Question

coupling rod of a locomotive double crank mechanism

Answer 1

mechanism) which consists of four links in the fig. in this mechanism, the links AD and BC (having equal length) act as cranks and are connected to the respective wheels. The link CD acts as a coupling rod and the link AB is fixed in order to maintain a constant centre to centre distance between them. This mechanism is meant for transmitting rotary motion from one wheel to the other wheel. Fig.1.26 Double rocker mechanism.In this mechanism, link 4 is fixed. Link 2 makes complete rotation, whereas links 3 & 4 oscillate (Fig.1.23d) Coupler Curves:The link connecting the driving crank with the follower crank in a four bar linkage is called the coupler. Similarly, in the case of a single slider crank mechanism the connecting rod is the coupler. During the motion of the mechanism any point attached to the coupler generates some path with respect to the fixed link. This path is called the coupler curve. The point, which generates the path is variously called the coupler point, trace point, tracing point, or tracer point. An example of the coupler curves generated by different coupler points is given in figure below. Mechanisms can be designed to generate any curve.