The necessity of transmitting the rotation motion between two shafts is commonly met in mechanical engineering. The most frequent solutions are represented mechanical systems known as couplings. The coupling solutions presented in literature depend on two main features: the relative position between the shafts and the variation of the transmission ratio. One of the most popular couplings is the Cardanic joint meant to transmit motion between intersecting axes. From technological point of view, to obtain the concurrence of all axes of the joints of the coupling it is a very difficult task. To overcome this aspect, it is assumed that the axes of the shafts are not intersecting and from the four joints of the Cardanic coupling, only the input joint remains a rotation one; the other three joints transform into cylindrical joints and thus allow for relative linear displacement of the elements besides rotation. In this manner, the new mechanism is a RCCC one. The paper presents the positional analysis of the mechanism applying the method of homogenous operators proposed by Hartenberg and Denavit. The analytical expressions of all displacements from the joints of the mechanism are obtained. The aspects referring to the obscurity occurring when inverse trigonometric functions are involved in describing the displacements and the way to avoid these are discussed.
展开▼
