Theory of Machine
Oldham’s coupling is an inversion of the kinematic chain used in

Rotary engine
Universal joint
Whitworth quick return mechanism
Elliptical trammels

ANSWER DOWNLOAD EXAMIANS APP

Theory of Machine
The relation l = (2/3).(j + 2) apply only to kinematic chains in which lower pairs are used. This may be used to kinematic chains in which higher pairs are used, but each higher pair may be taken as equivalent to

Any one of these
Two lower pairs and one additional link
One lower pair and two additional links
Two lower pairs and two additional links

ANSWER DOWNLOAD EXAMIANS APP