US3008749A

US3008749A - Lifting clamp

Info

Publication number: US3008749A
Application number: US725848A
Authority: US
Inventors: Willard E Gowan
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-04-02
Filing date: 1958-04-02
Publication date: 1961-11-14
Anticipated expiration: 1978-11-14

Description

W. E, GOWAN LIFTING CLAMP Filed April 2, 1958 wlLLARD E. GOWAN A ATTORNEYS NOV. 14

United States Patent 3,008,749 LIFTING CLAMP Willard E. Gowan, Rte. 2, Box 159, Arnold, M0. Filed Apr. 2, 1958, Ser. No. 725,848 7 Claims. (Cl. 294-86) The present invention relates to improvements in clamping devicesused for gripping and lifting heavy .metal sheets, plates and bars.

An object of the invention is to provide an improved lifting clamp of strong and rugged construction having extraordinary gripping power land lifting capacity for Vits size and weight.

Another object is to provide improved means in the form of coacting, toothed rollers for gripping the load object.

Yet -another object is directed to the provision of an improved lifting clamp having grip rollers Which are i `supported directly by the clamp body. Accordingly,

subjected to load forces.

Yet'another object is achieved in a lifting clamp of the character described wherein the gripping members have toothed surfaces in meshing, rolling contact with rack members arranged to direct and bold the grip member in tight wedging engagement with the load object.

These and other objects and advantages including construction features that make for economyA of manufacture are Iachieved in the lifting clamp illustrated and described herein.

I-n the drawing:

FIG. l is a perspective view showing the lift-ing clamp of my invention with a load object carried thereby;

FIG. 2 is a vertical sectional view through the clamp .with the clamping rollers arranged in a relatively retracted position, the section being taken at -a plane indicated by line 2-2 of FIG. l;

FIG. 3 is a sectional view similar to FIG. 2 but Ywith the rollers positioned near the vlower end of the clamp body, or in a normally gripping position;

FIG. 4 is a vertical sectional view taken at line 4-4 of FIG. 3;

FIG. 5 is a vertical sectional view taken fat a plane indicated by iine 5-.5 of FIG. 2, and

FIG. 6 illustrates the pattern `of the impression made Yby the roller elements on a load object.

,Referring now by numerals of reference tothe drawings, 8,designates the body of the Vclamp which is formed for the most part by a pair of opposed sideplates 9. Relatively thickened uppery parts 10 ofthe plates 9 are integrally united by av welded peripheral seam indicated at 11. The clamp body is provided with an eye 12 in the solid upper portion, the eye `12 serving to receive a hook 13 of a hoisting chain or cable. Below the eye -12 the-side plates 9 are spaced apart to accommodate between them the

grip rollers

14 and 14a and associated mechanismto be hereinafter described. for adjusting the y positionsfof the said rollersvin the clamp body. The side `plates taper downwardly from .a relativelysbroad mid- 'section kand .arepermanently united by welding to

bars

15 and 15a thatfit between and extend convergingly `along the lower side edges of kkplates 9. The bars 1 15 and 15a also herein referred to asrack bars, have offset shoulders 16 (FIG. 1) that interi-it with corresponding shoulders on the sideplates for `reinforcing the junction between plate 9 and the said rack bars.

koutwardly into the stop shoulders.

ice

As best appears in FIGS. l, 2 and 3, openings 17 of substantial size are present inthe sides off the body member, through .which openings the rollers and their control mechanism are introduced into the clamp body. The

.clamp .body is also provided with a transverse passagewayforY slot 18 dened by recesses 19 that extend longitudinally, Vlinwardly from the lower ends of the side ship.

The

rollers

14 and 14a are adapted to roll on the bars 15 .and 15a constituting tracks, the bars being provided .with rack teeth 21 that mesh with the teeth 20 of the associated roller. The teeth 21 prevent slippage of the rollers on thebars. `It will be noted that several of the teeth 22 near the upper ends ofthe rack bars are oiset inwardly with respect to the teeth 21.

Such resultsl in the formation of a stop shoulder or dwelling station 35 for the rollers. When the rollers are retracted to a position near the upper extremities of the bars (FIG. 2) they are detained there by the stop shoulders 35, the spring 33 tending to urge the rollers After thelever 30 is moved downwardly enough to move the rollers vdownwardly outof engagement with stop shoulders A35, it is seen that tension spring 33 imposes a downward force on lever 30 that tends to move the lever 3i), and hence tends to move the

arm members

24 and 27 fand Ythe entire roller assembly downwardly tothe position 'indicated in FIG. 3.

