This invention is directed to a wrench of the locking type which will grip objects of various sizes and hold these objects without the necessity of the wrench operator constantly applying force to the handles of the wrench. An over-center toggle type linkage is used to hold a lower pivoted jaw relative to an upper fixed jaw.
The primary object of this invention is to provide a wrench that automatically self-adjusts itself to various size objects. The wrench operator does not have to adjust a screw or other adjustment means before gripping an object.
Another object of this invention is to provide a wrench that in addition to self-adjusting to various sizes is also capable of gripping objects with a wide variation in clamping force. The degree of force applied to an object is controlled each time the wrench is closed or used by merely applying pressure on a special force control lever provided on the wrench.
Yet another object of this invention is to provide a wrench that lends itself to one hand operation. In one variation the wrench is provided with a force control lever on the top forward part of the upper handle, where it can be operated with ones thumb, while the wrench handles are closed by using ones hand and fingers. In standard manually adjusted wrenches of this type (A well-known brand or trade name of these standard wrenches is Vice-Grip.), the adjustment screw must be adjusted and often re-adjusted prior to use, and/or the adjustment screw must be turned with one hand while some force is applied to the wrench handles with the other hand to thereby arrive at a reasonable adjustment. In many circumstances (such as when parts must be held) this type of manual adjustment is very difficult or impossible.