Mechanical Engineering - Theory of machines - Discussion

With-worth quick return motion mechanism is a inversion of simple single slider mechanism with lower pair when we fixed the shortest link which is known as crank.

Because in single slider mechanism inversion there are two mechanism is possible when we fixed the crank one is with-worth QRMM and second one is rotary IC engine (GNOME engine).

Therefore according to the question given answer is wrong and correct answer is when shortest link is fixed.

Whitworth quick return motion is a 4 bar mechanism i.e. crank, slider, coupler, slotted bar. In this mechanism slider can slides into the slotted bar while the crank makes 360" rotation.

So, here the crank (input rotation) is not fixed as well as slider (slides) and slotted bar (oscillates) also not fixed because these are all having motions with respect to each other therefore the only link we must fix to rotate crank 360" is coupler.

I think answer given is wrong. In slider crank chain there is no coupling rod it is called as connecting rod. When connecting rod fixed we get crank and slotted lever mechanism. Whitworth return motion mechanism is formed when crank or smallest links fixed. So answer is [d].

Its correct what @Rahul said. Whitworth quick return mechanism is the 2nd inversion of slider crank mechanism. So, in 2nd inversion fixed link is the crank which is the smallest link in the mechanism.

No, the answer is wrong. When we fix coupler then it is slotted & crank mechanism so, the 2nd inversion of single slider MSM is quick return MSM and it is done by fixing the shortest link.

By fixing the crank/ smallest link Whitworth's quick return mechanism is obtained and by fixing the coupler/connecting rod slotted lever quick return mechanism is obtained.

D is the right answer, because Whitworth quick return mechanism is obtained when the crank is fixed and the crank is the smallest link also, So, D will be the right answer.

Right answer D.

Because QRM is 2nd inversion in slider crank mechanism. And this is double crank machine. This is find only when shortest link (crank) is fixed.

In whitworth quick return motion mechanism crank(smallest link) is fixed. In Crank slotted lever mechanism Coupler link is fixed. So The ANSWER given is WRONG.

D is the right answer because when fix the smallest link, obtain double crank mechanism and With-worth quick is the double crank mechanism.