Roller 14 is rotatively mounted on a pin 23- carried on the lower end of an arm member 24, constituting an offset lever. The fulcrum of arm member 24 is constituted by coaxial pins located substantially in the lrnigitudinal medial plane orf the passageway y18. Roller 14apis carried on a bearing pin 26 at the lower end of antarm member Z7 which is pivoted to arm member 24 by the pins 25. Arm member 24 has an arm portion 28 extending upwardly beyond the axis of Ypins25, portion 28 being connected by a pin 29 to -a lever 30.

Lever 30 is pivoted to the clamp body by a pin 31, one

yend 32 of which is threaded` in a threaded bore in one of the siderplates 9 of the body, as shown in FIG. 4. Unthreading and removal of the fulcrum pin 3,1 for lever 30 enables the Yentire roller assembly to be detached and removed from` the clamp body yas a unit through one of the side openings 17. Similarly, securement of the roller 'assembly to the body is effected by the single threaded pin 31.

A tensionA spring 3:3 is connected at its upper end to the lever 3i) and at .its lower end to the member. 27. Spring 33 acts directly on arm member 27 to urge the arm member 27 outwardly to maintain roller 14a .in meshing ...engagement rwith the sloping rack bar 15a.

jSpring 33 also acts through common pivot pins 25 to i urge the arm member 24 outwardlyto maintain roller 14 constantly in Amesh with i-ts rack bar 15. Thisre- `sults because of the counterclockwise force on memberV 27 `acting on arm member 24 through their connnon ivot pins 25 to vcreate a clockwise force on arm member 24, tending to .hold roller 14 .outwardly 3 to move the

arm members

24 and 27 and entire roller assembly downwardly to the positions thereof illustrated in FIG. 3 after the

rollers

14 and 14a are disengaged from stop shoulders 35, all as described previously.

The lever 30 projects outwardly of the clamp body and preferably carries a control chain 34 at its outer end.

From the foregoing description it will appear that the

grip rollers

14 and 14a are adapted to be retracted upwardly by swinging lever 30 upwardly. As they roll upwardly the rollers also move outwardly along the divergent rack bars 15. In their uppermost positions theY rollers are clear of the passageway 18 and are retained in their said upper positions, against the action of spring 33, by the stop shoulders formed on the said rack bars. The lifting clamp may then be applied by introducing the lo-ad object into the passage 18 of the clamp body and exerting a light downward tug on the control chain 34. The

rollers

14 and 14a are thereby caused to ride over the stop shoulders 35 of the rack bars and, moving downwardly under the action of spring 33, to come to rest wedged between the surfaces o-f the load objectand the sloping

rack bars

15 and 15a. When the clamp is lifted the load object becomes tightly gripped by the roller teeth, the downward lload yforce on the rol-1ers tending to increase their grip on the object. The object is released by raising the lever 30.

From the foregoing description it will be understood that the grip rollers are caused to move simultaneously along their rack bars, maintaining their opposed relationship in all positions. It will appear that the internal mechanism for controlling movement of the grip rollers and the grip rollers themselves are installed and removed as a unitary assembly to `and from the cl-amp body. It will further appear that load forces are transmitted to the clamping body directly from the grip rollers yand not through lany of the linkage by which movement ofthe grip rollers is controlled.

VWhereas l have describe-d a particular, preferred form of clamp, it will be understood that changes may be made in the described parts and their arrangement without departing from the spirit and full intendment of the invention which is defined by the appended claims.

I claim as my invention:

l. A lifting clamp comprising a hollow clamp body Vprovided with a passageway extending through opposite sides of the body and extending through the lower end of the body, the passageway extending upwardly from the lower end of the body, downwardly convergent tracks in said body, one track on each s-ide of said passageway, said tracks terminating at the sides of said passageway, rollers in said body, one roller engaging each track, a lever pivoted to the body, arm members in said body, means pivotally connecting said arm members, each arm member being connected to one roller, means pivotally connecting one of said arm members to said lever, and a tension spring interconnecting said lever with one of said arm members, the connection of the tension spring to the lever being at the same side of the levers pivotal connection to the body as the pivotal connection of the 'arm member to said lever, said rollers being extensible into the passageway while ltill engaging the tracks so as to grasp an article to be 'fted.

