Generalized transmission index and transmission quality for spatial linkages

Railroad crossings represent a significant danger in railroad transportation systems. Each year thousands of accidents occur that involve trains and other vehicles at unprotected railroad crossings, resulting in hundreds of fatalities and injuries. Additionally, derailments occur on average once every 6 h across the United States due to mechanical failures and improperly maintained track, endangering property and lives. The lack of electrical infrastructure in remote areas is a primary barrier impeding the installation of safety enhancements such as warning light systems and track health monitoring sensors that could reduce the frequency of such accidents. Providing on-demand power by harvesting energy from deflecting railroad track during the passage of trains is a promising approach compared with the cost of installing electrical power lines or the lack of robust solar and/or wind power solutions. This paper discusses the design and development of several power harvesting devices capable of scavenging p...

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Power harvesting systems design for railroad safety

Synthesis of indexing mechanisms with non-circular gears

The main objective of this work is to present a computational approach for design optimization of disc cam mechanisms with eccentric translating roller followers For this purpose, the objective function defined here takes into account the three major parameters that influence the final cam size, namely the base circle radius of the cam, the radius of the roller and the offset of the follower Furthermore, geometric constraints related to the maximum pressure angle and minimum radius of curvature are included to ensure good working conditions of the system Finally, an application example is presented and used to discuss the main assumptions and procedure adopted throughout this work

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A Computational Approach for Cam Size Optimization of Disc Cam-Follower Mechanisms With Translating Roller Followers

The planetary indexing cam mechanism is a type of indexing cam mechanism that employs planetary transmission structure. The mechanism is unusual compared to other planar cam mechanisms for the self-intersection occurs inevitably on the pitch curve of the cam. This results in the loss of contacts between a few rollers and cam profile. This paper investigates the effects of such loss of contacts on the transmission by analyzing the meshing procedure of the mechanism. The number of the self-intersection points on the pitch curve is determined in terms of the rotary index of the continuous curve. The meshing procedure is analyzed in detail and the pressure angles are calculated. The effects of the design parameters on the meshing status are studied and illustrated. At the end, it is pointed out that loss of contacts will not hamper the rightness of motion transfer in the mechanism if the design parameters are well selected.

Meshing Analysis of the Planetary Indexing Cam Mechanisms

A new approach, called a Relative Motion Method (RMM), is proposed for designing the shape of the disk cam, which uses the relative velocity and the relative acceleration of a follower respect to a cam to discover the profile coordinate, the pressure angle and the radius of curvature on the cam. It is characterized by the procedures of automatic derivation and solution with computers and the suitability not only for general disk cams with different kinds of follower, such as sharp edge follower, roller follower flat-faced follower, and so on, but also for the double-disk conjugate cams, single-disk conjugate cams and roller gear conjugate cams. A program for design automation of shape of the disk cam and the kinematics simulation of this kind of mechanism has been developed using the proposed approach with C++ language. Finally, an example is given.

Yuhua Zhang

Papers

A Computational Approach to Profile Generation of Planar Cam Mechanisms