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Publication numberUS3574381 A
Publication typeGrant
Publication dateApr 13, 1971
Filing dateNov 15, 1968
Priority dateNov 15, 1968
Publication numberUS 3574381 A, US 3574381A, US-A-3574381, US3574381 A, US3574381A
InventorsRobert M Ocheltree, Jack L Thompson
Original AssigneeJack L Thompson, Robert M Ocheltree
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Clamping tool
US 3574381 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

United States Patent V In Huntsman 294/94 Kok 294/96 Prcvost 294/100X Hutchinson 294/94 Herkner 294/96X Haas 294/94X FOREIGN PATENTS Great Britain 294/94 Primary Examiner-Evon C. Blunk Assistant ExaminerRoger S. Gaither Attorney-Nienow & Frater ABSTRACT: This invention relates to improvements in clamping tools of the kind in which a number of clamping elements are movable to change the separation between them in a given plane by the application of a force in a direction making an angle with that plane and usually perpendicular to the plane. The embodiment selected for illustration is a clamping tool whose elements are moved apart to clamping position by forcing a cam between spring elements to which the clamping elements are fixed.

CLAMPING TOOL This invention relates to improvements in clamping tools of the type in which clamping elements movable in one plane are moved to clamping position by application of forces at a distance and in a direction perpendicular to the plane of movement of the clamping elements.

While the invention is not limited thereto, it is particularly useful for incorporation of clamps of the expansible type. Some clamps have elements that are squeezed together upon the exterior of an object to be held in the clamp. Other clamps, called expansible clamps, have clamping elements that are adapted to be moved apart to accomplish clamping action. Such an expansible clamp is inserted into an opening in the article to be clamped.

In a broader sense the invention is applicable to devices of either type but its employment is particularly advantageous in the case of the expansible clamp. Accordingly, the embodiment selected for illustration in the drawings, and for specific description in the specification, is an expansible clamp. Various modifications are possible, the selected modification is particularly suited to extraction of the hydraulic valve-actuating pistons from internal combustion engines. Extraction of such pistons is a particularly difficult job in many, if not most, of the commercially available engines that employ them. It is an object of the invention to provide a tool by which those pistons can be removed although they be located at a point impossible for a mechanic to reach with his hand. A related object is to provide a tool requiring only one hand in operation and which can be used successfully for the task even when the mechanic is unable to see the piston he is attempting to remove. Other objects are to provide a tool which can be readily produced at'minimum cost, in a form that is safe to use, and in a form that is sufficiently rugged to obviate any need for special handling or special care. Another object is to provide a tool whose operation is readily apparent and which can be operated by either hand.

Certain of these and other objects and advantages of the invention which will hereinafter appear are realized in part by the provision of a clamping tool comprising a plurality of clamp elements movable toward and away from one another in a plane; means biasing those elements to predetermined distance from one another in that plane; interconnection means interconnecting clamp elements for movement together without changing their relative position; and by the provision of actuating means carried by the interconnection means for altering the position of the clamp elements relative to one another as a function of the degree of relative movement between the actuation means and the interconnection means.

In the drawings:

FIG. 1 is an isometric view of a tool embodying the invention, the clamping elements of which are shown to be clamped to the interior of a workpiece, here a hydraulic piston;

FIG. 2 is a view in side elevation of the tool of FIG. 1;

FIG. 3 is a cross-sectional view of the tool of FIGS. 1 and 2, taken on line 3-3 of FIG. 2; and

FIG. 4 is a view in front elevation of the lower end of the tool illustrating the relation between its several parts when the actuating means is actuated to move the clamping members to clamping position.

Referring to FIG. 1 of the drawing, the numeral designated generally a workpiece which it is desired to clamp. The workpiece 10 here shown is a piston which comprises a part of the hydraulic system for actuating the valves in an internal combustion engine. The piston fits within a bore such that a mechanic is precluded from removing it with his fingers and, as in many engines, there may be insufficient clearance for him to get his hand to the mouth of the bore. The clamp tool, generally designated 12, is arranged so that the mechanic can remove the piston, and replace it, without dismantling a substantial number of the engine parts.

The tool 12 is provided with clamp elements which are movable toward and away from one another in a plane to provide a clamping action. The typical hydraulic piston does not have a reduced diameter or any other configuration at its exposed ends by which its exterior surface may be grasped. Accordingly, the tool .12 is arranged so that its clamping elements are expanded into engagement with an interior wall of the piston. Most hydraulic valve-actuating pistons are provided with a groove on an interior surface which can be reached from the end of the piston and the clamping element in this embodiment is of dimension to engage that groove. It is to be understood that the clamping tool may have other configurations by which to adapt it to the specific configuration of other structures which it may be used to clamp. The configuration selected for this embodiment has the advantage that it is suitable for clamping a wide variety of structures in addition to hydraulic valve-lifting pistons.

