Forth inversion of Single Slider crank chain :
Crank and slotted lever quick return Mechanism (Crank and Rocker(lever) Mechanism)
This mechanism is mostly used in shaping machines, slotting machine and in rotary Internal Combustion Engine.
In this mechanism link AC (i.e. link 3) forming the turning pair is fixed, as shown fig. the link 3 corresponding to the connecting rod of a reciprocating steam engine.
The driving crank CB revolves with uniform angular speed about the fixed center C.
A sliding block attended to the crank pin at B slide along the slotted bar AP and thus causes AP to oscillate about the pivoted point A.
A short link PR transmits the motion from AP to the ram which carries the tool and reciprocate along the line of stroke.
The forward and cutting stroke occur when the crank rotates the position through angle β in clockwise direction.
The return stroke occur when the crank rotates through angle α in the clockwise direction crank has uniform angular speed.
Time of Cutting Stroke / Time of return = β/α
stroke = 3
Fifth inversion of Single Slider crank chain :
Whitworth Quick return motion Mechanism (Double Crank Mechanism).
This mechanism is mostly used in planer and slotter machines.
In this mechanism, the link CD (link 2) forming the turning pair is fixed, as shown in fig. The link 2 corresponds to a crank in a reciprocating steam engine.
The driving crank CA (link 3) rotates at uniform angular speed. The slider (link 4) attached to the crank pin at A slides along the slotted bar PA (link 1) which oscillate at a pivoted point D.
The connecting rod PR carries the ram at R to which a cutting tool is fixed. When the driving crank CA moves from the position CA1 to CA2 through an angle α in the clockwise direction, the tool moves from the left hand end of its stroke to the right hand end through a distance 2 PD.
Now when the driving crank moves from the position CA2 to CA1 through an angle β in the clockwise direction. The tool moves back from right hand end of its stoke to the left hand end.
Time of Cutting Stroke / Time of return stroke = α/β =
360 - α
360 - β = α
*It has two sliding and two turning pair.
