripping relation.

The invention hav-ing been generally described, specific embodiments will now be discussed in detail with reference to the accompanying drawings in which:

FIGURE 1 is an elevation view of one embodiment of a clamp according to the present invention shown with the jaws in a released condition and lshowing the lifting force to be applied substantially in a line with the center of gravity of a structural beam.

FlGURE 2 is a sectional view taken along the line 2-2 of FIGURE 1.

FIGURE 3 -is a sectional view taken along the line 3--3 in vFIGURE l.

FIGURE 4 is an elevation view of another embodiment of a clamp `according to the present invention shown approaching a beam to move it rfrom a horizontal to a vertical position. This form of the invention is pro-vided to automatically release the work load when placed upon a supporting surface.

`FIGURE 5 is a view of the clamp shown in FIGURE 4 gripping the beam in the process of being moved from the horizontal to the vertical position.

illustrated in the drawings is a clamp generally referred to by numeral 1-1. The clamp 11 includes a clamp body 12 having a generally U-shaped configuration defining a slot I13, which is suiciently wide to receive the flange 14 of a wide llange beam 15. The slot 13 should be Suficiently deep so that the major portion o-f the flange 14 extends into the slot. It will be understood that many diiferent articles such as I-bearns, H-beams, channels, angles, and the like can be lifted by a clamp according to this invention. y

The body 12 includes front and rear walls defining a hollow space in Ibetween as best shown in IFIGURE 2. Connected to body k12 on opposite sides of the slot 13 are a pair of jaws 17 and 13. I aw 17 lis movable transversely in the slot 13. A lower `portion of the jaw 17 has a ygripping surface 26 facing the slot 13. Such portion is integrally connected to an arm 17a which is pivotally mounted inside the hollow body 12 by a pin 19 to permit the transverse movement of the jaw. The upper end of the arm 17a is pivotally connected by pin 20 to linkage means 21. The opposite end of linkage 21 is in turn pivotaily connected to the inner end of lever 2S by pin 2-2. The linkage means 21 is preferably formed from two strap links .as best sho-wn in FIGURE 2. This linkage 21 allows the -force acting upon lever 25 to be directly transmitted to movable jaw 17. Pin 19 then permits the gripping surface 26 of jaw 17 to Ibe moved laterally in the slot 13 between an open inactive position as v'shown in FIG- URES 1 and 4 and a closed gripping position relative to the jaw 1S as shown in FIGURE 5. The yopposing jaw 18 is preferably xed against all movement except that it is rotatable about its own axis to prevent a beam from walking out of a gripped relationship by oscillation of the beam. This swivel jaw 18 is connected to body 12 by the bolt 27 and a loosely tightened nut 28 as sho-wn in FIGURE 1 and more fully described in the abo-ve mentioned copending application.

Lever of the clamp 11 is connected at its inner end to clamp body 12 by a pin 29 which extends through openings in the front and rear walis or" body 12. This pivotal connection allows the lever to freely pivot in the general plane of the body 12. The outer end of lever 25 is provided -with connection means which defines an aperture to which a lifting cable 34 may be connected by clevis 36. Thus when a lifting force is applied to the outer end `of the .lever a substantial moment is created in the lever causing it to pivot about bolt 29. The force thus exerted on lever 25 is directly transmitted through strap linkage -21 to the movable jaw 17 causing the jaw to move laterally in slot 13 into a gripping relation.

ln the operation of lifting the beam 15 by use of the clamp as shown in FIGURE 1, the slot 13 of the clamp 11 is placed over the flange 14 of the I-beam. A lifting force is then applied to the outer end of lever 25 through the action of the clevis 36 in aperture 35. A substantial moment is created which causes lever 25 to rotate upwardly about bolt 29. This force on the lever is transferred directly through pivot pin 22, strap linkage 21 and pivot pin 2) 4to the movable jaw 17, causing the flange 1d to be securely gripped between

jaws

17 and 18. It will be readily understood that this type of linkage7 which is an important feature of this invention, allows the movable jaw 17 to be directly and immediately responsive to the force upon the outer end of the lever 25 without looseness or play in the linkage.

Having been securely gripped, the beam 1S can now be lifted and transported to another supporting surface. As shown in FIGURE l, the lifting force applied to the outer end of lever 25 operates substantially in line with the center of gravity of a cross-sectional segment of beam 15 due to the lever 25 extending transversely of slot 13 a substantial distance, approaching one-half the depth of the beam. The beam 15 is, therefore, quite stable while being transported and its web remains substantially in a horizontal position. When the force on lifting cable 34- is released, gravity will cause the outer end of lever 25 to descend. The movable jaw 17 will then return, through the operation of linkage 21, to an inactive position in relation to the fixed jaw 18. Because the beam was lifted through its center of gravity and remained in this susbtantially horizontal position, it will be smoothly and uniformly placed on the new supporting surface when the clamp jaws are so released. The clamp 11 is now in a position to be removed from the beam.