Means are provided in the invention for biasing those clamping elements to a selected position or a selected spacing one from another, in the plane in which they move to accomplish clamping action. Advantageously, that means comprises a spring which may, as in the embodiment selected, be formed integrally with the clamping elements. The tool also comprises an interconnecting means by which all of the clamping elements are held together in predetermined position so that they can be moved around together. This element may be thought of as the body of the tool structure to which all of the clamps are connected and with respect to which they move to accomplish clamping action, but with respect to which the several clamping elements are held in fixed relative relation by the biasing means. Advantageously, as shown, this element of the invention comprises an elongate tubular member to one end of which all of the unitary biasing and clamping elements are connected.

The invention also comprises an actuating means by which the several clamping members are moved against the biasing means to a position in tight engagement with the structure to be clamped. In the preferred form of the invention this actuating means comprises a cam which cooperates with the biasing means or the clamping elements, or both. The cam is actuated by force applied at a distance from the clamping elements and cam and in a direction perpendicular to the plane at which the clamping elements are moved. This arrangement has the advantage that the clamping action is accomplished by a force directed along the line in which the tool is inserted and removed from work position.

Furthermore, in the preferred embodiment means are provided for maintaining the clamping element in any position to which they have been actuated by the application of a force without the need to maintain that force. This can then be accomplished in various ways within the invention. Advantageously, it is accomplished by the use of friction between the camming element and the cam surface with which it cooperates.

Referring again to the drawing, the embodiment shown comprises an interconnection member in the form of an elongate tube 14. It further comprises a clamp member 16, a biasing means in the form of a cantilever spring 18 one end of which is connected to the clamp member 16 and the other end of which is connected by any suitable means, as by welding m shown, to the lower end 20 of the tube 14. In this embodiment the lower end of the tube is notched and the upper end of the spring 18 is fitted into the notch where it is welded along a weld line 22. At its upper end 24 the tube 14 is fitted with a crosspiece 26 which is secured to the upper end by any convenient means such, for example, as by welding, as shown. The crosspiece 26 is arranged perpendicularly to the axis of the tube 14 with its center point coincident with the axis. The crossmember 26 extends laterally beyond the tube 14 on both sides to form an extension 28 on one side and an extension 30 on the other which can accommodate the index and forefinger of a hand holding the tool when the thumb of that hand is arranged in overlying relation to the upper end of the actuating means. The actuating structure comprises a rod having a cam at one end disposed between the clamping elements and their biasing means. The upper end of the rod extends beyond the tube 14 to a point above the crossmember 26 where it terminates in a structure suitable for the application of force lengthwise of the rod by the thumb of the user. In this embodiment a knurled knob 32 is fixed to the upper end of the actuating rod.

The whole of the actuating member is visible in the crosssectional view of FIG. 3. Thecrossmember 26 is provided with a central opening at 36 of diameter to accommodate the rod 34 with a sliding fit and by which the rod is kept centered, at least at its upper end, within the tube 14. At its lower end, the actuating member comprises a cam element 40 which is secured, by any convenient means such as by welding or brazing as shown, to the lower end of the actuating rod. The cam 40 cooperates with cam surfaces formed on and presented to the cam by the biasing means or the clamp elements. Advantageously, the clamp elements are integrally formed with the biasing means, each clamp element and its biasing means or spring comprising an L-shaped structure. The lower leg of the L-shaped structure is the clamping member and the other leg of the L-shaped structure is the biasing spring. While other numbers of clamping elements and biasing elements may be employed, this embodiment includes two clamping elements and springs. Thus, it includes two of the L-shaped structures. The lower legs of these structures, the clamping members, are movable toward and away from one another in a plane which is perpendicular or substantially perpendicular to the axis of tube 14 and the line of actuating rod movement The two L-shaped structures are connected at their upper ends to the lower end of tube 14 as previously described and the other arms of the L-shaped structures, here the longer upper arms, extend downwardly substantially in parallel except that in relaxed condition their lower ends, that is the end of the other legs where they are joined to the lower legs of the L-shaped structures, are closer together so that the other arms of the structures are tapered toward one another at a shallow angle. For identification, in FIGS. 3 and 4, the L- shaped structure 42 at the right comprises the spring element 44 and the clamping member 46. The L-shaped structure 48 at the left comprises the spring element 18 and the clamping member 16. The cam 40 fits between the spring members 18 and 44 and is tapered over a portion of its length at the same shallow angle'on which the spring members are arranged in relaxed condition. As the cam 40 is pushed down the angle between the spring members becomes more and more shallow. In the preferred form the sides of the cam 40 are rounded sufficiently so that there is engagement between the face of the cam and the surface of the over a substantial length of the surfaces at the inner side of springs 18 and 44 regardless of cam position. In FIG. 4, the cam 40 is shown in fully actuated position down toward the lower arms 16 and 46 of the L-shaped structures in which position the cam has effectively forced the arms or clamp elements 16 and 46 apart. Thus, the effect of actuation of the cam is apparent by comparing FIGS. 3 and 4. The cam, of course, can have other configurations but advantageously it is arranged so that in any position a significant area of its surface as distinguished from a line along its surface, is made to contact the spring elements 18 and 44. Moreover, the springs are arranged at an initial shallow angle so that the forces applied by the cam to those springs are applied at a wide angle. This arrangement insures sufficient frictional engagement between the cam and the cam surfaces of springs 18 and 44 so that the cam and the springs will remain in the relative position in which they have been placed by the actuation of the knurled knob 32 relative to the tube 14. Thus arranged, the position of the cam relative to the springs is maintained by frictional forces even against the bias of the springs 18 and 44 which tend to force the cam 40 in an upward direction thereby releasing the clamping elements 16 and 46. Because of the configuration described, which provides for a high degree of friction, the cam will remain in the position in which it is forced by pushing on the knurled knob 32 and it is unnecessary to maintain that force in order to maintain clamping pressure.

