designed by ebtx
There are three basic types of pliers. The ones that pinch the workpiece as a function of your hand pressure but not as a function of applied torque (like a pliers or channel lock) ... the ones that pinch the workpiece as a function of torque (pipe wrench) and the ones that don't pinch the workpiece at all but you can still apply torque (like a crescent wrench). This new design is like a combo thingy that can pinch like a pipe wrench in one way, works like a channel lock in another and as a crescent wrench. Well, take a look and see what you think. Has anyone seen this before anywhere? Let me know ... I get a real big kick out of re-inventing centuries old stuff.
Looks pretty old doesn't it?
I've kept it simple so you can see the "work" it performs. The U-clip slides up and down with the lower jaw because it is connected to it via the pivot dowel. This gives the clip-lower jaw some slop so that it can engage the upper jaw handle at various points. Now, the lower jaw touching the upper jaw piece nearest the pivot is the point of interest. There is a bump there where on one side the bump is higher than pivot line B. When in this position (as in the drawing), the jaws are locked and can only be unlocked by pulling open the handles and moving the bump lower than pivot line B.
This looks to be geometrically impossible in the drawing because I've exaggerated the angle through which the bump travels along the upper jaw piece. In actual construction, this angle would be quite small and there would be some slop where the jaw teeth meet. The set screw adjusts the amount of slop available. A tighter set screw would make the jaws harder to lock.
This mechanism is similar to a crescent wrench in that once the jaws are locked, they cannot move further in the lock direction as any more movement would make the piece tighter yet (not shown too well in the drawing). There would be some grinding of the teeth as the bump engages to the lock position (that's OK by me as it will be very little if the angle between lock and unlock is kept small enough.
When the bump is in the unlock position, the plier will act as a pipe wrench because another bump could be employed to engage the upper jaw piece to prevent it from moving beyond a specified angle. Once this angle is obtained, the set screw would engage the back of the upper jaw piece preventing the U-clip from sliding. However, before this happens, a pipe inserted between the jaws will force the set screw to engage the back of the upper jaw piece preventing it from sliding and the force at the set screw will be proportional to the force applied to the pipe as torque ... which means ... it's a pipe wrench too.
You can then slide the U-clip up and down to put the plier to any size workpiece within its range (like a channel lock).