Mono-cable logging system with intermediate tension control : computer simulation

Abstract

A cooperative research project with the USDA-Forest Service has shown the need for a mono-cable logging system with intermediate tension control as an alternative to road construction in the logging area. Intermediate control sheaves will be required to maintain optimum tension throughout long distances and large elevation changes. Preliminary designs have shown the need to model the system to demonstrate the system's feasability. A series of FORTRAN programs were written to simulate this system, building first upon single span solutions, with the eventual program including the capability of simulating the changes in tension of a system of up to 100 connected spans with as many as 200 loads traversing the system. The individual sheaves along the system path can be modeled as either control or idler sheaves. The solution of the necessary equations required the use of iterative solutions. Comparison was made of the Newton-Raphson method and Brown's method for the solution of a set of two non-linear equations with two unknowns. The model satisfies the simulation needs of the system. It allows the monitoring of tension, differential tension across sheaves, and changes in cable length required within each span. The program showed the feasibility of the system and gives direction for future modifications of the model to more closely simulate the actual situation. The program will provide a solid foundation for current and future work in this area and shows a valid procedure for future modeling.