US2533795A - Tongs - Google Patents

Description

Patented Dec. 1 2,l 19510 UNITED STATES PATENT OFFICE TONGS Harvey R. Hansen, Jr., Detroit, Mich.

Application July 28, 1947, Serial No. 764,178

4 Claims. l

This invention relates generally to gripping devices of the type employed to hold an object while the latter is being raised or transported and. refers more particularly to improvements 1n tongs.

One of the objects of this invention is to provide a gripping device comprising tongs having reliable means for iirmly gripping an object and having readily operable means for quickly releasing the object when desired.

A more detail object of this invention is to provide tongs having arms pivotally connected together adjacent the upper ends for relative swinging movement and having gripping dogs respectively pivoted to the lower end portions oi the arms for swinging movement from a released or inoperative position to an operative position wherein the dogs extend laterally inwardly from the arms into gripping engagement with an object between the arms.

Another feature of this invention is to provide tongs of the above type having latch means on each arm for engagement with the dog on the latter to hold the dogs in their operative or object gripping positions and having means for,

operating the latch means as a unit to simultaneously release both dogs from the object.

The foregoing as Well as other objects will be made more apparent as this description proceeds especially when considered in connection' with the accompanying drawing wherein:

Figure l is a Side elevational view partly in section oi a gripping device embodying tongs constructed in accordance with this invention and showing the gripping dogs in their operative and inoperative positions; and

Figure 2 is a fragmentary side elevational view of the tongs shown in Figure l. l

The gripping device forming the subject matter of this invention is in the form of tongs I9 comprising a pair of arms II, a pair of gripping dogs I2 and latch elements i3 for the dogs. The upper end portions of the arms II cross each other and are pivotally connected by a pin I4 permitting relative swinging movement of the arms in substantially parallel planes. The extreme upper ends of the arms are connected by links I5 to a lifting chain I6 in such a manner that up- Ward movement of the chain applies a force to the upper ends of the arms Il in a direction to swing the lower end portions of the arms in- Wardly or toward each other.

The lower end of each arm II is bifurcated to provide a recess I I of sufficient width to freely receive a gripping dog I2 and a latch element Cil ' ing movement of the arms to permit swinging ple, as a log between the arms Il.

movement of the dogs I2 from the released positions shown by the broken lines in Figure 1 of the drawing to the operative or gripping positions shown by the full lines in the same figure of the drawing. It will be noted that since the .dogs I2 are pivoted adjacent the upper ends to the respective arms I I the action of gravity urges the dogs to their inoperative or dotted line positions shown in Figure 1 of the drawing.

The latch elements I3 are respectively pivotally mounted at their upper ends on the arms II by pins I9 extending transversely of the recesses I'I above the pins I8 and anchored on the furcations of the arms. Thus, the latch elements I3 normally extend downwardly from the pins I9 and the latter are respectively spaced laterally outwardly from the pins I8 to position the lower or swinging ends of the latch elements at the laterally outer sides of the dogs I2 when the latter are in their inoperative positions. In this connection it is to be noted that the outer edges o1" the dogs I2 are arcuate and provide cam surfaces 20. The cam surfaces 2Q respectively engage the swinging ends of the latch elements at the laterally inner sides of the elements so that as the dogs I2 are swung in a clockwise direction about their respective pins I3 to the operative positions shown in Figure 1 oi' the drawing, the latch elements I3 are swung outwardly by the cam surfaces 26 on the dogs to clear the upper ends of the dogs. As soon as the upper ends of the dogs l2 clear the lower ends of the latch elements I3, the latter return by the action of gravity to their latched positions wherein the lower 4ends of the latch elements are positioned to respectively engage the inner edges of the upper ends of the dogs and hold the latter in their operative positions.

When the dogs I2 are held in their operative positions by the latch elements I9, the lower ends of the dogs project laterally inwardly from the lower ends of the arms Il and cooperate with one another to grip an object 2l such, for examlt will be noted from Figure l of the drawing that when an object is gripped by the dogs the force applied to the dogs by the weght of the object is transmitted directly to the pins I9 through the latch elements and accidental release of the dogs from the object is prevented. It will further be noted from Figure 1 of the drawing that pins or stops 22 are respectively secured to the lower ends of the arms in positions to limit the extent of swinging movement of the dogs l2 to their operative positions.

