US 3249351 A
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Description (OCR text may contain errors)
y 3, 1966 w. A. SMITH 3,249,351
CLAMP Filed Dec. 26, 1961 2 Sheets-Sheet l INVENTOR. Wilfred A. Smith gym/m W. A. SMITH May 3, 1966 CLAMP 2 Sheets-Sheet 2 Filed Dec. 26. 1961 Fig.4b
INVENTOR. Wilfred A. Smith United States Patent 3,249,351 CLAMP Wilfred A. Smith, La Honda, Calif. (1102 Vera Ave., Redwood City, Calif.) Filed Dec. 26, 1961, Ser. No. 161,978 4 Claims. (Cl. 269-236) This invention relates to a clamping device and more particularly to a cam operated clamp.
- Cam operated clamps have long been used in'a variety of applications. In most cases these prior art cam operated clamps in tightening the jaws of the clamp put an unusually high shearing force on the pin or other support member for the movable part of the clamp. Inasmuch as the pivotal supports for the clamp ja-w that is moved to clamp an article between the jaws of the clamp is ordinarily a rather light weight and small diameter member, in many cases the shear forcesare sufficiently great to break the pivotal support. Efforts to strengthen this point of weakness have not in the past been entirely saitsfactory because in enlarging the cross sectional area of the member the resulting clamp is bulky, unduly clumsy and in many cases hard to operate.
The present invention overcomes these deficiencies in prior art cam operating clamps by eliminating the use of the pivotal support member as a stress bearing member during and after the clamp is closed. Basically the present invention includes a pivotally supported jaw on one end .of the clamp and a cam lever cooperating therewith which acts to move the jaw closer to the fixed or opposite end of the clamp by hearing against cam surfaces on the frame of the clamp and on the movable jaw so that, as a result, the forces exerted on the frame of the clamp act directly through the cam rather than by way of the pivotal jaw support.
Therefore, the principal object of this invention is to provide a ca m actuated clamp wherein the support member for the movable jaw is not placed under stress as the clamp is closed.
Another object of the invention is to provide a cam actuated clamp having the above described characteristics which is economical to manufacture and simple to use.
Features of the invention generally pertain to various embodiments by which the principle of camming the movable jaw into a closed position between the jaw or the work piece and the frame itself is operative, which operation avoids stressing the member that pivotally connects the movable jaw and theframe of the clamp.
In one feature of the invention, the movable jaw is a I flat plate pivotally supported with two degrees of freedom in :a pair of vertical slots at one end of the clamp frame in such a way that the cam carried by the lever or operating arm acts to move the jaw plate away from the frame and toward the other jaw as the clamp is closed.
In another exemplary embodiment of the invention, the lever is loosely, pivotally supported at one end of the frame and the cam carried by it acts to pull the clamp tight by forcing the frame outwardly away from one side of the work surface of the board or other member to be clamped between the jaws of the clamp as the fixed jaw grips the opposite side of the work piece. That is to say, the lever and cam carried by it act as the movable jaw so that a finm grip on a piece of lumber or other material is obtained without having a separate jaw and lever as is the case in the first mentioned embodiment.
These and other objects, advantages and features of the invention may be more clearly understood when the following detailed description is read with reference to the drawings, in which:
'FIG. 1 is an end elevational view of one embodiment of the clamp taken shbstantially on line 1-1 of FIG. 3
3,249,351 Patented May 3, 1966 FIG. 2a is a side view of a first embodiment of the I present invention with the clamp in the open position;
FIG. 2b is a side view of the first embodiment of the present invention with the clamp in the closed position;
FIG. 3 is a plan view of the first embodiment of the invention of FIGS. 2a and 2b;
FIG. 4a is a side view of a second embodiment of the present invention with the clamp in the open position;
FIG. 4b is a side view of a second embodiment of the present invention with the clamp in the closed position; and
FIG. 5 is a plan view of the second embodiment of the invention of FIGS. 4a and 4b.
For purposes of convenience and clarity of understanding the use of the present clamp will be described in particular reference to the clamping of wood members, particularly for example 2 x 4s, as they may be used in the construction of concrete pouring forms and the like. Thus, for example, the embodiment of the clamp of FIGS. 1-3 is shown in reference to clamping pairs of 2 x 4s 10 in spaced parallel arrangement as may be desirable to do in clamping horizontal 2 x 4'5, known as Whalers, exteriorly of concrete form structures (not shown). However, it is understood that the scope of the invention is in no way limited to any particular use or uses to which it may be put, and obviously, many other uses for a clamp embodying the invention can be envisioned. I
The first embodiment of the invention, 11 is illustrated in detail in FIGS. 2 and 3. The clamp includes a C-shaped frame 21 having an elongate leg 22 on its lower end and a transverse cross piece 23 welded or otherwise affixed to its end and lying in a plane transverse to the plane of leg 22. The other end of the frame 21 has a shoulder 24, with a circular aperture 25 formed therein. The lever 26 carrying a cam 27 is pivotally supported through apertures 25 by a pin 28, the diameter of which is smaller than the apertures 25. This assures a loose fit between the pin 28 and the sides defining the apertures 25 which leaves a limited t-wo degree of freedom structure in respect to lever 26 and integral cam 27, i.e. there may occur rotational movement and a limited amount of movement due to the diameter of pin 28, which carries lever 26 and cam 27, being less than the diameter of the supporting apertures 25.
