Quick-Return Mechanism Revisited

In this paper, the teaching and learning experiences of the author with two summer interns at one of the educational institutions in India is presented. These are the senior mechanical engineering students from two different engineering colleges in India who spent nearly two months at the institute where the author spent a 3-month sabbatical as a visiting faculty. Although these two students took the "Theory of Machines" course at their college, a complete understanding of kinematic and dynamic analyses of mechanisms such as a quick-return linkage seemed to be not realized well by them. In addition to the students from India, there are other mechanical engineering students who were taking a Design and Analysis of Mechanical Systems and Assemblies course as a directed study. The students were taught the basics of loop-closure equations pertaining to the kinematic and dynamic analysis of an example quick-return and other planar mechanisms. All these students developed an Excel based program to perform calculations and plot the various characteristics such as variation of quick return ratio as a function of the critical link lengths, kinematic and dynamic characteristics of the linkage. Studies related to partially balance the system are also under way, mostly using a CAE tool. The students modeled the linkage using the motion simulation application that is commonly available in any CAE tool such as Catia, UG-NX, NX I-DEAS, or SolidWorks. Other math tools such as MatLab Simulink, MapleSim, etc., are also available to study planar mechanism kinematics. Finally, the students in India used the available laboratory experimental apparatus to verify some of the theoretical calculations. The performance metric is a final report that included the learning outcomes and recommendations for further work.