FIGURE 4 illustrates clamp 11 which is an alternative embodiment of the invention. Clamp 11 is identical with clamp 11 except that the former employs a diderent type of connection at the outer end of the lever 25. Such connection is designated by the numeral 33. In this ernbodiment a bifurcated clevis 4t) is interposed between the outer end of lever 25 and the lifting cable 34. Further, the outer end of lever 25 'is here provided with an inclined slot 41 to which the bifurcated lower end of the clevis 46 is connected by bolt 42 which extends through the slot 41. If desired, a suitable bushing may be provided about bolt 42. This bolt and bushinfy are free to slide longitudinally within slot 41 and the clevis is free to pivot in the general plane of lever 25 and clamp body 12 due to the fact that the

pivotal connections

29 and 42 are substantially parallel. The upper end of the clevis defines a ring i3 for attachment of a lifting cable or the like through which a lifting force is applied to the clamp.

Extending through the bifurcated lower portion of clevis `4tl is a pin 44, positioned so that it is spaced above the upper surface of the outer end of the lever 25. Outward pivotal movement of clevis 40 is limited by stop pin 4S connected to the outer end of lever 25. An inclined cam surface 46 extends downwardly and inwardly from the top of an upward protrusion 47 located at the outer end of lever 25. Cam surface 46 terminates in a recess 48 which extends longitudinally outwardly in lever 25.

The clamp 11 of FIGURES 4 and 5 may be employed d to lift the `eam 15 in the same manner as described for clamp 11.

To explain the operation of lifting beam 15 by the clamp as embodied in FIGURE 4, it will first be assumed that such clamp is oriented as shown in FIGURE 1 with the web of beam 15 extending to the left of liange 14. Clamp 11' is then placed over the beam with the clevis 4t) retained in an inwardly pivoted position by the engagement of pin 44 with recess 48. Slot 13 is lowered over flange 14 so that the flange extends inwardly a substantial distance between

jaws

17 and 18 with the pin 44 disengaged from recess 48 and the clevis rotated outwardly relative to lever 25 A liftinf7 force transmitted through cable 34 then applies a substantial moment to lever 25' through clevis 40 and bolt 42. The outer end of lever 25 is thereby raised pivotally about bolt 29, urging pin 22 against strap link 21, which in turn moves jaw 17 into an active position by acting on pin 2t). Flange 14 is thus securely gripped between

jaws

17 and 18 and can now be moved to a new supporting surface. Again, this linkage allows the jaw 17 to be directly and immediately responsive to movement of the lever 25 without play and improves the eicient operation of the clamp.

When the beam 15 is placed upon a new supporting surface, the lifting force on cable 34 is released, and bolt 42 descends in slot 41 by the force of gravity on clevis 49. Pin 44 simultaneously engages cam surface 45 and the clevis rotates inwardly until pin 44 engages recess 4S, releasably locking the clevis in this inwardly pivoted position.

As more fully described in my ccs-pending application, when the clevis 4t) is locked in this inward position, any force applied to cable 34 now acts in substantial alignment with slot 13 and imposes substantially no moment on lever 25. Therefore, jaw 17 is retained in an inactive position and the clamp canV be removed upwardly without the aid of an operator manually detaching it from the beam.

FIGURES 4 and 5 show the clamp as shown in F1Cr- URE 4 being employed to move beam 15 from a horizontal to a vertical position. This is I'accomplished by placing lever 25' of the clamp transversely outside` of the web portion of the beam, as shown in FIGURES 4 and 5. This operation is also more fully described in my lo-pending application.

While the invention has been described with reference to preferred embodiments, many other modications may be made by persons skilled in the art without departing from the scope of the invention which is defined solely by the appended claims.

What is claimed is:

l. A lifting clamp comprising a clamp body having a slot which is vertical when said clamp is in normal lifting position to receive one end of a vertical flange of a horizontal I-beam, a pair of opposed jaws connected to Said body on opposite sides of said slot, one of said jaws being movable between an inactive and a gripping position relative to the other'jaw, said movable jaw comprising an elongated upright -arm pivotally connected by a first pin to said body with upper and lower arm portions above and below said rst pin and facing said slot, lever means pivotally connected to said body by a second pin spaced above said lirst pin and connected to said upper arm of said movable jaw to urge said movable jaw toward said gripping and inactive positions when the outer end of said lever means is raised and depressed respectively, said lever means having a relatively long portion on one side of said second pin extending transversely of said slot and a relatively short portion on the other side of said second pin, said long lever portion extending a substantial horizontal distance outwardly from said body and being on the same side of said slot as said movable jaw so that said long lever portion extends over the I-beam web when said movable jaw is on the inside of the I-beam flange, said long lever portion having at its outer end connection means spaced a substantial horizontal distance from said slot, whereby a 5 vertical lifting force may be applied to said connection means along a line passing near the center of gravity or the I-bearn to bring said jaws into said gripping relation and lift the l-beam without substantial canting of the I-bearn.

