First inversion of Double slider crank chain:
Elliptical Trammel
It is an instrument used for drawing ellipses. This inversion is obtained by fixing the slotted plate (link 4), as shown in Fig.
The fixed plate or link 4 has two straight grooves cut in it, at right angles to each other.
The link 1 and link 3, are known as sliders and form sliding pairs with link 4. The link AB (link 2) is a bar which forms turning pair with links land 3.
When the links 1 and 3 slide along their respective grooves, any point on the link 2 such as P traces out an ellipse on the surface of link 4, as shown in Fig.
A little consideration will show that AP and BP are the semi-major axis and semi- minor axis of the ellipse respectively.
Second inversion of Double slider crank chain :
Scotch Yoke Mechanism
The Scotch yoke is a mechanism for converting the linear motion of a slider into rotational motion or vice-versa. The piston or other reciprocating part is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part.
This mechanism is used for converting rotary motion into a reciprocating In Fig. motion. The inversion is obtained by fixing either the link 1 or link 3.
link 1 is fixed.
In this mechanism, when the link 2 (which corresponds to crank) rotates about B as centre, the link 4 (which to a frame) corresponds reciprocates.
The fixed link 1 guides the frame.
