Patent Publication Number: US-4258908-A

Title: Chela-form clamp

Description:
FIELD OF THE INVENTION AND PRIOR ART 
     The invention relates to improvements in a chela-form clamp, particularly of the kind which comprises an L-shaped member having a short leg and a long leg joined by a knee, a second L-shaped member having a short leg and a leg of intermediate length also joined by a knee, in which the leg of intermediate length is journaled in the mid-portion of the long leg, and in which the L-shaped legs comprise spaced-apart complementary members joined together by spacers, apposed clamping faces at the ends of the short legs, a first block journaled in the complementary members at the knee of the second L-shaped leg, a second block journaled in the complementary members at the end of the long leg, an elongate member passing through the second block and having a thrust connection with the first block, and thread means operative when the elongate member is turned to exert thrust on the first block and to force the first and second blocks apart, in order to bring the clamping faces closer together or to exert pressure on the clamping faces when they are already as close together as possible. 
     Clamps of the character described are known in the art. In one, the thread means is of the quick-release type whereby the elongate member can be rapidly moved to set the clamping faces in clamping position and then turned to generate the thrust necessary to effect the desired clamping operation. In the devices heretofore available, considerable difficulty has been encountered in obtaining the desired pressure on the clamping faces because the angle of thrust is such that an excessive degree of friction is engendered between the thrust end of the elongate member and the thrust block. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide an improved chela-form clamp. It is a further object of the invention to provide an improved chela-form clamp in which relatively high pressures can be applied to the clamping faces without engendering excessive friction in the elongate member. It is a further object of the invention to avoid the disadvantages of the prior art and to obtain the advantages as will appear as the description proceeds. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The invention relates to improvements in a chela-form clamp of the class above-described, characterized by a radial bore in the first block adapted to receive the thrust end of the elongate member, by the radial bore having a conical bottom, by a steel ball in the bore having circle contact with the conical bottom thereof, by the thrust end of the elongate member having an axial conical depression therein having circle contact with the ball, and by means for rotatably anchoring the thrust end in the axial bore. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a side elevation. 
     FIG. 2 is a section taken along lines 2--2 of FIG. 1. 
     FIG. 3 is a section taken along lines 3--3 of FIG. 2. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 there is shown a chela-form clamp having L-shaped member 10 having a short leg 12 and a long leg 14 joined by a knee 16, a second L-shaped member 18, having a short leg 20 and a leg of intermediate length 22 and a knee 24. The leg of intermediate length 22 is journaled at 26 near the middle of the long leg 14. 
     Each of the L-shaped members is made of two spaced-apart complementary pieces fastened together by spacers 28. At the end of the short legs 12 and 20 are journaled blocks 30 and 32 which also serve as spacers for the complementary members and as clamping faces. 
     Journaled between the complementary members at the knee 24 is a block 34 which is generally cylindrical in shape and has axial trunnions 36 journaled in the complementary members of the knee 24, as shown in in FIG. 2. Also, at the end of the long leg is a second block 38 jounaled there by trunnions 40. 
     Passing through the second block 38 is an elongate member 42 having a thrust end 44 disposed in an axial bore 46 in the first block 34. A quick-release thread is provided in the block 38 so that, when the handle 48 is turned clockwise, a thrust is exerted on block 34 and blocks 34 and 38 are spread apart and clamping faces 30 and 32 are brought into clamping position. 
     The bottom of the bore 46 is conical in shape, as shown at 50, and the thrust end 44 of elongate member 42 has a complementary conical depression 52. A steel ball 54 is seated in the bottom of the bore 46 and has circle contact with the conical bottom 50 of the bore and circle contact with the conical depression 52 in the thrust end 44 of the elongate member 42. Thus, when a thrust is put on the elongate member 42, the circle-circle contact on the steel ball 54 relieves the friction so that a great deal of pressure can be put on the clamping faces 30 and 32. 
     The thrust end 44 has a circumferential groove 56 to accomodate the key 58 to rotatably hold the thrust end 44 of the elongate member 42 and the bore 46. 
     The conical surfaces at 50 and 52 can, if desired, be case hardened or otherwise hardened to enhance the anti-friction effect. 
     It is to be understood that the invention is not to be limited to the exact details of operation or structure shown and described, as obvious modifications and equivalents will be apparent to one skilled in the art.