Patent ID: 7454837

Claim:
A pair of effort-saving shears primarily comprising: a first shear element having a first blade portion at one end, a combining portion at the opposite end comprising a pivot hole and a shear element combining hole, and a first handle further attached to the first shear element; a second shear element having a second blade portion at one end, and a combining portion at the opposite end comprising a shear element combining hole; a handle shaft axially positioned in a second handle having a pivot hole and having a combining portion at one end; an effort-saving transmission assembly including a toothed block fixed on one side of the combining portion of the second shear element, the toothed block having two side walls, and a toothed hole having at least two side walls provided on the combining portion of the second shear element, wherein the toothed hole and toothed block each have a tooth respectively, and wherein the combining portion of the second shear element overlaps the combining portion of the handle shaft to make the toothed hole enclose and partially engage the toothed block by parts of the teeth thereof, while the combining portion of the first shear element overlaps the combining portion of the second shear element; a pivot member, piercing through the pivot holes of the first shear element and the handle shaft to be placed between the toothed hole and the toothed block far from said teeth; and a shear element combining pin piercing through the shear element combining holes of the first and second shear elements wherein, the at least two sidewalls of the toothed hole adjacent to said tooth of the toothed hole are a first retaining edge and a second retaining edge while the two sidewalls of the toothed block adjacent to said tooth of the toothed block are a first block edge and a second block edge so that when the first and second shear elements are opened at a predetermined angle, the second block edge of the toothed block presses on the second retaining edge of the toothed hole; when the first and second shear elements are closed, the first block edge of the toothed block presses on the first retaining edge of the toothed hole wherein, a first positioning recess, and a second positioning recess are provided at one side of the toothed hole opposite from the tooth; and a recess is provided on the toothed block at the side far from the tooth; so that when the first and second shear elements are opened at a predetermined angle, the pivot member is held between the recess and second positioning recess; when the first and second shear elements are closed, the pivot member is held between the recess and first positioning recess.