2. A lifting clamp comprising a clamp body having a slot which is vertical when said clamp is in normal lifting position to receive one end of a vertical flange of a horizontal l-beam, a pair of opposed jaws connected to said body on opposite sides of said slot, one of said jaws being movable between an inactive and a gripping position relative to the other jaw, said movable jaw comprising an elongated upright arm pivotaily connected by a first pin to said body with upper and lower arm portions above and below said rst pin respectively, said lower arm portion having a gripping surface below said first pin and facing said slot, lever means pivotally connected to said body by a second pin spaced above said rst pin, said lever means having a relatively long portion on one side of said second pin extending gener-ally perpendicular to said slot a substantial distance outwardly from said body and a relatively short portion on the other side of said second pin, extending downwardly from said second pin, said long lever portion being on the same side of said slot as said movable jaw so that said long lever portion extends over the I-beam web when said movable jaw is on the inside of the I-beam iange, and a link pivotally connected by a third pin to the lower end of said short lever portion and by a fourth pin spaced horizontally from said third pin to the upper end of said upper arm portion, said long lever portion having at its outer end connection means spaced a substantial distance horizontally from said slot, whereby a vertical lifting force may be applied to said connection means along a line passing near the center of gravity of the I-beam to bring said jaws into said gripping relation and lift the I-beam without substantial canting of the I-bearn.

3. A lifting clamp comprising a clamp body having a slot which is vertical when said clamp is in norm-al lifting position to receive one end of a vertical iiange of a horizontal -beam, a pair of opposed jaws connected to said body on opposite sides of said slot, one of said jaws being movable between an inactive and a gripping position relative to the other jaw, said movable jaw comprising an elongated upright arm pivotally connected by a first pin to said body with upper and lower arm portions above and below said i'irst pin respectively, said lower Iarm portion having a gripping surface below said first pin and facing said slot, lever means pivotally connected to said body by a second pin spaced above said irst pin, said lever means having a relatively long portion on one side of said second pin extending generally perpendicular to said slot a substantial distance outwardly from said body and a relatively short portion on the other side of said second pin extending downwardly from said second pin, said long lever portion being on the same side of said slot as said movable jaw so that said long lever portion extends over the I-beam web when said movable jaw is on the inside of the Lbeam flange, and a link pivotally connected by a third pin to the lower end of said short lever portion and by a fourth pin spaced horizontally from said third pin to the upper end of said upper arm portion, said long lever portion having at its outer end connection means spaced a substantial distance horizontaily from said slot, whereby a vertical lifting force may be appiied to said connection means Ialong a line passing near the center of gravity of the l-bearn to bring said jaws into said gripping relation and lift the l-beam without substantial canting of the -beam, said connection means comprising a clevis having at its upper end means for securing a lifting cable thereto and at its lower end a pivotal connection to the outer end of said long lever portion, said cievis having a iirst position pivoted about said clevis pivotal connection outwardly relative to said lever means where lifting force applied to the upper end of the clevis extends along a line laterally spaced a substantial distance from said slot to exert a substantial moment on said lever means to bring said jaws into :a gripping relation, and releasable means to retain said clevis in a second position pivoted about said pivotal connection inwardly relative to said lever means where lifting force applied to the upper end of the clevis extends along a line substantially aligned with said .slot to exert substantially no moment on said lever means to leave said jaws in inactive relation.

References Cited in the le of this patent UNITED STATES PATENTS 2,284,006 McLellan May 26, 1942 2,360,602 Waldrup Oct. 17, 1944 2,393,101 Gardner Ian. 15, 1946 2,851,300 Thayer Sept. 9, 1958 3,008,750 Wansley Nov. 14, 1961 3,071,406 Lucker Jan. 1, 1963

Claims

1. A LIFTING CLAMP COMPRISING A CLAMP BODY HAVING A SLOT WHICH IS VERTICAL WHEN SAID CLAMP IS IN NORMAL LIFTING POSITION TO RECEIVE ONE END OF A VERTICAL FLANGE OF A HORIZONTAL I-BEAM, A PAIR OF OPPOSED JAW CONNECTED TO SAID BODY ON OPPOSITE SIDES OF SAID SLOT, ONE OF SAID JAWS BEING MOVABLE BETWEEN IN INACTIVE AND A GRIPPING POSITION RELATIVE TO THE OTHER JAW, SAID MOVABLE JAW COMPRISING AN ELONGATED UPRIGHT ARM PIVOTALLY CONNECTED BY A FIRST PIN TO SAID BODY WITH UPPER AND LOWER ARM PORTIONS ABOVE AND BELOW SAID FIRST PIN AND FACING SAID SLOT, LEVER MEANS PIVOTALLY CONNECTED TO SAID BODY BY A SECOND PIN SPACED ABOVE SAID FIRST PIN AND CONNECTED TO SAID UPPER ARM OF SAID MOVABLE JAW TO URGE SAID MOVABLE JAW TOWARD SAID GRIPPING AND INACTIVE POSITIONS WHEN THE OUTER END OF SAID LEVER MEANS IS RAISED AND DEPRESSED RESPECTIVELY, SAID LEVER MEANS HAVING A RELATIVELY LONG PORTION ON ONE SIDE OF SAID SECOND PIN EXTENDING TRANSVERSELY OF SAID SLOT AND A RELATIVELY