Third Inversion:

This inversion is attained by fixing link 3. Some of the applications of this inversion are oscillating cylinder engine & crank and slotted lever rapid return motion mechanism of a shaper machine. Link 1 act as a slider that slides in slotted or cylindrical link 4. Link 2 acts as a crank. The oscillating cylinder engine is illustrated in fig (a)

   (a) Oscillating Cylinder Engine

  (b) Crank and Slotted Lever Mechanism

The motion of link 4 in crank & slotted lever rapid return motion mechanism may be taped by link 5 and may be transferred to ram. O₂A₁ & O₂A₂ are two positions of crank while link 4 shall be tangential to the crank circle and equivalent to that ram will have upmost positions. While crank travels from position O₂A₁ & O₂A₂ forward stroke occurs. While crank moves again from position O₂A₂ to O₂A₁ return stroke takes place. Thus, for constant angular velocity for crank 'ω'.