in operation of the tool it is necessary only to ensure that the cam 40 is retracted sufficiently to permit the springs 18 and 44 to move the clamp elements 16 and 46 together in a degree that permits their insertion together within the element to be clamped. The clamp elements having been inserted into the structure to be clamped, the tool user grasps the upper end of the tool and forces the knurled knob 32 toward the crossmember 26. This is conveniently done by placing the thumb of the hand which is to hold the tool against the upper face of the knurled knob and by placing the index and middle fingers of that hand beneath the two side extensions 28 and 30 of the crossmember 26. The cam is actuated by squeezing the fingers together. Means are incorporated by which the degree of motion of the cam is limited. Advantageously this means comprises a stop 50 carried by the rod at a point above the crossmember 26 such that the stop limits the degree in which the rod may be moved relative to the clamp elements. Lest the cam become dislodged from the clampingelements, means are included which confine the rod to axial movement relative to the tube. This means here comprises a sleeve 52 which has outside diameter to fit tightly within the tube 14 and inside diameter to guide, but not retain, axial movement of the rod 34.

Although we have shown and described certain specific embodiments of our invention, we are fully aware that many modifications thereof are possible. Our invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

We claim:

1. A clamping tool comprising in combination:

a plurality of clamp elements movable in a plane toward and away from one another;

means biasing said elements to predetermined distance from one another in that plane;

interconnection means connected to each of said clamp elements for moving them together without change in their relative position;

actuation means carried by said interconnection means for altering the position of the said elements relative to one another in said plane as a function of the degree of relative movement between said actuation means and said interconnection means and as an incident to such movement;

in which said interconnection means comprises an elongate tube;

in which said clamp elements comprise a pair of L-shaped metal strips the lower legs of which extend in opposite directions and the other legs of which are welded at their upper end regions to a lower end region of said tube and are resilient and comprise said biasing means;

said clamp elements, when relaxed, extending from their connection with said tube such that their other legs converge toward one another at their juncture with said lower legs and are capable of being forced, against said bias, to a position in which they extend substantially in parallel over a portion of their length; and

in which said actuation means comprises a pushrod slidably mounted axially within said tube and having an upper end extending from the upper end of the tube and a lower end extending from the lower end of the tube, a knob fixed to the upper end of the pushrod, and a cam carried by the lower end of the pushrod and disposed between said clamping elements, said cam comprising a camming surface over a portion of its length which is engageable with surfaces of said clamping elements as an incident to relative movement between them occasioned by axial movement of the pushrod relative to the tube, the camming surface being tapered from its upper to its lower end in a degree which increases toward its lower end, the width of said camming surface toward its upper end being opposite said cam. v

3. The invention defined in claim 2 which further comprises means carried by said pushrod for limiting relative motion between the pushrod and the tube such that said cam is confined to movement in the region between said clamping elements and such that said cam is movable to a point at which said clamping elements are forced apart a distance corresponding to the maximum width of said cam.

v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 Dated pr 13 1971 Inventor) Robert M. Ocheltree et :11.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet I72] "Jack L. Thompson" should read Jack L. Thomson Signed and sealed this 11th day of April 1972 (SEAL) Attest:


Commissioner of Paten Attesting Officer

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U.S. Classification294/94
International ClassificationB25B9/00
Cooperative ClassificationB25B9/00
European ClassificationB25B9/00