Clamping device

In a pressing apparatus which includes a fixed member, a movable member, a threaded shaft passing through the fixed and movable members for moving the movable member with respect to the fixed member for pressing an object between the fixed and movable members, and a handle for turning the threaded shaft, the improvement comprising:

• a pressing head located on the threaded shaft, said pressing head having an outer diameter greater than the diameter of the threaded portion of the threaded shaft and said pressing head having external threads, said head threads being finer threads than the threads of the threaded shaft,
• a pressing cap having internal threads complementary with said external threads of said pressing head for engaging said head threads, whereby said pressing cap is capable of exerting stronger pressing power upon the object between the fixed and movable members after the threaded shaft has moved the movable member so that the object is pressed between the fixed and movable members,
• the movable member includes a nonthreaded opening through which a portion of the threaded shaft passes and in which the threaded shaft turns freely, and
• the fixed member includes a threaded hole whose threads engage the threads of the threaded shaft, whereby, by turning the threaded shaft in a predetermined tightening direction, the threaded shaft forces the movable member toward the fixed member until the movable member presses the object between the movable and fixed members,
• one end of the threaded shaft includes a relatively small bolt head formation for receiving one end of a two-ended handle,
• the outer surface of the pressing cap includes a fitting for a relatively large socket located on the other end of the handle, said socket capable of being turned to exert the stronger pressing power after the threaded shaft has moved the movable member to press the object between the fixed and movable members, further including loosening pin means for moving the movable member away from the fixed member when the threaded shaft is turned in a predetermined loosening direction, said loosening means being spaced from the fixed member thereby permitting said loosening means to move when the threaded shaft is tightly pressing said pressing cap.