2. A lifting clamp comprising a hollow clamp body provided with a passageway extending through opposite sides of the body and extending through the lower end of the body, the passageway extending upwardly from the lower end of the body, a pair of downwardly convergent tracks in said body, one track being disposed on each side of said passageway, said tracks terminating yat the sides of said passageway, rollers in said body, one roller engaging each track, a lever pivoted to the body, a pair of arm members in said body, said arm members having their lower ends connected to the rollers, means pivotally connecting the opposite end of one arm member to the other arm member intermediate its ends, means pivotally connecting the opposite end of said other arm member to said lever, and a tension spring connected to the lever at the same side of its pivotal connection to the body as the pivotal connection of the said other arm member to said lever, and connected to one of said arm members, the tension spring tending to urge said rollers outwardly and downwardly against said tracks, said rollers being extensible into the passageway while still engaging the tracks so as to grasp an article to be lifted.

3. A lifting clamp comprising a hollow clamp body provided with a passageway extending through opposite sides of the body and extending through the lower end of the body, the passageway extending upwardly from the lower end of the body, downwardly convergent tracks in said body, one track being disposed on each Vside of said passageway, said tracks terminating at the sides of said passageway, rollers in said body, one roller engaging each track, said rollers being adapted to move away and toward each other in said passageway while engaging the tracks so as to release and grasp respectively lan article to be lifted, a lever pivoted to said body above said rollers, a first arm member and a second arm member in said body below the lever and above the rollers, said arm members having their lower ends connected to said rollers, the opposite end of said first arm member being pivotally connected to the second arm member intermediate the ends of said second arm member, the opposite end of said second arm member being pivotally connected to said lever, and a tension spring interconnecting said lever with said first arm member, the connection of said tension spring with said llever being at the same side of the levers pivotal connection to the body as the pivotal connection of the second arm mernber to said lever and at a distance farther from the levers pivotal connection to the bodyl than the pivotal connection of the second farm member to said lever, said tension spring tending to urge said rollers outwardly and downwardly against said tracks.

4'. A lifting clamp comprising a hollow clamp body provided with a passageway extending through opposite sides of the body and extending through the lower end of the body, the passageway extending upwardly from the lower end of the body, tracks in said body, one track being disposed on each side of said passageway, the tracks terminating at the sides of the passageway, rollers insaid body, one roller engaging each track, said tracks being downwardly oonvengent adapting said rollers to move toward and away from each other in said passageway while engaging the tracks so as to grasp and release respectively an article to be lifted, `a lever pivoted to said body above said rollers, a pair of arm members in said body below the lever and above the rollers, said arm members being pivoted together, each of said arm members being connected to one of said rollers, means pivotally connecting one of said arm members to said lever at one side of the pivotal connection of such lever to said body, and a tension spring connected to the lever at the same side of the levers pivotal connection to the ,body as the pivotal connection of the one arm memsaid roller outwardly against said stop shoulder, said stop shoulder retaining the rollers in retracted position. 6. The combination and arrangement of elements as recited above claim 4, but further characterized in that the tension spring has one end connected to the lever at the same side of the levers pivotal connection to the body as the pivotal connection of the one arm member to said lever and at a distance farther from the levers pivotal connection to the body than the pivotal connection of the arm mem-ber to said lever, the tension spring having its other end connected to the other of the arm members, the tension spring tending to urge said lever downwardly and tending to urge said arm members apart and said rollers outwardly against said tracks.

7. A lifting clamp comprising a hollow clamp body provided Iwith a passageway extending through opposite sides of the body and extending through the lower end of the body, the passageway extending upwardly from the lower end of the body, tracks in said body, one track bein-g disposed o-n each side lof said passageway, said tracks terminating at the sides o-f the passageway, rollers in said body, one roller engaging each track, said tracks being downwardly convergent enabling said rollers to move toward and away from each other in said passageway while engaging the tracks so as to grasp and release respectively an article to be lifted, a lever pivoted to said body above said rollers, 'a first arm member and a second arm member in said body below the lever and above the rollers, means pivoting one end of the first arm member to the said second arm member intermediate the ends of said second arm member, said arm members having their lower ends connected to said rollers, means pivotally connecting the upper end of said second arm member to said lever, a tension spring having one end connected to the lever at the same side of the levers pivotal connection to the body as the pivotal connection of the semnd arm member Ato said leve-r and at a distance `farther from the levers pivotal connection to the body tha-n the pivotal connection of said second arm member to said lever, the tension spring having its other end connected to said rst arm member, and a stop shoulder intermediate of at least one of said tracks engaging the roller on said track when the lever is raised, the tension spring tending to urge the rollers outwardly and hence tending to urge one of the rollers against the stop shoulder so as to retain said rollers in a retracted position, the tension spring tending to urge the lever downwardly, and lnence tending to urge the rollers downwardly on said tracks.

References Cited in the le of this patent UNITED STATES PATENTS 2,387,408 Pertuit Oct. 23, 1945 2,461,394 Plante Feb. 8, 1949 2,559,223 Murray July 3, 1951