The dogs l2 remain in their operative positions until the latch elements i3 are swung upwardly and outwardly out of the path of travel of the upper ends of the dogs. This is accomplished by providing a cable 2t having the opposite ends respectively connected to the swinging ends of the latch elements at the laterally outer sides thereof. The ends of the cable are passed up: wardly over pins 2d and through suitable guides 25 secured to the arms il. A suitable handle 2Q is secured to the cable 23 intermediate the ends thereof in a position to enable the same to be readily gripped by the operator. The construction is such that a downward pull on the cable intermediate the ends thereof simultaneously swings the latch elements ESS outwardly to their released positie-ns against the pins 2d. When in this position the dogs are released from the-latch elements and are free to swing in a counter-clockwiserdirection to release the object gripped there- Veach dog at one side of the pivot axis thereof and a latch engaging part on each dog at the opposite side of said pivot axis, a pair oflatch elements having the upper ends respectively pivotally supported on the arms at points spaced above the dogs and having the lower end portions engageable with the latch engaging surfaces on the dogs to locate the gripping portions of the dogs in positions to grip an object locatedbetween the arms, and selectively operable means connected to the swinging ends of the latch elements for simultaneously swinging the. latch elements outwardly to release the dogs.

2. A device for gripping objects, comprising tongs having a pair of arms pivotally connected together at the upper ends thereof for swinging movement toward and away from one another, a pair of dogs respectively pivotally connected intermediate the ends thereof on the lower end portions oi the arms, a gripping portiony on each dog at one side of the pivot axis and a latch engaging part on each dog at the opposite side of the pivot axis, said dogs being normally urged to positions wherein the gripping portions there-V of extend in a downward direction from the pivot axes, a pair of latch elements havingA the upper ends respectively pivotally supported on the arms at points spaced above the dogs and having the lower end portions respectively engageable with the latch surfaces on the dogs to hold the latter in positions wherein the gripping portions project inwardly with respect to the arms, a flexible linear member having the opposite ends respectively connected to the lower ends ofthe latch elements at the outer edges thereof and extending upwardly along the respective arms and having an intermediate portion accessible for manipulation to simultaneously swing the latch elements out of engagement with the dogs.

3. A device for gripping objects, comprising tongs having a pair of arms pivotally connected together adjacent the upper ends thereof for swinging movement toward and away from each other, a pair of dogs respectively pivotally connegated intermediate the ends Vto the lower end portidnsV of the arms, a gripping portion on each dog at one side of the pivot axis and a latch engaging part on each dog at the opposite side of the pivot axis, said dogs being normally urged to positions wherein the gripping portions extend ina downward direction from the pivot axes, a pair of latch elements having the upper ends respe@tivelyv pivotally connected to the arms at points spaced above the dogs and having the lower swinging ends extending downwardly to positions adjacent the outer edges of the dogs whereby inward swinging movement of the dogs to their object gripping Positions engages. the outer edges ci' said dogswith the lower swinging ends of the` latch elementsland camsy thev lower ends of the latch elements into engagement with the latch engaging parts on the dogs to latch the latter in their object gripping positions, and means for selectively swinging thelatch elements outwardly to release the same 4from said dogs.

4. A device for gripping objects, comprising tongs having a pair of arms pivotally connected together adjacent the upper ends thereof for swingingY movement toward andV away from each other, a. pai; of dogs respectively pivotally connectedV intermediate the ends tothe lower end portions of the arms, a gripping portion en each dog at one side of the pivot axis and a latch engaging part on each dog at the opposite side of the pivot axis, said dogs being normally urged to positions wherein the gripping portions ex- ,tend in a downward direction. fromthepivot axes and having arcuate camjsurfaces. at the outer `edges thereof, a pair of latch elements having the upper ends respectively pivotally connected to the arms at points spaced above the dogs' and having the lower ends extending Vdownwardly to positionsv adjacent thecam surfaces at the outer edges of the dogswherebyinward swingingmovement of thek dogs to ther object. gripping posiu tions engasesthe cam surfaces on the dogs with the lower ends of the latch elementsand swings the latter eutwardly .sumciently to .enablethe latch engaging surfaces en .thev dogs to. assume positions below the lowerends of the. latchelements. the locaties ofA the nirctaxes of inenten 'elements vwith respect EQ the, iYQt axes of the dOgS btllg'sllh. thatthe lo r ends. of the latch elements are normally nes lenedteengage the latchisuriaces on the dogs, ble linear member connected. t0 the. latch elements f0.1? Simuita latter outwardly to releasethe de y. swinging "the REFERENCES 011th The fcllowing references are ef record in the le of.y this patent:

UNITED STATES PA'LENTS;

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