In order to close the clamp illustrated in FIGS. 2 and 3, the lever 26 is moved downwardly in the direction of the arrow to the position illustrated in FIG. 2b and the cam 27 bears against the inside surface 29 of the frame 21 and against the top part of the clamped member 31 illustrated by dotted lines in the FIGS. 2a and 212. It will be noted that the upper part 32 of the cam 27 is formed to cooperate with interior surfaces 29 of the frame so as to not only cam against that surface as its lower end or movable jaw portion 33 cams against the upper surface of the work piece 31 but it also provides a locking function (particularly seen in FIG. 2b) after the lever 26 is fully closed. Furthermore, the lever 26 rests against the work member 31 in the closed position to stabilize the clamp and work pieces with which it cooperates.
More particularly, as can be seen in FIG. 3, in order to utilize the clamp 11 forming the first embodiment of the present invention, the transverse member 23 attached to the outward free end of leg 22 is disposed between a pair of 2 x 4s, for example, and at right angles to the longitudinal axes with the upright part 21a of the frame 21 lying in between the 2 x 4s. The width of the cam surfaces 27 associated with the lever 26 are sufficiently great to bear against the top parts of the 2x4s 31 thereby providing a firm connection between the parts. Beyond providing this clamping action, the thickness of the upright leg 21a may be varied to provide a predetermined spacing between the members.
It will be observed from FIG. 2b particularly, that when the clamp 11 is closed, the pin 28is not under any stress but is disposed loosely in the apertures 25. As a result of this construction, the pin 28 may be relatively light without affecting the ruggedness of the clamp itself. The p n acts as a retaining member, not a load bearing one.
Turning to the second embodiment of the present invention (illustrated in FIGS. 4 and 5), though the structure is somewhat different the basic operating principle is the same. The second embodiment clamp 12 includes a C-shaped frame 41 having a fixed jaw 4-2 attached to the lower leg of the C and a movable jaw pivotally supported adjacent the other leg of the C-shaped frame 41. More particularly, the movable jaw 43 has a pin 44 fixedly attached through it and oriented at right angle to the plane of the frame 41. The upper leg 45 of the frame 41 comprises a bifurcated fork having vertical slots 46 formed in the tines 47 of the fork. The pin 44 resides in the slots 46 and permits the jaw 43 to move with two degrees of freedom. The lever 48 has a transverse cam member 49 affixed to its lower end which lies under upper leg 45 and upon rotation, as illustrated .by the arrow, cams the movable jaw 43 away from the upper leg 45 (see FIG. 4b).
As the movable jaw 43 is cammed downwardly against the work piece 41 (shown by dotted lines), the pivotal support pin 44 rides downwardly in the slots 46, though even after the clamping action is effected as illustrated in FIG. 4b the .pin 44 is loosely disposed in the slots 46. Here again the pin 44 may be relatively light since the camming action takes place between the jaw 43 and the interior side 51 of the upper leg 45 of the frame 41.
While thev foregoing invention has been described with respect to two exemplary embodiments, it should be apparent to those skilled in the art that other changes and variations in the basic concept can be effected without departing from the spirit and scope of the invention. For this reason the invention should only 'be limited to the extent of the claims.
What is claimed is:
1. A cam actuated clamp to hold boards, braces and the like together comprising, in combination, a C frame having a camming surface on one end, a movable jaw portion mounted at said one end of C frame, a lever pivotally supported at said one end of C frame and having a cam formed thereon for cooperative engagement with said camming surface and urging said movable jaw to its clamping position, pin means operable to pivot said lever thereby forcing and holding said cooperative engagement with said camming surface and placing said movable jaw in its clamping position without stressing the pivotal support for said lever.
2. A cam actuated clamp in accordance with claim 1 wherein said movable jaw portion and cam are integral parts of said lever.
3. A cam actuated clamp in accordance with claim 1 wherein said movable jaw portion is a pivotally supported member and said cam has two cam surfaces which act to increase the spacing between said frame and said member to thereby reduce the opening between the jaws of the clamp as the lever is .moved to a closed position. i
4. A cam actuated clamp comprising, in combination, a C frame having a jaw on one leg and a camming surface on the other leg, a movable ,jaw pivotally supported on said other leg for movement with at least one degree of freedom, and a lever pivotally supported on said frame and having a cam formed on one end operable to engage said cam surface and force said movable jaw away from the frame. while preventing said jaw pivotal support from assuming any sensible part of the load.
References Cited by the Examiner UNITED STATES PATENTS 502,533 8/1893 Scales 269231 X 630,900 8/1899 Kohl 269 231 X 990,517 4/1911 Blodgett 269-231 1,603,191 10/1926 Camblin 269-231 X 2,925,109 2/1960 Walker 269236 X FOREIGN PATENTS 979,161 12/1950 France. 726,000 10/ 1942 Germany.
WILLIAM W. DYER,'JR., Primary Examiner.
THOMAS J. HICKEY, Examiner.
FREDERICK R. HANDREN, Assistant Examiner. 1